1
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Synthesis, Characterization, Biological Evaluation, and In Silico Studies of Imidazolium-, Pyridinium-, and Ammonium-Based Ionic Liquids Containing n-Butyl Side Chains. Molecules 2022; 27:molecules27196650. [PMID: 36235187 PMCID: PMC9572234 DOI: 10.3390/molecules27196650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 09/23/2022] [Accepted: 09/26/2022] [Indexed: 11/17/2022] Open
Abstract
Ionic liquids (ILs) have emerged as active pharmaceutical ingredients because of their excellent antibacterial and biological activities. Herein, we used the green-chemistry-synthesis procedure, also known as the metathesis method, to develop three series of ionic liquids using 1-methyl-3-butyl imidazolium, butyl pyridinium, and diethyldibutylammonium as cations, and bromide (Br−), methanesulfonate (CH3SO3−), bis(trifluoromethanesulfonyl)imide (NTf2−), dichloroacetate (CHCl2CO2−), tetrafluoroborate (BF4−), and hydrogen sulfate (HSO4−) as anions. Spectroscopic methods were used to validate the structures of the lab-synthesized ILs. We performed an agar well diffusion assay by using pathogenic bacteria that cause various infections (Escherichia coli; Enterobacter aerogenes; Klebsiella pneumoniae; Proteus vulgaris; Pseudomonas aeruginosa; Streptococcus pneumoniae; Streptococcus pyogenes) to scrutinize the in vitro antibacterial activity of the ILs. It was established that the nature and unique combination of the cations and anions were responsible for the antibacterial activity of the ILs. Among the tested ionic liquids, the imidazolium cation and NTf2− and HSO4− anions exhibited the highest antibacterial activity. The antibacterial potential was further investigated by in silico studies, and it was observed that bis(trifluoromethanesulfonyl)imide (NTf2−) containing imidazolium and pyridinium ionic liquids showed the maximum inhibition against the targeted bacterial strains and could be utilized in antibiotics. These antibacterial activities float the ILs as a promising alternative to the existing antibiotics and antiseptics.
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2
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Hassan R, Asghar MA, Iqbal M, Qaