1
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Stewart NK, Toth M, Quan P, Beer M, Buynak JD, Smith CA, Vakulenko SB. Restricted Rotational Flexibility of the C5α-Methyl-Substituted Carbapenem NA-1-157 Leads to Potent Inhibition of the GES-5 Carbapenemase. ACS Infect Dis 2024; 10:1232-1249. [PMID: 38511828 DOI: 10.1021/acsinfecdis.3c00683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
Carbapenem antibiotics are used as a last-resort treatment for infections caused by multidrug-resistant bacteria. The wide spread of carbapenemases in Gram-negative bacteria has severely compromised the utility of these drugs and represents a serious public health threat. To combat carbapenemase-mediated resistance, new antimicrobials and inhibitors of these enzymes are urgently needed. Here, we describe the interaction of the atypically C5α-methyl-substituted carbapenem, NA-1-157, with the GES-5 carbapenemase. MICs of this compound against Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii producing the enzyme were reduced 4-16-fold when compared to MICs of the commercial carbapenems, reaching clinically sensitive breakpoints. When NA-1-157 was combined with meropenem, a strong synergistic effect was observed. Kinetic and ESI-LC/MS studies demonstrated that NA-1-157 is a potent inhibitor of GES-5, with a high inactivation efficiency of (2.9 ± 0.9) × 105 M-1 s-1. Acylation of GES-5 by NA-1-157 was biphasic, with the fast phase completing within seconds, and the slow phase taking several hours and likely proceeding through a reversible tetrahedral intermediate. Deacylation was extremely slow (k3 = (2.4 ± 0.3) × 10-7 s-1), resulting in a residence time of 48 ± 6 days. MD simulation of the GES-5-meropenem and GES-5-NA-1-157 acyl-enzyme complexes revealed that the C5α-methyl group in NA-1-157 sterically restricts rotation of the 6α-hydroxyethyl group preventing ingress of the deacylating water into the vicinity of the scissile bond of the acyl-enzyme intermediate. These data demonstrate that NA-1-157 is a potent irreversible inhibitor of the GES-5 carbapenemase.
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Affiliation(s)
- Nichole K Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Pojun Quan
- Department of Chemistry, Southern Methodist University, Dallas, Texas 75275, United States
| | - Michael Beer
- School of Cellular and Molecular Medicine, University of Bristol, Bristol BS8 1TD, U.K
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
| | - John D Buynak
- Department of Chemistry, Southern Methodist University, Dallas, Texas 75275, United States
| | - Clyde A Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California 94025, United States
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Sergei B Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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2
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Meng Q, Moinuddin SGA, Celoy RM, Smith CA, Young RP, Costa MA, Freeman RA, Fukaya M, Kim DN, Cort JR, Hawes MC, van Etten HD, Pandey P, Chittiboyina AG, Ferreira D, Davin LB, Lewis NG. Dirigent isoflavene-forming PsPTS2: 3D structure, stereochemical, and kinetic characterization comparison with pterocarpan-forming PsPTS1 homolog in pea. J Biol Chem 2024; 300:105647. [PMID: 38219818 PMCID: PMC10882141 DOI: 10.1016/j.jbc.2024.105647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 12/21/2023] [Accepted: 01/05/2024] [Indexed: 01/16/2024] Open
Abstract
Pea phytoalexins (-)-maackiain and (+)-pisatin have opposite C6a/C11a configurations, but biosynthetically how this occurs is unknown. Pea dirigent-protein (DP) PsPTS2 generates 7,2'-dihydroxy-4',5'-methylenedioxyisoflav-3-ene (DMDIF), and stereoselectivity toward four possible 7,2'-dihydroxy-4',5'-methylenedioxyisoflavan-4-ol (DMDI) stereoisomers was investigated. Stereoisomer configurations were determined using NMR spectroscopy, electronic circular dichroism, and molecular orbital analyses. PsPTS2 efficiently converted cis-(3R,4R)-DMDI into DMDIF 20-fold faster than the trans-(3R,4S)-isomer. The 4R-configured substrate's near β-axial OH orientation significantly enhanced its leaving group abilities in generating A-ring mono-quinone methide (QM), whereas 4S-isomer's α-equatorial-OH was a poorer leaving group. Docking simulations indicated that the 4R-configured β-axial OH was closest to Asp51, whereas 4S-isomer's α-equatorial OH was further away. Neither cis-(3S,4S)- nor trans-(3S,4R)-DMDIs were substrates, even with the former having C3/C4 stereochemistry as in (+)-pisatin. PsPTS2 used cis-(3R,4R)-7,2'-dihydroxy-4'-methoxyisoflavan-4-ol [cis-(3R,4R)-DMI] and C3/C4 stereoisomers to give 2',7-dihydroxy-4'-methoxyisoflav-3-ene (DMIF). DP homologs may exist in licorice (Glycyrrhiza pallidiflora) and tree legume Bolusanthus speciosus, as DMIF occurs in both species. PsPTS1 utilized cis-(3R,4R)-DMDI to give (-)-maackiain 2200-fold more efficiently than with cis-(3R,4R)-DMI to give (-)-medicarpin. PsPTS1 also slowly converted trans-(3S,4R)-DMDI into (+)-maackiain, reflecting the better 4R configured OH leaving group. PsPTS2 and PsPTS1 provisionally provide the means to enable differing C6a and C11a configurations in (+)-pisatin and (-)-maackiain, via identical DP-engendered mono-QM bound intermediate generation, which PsPTS2 either re-aromatizes to give DMDIF or PsPTS1 intramolecularly cyclizes to afford (-)-maackiain. Substrate docking simulations using PsPTS2 and PsPTS1 indicate cis-(3R,4R)-DMDI binds in the anti-configuration in PsPTS2 to afford DMDIF, and the syn-configuration in PsPTS1 to give maackiain.
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Affiliation(s)
- Qingyan Meng
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - Syed G A Moinuddin
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - Rhodesia M Celoy
- School of Plant Sciences, University of Arizona, Tucson, Arizona, USA
| | - Clyde A Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California, USA
| | - Robert P Young
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Michael A Costa
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - Rachel A Freeman
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - Masashi Fukaya
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - Doo Nam Kim
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - John R Cort
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA; Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Martha C Hawes
- School of Plant Sciences, University of Arizona, Tucson, Arizona, USA
| | - Hans D van Etten
- School of Plant Sciences, University of Arizona, Tucson, Arizona, USA
| | - Pankaj Pandey
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi, USA
| | - Amar G Chittiboyina
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi, USA
| | - Daneel Ferreira
- National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, Mississippi, USA; Division of Pharmacognosy, Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, Mississippi, USA
| | - Laurence B Davin
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - Norman G Lewis
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA.
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3
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Zhai L, Bonds AC, Smith CA, Oo H, Chou JCC, Welander PV, Dassama LMK. Novel sterol binding domains in bacteria. eLife 2024; 12:RP90696. [PMID: 38329015 PMCID: PMC10942540 DOI: 10.7554/elife.90696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024] Open
Abstract
Sterol lipids are widely present in eukaryotes and play essential roles in signaling and modulating membrane fluidity. Although rare, some bacteria also produce sterols, but their function in bacteria is not known. Moreover, many more species, including pathogens and commensal microbes, acquire or modify sterols from eukaryotic hosts through poorly understood molecular mechanisms. The aerobic methanotroph Methylococcus capsulatus was the first bacterium shown to synthesize sterols, producing a mixture of C-4 methylated sterols that are distinct from those observed in eukaryotes. C-4 methylated sterols are synthesized in the cytosol and localized to the outer membrane, suggesting that a bacterial sterol transport machinery exists. Until now, the identity of such machinery remained a mystery. In this study, we identified three novel proteins that may be the first examples of transporters for bacterial sterol lipids. The proteins, which all belong to well-studied families of bacterial metabolite transporters, are predicted to reside in the inner membrane, periplasm, and outer membrane of M. capsulatus, and may work as a conduit to move modified sterols to the outer membrane. Quantitative analysis of ligand binding revealed their remarkable specificity for 4-methylsterols, and crystallographic structures coupled with docking and molecular dynamics simulations revealed the structural bases for substrate binding by two of the putative transporters. Their striking structural divergence from eukaryotic sterol transporters signals that they form a distinct sterol transport system within the bacterial domain. Finally, bioinformatics revealed the widespread presence of similar transporters in bacterial genomes, including in some pathogens that use host sterol lipids to construct their cell envelopes. The unique folds of these bacterial sterol binding proteins should now guide the discovery of other proteins that handle this essential metabolite.
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Affiliation(s)
- Liting Zhai
- Department of Chemistry and Sarafan ChEM-H, Stanford UniversityStanfordUnited States
| | - Amber C Bonds
- Department of Earth System Science, Stanford UniversityStanfordUnited States
| | - Clyde A Smith
- Department of Chemistry and Stanford Synchrotron Radiation Lightsource, Stanford UniversityStanfordUnited States
| | - Hannah Oo
- Department of Chemistry and Sarafan ChEM-H, Stanford UniversityStanfordUnited States
| | | | - Paula V Welander
- Department of Earth System Science, Stanford UniversityStanfordUnited States
| | - Laura MK Dassama
- Department of Chemistry and Sarafan ChEM-H, Stanford UniversityStanfordUnited States
- Department of Microbiology and Immunology, Stanford University School of MedicineStanfordUnited States
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Smith CA, Stewart NK, Toth M, Quan P, Buynak JD, Vakulenko SB. The C5α-Methyl-Substituted Carbapenem NA-1-157 Exhibits Potent Activity against Klebsiella spp. Isolates Producing OXA-48-Type Carbapenemases. ACS Infect Dis 2023; 9:1123-1136. [PMID: 37130087 PMCID: PMC10722881 DOI: 10.1021/acsinfecdis.3c00059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The wide spread of carbapenem-hydrolyzing β-lactamases in Gram-negative bacteria has diminished the utility of the last-resort carbapenem antibiotics, significantly narrowing the available therapeutic options. In the Enterobacteriaceae family, which includes many important clinical pathogens such as Klebsiella pneumoniae and Escherichia coli, production of class D β-lactamases from the OXA-48-type family constitutes the major mechanism of resistance to carbapenems. To address the public health threat posed by these enzymes, novel, effective therapeutics are urgently needed. Here, we report evaluation of a novel, C5α-methyl-substituted carbapenem, NA-1-157, and show that its MICs against bacteria producing OXA-48-type enzymes were reduced by 4- to 32-fold when compared to meropenem. When combined with commercial carbapenems, the potency of NA-1-157 was further enhanced, resulting in target potentiation concentrations ranging from 0.125 to 2 μg/mL. Kinetic studies demonstrated that the compound is poorly hydrolyzed by OXA-48, with a catalytic efficiency 30- to 50-fold lower than those of imipenem and meropenem. Acylation of OXA-48 by NA-1-157 was severely impaired, with a rate 10,000- to 36,000-fold slower when compared to the commercial carbapenems. Docking, molecular dynamics, and structural studies demonstrated that the presence of the C5α-methyl group in NA-1-157 creates steric clashes within the active site, leading to differences in the position and the hydrogen-bonding pattern of the compound, which are incompatible with efficient acylation. This study demonstrates that NA-1-157 is a promising novel carbapenem for treatment of infections caused by OXA-48-producing bacterial pathogens.
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Affiliation(s)
- Clyde A Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California 94025, United States
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Nichole K Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Pojun Quan
- Department of Chemistry, Southern Methodist University, Dallas, Texas 75275, United States
| | - John D Buynak
- Department of Chemistry, Southern Methodist University, Dallas, Texas 75275, United States
| | - Sergei B Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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5
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Meng Q, Kim SJ, Costa MA, Moinuddin SGA, Celoy RM, Smith CA, Cort JR, Davin LB, Lewis NG. Dirigent protein subfamily function and structure in terrestrial plant phenol metabolism. Methods Enzymol 2023; 683:101-150. [PMID: 37087184 DOI: 10.1016/bs.mie.2023.02.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/24/2023]
Abstract
Aquatic plant transition to land, and subsequent terrestrial plant species diversification, was accompanied by the emergence and massive elaboration of plant phenol chemo-diversity. Concomitantly, dirigent protein (DP) and dirigent-like protein subfamilies, derived from large multigene families, emerged and became extensively diversified. DP biochemical functions as gateway entry points into new and diverse plant phenol skeletal types then markedly expanded. DPs have at least eight non-uniformly distributed subfamilies, with different DP subfamily members of known biochemical/physiological function now implicated as gateway entries to lignan, lignin, aromatic diterpenoid, pterocarpan and isoflavene pathways. While some other DP subfamily members have jacalin domains, both these and indeed the majority of DPs throughout the plant kingdom await discovery of their biochemical roles. Methods and approaches were developed to discover DP biochemical function as gateway entry points to distinct plant phenol skeletal types in land plants. Various DP 3D X-ray structural determinations enabled structure-based comparative sequence analysis and modeling to understand similarities and differences among the different DP subfamilies. We consider that the core DP β-barrel fold and associated characteristics are likely common to all DPs, with several residues conserved and nearly invariant. There is also considerable variation in residue composition and topography of the putative substrate binding pockets, as well as substantial differences in several loops, such as the β1-β2 loop. All DPs likely bind and stabilize quinone methide intermediates, while guiding distinctive regio- and/or stereo-chemical entry into Nature's chemo-diverse land plant phenol metabolic classes.
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Affiliation(s)
- Qingyan Meng
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Sung-Jin Kim
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Michael A Costa
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Syed G A Moinuddin
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Rhodesia M Celoy
- School of Plant Sciences, University of Arizona, Tucson, AZ, United States
| | - Clyde A Smith
- Stanford Synchrotron Radiation Lightsource, Menlo Park, CA, United States
| | - John R Cort
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States; Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Laurence B Davin
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Norman G Lewis
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States.
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6
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Toth M, Stewart NK, Smith CA, Lee M, Vakulenko SB. The l,d-Transpeptidase Ldt Ab from Acinetobacter baumannii Is Poorly Inhibited by Carbapenems and Has a Unique Structural Architecture. ACS Infect Dis 2022; 8:1948-1961. [PMID: 35973205 PMCID: PMC9764404 DOI: 10.1021/acsinfecdis.2c00321] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
l,d-Transpeptidases (LDTs) are enzymes that catalyze reactions essential for biogenesis of the bacterial cell wall, including formation of 3-3 cross-linked peptidoglycan. Unlike the historically well-known bacterial transpeptidases, the penicillin-binding proteins (PBPs), LDTs are resistant to inhibition by the majority of β-lactam antibiotics, with the exception of carbapenems and penems, allowing bacteria to survive in the presence of these drugs. Here we report characterization of LdtAb from the clinically important pathogen, Acinetobacter baumannii. We show that A. baumannii survives inactivation of LdtAb alone or in combination with PBP1b or PBP2, while simultaneous inactivation of LdtAb and PBP1a is lethal. Minimal inhibitory concentrations (MICs) of all 13 β-lactam antibiotics tested decreased 2- to 8-fold for the LdtAb deletion mutant, while further decreases were seen for both double mutants, with the largest, synergistic effect observed for the LdtAb + PBP2 deletion mutant. Mass spectrometry experiments showed that LdtAb forms complexes in vitro only with carbapenems. However, the acylation rate of these antibiotics is very slow, with the reaction taking longer than four hours to complete. Our X-ray crystallographic studies revealed that LdtAb has a unique structural architecture and is the only known LDT to have two different peptidoglycan-binding domains.
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Affiliation(s)
- Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Nichole K Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Clyde A Smith
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, Menlo Park, California 94025, United States
| | - Mijoon Lee
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
- Mass Spectrometry and Proteomics Facility, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Sergei B Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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7
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Smith CA, Ebrahimpour A, Novikova L, Farina D, Bailey AO, Russell WK, Jain A, Saltzman AB, Malovannaya A, Prasad BV, Hu L, Ghebre YT. Esomeprazole covalently interacts with the cardiovascular enzyme dimethylarginine dimethylaminohydrolase: Insights into the cardiovascular risk of proton pump inhibitors. Biochim Biophys Acta Gen Subj 2022; 1866:130149. [DOI: 10.1016/j.bbagen.2022.130149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 03/31/2022] [Accepted: 04/07/2022] [Indexed: 11/28/2022]
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8
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Smith CA, Stewart NK, Toth M, Vakulenko SB. Structural and mechanistic studies on carbapenem-hydrolysing class D serine β-lactamases leading to improved inhibitor design. Acta Crystallogr A Found Adv 2021. [DOI: 10.1107/s0108767321095763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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9
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Smith CA. Making sense of SFX data: standards for data and structure validation for a non-standard experiment that has come of age. IUCrJ 2021; 8:482-484. [PMID: 34257999 PMCID: PMC8256701 DOI: 10.1107/s2052252521006552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
SFX diffraction data collection at XFELs is becoming more accessible. To extract the most useful biological information from these non-standard experiments, standards for SFX data analysis and structure validation must be redefined.
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Affiliation(s)
- Clyde A. Smith
- Stanford Synchrotron Radiation Lightsource, and Department of Chemistry, Stanford University, Menlo Park, CA, USA
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10
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Stewart NK, Toth M, Stasyuk A, Vakulenko SB, Smith CA. In Crystallo Time-Resolved Interaction of the Clostridioides difficile CDD-1 enzyme with Avibactam Provides New Insights into the Catalytic Mechanism of Class D β-lactamases. ACS Infect Dis 2021; 7:1765-1776. [PMID: 33908775 PMCID: PMC8808381 DOI: 10.1021/acsinfecdis.1c00094] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Class D β-lactamases have risen to notoriety due to their wide spread in bacterial pathogens, propensity to inactivate clinically important β-lactam antibiotics, and ability to withstand inhibition by the majority of classical β-lactamase inhibitors. Understanding the catalytic mechanism of these enzymes is thus vitally important for the development of novel antibiotics and inhibitors active against infections caused by antibiotic-resistant bacteria. Here we report an in crystallo time-resolved study of the interaction of the class D β-lactamase CDD-1 from Clostridioides difficile with the diazobicyclooctane inhibitor, avibactam. We show that the catalytic carboxylated lysine, a residue that is essential for both acylation and deacylation of β-lactams, is sequestered within an internal sealed pocket of the enzyme. Time-resolved snapshots generated in this study allowed us to observe decarboxylation of the lysine and movement of CO2 and water molecules through a transient channel formed between the lysine pocket and the substrate binding site facilitated by rotation of the side chain of a conserved leucine residue. These studies provide novel insights on avibactam binding to CDD-1 and into the catalytic mechanism of class D β-lactamases in general.
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Affiliation(s)
- Nichole K Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Anastasiya Stasyuk
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California 94025, United States
| | - Sergei B Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Clyde A Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California 94025, United States
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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11
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Abstract
Avibactam is a potent diazobicyclooctane inhibitor of class A and C β-lactamases. The inhibitor also exhibits variable activity against some class D enzymes from Gram-negative bacteria; however, its interaction with recently discovered class D β-lactamases from Gram-positive bacteria has not been studied. Here, we describe microbiological, kinetic, and mass spectrometry studies of the interaction of avibactam with CDD-1, a class D β-lactamase from the clinically important pathogen Clostridioides difficile, and show that avibactam is a potent irreversible mechanism-based inhibitor of the enzyme. X-ray crystallographic studies at three time-points demonstrate the rapid formation of a stable CDD-1-avibactam acyl-enzyme complex and highlight differences in the anchoring of the inhibitor by class D enzymes from Gram-positive and Gram-negative bacteria.
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Affiliation(s)
- Nichole K Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Anastasiya Stasyuk
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California 94025, United States
| | - Mijoon Lee
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Clyde A Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California 94025, United States
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Sergei B Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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12
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Schuller M, Correy GJ, Gahbauer S, Fearon D, Wu T, Díaz RE, Young ID, Carvalho Martins L, Smith DH, Schulze-Gahmen U, Owens TW, Deshpande I, Merz GE, Thwin AC, Biel JT, Peters JK, Moritz M, Herrera N, Kratochvil HT, Aimon A, Bennett JM, Brandao Neto J, Cohen AE, Dias A, Douangamath A, Dunnett L, Fedorov O, Ferla MP, Fuchs MR, Gorrie-Stone TJ, Holton JM, Johnson MG, Krojer T, Meigs G, Powell AJ, Rack JGM, Rangel VL, Russi S, Skyner RE, Smith CA, Soares AS, Wierman JL, Zhu K, O'Brien P, Jura N, Ashworth A, Irwin JJ, Thompson MC, Gestwicki JE, von Delft F, Shoichet BK, Fraser JS, Ahel I. Fragment binding to the Nsp3 macrodomain of SARS-CoV-2 identified through crystallographic screening and computational docking. Sci Adv 2021; 7:eabf8711. [PMID: 33853786 PMCID: PMC8046379 DOI: 10.1126/sciadv.abf8711] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 02/24/2021] [Indexed: 05/19/2023]
Abstract
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) macrodomain within the nonstructural protein 3 counteracts host-mediated antiviral adenosine diphosphate-ribosylation signaling. This enzyme is a promising antiviral target because catalytic mutations render viruses nonpathogenic. Here, we report a massive crystallographic screening and computational docking effort, identifying new chemical matter primarily targeting the active site of the macrodomain. Crystallographic screening of 2533 diverse fragments resulted in 214 unique macrodomain-binders. An additional 60 molecules were selected from docking more than 20 million fragments, of which 20 were crystallographically confirmed. X-ray data collection to ultra-high resolution and at physiological temperature enabled assessment of the conformational heterogeneity around the active site. Several fragment hits were confirmed by solution binding using three biophysical techniques (differential scanning fluorimetry, homogeneous time-resolved fluorescence, and isothermal titration calorimetry). The 234 fragment structures explore a wide range of chemotypes and provide starting points for development of potent SARS-CoV-2 macrodomain inhibitors.
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Affiliation(s)
- Marion Schuller
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Galen J Correy
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA 94158, USA
| | - Stefan Gahbauer
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA 94158, USA
| | - Daren Fearon
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0FA UK
| | - Taiasean Wu
- Institute for Neurodegenerative Disease, University of California San Francisco, San Francisco, CA 94158, USA
- Chemistry and Chemical Biology Graduate Program, University of California San Francisco, San Francisco, CA 94158, USA
| | - Roberto Efraín Díaz
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA 94158, USA
- Tetrad Graduate Program, University of California San Francisco, San Francisco, CA 94158, USA
| | - Iris D Young
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA 94158, USA
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, San Francisco, CA 94158, USA
| | - Luan Carvalho Martins
- Biochemistry Department, Institute for Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Dominique H Smith
- Helen Diller Family Comprehensive Cancer, University of California San Francisco, San Francisco, CA 94158, USA
| | - Ursula Schulze-Gahmen
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, San Francisco, CA 94158, USA
| | - Tristan W Owens
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, San Francisco, CA 94158, USA
| | - Ishan Deshpande
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, San Francisco, CA 94158, USA
| | - Gregory E Merz
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, San Francisco, CA 94158, USA
| | - Aye C Thwin
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, San Francisco, CA 94158, USA
| | - Justin T Biel
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, San Francisco, CA 94158, USA
| | - Jessica K Peters
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, San Francisco, CA 94158, USA
| | - Michelle Moritz
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, San Francisco, CA 94158, USA
| | - Nadia Herrera
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, San Francisco, CA 94158, USA
| | - Huong T Kratochvil
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, San Francisco, CA 94158, USA
| | - Anthony Aimon
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0FA UK
| | - James M Bennett
- Centre for Medicines Discovery, University of Oxford, South Parks Road, Headington OX3 7DQ, UK
| | - Jose Brandao Neto
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0FA UK
| | - Aina E Cohen
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Center, Menlo Park, CA 94025, USA
| | - Alexandre Dias
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0FA UK
| | - Alice Douangamath
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0FA UK
| | - Louise Dunnett
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0FA UK
| | - Oleg Fedorov
- Centre for Medicines Discovery, University of Oxford, South Parks Road, Headington OX3 7DQ, UK
| | - Matteo P Ferla
- Wellcome Centre for Human Genetics, University of Oxford, Old Road Campus, Oxford OX3 7BN, UK
| | - Martin R Fuchs
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Tyler J Gorrie-Stone
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0FA UK
| | - James M Holton
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Center, Menlo Park, CA 94025, USA
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94158, USA
- Department of Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | | | - Tobias Krojer
- Centre for Medicines Discovery, University of Oxford, South Parks Road, Headington OX3 7DQ, UK
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Headington OX3 7DQ, UK
| | - George Meigs
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94158, USA
- Department of Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Ailsa J Powell
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0FA UK
| | | | - Victor L Rangel
- Centre for Medicines Discovery, University of Oxford, South Parks Road, Headington OX3 7DQ, UK
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Headington OX3 7DQ, UK
- School of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, São Paulo, Brazil
| | - Silvia Russi
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Center, Menlo Park, CA 94025, USA
| | - Rachael E Skyner
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0FA UK
| | - Clyde A Smith
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Center, Menlo Park, CA 94025, USA
| | - Alexei S Soares
- Photon Sciences, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Jennifer L Wierman
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Center, Menlo Park, CA 94025, USA
| | - Kang Zhu
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Peter O'Brien
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK
| | - Natalia Jura
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94158, USA
| | - Alan Ashworth
- Helen Diller Family Comprehensive Cancer, University of California San Francisco, San Francisco, CA 94158, USA
| | - John J Irwin
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA 94158, USA
| | - Michael C Thompson
- Department of Chemistry and Biochemistry, University of California Merced, Merced, CA 95343, USA
| | - Jason E Gestwicki
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA 94158, USA
- Institute for Neurodegenerative Disease, University of California San Francisco, San Francisco, CA 94158, USA
| | - Frank von Delft
- Centre for Medicines Discovery, University of Oxford, South Parks Road, Headington OX3 7DQ, UK
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Headington OX3 7DQ, UK
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, UK.
- Department of Biochemistry, University of Johannesburg, Auckland Park 2006, South Africa
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0FA UK
| | - Brian K Shoichet
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA 94158, USA.
| | - James S Fraser
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA 94158, USA.
| | - Ivan Ahel
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
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13
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Terzyan SS, Nguyen LT, Burgett AWG, Heroux A, Smith CA, You Y, Hanigan MH. Crystal structures of glutathione- and inhibitor-bound human GGT1: critical interactions within the cysteinylglycine binding site. J Biol Chem 2021; 296:100066. [PMID: 33187988 PMCID: PMC7949050 DOI: 10.1074/jbc.ra120.016265] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/06/2020] [Accepted: 11/13/2020] [Indexed: 11/06/2022] Open
Abstract
Overexpression of γ-glutamyl transpeptidase (GGT1) has been implicated in an array of human diseases including asthma, reperfusion injury, and cancer. Inhibitors are needed for therapy, but development of potent, specific inhibitors of GGT1 has been hampered by a lack of structural information regarding substrate binding and cleavage. To enhance our understanding of the molecular mechanism of substrate cleavage, we have solved the crystal structures of human GGT1 (hGGT1) with glutathione (a substrate) and a phosphate-glutathione analog (an irreversible inhibitor) bound in the active site. These are the first structures of any eukaryotic GGT with the cysteinylglycine region of the substrate-binding site occupied. These structures and the structure of apo-hGGT reveal movement of amino acid residues within the active site as the substrate binds. Asn-401 and Thr-381 each form hydrogen bonds with two atoms of GSH spanning the γ-glutamyl bond. Three different atoms of hGGT1 interact with the carboxyl oxygen of the cysteine of GSH. Interactions between the enzyme and substrate change as the substrate moves deeper into the active site cleft. The substrate reorients and a new hydrogen bond is formed between the substrate and the oxyanion hole. Thr-381 is locked into a single conformation as an acyl bond forms between the substrate and the enzyme. These data provide insight on a molecular level into the substrate specificity of hGGT1 and provide an explanation for seemingly disparate observations regarding the enzymatic activity of hGGT1 mutants. This knowledge will aid in the design of clinically useful hGGT1 inhibitors.
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Affiliation(s)
- Simon S Terzyan
- Laboratory of Biomolecular Structure and Function, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Luong T Nguyen
- Department of Pharmaceutical Sciences, The State University of New York at Buffalo, Buffalo, New York, USA
| | - Anthony W G Burgett
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Annie Heroux
- Energy Sciences Directorate/Photon Science Division, Brookhaven National Laboratory, Upton, New York, USA
| | - Clyde A Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California, USA
| | - Youngjae You
- Department of Pharmaceutical Sciences, The State University of New York at Buffalo, Buffalo, New York, USA
| | - Marie H Hanigan
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA.
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14
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Schuller M, Correy GJ, Gahbauer S, Fearon D, Wu T, Díaz RE, Young ID, Martins LC, Smith DH, Schulze-Gahmen U, Owens TW, Deshpande I, Merz GE, Thwin AC, Biel JT, Peters JK, Moritz M, Herrera N, Kratochvil HT, Aimon A, Bennett JM, Neto JB, Cohen AE, Dias A, Douangamath A, Dunnett L, Fedorov O, Ferla MP, Fuchs M, Gorrie-Stone TJ, Holton JM, Johnson MG, Krojer T, Meigs G, Powell AJ, Rangel VL, Russi S, Skyner RE, Smith CA, Soares AS, Wierman JL, Zhu K, Jura N, Ashworth A, Irwin J, Thompson MC, Gestwicki JE, von Delft F, Shoichet BK, Fraser JS, Ahel I. Fragment Binding to the Nsp3 Macrodomain of SARS-CoV-2 Identified Through Crystallographic Screening and Computational Docking. bioRxiv 2020:2020.11.24.393405. [PMID: 33269349 PMCID: PMC7709169 DOI: 10.1101/2020.11.24.393405] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The SARS-CoV-2 macrodomain (Mac1) within the non-structural protein 3 (Nsp3) counteracts host-mediated antiviral ADP-ribosylation signalling. This enzyme is a promising antiviral target because catalytic mutations render viruses non-pathogenic. Here, we report a massive crystallographic screening and computational docking effort, identifying new chemical matter primarily targeting the active site of the macrodomain. Crystallographic screening of diverse fragment libraries resulted in 214 unique macrodomain-binding fragments, out of 2,683 screened. An additional 60 molecules were selected from docking over 20 million fragments, of which 20 were crystallographically confirmed. X-ray data collection to ultra-high resolution and at physiological temperature enabled assessment of the conformational heterogeneity around the active site. Several crystallographic and docking fragment hits were validated for solution binding using three biophysical techniques (DSF, HTRF, ITC). Overall, the 234 fragment structures presented explore a wide range of chemotypes and provide starting points for development of potent SARS-CoV-2 macrodomain inhibitors.
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Affiliation(s)
- Marion Schuller
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Galen J. Correy
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, CA, USA
| | - Stefan Gahbauer
- Department of Pharmaceutical Chemistry, University of California San Francisco San Francisco, CA, USA
| | - Daren Fearon
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Taiasean Wu
- Institute for Neurodegenerative Disease, University of California San Francisco, CA, USA
- Chemistry and Chemical Biology Graduate Program, University of California San Francisco, CA, USA
| | - Roberto Efraín Díaz
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, CA, USA
- Tetrad Graduate Program, University of California San Francisco, CA, USA
| | - Iris D. Young
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, CA, USA
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, CA, USA
| | - Luan Carvalho Martins
- Biochemistry Department, Institute for Biological Sciences, Federal University of Minas Gerais. Belo Horizonte, Brazil
| | - Dominique H. Smith
- Helen Diller Family Comprehensive Cancer, University of California San Francisco, CA, USA
| | - Ursula Schulze-Gahmen
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, CA, USA
| | - Tristan W. Owens
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, CA, USA
| | - Ishan Deshpande
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, CA, USA
| | - Gregory E. Merz
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, CA, USA
| | - Aye C. Thwin
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, CA, USA
| | - Justin T. Biel
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, CA, USA
| | - Jessica K. Peters
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, CA, USA
| | - Michelle Moritz
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, CA, USA
| | - Nadia Herrera
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, CA, USA
| | - Huong T. Kratochvil
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, CA, USA
| | - QCRG Structural Biology Consortium
- Quantitative Biosciences Institute (QBI) Coronavirus Research Group Structural Biology Consortium, University of California San Francisco, CA, USA
| | - Anthony Aimon
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - James M. Bennett
- Centre for Medicines Discovery, University of Oxford, South Parks Road, Headington, OX3 7DQ, UK
| | - Jose Brandao Neto
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Aina E. Cohen
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Center, Menlo Park, CA 94025, USA
| | - Alexandre Dias
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Alice Douangamath
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Louise Dunnett
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Oleg Fedorov
- Centre for Medicines Discovery, University of Oxford, South Parks Road, Headington, OX3 7DQ, UK
| | - Matteo P. Ferla
- Wellcome Centre for Human Genetics, University of Oxford, Old Road Campus, Oxford OX3 7BN, UK
| | - Martin Fuchs
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA
| | - Tyler J. Gorrie-Stone
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - James M. Holton
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Center, Menlo Park, CA 94025, USA
- Department of Biochemistry and Biophysics, University of California San Francisco, CA, USA
- Department of Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | | | - Tobias Krojer
- Centre for Medicines Discovery, University of Oxford, South Parks Road, Headington, OX3 7DQ, UK
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Headington OX3 7DQ, UK
| | - George Meigs
- Department of Biochemistry and Biophysics, University of California San Francisco, CA, USA
- Department of Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Ailsa J. Powell
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | | | - Victor L Rangel
- Centre for Medicines Discovery, University of Oxford, South Parks Road, Headington, OX3 7DQ, UK
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Headington OX3 7DQ, UK
- School of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, São Paulo, Brazil
| | - Silvia Russi
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Center, Menlo Park, CA 94025, USA
| | - Rachael E. Skyner
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Clyde A. Smith
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Center, Menlo Park, CA 94025, USA
| | | | - Jennifer L. Wierman
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Center, Menlo Park, CA 94025, USA
| | - Kang Zhu
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Natalia Jura
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, CA, USA
| | - Alan Ashworth
- Helen Diller Family Comprehensive Cancer, University of California San Francisco, CA, USA
| | - John Irwin
- Department of Pharmaceutical Chemistry, University of California San Francisco San Francisco, CA, USA
| | - Michael C. Thompson
- Department of Chemistry and Chemical Biology, University of California Merced, CA, USA
| | - Jason E. Gestwicki
- Department of Pharmaceutical Chemistry, University of California San Francisco San Francisco, CA, USA
- Institute for Neurodegenerative Disease, University of California San Francisco, CA, USA
| | - Frank von Delft
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
- Centre for Medicines Discovery, University of Oxford, South Parks Road, Headington, OX3 7DQ, UK
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Headington OX3 7DQ, UK
- Department of Biochemistry, University of Johannesburg, Auckland Park, 2006, South Africa
| | - Brian K. Shoichet
- Department of Pharmaceutical Chemistry, University of California San Francisco San Francisco, CA, USA
| | - James S. Fraser
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, CA, USA
| | - Ivan Ahel
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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15
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Jonk Y, Snow KI, Thayer D, McGuire C, Bratesman S, Smith CA, Ziller E. Pent-up demand for care among dual-eligible victims of elder financial exploitation in Maine. J Elder Abuse Negl 2020; 32:334-356. [PMID: 32886027 DOI: 10.1080/08946566.2020.1806980] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Elder financial exploitation (EFE), the misuse of a vulnerable adult's property or resources for personal gain, is a form of elder abuse. This study addresses whether dual-eligible EFE victims were experiencing pent-up demand for health services alleviated through investigation by Adult Protective Services (APS). A quasi-experimental design addressed health service utilization and costs for 131 dual-eligible Maine APS clients over age 60 with substantiated allegations of EFE relative to comparable non-APS controls. APS case files spanning 2007-2012 were linked to 2006-2014 Medicare and Medicaid claims data. Service utilization and costs were analyzed 1 year prior, during, and 2 years after the initial APS investigation. Difference in differences logistic regression and generalized linear models addressed the likelihood of incurring costs and expenditure levels relative to matched controls, respectively. Victims of EFE had higher overall odds of using inpatient and long-term services and supports (LTSS) and higher odds of using LTSS post-investigation than controls. Higher overall levels of outpatient and prescriptions expenditures and higher inpatient expenditures during the APS event year contributed toward APS clients incurring $1,142 higher PMPM total costs than controls. Victims of EFE were experiencing significant pent-up demand for health services post-APS involvement.
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Affiliation(s)
- Yvonne Jonk
- Muskie School of Public Service, University of Southern Maine , Portland, ME, USA
| | - Kimberly I Snow
- Muskie School of Public Service, University of Southern Maine , Portland, ME, USA
| | - D Thayer
- Muskie School of Public Service, University of Southern Maine , Portland, ME, USA
| | - C McGuire
- Muskie School of Public Service, University of Southern Maine , Portland, ME, USA
| | - S Bratesman
- Muskie School of Public Service, University of Southern Maine , Portland, ME, USA
| | - C A Smith
- School of Social Work, University of Maryland , Baltimore, School of Social Work, MD, USA
| | - E Ziller
- Muskie School of Public Service, University of Southern Maine , Portland, ME, USA
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16
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Meng Q, Moinuddin SGA, Kim SJ, Bedgar DL, Costa MA, Thomas DG, Young RP, Smith CA, Cort JR, Davin LB, Lewis NG. Pterocarpan synthase (PTS) structures suggest a common quinone methide-stabilizing function in dirigent proteins and proteins with dirigent-like domains. J Biol Chem 2020; 295:11584-11601. [PMID: 32565424 PMCID: PMC7450108 DOI: 10.1074/jbc.ra120.012444] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 06/17/2020] [Indexed: 11/28/2022] Open
Abstract
The biochemical activities of dirigent proteins (DPs) give rise to distinct complex classes of plant phenolics. DPs apparently began to emerge during the aquatic-to-land transition, with phylogenetic analyses revealing the presence of numerous DP subfamilies in the plant kingdom. The vast majority (>95%) of DPs in these large multigene families still await discovery of their biochemical functions. Here, we elucidated the 3D structures of two pterocarpan-forming proteins with dirigent-like domains. Both proteins stereospecifically convert distinct diastereomeric chiral isoflavonoid precursors to the chiral pterocarpans, (-)- and (+)-medicarpin, respectively. Their 3D structures enabled comparisons with stereoselective lignan- and aromatic terpenoid-forming DP orthologs. Each protein provides entry into diverse plant natural products classes, and our experiments suggest a common biochemical mechanism in binding and stabilizing distinct plant phenol-derived mono- and bis-quinone methide intermediates during different C-C and C-O bond-forming processes. These observations provide key insights into both their appearance and functional diversification of DPs during land plant evolution/adaptation. The proposed biochemical mechanisms based on our findings provide important clues to how additional physiological roles for DPs and proteins harboring dirigent-like domains can now be rationally and systematically identified.
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Affiliation(s)
- Qingyan Meng
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - Syed G A Moinuddin
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - Sung-Jin Kim
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - Diana L Bedgar
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - Michael A Costa
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - Dennis G Thomas
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Robert P Young
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Clyde A Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California, USA
| | - John R Cort
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Laurence B Davin
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
| | - Norman G Lewis
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA
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17
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Smith CA, Nolan J, Tritz DJ, Heavener TE, Pelton J, Cook K, Vassar M. Evaluation of reproducible and transparent research practices in pulmonology. Pulmonology 2020; 27:134-143. [PMID: 32739326 DOI: 10.1016/j.pulmoe.2020.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 07/01/2020] [Accepted: 07/03/2020] [Indexed: 10/23/2022] Open
Abstract
BACKGROUND Study reproducibility is valuable for validating or refuting results. Provision of reproducibility indicators, such as materials, protocols, and raw data in a study improve its potential for reproduction. Efforts to reproduce noteworthy studies in the biomedical sciences have resulted in an overwhelming majority of them being found to be unreplicable, causing concern for the integrity of research in other fields, including medical specialties. Here, we analyzed the reproducibility of studies in the field of pulmonology. METHODS 500 pulmonology articles were randomly selected from an initial PubMed search for data extraction. Two authors scoured these articles for reproducibility indicators including materials, protocols, raw data, analysis scripts, inclusion in systematic reviews, and citations by replication studies as well as other factors of research transparency including open accessibility, funding source and competing interest disclosures, and study preregistration. FINDINGS Few publications included statements regarding materials (10%), protocols (1%), data (15%), and analysis script (0%) availability. Less than 10% indicated preregistration. More than half of the publications analyzed failed to provide a funding statement. Conversely, 63% of the publications were open access and 73% included a conflict of interest statement. INTERPRETATION Overall, our study indicates pulmonology research is currently lacking in efforts to increase replicability. Future studies should focus on providing sufficient information regarding materials, protocols, raw data, and analysis scripts, among other indicators, for the sake of clinical decisions that depend on replicable or refutable results from the primary literature.
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Affiliation(s)
- C A Smith
- Department of Psychiatry and Behavioral Sciences, Oklahoma State University Center for Health Sciences, 1111 W. 17th St., Tulsa, OK 74107 USA.
| | - J Nolan
- Kansas City University of Medicine and Biosciences, 2901 St Johns Blvd, Joplin, MO 64804, USA
| | - D J Tritz
- Department of Psychiatry and Behavioral Sciences, Oklahoma State University Center for Health Sciences, 1111 W. 17th St., Tulsa, OK 74107 USA
| | - T E Heavener
- Department of Medicine, Citizens Memorial Hospital, 1500 N. Oakland Ave, Bolivar, MO 65613 USA
| | - J Pelton
- Department of Internal Medicine, Oklahoma State University Medical Center, 744 W. 9th St., Tulsa, OK 74127 USA
| | - K Cook
- Department of Internal Medicine, Oklahoma State University Medical Center, 744 W. 9th St., Tulsa, OK 74127 USA
| | - M Vassar
- Department of Psychiatry and Behavioral Sciences, Oklahoma State University Center for Health Sciences, 1111 W. 17th St., Tulsa, OK 74107 USA
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18
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Smith CA, Tuson A, Thornton C, Dahlen HG. The safety and effectiveness of mind body interventions for women with pregnancy induced hypertension and or preeclampsia: A systematic review and meta-analysis. Complement Ther Med 2020; 52:102469. [PMID: 32951719 DOI: 10.1016/j.ctim.2020.102469] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 06/02/2020] [Accepted: 06/03/2020] [Indexed: 01/22/2023] Open
Abstract
OBJECTIVES To undertake a systematic review of the safety and effectiveness of mind body approaches for women with hypertensive disorders in pregnancy (HDP). DESIGN A search was undertaken of databases from inception to 2019 for randomised and quasi randomised controlled trials. MAIN OUTCOME MEASURES The primary outcome was a reduction in systolic and / or diastolic blood pressure for women with hypertension and or preeclampsia in pregnancy. RESULTS 121 studies were identified and eight studies were included in this review. These included mind body interventions examining yoga, guided imagery, relaxation, music, and acupuncture for HDP. Two studies of relaxation found a reduction in systolic (MD -11.3, 95%CI -13.23 to -9.39) and diastolic blood pressure (MD -6.59, 95%CI -9.43 to -3.75) and reduced stress (MD -11.4, 95%CI -16.5 to -6.3). In one study of yoga, the risk of developing HDP was reduced (RR 0.28, 95% CI 0.09 to 0.91, 59 women) and a second study found a reduction in stress at the end of the intervention of yoga. One trial of guided imagery found a reduction in mean arterial blood pressure compared to the control (4.35, 95% -8.04 to -0.66, p=0.02). Overall there was no effect on the development of preeclampsia, use of anti-hypertensive medication and any neonatal outcomes from the interventions evaluated. Few trials reported on safety outcomes, one trial of acupuncture reported one case of placental abruption and three cases of acupuncture related side effects. CONCLUSION Few high quality trials have examined the effectiveness and safety of mind body interventions to manage HDP. Relaxation, yoga, guided imagery and music may have some potential benefit. Safety issues are completely unclear and thus the risk-benefit ratio of all interventions could not be determined. Further research is recommended.
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Affiliation(s)
- C A Smith
- NICM Health Research Institute, Western Sydney University, Penrith, 2751, Australia.
| | - A Tuson
- Registered Midwife and Western Sydney University Summer Scholar, Western Sydney University Penrith, 2751, Australia.
| | - Charlene Thornton
- College of Nursing and Health Sciences, Flinders University, Bedford Park, 5042, Australia.
| | - Hannah G Dahlen
- School of Nursing and Midwifery, Western Sydney University, Penrith, 2751, Australia.
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19
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Stewart NK, Bhattacharya M, Toth M, Smith CA, Vakulenko SB. A surface loop modulates activity of the Bacillus class D β-lactamases. J Struct Biol 2020; 211:107544. [PMID: 32512156 DOI: 10.1016/j.jsb.2020.107544] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 05/25/2020] [Accepted: 06/02/2020] [Indexed: 12/23/2022]
Abstract
The expression of β-lactamases is a major mechanism of bacterial resistance to the β-lactam antibiotics. Four molecular classes of β-lactamases have been described (A, B, C and D), however until recently the class D enzymes were thought to exist only in Gram-negative bacteria. In the last few years, class D enzymes have been discovered in several species of Gram-positive microorganisms, such as Bacillus and Clostridia, and an investigation of their kinetic and structural properties has begun in earnest. Interestingly, it was observed that some species of Bacillus produce two distinct class D β-lactamases, one highly active and the other with only basal catalytic activity. Analysis of amino acid sequences of active (BPU-1 from Bacillus pumilus) and inactive (BSU-2 from Bacillus subtilis and BAT-2 from Bacillus atrophaeus) enzymes suggests that presence of three additional amino acid residues in one of the surface loops of inefficient β-lactamases may be responsible for their severely diminished activity. Our structural and docking studies show that the elongated loop of these enzymes severely restricts binding of substrates. Deletion of the three residues from the loops of BSU-2 and BAT-2 β-lactamases relieves the steric hindrance and results in a significant increase in the catalytic activity of the enzymes. These data show that this surface loop plays an important role in modulation of the catalytic activity of Bacillus class D β-lactamases.
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Affiliation(s)
- Nichole K Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, USA
| | | | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, USA
| | - Clyde A Smith
- Department of Chemistry, Stanford University, Stanford, CA, USA; Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, CA, USA.
| | - Sergei B Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, USA.
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20
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Rygg JR, Smith RF, Lazicki AE, Braun DG, Fratanduono DE, Kraus RG, McNaney JM, Swift DC, Wehrenberg CE, Coppari F, Ahmed MF, Barrios MA, Blobaum KJM, Collins GW, Cook AL, Di Nicola P, Dzenitis EG, Gonzales S, Heidl BF, Hohenberger M, House A, Izumi N, Kalantar DH, Khan SF, Kohut TR, Kumar C, Masters ND, Polsin DN, Regan SP, Smith CA, Vignes RM, Wall MA, Ward J, Wark JS, Zobrist TL, Arsenlis A, Eggert JH. X-ray diffraction at the National Ignition Facility. Rev Sci Instrum 2020; 91:043902. [PMID: 32357733 DOI: 10.1063/1.5129698] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 03/20/2020] [Indexed: 06/11/2023]
Abstract
We report details of an experimental platform implemented at the National Ignition Facility to obtain in situ powder diffraction data from solids dynamically compressed to extreme pressures. Thin samples are sandwiched between tamper layers and ramp compressed using a gradual increase in the drive-laser irradiance. Pressure history in the sample is determined using high-precision velocimetry measurements. Up to two independently timed pulses of x rays are produced at or near the time of peak pressure by laser illumination of thin metal foils. The quasi-monochromatic x-ray pulses have a mean wavelength selectable between 0.6 Å and 1.9 Å depending on the foil material. The diffracted signal is recorded on image plates with a typical 2θ x-ray scattering angle uncertainty of about 0.2° and resolution of about 1°. Analytic expressions are reported for systematic corrections to 2θ due to finite pinhole size and sample offset. A new variant of a nonlinear background subtraction algorithm is described, which has been used to observe diffraction lines at signal-to-background ratios as low as a few percent. Variations in system response over the detector area are compensated in order to obtain accurate line intensities; this system response calculation includes a new analytic approximation for image-plate sensitivity as a function of photon energy and incident angle. This experimental platform has been used up to 2 TPa (20 Mbar) to determine the crystal structure, measure the density, and evaluate the strain-induced texturing of a variety of compressed samples spanning periods 2-7 on the periodic table.
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Affiliation(s)
- J R Rygg
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - R F Smith
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - A E Lazicki
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - D G Braun
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - D E Fratanduono
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - R G Kraus
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - J M McNaney
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - D C Swift
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - C E Wehrenberg
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - F Coppari
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - M F Ahmed
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - M A Barrios
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - K J M Blobaum
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - G W Collins
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - A L Cook
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - P Di Nicola
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - E G Dzenitis
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - S Gonzales
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - B F Heidl
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - M Hohenberger
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - A House
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - N Izumi
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - D H Kalantar
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - S F Khan
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - T R Kohut
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - C Kumar
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - N D Masters
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - D N Polsin
- Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
| | - S P Regan
- Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
| | - C A Smith
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - R M Vignes
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - M A Wall
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - J Ward
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - J S Wark
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - T L Zobrist
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - A Arsenlis
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - J H Eggert
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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21
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Marchany-Rivera D, Smith CA, Rodriguez-Perez JD, López-Garriga J. Lucina pectinata oxyhemoglobin (II-III) heterodimer pH susceptibility. J Inorg Biochem 2020; 207:111055. [PMID: 32217352 DOI: 10.1016/j.jinorgbio.2020.111055] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 02/27/2020] [Accepted: 03/02/2020] [Indexed: 10/24/2022]
Abstract
Lucina pectinata live in high concentrations of hydrogen sulfide (H2S) and contains one hemoglobin, Hemoglobin I (HbI), transporting H2S and two hemoglobins, Hemoglobin II (HbII) and Hemoglobin (HbIII), transferring dioxygen to symbionts. HbII and HbIII contain B10 tyrosine (Tyr) and E7 glutamine (Gln) in the heme pocket generating an efficient hydrogen bonding network with the (HbII-HbIII)-O2 species, leading to very low ligand dissociation rates. The results indicate that the oxy-hemeprotein is susceptible to pH from 4 to 9, at acidic conditions, and as a function of the potassium ferricyanide concentration, 100% of the met-aquo derivative is produced. Without a strong oxidant, pH 5 generates a small concentration of the met-aquo complex. The process is accelerated by the presence of salts, as indicated by the crystallization structures and UV-Vis spectra. The results suggest that acidic pH generates conformational changes associated with B10 and E7 heme pocket amino acids, weakening the (HbII-HbIII)-O2 hydrogen bond network. The observation is supported by X-ray crystallography, since at pH 4 and 5, the heme-Fe tends to oxidize, while at pH 7, the oxy-heterodimer is present. Conformational changes also are observed at higher pH by the presence of a 605 nm transition associated with the iron heme-Tyr interaction. Therefore, pH is one crucial factor regulating the (HbII-HbIII)-O2 complex hydrogen-bonding network. Thus, it can be proposed that the hydrogen bonding adjustments between the heme bound O2 and the Tyr and Gln amino acids contribute to oxygen dissociation from the (HbII-HbIII)-O2 system.
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Affiliation(s)
- Darya Marchany-Rivera
- Department of Chemistry, P.O. Box 9000, University of Puerto Rico, Mayagüez Campus, 00681, Puerto Rico.
| | - Clyde A Smith
- Stanford Linear Accelerator Center (SLAC) National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
| | - Josiris D Rodriguez-Perez
- Department of Chemistry, P.O. Box 9000, University of Puerto Rico, Mayagüez Campus, 00681, Puerto Rico.
| | - Juan López-Garriga
- Department of Chemistry, P.O. Box 9000, University of Puerto Rico, Mayagüez Campus, 00681, Puerto Rico.
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22
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Stewart NK, Smith CA, Toth M, Stasyuk A, Vakulenko SB. The crystal structures of CDD-1, the intrinsic class D β-lactamase from the pathogenic Gram-positive bacterium Clostridioides difficile, and its complex with cefotaxime. J Struct Biol 2019; 208:107391. [PMID: 31550535 PMCID: PMC6903424 DOI: 10.1016/j.jsb.2019.09.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 09/18/2019] [Accepted: 09/20/2019] [Indexed: 02/04/2023]
Abstract
Class D β-lactamases, enzymes that degrade β-lactam antibiotics and are widely spread in Gram-negative bacteria, were for a long time not known in Gram-positive organisms. Recently, these enzymes were identified in various non-pathogenic Bacillus species and subsequently in Clostridioides difficile, a major clinical pathogen associated with high morbidity and mortality rates. Comparison of the BPU-1 enzyme from Bacillus pumilus with the CDD-1 and CDD-2 enzymes from C. difficile demonstrated that the latter enzymes have broadened their substrate profile to efficiently hydrolyze the expanded-spectrum methoxyimino cephalosporins, cefotaxime and ceftriaxone. These two antibiotics are major contributors to the development of C. difficile infection, as they suppress sensitive bacterial microflora in the gut but fail to kill the pathogen which is highly resistant to these drugs. To gain insight into the structural features that contribute to the expansion of the substrate profile of CDD enzymes compared to BPU-1, we solved the crystal structures of CDD-1 and its complex with cefotaxime. Comparison of CDD-1 structures with those of class D enzymes from Gram-negative bacteria showed that in the cefotaxime-CDD-1 complex, the antibiotic is bound in a substantially different mode due to structural differences in the enzymes' active sites. We also found that CDD-1 has a uniquely long Ω-loop when compared to all other class D β-lactamases. This Ω-loop extension allows it to engage in hydrogen bonding with the acylated cefotaxime, thus providing additional stabilizing interactions with the substrate which could be responsible for the high catalytic activity of the enzyme for expanded-spectrum cephalosporins.
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Affiliation(s)
- Nichole K Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, USA
| | - Clyde A Smith
- Department of Chemistry, Stanford University, Stanford, CA, USA; Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, CA, USA.
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, USA
| | - Anastasiya Stasyuk
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, CA, USA
| | - Sergei B Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, USA.
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23
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Smith CA, Toth M, Stewart NK, Maltz L, Vakulenko SB. Structural basis for the diversity of the mechanism of nucleotide hydrolysis by the aminoglycoside-2''-phosphotransferases. Acta Crystallogr D Struct Biol 2019; 75:1129-1137. [PMID: 31793906 DOI: 10.1107/s2059798319015079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/07/2019] [Indexed: 11/10/2022]
Abstract
Aminoglycoside phosphotransferases (APHs) are one of three families of aminoglycoside-modifying enzymes that confer high-level resistance to the aminoglycoside antibiotics via enzymatic modification. This has now rendered many clinically important drugs almost obsolete. The APHs specifically phosphorylate hydroxyl groups on the aminoglycosides using a nucleotide triphosphate as the phosphate donor. The APH(2'') family comprises four distinct members, isolated primarily from Enterococcus sp., which vary in their substrate specificities and also in their preference for the phosphate donor (ATP or GTP). The structure of the ternary complex of APH(2'')-IIIa with GDP and kanamycin was solved at 1.34 Å resolution and was compared with substrate-bound structures of APH(2'')-Ia, APH(2'')-IIa and APH(2'')-IVa. In contrast to the case for APH(2'')-Ia, where it was proposed that the enzyme-mediated hydrolysis of GTP is regulated by conformational changes in its N-terminal domain upon GTP binding, APH(2'')-IIa, APH(2'')-IIIa and APH(2'')-IVa show no such regulatory mechanism, primarily owing to structural differences in the N-terminal domains of these enzymes.
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Affiliation(s)
- Clyde A Smith
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Nichole K Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Lauren Maltz
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Sergei B Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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24
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Smith CA, Stewart NK, Toth M, Vakulenko SB. Structural Insights into the Mechanism of Carbapenemase Activity of the OXA-48 β-Lactamase. Antimicrob Agents Chemother 2019; 63:e01202-19. [PMID: 31358584 PMCID: PMC6761500 DOI: 10.1128/aac.01202-19] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 07/24/2019] [Indexed: 01/02/2023] Open
Abstract
Carbapenem-hydrolyzing class D carbapenemases (CHDLs) are enzymes that produce resistance to the last-resort carbapenem antibiotics, severely compromising the available therapeutic options for the treatment of life-threatening infections. A broad variety of CHDLs, including OXA-23, OXA-24/40, and OXA-58, circulate in Acinetobacter baumannii, while the OXA-48 CHDL is predominant in Enterobacteriaceae Extensive structural studies of A. baumannii enzymes have provided important information regarding their interactions with carbapenems and significantly contributed to the understanding of the mechanism of their carbapenemase activity. However, the interactions between carbapenems and OXA-48 have not yet been elucidated. We determined the X-ray crystal structures of the acyl-enzyme complexes of OXA-48 with four carbapenems, imipenem, meropenem, ertapenem, and doripenem, and compared them with those of known carbapenem complexes of A. baumannii CHDLs. In the A. baumannii enzymes, acylation by carbapenems triggers significant displacement of one of two conserved hydrophobic surface residues, resulting in the formation of a channel for entry of the deacylating water into the active site. We show that such a channel preexists in apo-OXA-48 and that only minor displacement of the conserved hydrophobic surface residues occurs upon the formation of OXA-48 acyl-enzyme intermediates. We also demonstrate that the extensive hydrophobic interactions that occur between a conserved hydrophobic bridge of the A. baumannii CHDLs and the carbapenem tails are lost in OXA-48 in the absence of an equivalent bridge structure. These data highlight significant differences between the interactions of carbapenems with OXA-48 and those with A. baumannii enzymes and provide important insights into the mechanism of carbapenemase activity of the major Enterobacteriaceae CHDL, OXA-48.
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Affiliation(s)
- Clyde A Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California, USA
| | - Nichole K Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Sergei B Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
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25
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Ewings RA, Stewart JR, Perring TG, Bewley RI, Le MD, Raspino D, Pooley DE, Škoro G, Waller SP, Zacek D, Smith CA, Riehl-Shaw RC. Upgrade to the MAPS neutron time-of-flight chopper spectrometer. Rev Sci Instrum 2019; 90:035110. [PMID: 30927771 DOI: 10.1063/1.5086255] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/01/2019] [Indexed: 05/23/2023]
Abstract
The MAPS direct geometry time-of-flight chopper spectrometer at the ISIS pulsed neutron and muon source has been in operation since 1999, and its novel use of a large array of position-sensitive neutron detectors paved the way for a later generations of chopper spectrometers around the world. Almost two decades of experience of user operations on MAPS, together with lessons learned from the operation of new generation instruments, led to a decision to perform three parallel upgrades to the instrument. These were to replace the primary beamline collimation with supermirror neutron guides, to install a disk chopper, and to modify the geometry of the poisoning in the water moderator viewed by MAPS. Together, these upgrades were expected to increase the neutron flux substantially, to allow more flexible use of repetition rate multiplication and to reduce some sources of background. Here, we report the details of these upgrades and compare the performance of the instrument before and after their installation as well as to Monte Carlo simulations. These illustrate that the instrument is performing in line with, and in some respects in excess of, expectations. It is anticipated that the improvement in performance will have a significant impact on the capabilities of the instrument. A few examples of scientific commissioning are presented to illustrate some of the possibilities.
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Affiliation(s)
- R A Ewings
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - J R Stewart
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - T G Perring
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - R I Bewley
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - M D Le
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - D Raspino
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - D E Pooley
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - G Škoro
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - S P Waller
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - D Zacek
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - C A Smith
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - R C Riehl-Shaw
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
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26
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Stewart NK, Smith CA, Antunes NT, Toth M, Vakulenko SB. Role of the Hydrophobic Bridge in the Carbapenemase Activity of Class D β-Lactamases. Antimicrob Agents Chemother 2019; 63:e02191-18. [PMID: 30530607 PMCID: PMC6355612 DOI: 10.1128/aac.02191-18] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 11/29/2018] [Indexed: 01/25/2023] Open
Abstract
Class D carbapenemases are enzymes of the utmost clinical importance due to their ability to confer resistance to the last-resort carbapenem antibiotics. We investigated the role of the conserved hydrophobic bridge in the carbapenemase activity of OXA-23, the major carbapenemase of the important pathogen Acinetobacter baumannii We show that substitution of the bridge residue Phe110 affects resistance to meropenem and doripenem and has little effect on MICs of imipenem. The opposite effect was observed upon substitution of the other bridge residue Met221. Complete disruption of the bridge by the F110A/M221A substitution resulted in a significant loss of affinity for doripenem and meropenem and to a lesser extent for imipenem, which is reflected in the reduced MICs of these antibiotics. In the wild-type OXA-23, the pyrrolidine ring of the meropenem tail forms a hydrophobic interaction with Phe110 of the bridge. Similar interactions would ensue with ring-containing doripenem but not with imipenem, which lacks this ring. Our structural studies showed that this interaction with the meropenem tail is missing in the F110A/M221A mutant. These data explain why disruption of the interaction between the enzyme and the carbapenem substrate impacts the affinity and MICs of meropenem and doripenem to a larger degree than those of imipenem. Our structures also show that the bridge directs the acylated carbapenem into a specific tautomeric conformation. However, it is not this conformation but rather the stabilizing interaction between the tail of the antibiotic and the hydrophobic bridge that contributes to the carbapenemase activity of class D β-lactamases.
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Affiliation(s)
- Nichole K Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Clyde A Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California, USA
| | - Nuno T Antunes
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Sergei B Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
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27
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Abstract
CA 549 is one of several carcinoma associated mucin antigens proposed as a breast cancer tumor marker. In this study, the performance characteristics of the CA 549 assay were validated and the clinical utility of the test was compared with that of other breast cancer markers including CA 15-3, CA M26, CA M29 and carcinoembryonic antigen. The upper limit of normal was established as 15.5 U/ml based on data for 250 control subjects apparently free of disease. Overall, CA 549 had a low negative predictive value (0.51) due to a low sensitivity in the detection of early breast cancer. However, the test had a high positive predictive value (0.93) reflecting a high specificity for the disease. In 56 patients with advanced breast cancer, the sensitivity was 0.71 for CA 549 alone and 0.79-0.84 for CA 549 combined with any of the other markers studied.
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Smith CA, Bhattacharya M, Toth M, Stewart NK, Vakulenko SB. Aminoglycoside resistance profile and structural architecture of the aminoglycoside acetyltransferase AAC(6')-Im. Microb Cell 2017; 4:402-410. [PMID: 29234669 PMCID: PMC5722643 DOI: 10.15698/mic2017.12.602] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Aminoglycoside 6'-acetyltransferase-Im (AAC(6')-Im) is the closest monofunctional homolog of the AAC(6')-Ie acetyltransferase of the bifunctional enzyme AAC(6')-Ie/APH(2")-Ia. The AAC(6')-Im acetyltransferase confers 4- to 64-fold higher MICs to 4,6-disubstituted aminoglycosides and the 4,5-disubstituted aminoglycoside neomycin than AAC(6')-Ie, yet unlike AAC(6')-Ie, the AAC(6')-Im enzyme does not confer resistance to the atypical aminoglycoside fortimicin. The structure of the kanamycin A complex of AAC(6')-Im shows that the substrate binds in a shallow positively-charged pocket, with the N6' amino group positioned appropriately for an efficient nucleophilic attack on an acetyl-CoA cofactor. The AAC(6')-Ie enzyme binds kanamycin A in a sufficiently different manner to position the N6' group less efficiently, thereby reducing the activity of this enzyme towards the 4,6-disubstituted aminoglycosides. Conversely, docking studies with fortimicin in both acetyltransferases suggest that the atypical aminoglycoside might bind less productively in AAC(6')-Im, thus explaining the lack of resistance to this molecule.
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Affiliation(s)
- Clyde A Smith
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Monolekha Bhattacharya
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Nichole K Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Sergei B Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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Crawford DF, Smith CA, Whyte G. Image-based closed-loop feedback for highly mono-dispersed microdroplet production. Sci Rep 2017; 7:10545. [PMID: 28874820 PMCID: PMC5585215 DOI: 10.1038/s41598-017-11254-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 08/21/2017] [Indexed: 11/19/2022] Open
Abstract
Micron-scale droplets isolated by an immiscible liquid can provide miniaturised reaction vessels which can be manipulated in microfluidic networks, and has seen a rapid growth in development. In many experiments, the precise volume of these microdroplets is a critical parameter which can be influenced by many external factors. In this work, we demonstrate the combination of imaging-based feedback and pressure driven pumping to accurately control the size of microdroplets produced in a microfluidic device. The use of fast-response, pressure-driving pumps allows the microfluidic flow to be quickly and accurately changed, while directly measuring the droplet size allows the user to define the more meaningful parameters of droplet size and generation frequency rather than flow rates or pressures. The feedback loop enables the drift correction of pressure based pumps, and leads to a large increase in the mono-dispersity of the droplets produced over long periods. We also show how this can be extended to control multiple liquid flows, allowing the frequency of droplet formation or the average concentration of living cells per droplet to be controlled and kept constant.
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Affiliation(s)
- D F Crawford
- Institute of Biochemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - C A Smith
- Sphere Fluidics Limited, The Jonas-Webb Building, Babraham Research Campus, Babraham, Cambridge, CB22 3AT, UK
| | - G Whyte
- Institute of Biochemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
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Toth M, Smith CA, Antunes NT, Stewart NK, Maltz L, Vakulenko SB. The role of conserved surface hydrophobic residues in the carbapenemase activity of the class D β-lactamases. Acta Crystallogr D Struct Biol 2017; 73:692-701. [PMID: 28777084 PMCID: PMC5571744 DOI: 10.1107/s2059798317008671] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 06/11/2017] [Indexed: 01/12/2023] Open
Abstract
Carbapenem-hydrolyzing class D β-lactamases (CHDLs) produce resistance to the last-resort carbapenem antibiotics and render these drugs ineffective for the treatment of life-threatening infections. Here, it is shown that among the clinically important CHDLs, OXA-143 produces the highest levels of resistance to carbapenems and has the highest catalytic efficiency against these substrates. Structural data demonstrate that acylated carbapenems entirely fill the active site of CHDLs, leaving no space for water molecules, including the deacylating water. Since the entrance to the active site is obstructed by the acylated antibiotic, the deacylating water molecule must take a different route for entry. It is shown that in OXA-143 the movement of a conserved hydrophobic valine residue on the surface opens a channel to the active site of the enzyme, which would not only allow the exchange of water molecules between the active site and the milieu, but would also create extra space for a water molecule to position itself in the vicinity of the scissile bond of the acyl-enzyme intermediate to perform deacylation. Structural analysis of the OXA-23 carbapenemase shows that in this enzyme movement of the conserved leucine residue, juxtaposed to the valine on the molecular surface, creates a similar channel to the active site. These data strongly suggest that all CHDLs may employ a mechanism whereupon the movement of highly conserved valine or leucine residues would allow a water molecule to access the active site to promote deacylation. It is further demonstrated that the 6α-hydroxyethyl group of the bound carbapenem plays an important role in the stabilization of this channel. The recognition of a universal deacylation mechanism for CHDLs suggests a direction for the future development of inhibitors and novel antibiotics for these enzymes of utmost clinical importance.
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Affiliation(s)
- Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Clyde A. Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California, USA
| | - Nuno T. Antunes
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Nichole K. Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Lauren Maltz
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California, USA
| | - Sergei B. Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
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Abstract
Retinal ganglion cell (RGC) loss is the hallmark of optic neuropathies, including glaucoma, where damage to RGC axons occurs at the level of the optic nerve head. In experimental glaucoma, damage is assessed at the axon level (in the retinal nerve fibre layer and optic nerve head) or at the soma level (in the retina). In clinical glaucoma where measurements are generally limited to non-invasive techniques, structural measurements of the retinal nerve fibre layer and optic nerve head, or functional measurements with perimetry provide surrogate estimates of RGC integrity. These surrogate measurements, while clinically useful, are several levels removed from estimating actual RGC loss. Advances in imaging, labelling techniques, and transgenic medicine are making enormous strides in experimental glaucoma, providing knowledge on the pathophysiology of glaucoma, its progression and testing new therapeutic avenues. Advances are also being made in functional imaging of RGCs. Future efforts will now be directed towards translating these advances to clinical care.
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Affiliation(s)
- C A Smith
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada
| | - J R Vianna
- Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
| | - B C Chauhan
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
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Smith CA, Nossoni Z, Toth M, Stewart NK, Frase H, Vakulenko SB. Role of the Conserved Disulfide Bridge in Class A Carbapenemases. J Biol Chem 2016; 291:22196-22206. [PMID: 27590339 PMCID: PMC5063999 DOI: 10.1074/jbc.m116.749648] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 08/31/2016] [Indexed: 08/30/2023] Open
Abstract
Some members of the class A β-lactamase family are capable of conferring resistance to the last resort antibiotics, carbapenems. A unique structural feature of these clinically important enzymes, collectively referred to as class A carbapenemases, is a disulfide bridge between invariant Cys69 and Cys238 residues. It was proposed that this conserved disulfide bridge is responsible for their carbapenemase activity, but this has not yet been validated. Here we show that disruption of the disulfide bridge in the GES-5 carbapenemase by the C69G substitution results in only minor decreases in the conferred levels of resistance to the carbapenem imipenem and other β-lactams. Kinetic and circular dichroism experiments with C69G-GES-5 demonstrate that this small drop in antibiotic resistance is due to a decline in the enzyme activity caused by a marginal loss of its thermal stability. The atomic resolution crystal structure of C69G-GES-5 shows that two domains of this disulfide bridge-deficient enzyme are held together by an intensive hydrogen-bonding network. As a result, the protein architecture and imipenem binding mode remain unchanged. In contrast, the corresponding hydrogen-bonding networks in NMCA, SFC-1, and SME-1 carbapenemases are less intensive, and as a consequence, disruption of the disulfide bridge in these enzymes destabilizes them, which causes arrest of bacterial growth. Our results demonstrate that the disulfide bridge is essential for stability but does not play a direct role in the carbapenemase activity of the GES family of β-lactamases. This would likely apply to all other class A carbapenemases given the high degree of their structural similarity.
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Affiliation(s)
- Clyde A Smith
- From the Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California 94025 and
| | - Zahra Nossoni
- the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Marta Toth
- the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Nichole K Stewart
- the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Hilary Frase
- the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Sergei B Vakulenko
- the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
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Yang W, Wu G, Broeckel U, Smith CA, Turner V, Haidar CE, Wang S, Carter R, Karol SE, Neale G, Crews KR, Yang JJ, Mullighan CG, Downing JR, Evans WE, Relling MV. Comparison of genome sequencing and clinical genotyping for pharmacogenes. Clin Pharmacol Ther 2016; 100:380-8. [PMID: 27311679 DOI: 10.1002/cpt.411] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 05/23/2016] [Accepted: 06/13/2016] [Indexed: 12/28/2022]
Abstract
We compared whole exome sequencing (WES, n = 176 patients) and whole genome sequencing (WGS, n = 68) and clinical genotyping (DMET array-based approach) for interrogating 13 genes with Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines. We focused on 127 CPIC important variants: 103 single nucleotide variations (SNV), 21 insertion/deletions (Indel), HLA-B alleles, and two CYP2D6 structural variations. WES and WGS provided interrogation of nonoverlapping sets of 115 SNV/Indels with call rate >98%. Among 68 loci interrogated by both WES and DMET, 64 loci (94.1%, confidence interval [CI]: 85.6-98.4%) showed no discrepant genotyping calls. Among 66 loci interrogated by both WGS and DMET, 63 loci (95.5%, CI: 87.2-99.0%) showed no discrepant genotyping calls. In conclusion, even without optimization to interrogate pharmacogenetic variants, WES and WGS displayed potential to provide reliable interrogation of most pharmacogenes and further validation of genome sequencing in a clinical lab setting is warranted.
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Affiliation(s)
- W Yang
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - G Wu
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - U Broeckel
- Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - C A Smith
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - V Turner
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - C E Haidar
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - S Wang
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - R Carter
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - S E Karol
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - G Neale
- Hartwell Center, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - K R Crews
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - J J Yang
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - C G Mullighan
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - J R Downing
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - W E Evans
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - M V Relling
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
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Levett KM, Smith CA, Bensoussan A, Dahlen HG. Complementary therapies for labour and birth study: a randomised controlled trial of antenatal integrative medicine for pain management in labour. BMJ Open 2016; 6:e010691. [PMID: 27406639 PMCID: PMC4947718 DOI: 10.1136/bmjopen-2015-010691] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVE To evaluate the effect of an antenatal integrative medicine education programme in addition to usual care for nulliparous women on intrapartum epidural use. DESIGN Open-label, assessor blind, randomised controlled trial. SETTING 2 public hospitals in Sydney, Australia. POPULATION 176 nulliparous women with low-risk pregnancies, attending hospital-based antenatal clinics. METHODS AND INTERVENTION The Complementary Therapies for Labour and Birth protocol, based on the She Births and acupressure for labour and birth courses, incorporated 6 evidence-based complementary medicine techniques: acupressure, visualisation and relaxation, breathing, massage, yoga techniques, and facilitated partner support. Randomisation occurred at 24-36 weeks' gestation, and participants attended a 2-day antenatal education programme plus standard care, or standard care alone. MAIN OUTCOME MEASURES Rate of analgesic epidural use. Secondary: onset of labour, augmentation, mode of birth, newborn outcomes. RESULTS There was a significant difference in epidural use between the 2 groups: study group (23.9%) standard care (68.7%; risk ratio (RR) 0.37 (95% CI 0.25 to 0.55), p≤0.001). The study group participants reported a reduced rate of augmentation (RR=0.54 (95% CI 0.38 to 0.77), p<0.0001); caesarean section (RR=0.52 (95% CI 0.31 to 0.87), p=0.017); length of second stage (mean difference=-0.32 (95% CI -0.64 to 0.002), p=0.05); any perineal trauma (0.88 (95% CI 0.78 to 0.98), p=0.02) and resuscitation of the newborn (RR=0.47 (95% CI 0.25 to 0.87), p≤0.015). There were no statistically significant differences found in spontaneous onset of labour, pethidine use, rate of postpartum haemorrhage, major perineal trauma (third and fourth degree tears/episiotomy), or admission to special care nursery/neonatal intensive care unit (p=0.25). CONCLUSIONS The Complementary Therapies for Labour and Birth study protocol significantly reduced epidural use and caesarean section. This study provides evidence for integrative medicine as an effective adjunct to antenatal education, and contributes to the body of best practice evidence. TRIAL REGISTRATION NUMBER ACTRN12611001126909.
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Affiliation(s)
- Kate M Levett
- National Institute for Complementary Medicines (NICM), Western Sydney University, Sydney, Australia
| | - C A Smith
- National Institute for Complementary Medicines (NICM), Western Sydney University, Sydney, Australia
| | - A Bensoussan
- National Institute for Complementary Medicines (NICM), Western Sydney University, Sydney, Australia
| | - H G Dahlen
- School of Nursing and Midwifery, Western Sydney University, Sydney, Australia
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Levett KM, Smith CA, Bensoussan A, Dahlen HG. The Complementary Therapies for Labour and Birth Study making sense of labour and birth - Experiences of women, partners and midwives of a complementary medicine antenatal education course. Midwifery 2016; 40:124-31. [PMID: 27428108 DOI: 10.1016/j.midw.2016.06.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 05/03/2016] [Accepted: 06/08/2016] [Indexed: 11/17/2022]
Abstract
OBJECTIVE to gain insight into the experiences of women, partners and midwives who participated in the Complementary Therapies for Labour and Birth Study, an evidence based complementary medicine (CM) antenatal education course. DESIGN qualitative in-depth interviews and a focus group as part of the Complementary Therapies for Labour and Birth Study. SETTING AND PARTICIPANTS thirteen low risk primiparous women and seven partners who had participated in the study group of a randomised controlled trial of the complementary therapies for labour and birth study, and 12 midwives caring for these women. The trial was conducted at two public hospitals, and through the Western Sydney University in Sydney, Australia. INTERVENTIONS the Complementary Therapies for Labour and Birth (CTLB) protocol, based on the She Births® course and the Acupressure for labour and birth protocol, incorporated six evidence-based complementary medicine (CM) techniques; acupressure, relaxation, visualisation, breathing, massage, yoga techniques and incorporated facilitated partner support. Randomisation to the trial occurred at 24-36 weeks' gestation, and participants attended a two-day antenatal education programme, plus standard care, or standard care alone. FINDINGS the overarching theme identified in the qualitative data was making sense of labour and birth. Women used information about normal birth physiology from the course to make sense of labour, and to utilise the CM techniques to support normal birth and reduce interventions in labour. Women's, partners' and midwives' experience of the course and its use during birth gave rise to supporting themes such as: working for normal; having a toolkit; and finding what works. KEY CONCLUSIONS the Complementary Therapies for Labour and Birth Study provided women and their partners with knowledge to understand the physiology of normal labour and birth and enabled them to use evidence-based CM tools to support birth and reduce interventions. IMPLICATIONS FOR PRACTICE the Complementary Therapies for Labour and Birth Study introduces concepts of what constitutes normal birth and provides skills to support women, partners and midwives. It appears to be an effective form of antenatal education that supports normal birth, and maternity services need to consider how they can reform current antenatal education in line with this evidence.
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Affiliation(s)
- K M Levett
- National Institute of Complementary Medicines (NICM), Western Sydney University, Sydney, Australia.
| | - C A Smith
- National Institute of Complementary Medicines (NICM), Western Sydney University, Sydney, Australia.
| | - A Bensoussan
- National Institute of Complementary Medicines (NICM), Western Sydney University, Sydney, Australia.
| | - H G Dahlen
- School of Nursing and Midwifery, Western Sydney University, Sydney, Australia.
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Vignes RM, Ahmed MF, Eggert JH, Fisher AC, Kalantar DH, Masters ND, Smith CA, Smith RF. TARDIS-C: A target diagnostic for measuring material structure at high pressure. ACTA ACUST UNITED AC 2016. [DOI: 10.1088/1742-6596/717/1/012115] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ratz PH, Miner AS, Huang Y, Smith CA, Barbee RW. Vascular smooth muscle desensitization in rabbit epigastric and mesenteric arteries during hemorrhagic shock. Am J Physiol Heart Circ Physiol 2016; 311:H157-67. [PMID: 27199133 DOI: 10.1152/ajpheart.00926.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 05/10/2016] [Indexed: 01/08/2023]
Abstract
The decompensatory phase of hemorrhage (shock) is caused by a poorly defined phenomenon termed vascular hyporeactivity (VHR). VHR may reflect an acute in vivo imbalance in levels of contractile and relaxant stimuli favoring net vascular smooth muscle (VSM) relaxation. Alternatively, VHR may be caused by intrinsic VSM desensitization of contraction resulting from prior exposure to high levels of stimuli that temporarily adjusts cell signaling systems. Net relaxation, but not desensitization, would be expected to resolve rapidly in an artery segment removed from the in vivo shock environment and examined in vitro in a fresh solution. Our aim was to 1) induce shock in rabbits and apply an in vitro mechanical analysis on muscular arteries isolated pre- and postshock to determine whether VHR involves intrinsic VSM desensitization, and 2) identify whether net VSM relaxation induced by nitric oxide and cyclic nucleotide-dependent protein kinase activation in vitro can be sustained for some time after relaxant stimulus washout. The potencies of phenylephrine- and histamine-induced contractions in in vitro epigastric artery removed from rabbits posthemorrhage were decreased by ∼0.3 log units compared with the control contralateral epigastric artery removed prehemorrhage. Moreover, a decrease in KCl-induced tonic, relative to phasic, tension of in vitro mesenteric artery correlated with the degree of shock severity as assessed by rates of lactate and K(+) accumulation. VSM desensitization was also caused by tyramine in vivo and PE in vitro, but not by relaxant agents in vitro. Together, these results support the hypothesis that VHR during hemorrhagic decompensation involves contractile stimulus-induced long-lasting, intrinsic VSM desensitization.
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Affiliation(s)
- P H Ratz
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia; and
| | - A S Miner
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia; and
| | - Y Huang
- Departments of Emergency Medicine and Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia
| | - C A Smith
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia; and
| | - R W Barbee
- Departments of Emergency Medicine and Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia
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38
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Liu X, Painter RE, Enesa K, Holmes D, Whyte G, Garlisi CG, Monsma FJ, Rehak M, Craig FF, Smith CA. High-throughput screening of antibiotic-resistant bacteria in picodroplets. Lab Chip 2016; 16:1636-43. [PMID: 27033300 DOI: 10.1039/c6lc00180g] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The prevalence of clinically-relevant bacterial strains resistant to current antibiotic therapies is increasing and has been recognized as a major health threat. For example, multidrug-resistant tuberculosis and methicillin-resistant Staphylococcus aureus are of global concern. Novel methodologies are needed to identify new targets or novel compounds unaffected by pre-existing resistance mechanisms. Recently, water-in-oil picodroplets have been used as an alternative to conventional high-throughput methods, especially for phenotypic screening. Here we demonstrate a novel microfluidic-based picodroplet platform which enables high-throughput assessment and isolation of antibiotic-resistant bacteria in a label-free manner. As a proof-of-concept, the system was used to isolate fusidic acid-resistant mutants and estimate the frequency of resistance among a population of Escherichia coli (strain HS151). This approach can be used for rapid screening of rare antibiotic-resistant mutants to help identify novel compound/target pairs.
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Affiliation(s)
- X Liu
- Sphere Fluidics Limited, The Jonas Webb Building, Babraham Research Campus, Babraham, Cambridge, CB22 3AT, UK.
| | - R E Painter
- Merck Research Labs, Merck & Co., Inc., 2015 Galloping Hill Road, K15, Kenilworth, NJ07033, USA
| | - K Enesa
- Sphere Fluidics Limited, The Jonas Webb Building, Babraham Research Campus, Babraham, Cambridge, CB22 3AT, UK.
| | - D Holmes
- Sphere Fluidics Limited, The Jonas Webb Building, Babraham Research Campus, Babraham, Cambridge, CB22 3AT, UK.
| | - G Whyte
- School of Engineering & Physical Sciences, Institute of Biological Chemistry, Biophysics & Bioengineering, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - C G Garlisi
- Merck Research Labs, Merck & Co., Inc., 2015 Galloping Hill Road, K15, Kenilworth, NJ07033, USA
| | - F J Monsma
- Merck Research Labs, Merck & Co., Inc., 2015 Galloping Hill Road, K15, Kenilworth, NJ07033, USA
| | - M Rehak
- Sphere Fluidics Limited, The Jonas Webb Building, Babraham Research Campus, Babraham, Cambridge, CB22 3AT, UK.
| | - F F Craig
- Sphere Fluidics Limited, The Jonas Webb Building, Babraham Research Campus, Babraham, Cambridge, CB22 3AT, UK.
| | - C A Smith
- Sphere Fluidics Limited, The Jonas Webb Building, Babraham Research Campus, Babraham, Cambridge, CB22 3AT, UK.
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Smith CA, Antunes NT, Stewart NK, Frase H, Toth M, Kantardjieff KA, Vakulenko S. Structural Basis for Enhancement of Carbapenemase Activity in the OXA-51 Family of Class D β-Lactamases. ACS Chem Biol 2015; 10:1791-6. [PMID: 26042471 DOI: 10.1021/acschembio.5b00090] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Class D β-lactamases of Acinetobacter baumannii are enzymes of the utmost clinical importance, producing resistance to last resort carbapenem antibiotics. Although the OXA-51-like enzymes constitute the largest family of class D β-lactamases, they are poorly studied and their importance in conferring carbapenem resistance is controversial. We present the detailed microbiological, kinetic, and structural characterization of the eponymous OXA-51 β-lactamase. Kinetic studies show that OXA-51 has low catalytic efficiency for carbapenems, primarily due to the low affinity of the enzyme for these substrates. Structural studies demonstrate that this low affinity results from the obstruction of the enzyme active site by the side chain of Trp222, which presents a transient steric barrier to an incoming carbapenem substrate. The Trp222Met substitution relieves this steric hindrance and elevates the affinity of the mutant enzyme for carbapenems by 10-fold, significantly increasing the levels of resistance to these antibiotics. The ability of OXA-51 to evolve into a robust carbapenemase as the result of a single amino acid substitution may, in the near future, elevate the ubiquitous enzymes of the OXA-51 family to the status of the most deleterious A. baumannii carbapenemases, with dire clinical consequences.
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Affiliation(s)
- Clyde A. Smith
- Stanford
Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California 94025, United States
| | - Nuno Tiago Antunes
- Department
of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Nichole K. Stewart
- Department
of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Hilary Frase
- Department
of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Marta Toth
- Department
of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Katherine A. Kantardjieff
- College
of Science and Mathematics, California State University, San Marcos, California 92078, United States
| | - Sergei Vakulenko
- Department
of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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40
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Terzyan SS, Burgett AWG, Heroux A, Smith CA, Mooers BHM, Hanigan MH. Human γ-Glutamyl Transpeptidase 1: STRUCTURES OF THE FREE ENZYME, INHIBITOR-BOUND TETRAHEDRAL TRANSITION STATES, AND GLUTAMATE-BOUND ENZYME REVEAL NOVEL MOVEMENT WITHIN THE ACTIVE SITE DURING CATALYSIS. J Biol Chem 2015; 290:17576-86. [PMID: 26013825 DOI: 10.1074/jbc.m115.659680] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Indexed: 12/31/2022] Open
Abstract
γ-Glutamyl transpeptidase 1 (GGT1) is a cell surface, N-terminal nucleophile hydrolase that cleaves glutathione and other γ-glutamyl compounds. GGT1 expression is essential in cysteine homeostasis, and its induction has been implicated in the pathology of asthma, reperfusion injury, and cancer. In this study, we report four new crystal structures of human GGT1 (hGGT1) that show conformational changes within the active site as the enzyme progresses from the free enzyme to inhibitor-bound tetrahedral transition states and finally to the glutamate-bound structure prior to the release of this final product of the reaction. The structure of the apoenzyme shows flexibility within the active site. The serine-borate-bound hGGT1 crystal structure demonstrates that serine-borate occupies the active site of the enzyme, resulting in an enzyme-inhibitor complex that replicates the enzyme's tetrahedral intermediate/transition state. The structure of GGsTop-bound hGGT1 reveals its interactions with the enzyme and why neutral phosphonate diesters are more potent inhibitors than monoanionic phosphonates. These structures are the first structures for any eukaryotic GGT that include a molecule in the active site covalently bound to the catalytic Thr-381. The glutamate-bound structure shows the conformation of the enzyme prior to release of the final product and reveals novel information regarding the displacement of the main chain atoms that form the oxyanion hole and movement of the lid loop region when the active site is occupied. These data provide new insights into the mechanism of hGGT1-catalyzed reactions and will be invaluable in the development of new classes of hGGT1 inhibitors for therapeutic use.
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Affiliation(s)
- Simon S Terzyan
- From the Macromolecular Crystallography Laboratory, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Anthony W G Burgett
- the Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019
| | - Annie Heroux
- the Energy Sciences Directorate/Photon Science Division, Brookhaven National Laboratory, Upton, New York 11973
| | - Clyde A Smith
- the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025
| | - Blaine H M Mooers
- the Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, and
| | - Marie H Hanigan
- the Department of Cell Biology, University of Oklahoma Health Sciences Center, Stanton L. Young Biomedical Research Center, Oklahoma City, Oklahoma 73104
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41
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42
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43
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Kim KW, Smith CA, Daily MD, Cort JR, Davin LB, Lewis NG. Trimeric structure of (+)-pinoresinol-forming dirigent protein at 1.95 Å resolution with three isolated active sites. J Biol Chem 2015; 290:1308-18. [PMID: 25411250 PMCID: PMC4340379 DOI: 10.1074/jbc.m114.611780] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 11/11/2014] [Indexed: 11/28/2022] Open
Abstract
Control over phenoxy radical-radical coupling reactions in vivo in vascular plants was enigmatic until our discovery of dirigent proteins (DPs, from the Latin dirigere, to guide or align). The first three-dimensional structure of a DP ((+)-pinoresinol-forming DP, 1.95 Å resolution, rhombohedral space group H32)) is reported herein. It has a tightly packed trimeric structure with an eight-stranded β-barrel topology for each DP monomer. Each putative substrate binding and orientation coupling site is located on the trimer surface but too far apart for intermolecular coupling between sites. It is proposed that each site enables stereoselective coupling (using either two coniferyl alcohol radicals or a radical and a monolignol). Interestingly, there are six differentially conserved residues in DPs affording either the (+)- or (-)-antipodes in the vicinity of the putative binding site and region known to control stereoselectivity. DPs are involved in lignan biosynthesis, whereas dirigent domains/sites have been implicated in lignin deposition.
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Affiliation(s)
- Kye-Won Kim
- From the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340
| | - Clyde A Smith
- the Stanford Synchrotron Radiation Lightsource, Menlo Park, California 94025, and
| | - Michael D Daily
- the Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354
| | - John R Cort
- the Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354
| | - Laurence B Davin
- From the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340
| | - Norman G Lewis
- From the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340,
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44
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Abstract
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Carbapenems are the last resort antibiotics
for treatment of life-threatening
infections. The GES β-lactamases are important contributors
to carbapenem resistance in clinical bacterial pathogens. A single
amino acid difference at position 170 of the GES-1, GES-2, and GES-5
enzymes is responsible for the expansion of their substrate profile
to include carbapenem antibiotics. This highlights the increasing
need to understand the mechanisms by which the GES β-lactamases
function to aid in development of novel therapeutics. We demonstrate
that the catalytic efficiency of the enzymes with carbapenems meropenem,
ertapenem, and doripenem progressively increases (100-fold) from GES-1
to -5, mainly due to an increase in the rate of acylation. The data
reveal that while acylation is rate limiting for GES-1 and GES-2 for
all three carbapenems, acylation and deacylation are indistinguishable
for GES-5. The ertapenem–GES-2 crystal structure shows that
only the core structure of the antibiotic interacts with the active
site of the GES-2 β-lactamase. The identical core structures
of ertapenem, doripenem, and meropenem are likely responsible for
the observed similarities in the kinetics with these carbapenems.
The lack of a methyl group in the core structure of imipenem may provide
a structural rationale for the increase in turnover of this carbapenem
by the GES β-lactamases. Our data also show that in GES-2 an
extensive hydrogen-bonding network between the acyl-enzyme complex
and the active site water attenuates activation of this water molecule,
which results in poor deacylation by this enzyme.
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Affiliation(s)
- Nichole K Stewart
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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45
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Cohen AE, Soltis SM, González A, Aguila L, Alonso-Mori R, Barnes CO, Baxter EL, Brehmer W, Brewster AS, Brunger AT, Calero G, Chang JF, Chollet M, Ehrensberger P, Eriksson TL, Feng Y, Hattne J, Hedman B, Hollenbeck M, Holton JM, Keable S, Kobilka BK, Kovaleva EG, Kruse AC, Lemke HT, Lin G, Lyubimov AY, Manglik A, Mathews II, McPhillips SE, Nelson S, Peters JW, Sauter NK, Smith CA, Song J, Stevenson HP, Tsai Y, Uervirojnangkoorn M, Vinetsky V, Wakatsuki S, Weis WI, Zadvornyy OA, Zeldin OB, Zhu D, Hodgson KO. Goniometer-based femtosecond crystallography with X-ray free electron lasers. Proc Natl Acad Sci U S A 2014; 111:17122-7. [PMID: 25362050 PMCID: PMC4260607 DOI: 10.1073/pnas.1418733111] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The emerging method of femtosecond crystallography (FX) may extend the diffraction resolution accessible from small radiation-sensitive crystals and provides a means to determine catalytically accurate structures of acutely radiation-sensitive metalloenzymes. Automated goniometer-based instrumentation developed for use at the Linac Coherent Light Source enabled efficient and flexible FX experiments to be performed on a variety of sample types. In the case of rod-shaped Cpl hydrogenase crystals, only five crystals and about 30 min of beam time were used to obtain the 125 still diffraction patterns used to produce a 1.6-Å resolution electron density map. For smaller crystals, high-density grids were used to increase sample throughput; 930 myoglobin crystals mounted at random orientation inside 32 grids were exposed, demonstrating the utility of this approach. Screening results from cryocooled crystals of β2-adrenoreceptor and an RNA polymerase II complex indicate the potential to extend the diffraction resolution obtainable from very radiation-sensitive samples beyond that possible with undulator-based synchrotron sources.
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Affiliation(s)
| | | | | | | | | | - Christopher O Barnes
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | | | | | - Aaron S Brewster
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Axel T Brunger
- Molecular and Cellular Physiology, and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305
| | - Guillermo Calero
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | | | | | | | | | | | - Johan Hattne
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | | | | | - James M Holton
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158; and
| | - Stephen Keable
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59715
| | | | | | | | | | - Guowu Lin
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Artem Y Lyubimov
- Molecular and Cellular Physiology, and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305
| | | | | | | | | | - John W Peters
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59715
| | - Nicholas K Sauter
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | | | - Jinhu Song
- Stanford Synchrotron Radiation Lightsource
| | - Hilary P Stevenson
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Yingssu Tsai
- Stanford Synchrotron Radiation Lightsource, Departments of Chemistry
| | - Monarin Uervirojnangkoorn
- Molecular and Cellular Physiology, and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305
| | | | - Soichi Wakatsuki
- Photon Science, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025; Structural Biology, and
| | - William I Weis
- Molecular and Cellular Physiology, and Structural Biology, and
| | - Oleg A Zadvornyy
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59715
| | - Oliver B Zeldin
- Molecular and Cellular Physiology, and Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305
| | | | - Keith O Hodgson
- Stanford Synchrotron Radiation Lightsource, Departments of Chemistry,
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46
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Smith CA, Toth M, Weiss TM, Frase H, Vakulenko SB. Structure of the bifunctional aminoglycoside-resistance enzyme AAC(6')-Ie-APH(2'')-Ia revealed by crystallographic and small-angle X-ray scattering analysis. Acta Crystallogr D Biol Crystallogr 2014; 70:2754-64. [PMID: 25286858 PMCID: PMC4188014 DOI: 10.1107/s1399004714017635] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 07/31/2014] [Indexed: 11/11/2022]
Abstract
Broad-spectrum resistance to aminoglycoside antibiotics in clinically important Gram-positive staphylococcal and enterococcal pathogens is primarily conferred by the bifunctional enzyme AAC(6')-Ie-APH(2'')-Ia. This enzyme possesses an N-terminal coenzyme A-dependent acetyltransferase domain [AAC(6')-Ie] and a C-terminal GTP-dependent phosphotransferase domain [APH(2'')-Ia], and together they produce resistance to almost all known aminoglycosides in clinical use. Despite considerable effort over the last two or more decades, structural details of AAC(6')-Ie-APH(2'')-Ia have remained elusive. In a recent breakthrough, the structure of the isolated C-terminal APH(2'')-Ia enzyme was determined as the binary Mg2GDP complex. Here, the high-resolution structure of the N-terminal AAC(6')-Ie enzyme is reported as a ternary kanamycin/coenzyme A abortive complex. The structure of the full-length bifunctional enzyme has subsequently been elucidated based upon small-angle X-ray scattering data using the two crystallographic models. The AAC(6')-Ie enzyme is joined to APH(2'')-Ia by a short, predominantly rigid linker at the N-terminal end of a long α-helix. This α-helix is in turn intrinsically associated with the N-terminus of APH(2'')-Ia. This structural arrangement supports earlier observations that the presence of the intact α-helix is essential to the activity of both functionalities of the full-length AAC(6')-Ie-APH(2'')-Ia enzyme.
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Affiliation(s)
- Clyde A. Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, CA 94025, USA
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Thomas M. Weiss
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, CA 94025, USA
| | - Hilary Frase
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Sergei B. Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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47
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Smith CA, Richardson SM, Eagle MJ, Rooney P, Board T, Hoyland JA. The use of a novel bone allograft wash process to generate a biocompatible, mechanically stable and osteoinductive biological scaffold for use in bone tissue engineering. J Tissue Eng Regen Med 2014; 9:595-604. [PMID: 24945627 DOI: 10.1002/term.1934] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 04/29/2014] [Accepted: 05/21/2014] [Indexed: 01/02/2023]
Abstract
Fresh-frozen biological allograft remains the most effective substitute for the 'gold standard' autograft, sharing many of its osteogenic properties but, conversely, lacking viable osteogenic cells. Tissue engineering offers the opportunity to improve the osseointegration of this material through the addition of mesenchymal stem cells (MSCs). However, the presence of dead, immunogenic and potentially harmful bone marrow could hinder cell adhesion and differentiation, graft augmentation and incorporation, and wash procedures are therefore being utilized to remove the marrow, thereby improving the material's safety. To this end, we assessed the efficiency of a novel wash technique to produce a biocompatible, biological scaffold void of cellular material that was mechanically stable and had osteoinductive potential. The outcomes of our investigations demonstrated the efficient removal of marrow components (~99.6%), resulting in a biocompatible material with conserved biomechanical stability. Additionally, the scaffold was able to induce osteogenic differentiation of MSCs, with increases in osteogenic gene expression observed following extended culture. This study demonstrates the efficiency of the novel wash process and the potential of the resultant biological material to serve as a scaffold in bone allograft tissue engineering.
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Affiliation(s)
- C A Smith
- Centre for Tissue Injury and Repair, University of Manchester, UK
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48
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Smith CA, Toth M, Bhattacharya M, Frase H, Vakulenko SB. Structure of the phosphotransferase domain of the bifunctional aminoglycoside-resistance enzyme AAC(6')-Ie-APH(2'')-Ia. Acta Crystallogr D Biol Crystallogr 2014; 70:1561-71. [PMID: 24914967 PMCID: PMC4051501 DOI: 10.1107/s1399004714005331] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 03/07/2014] [Indexed: 01/04/2023]
Abstract
The bifunctional acetyltransferase(6')-Ie-phosphotransferase(2'')-Ia [AAC(6')-Ie-APH(2'')-Ia] is the most important aminoglycoside-resistance enzyme in Gram-positive bacteria, conferring resistance to almost all known aminoglycoside antibiotics in clinical use. Owing to its importance, this enzyme has been the focus of intensive research since its isolation in the mid-1980s but, despite much effort, structural details of AAC(6')-Ie-APH(2'')-Ia have remained elusive. The structure of the Mg2GDP complex of the APH(2'')-Ia domain of the bifunctional enzyme has now been determined at 2.3 Å resolution. The structure of APH(2'')-Ia is reminiscent of the structures of other aminoglycoside phosphotransferases, having a two-domain architecture with the nucleotide-binding site located at the junction of the two domains. Unlike the previously characterized APH(2'')-IIa and APH(2'')-IVa enzymes, which are capable of utilizing both ATP and GTP as the phosphate donors, APH(2'')-Ia uses GTP exclusively in the phosphorylation of the aminoglycoside antibiotics, and in this regard closely resembles the GTP-dependent APH(2'')-IIIa enzyme. In APH(2'')-Ia this GTP selectivity is governed by the presence of a `gatekeeper' residue, Tyr100, the side chain of which projects into the active site and effectively blocks access to the adenine-binding template. Mutation of this tyrosine residue to a less bulky phenylalanine provides better access for ATP to the NTP-binding template and converts APH(2'')-Ia into a dual-specificity enzyme.
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Affiliation(s)
- Clyde A. Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, CA 94025, USA
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Monolekha Bhattacharya
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Hilary Frase
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Sergei B. Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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49
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Omotehara T, Smith CA, Mantani Y, Kobayashi Y, Tatsumi A, Nagahara D, Hashimoto R, Hirano T, Umemura Y, Yokoyama T, Kitagawa H, Hoshi N. Spatiotemporal expression patterns of doublesex and mab-3 related transcription factor 1 in the chicken developing gonads and Mullerian ducts. Poult Sci 2014; 93:953-8. [PMID: 24706973 DOI: 10.3382/ps.2013-03672] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Sex of birds is genetically determined by the inheritance of sex chromosomes (ZZ for male and ZW for female), and the Z-linked gene named doublesex and mab-3 related transcription factor 1 (DMRT1) is a candidate sex-determining gene in avian species. However, the mechanisms underlying sex determination in birds are not yet understood, and the expression patterns of the DMRT1 protein in urogenital tissues have not been identified. In the current study, we used immunohistochemistry to investigate the detailed expression patterns of the DMRT1 protein in the urogenital systems (including Müllerian ducts) in male and female chicken embryos throughout embryonic development. Gonadal somatic cells in the male indifferent gonads showed stronger expressions of DMRT1 compared with those in the female indifferent gonads well before the presumptive period of the sex determination, and Sertoli cells forming testicular cords expressed DMRT1 in the testes after sex determination. Germ cells expressed DMRT1 equally in males and females after sex determination. The expression was continuous in males, but in females it gradually disappeared from the germ cells in the central part of the cortex of the left ovary toward both edges. The DMRT1 was also detected in the tubal ridge, which is a precursor of the Müllerian duct, and at the mesenchyme and outermost coelomic epithelium of the Müllerian duct in both sexes. Strong expression was observed in the males, but it was restricted to coelomic epithelium after the regression of the duct started. Thus, we observed the detailed spatiotemporal expression patterns of DMRT1 in the developing chicken urogenital systems throughout embryonic development, suggesting its various roles in the development of urogenital tissues in the chicken embryo.
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Affiliation(s)
- T Omotehara
- Department of Animal Science, Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo 657-8501, Japan
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50
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Levett KM, Smith CA, Dahlen HG, Bensoussan A. Acupuncture and acupressure for pain management in labour and birth: a critical narrative review of current systematic review evidence. Complement Ther Med 2014; 22:523-40. [PMID: 24906592 DOI: 10.1016/j.ctim.2014.03.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 02/27/2014] [Accepted: 03/30/2014] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Reviews of maternity services highlight the need for a reduction of medical interventions for women with low risk pregnancies and births to prevent the potential cascade of interventions and their associated risks. Complementary medicines (CM) such as acupuncture and acupressure have claimed to be effective in reducing interventions in labour; however, systematic reviews of evidence to date are conflicting. AIMS To examine current evidence from systematic reviews on the topic of acupuncture and acupressure for pain management in labour and birth, and to evaluate the methodological and treatment frameworks applied to this evidence. METHODS A search limited to systematic reviews of the MEDLINE, CINAHL, PUBMED, EMBASE and Cochrane databases was performed in December 2013 using the keywords 'CAM', 'alternative medicine', 'complementary medicine', 'complementary therapies', 'traditional medicine', 'Chinese Medicine', 'Traditional Chinese Medicine', 'acupuncture', 'acupressure', cross-referenced with 'childbirth', 'birth', labo*r', and 'delivery'. The quality of the evidence is also evaluated in the context of study design. RESULTS The RCTs included in these systematic reviews differed in terms of study designs, research questions, treatment protocols and outcome measures, and yielded some conflicting results. It may be inappropriate to include these together in a systematic review, or pooled analysis, of acupuncture for labour with an expectation of an overall conclusion for efficacy. Trials of acupuncture and acupressure in labour show promise, but further studies are required. CONCLUSION The use of current systematic reviews of the evidence for acupuncture and acupressure for labour and birth may be misleading. Appropriate methods and outcome measures for investigation of acupuncture and acupressure treatment should more carefully reflect the research question being asked. The use of pragmatic trials designs with woman-centred outcomes may be appropriate for evaluating the effectiveness of these therapies.
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Affiliation(s)
- K M Levett
- National Institute for Complementary Medicine, University of Western Sydney, Penrith, New South Wales, Australia.
| | - C A Smith
- National Institute for Complementary Medicine, University of Western Sydney, Penrith, New South Wales, Australia.
| | - H G Dahlen
- School of Nursing and Midwifery, University of Western Sydney, Penrith, New South Wales, Australia.
| | - A Bensoussan
- National Institute for Complementary Medicine, University of Western Sydney, Penrith, New South Wales, Australia.
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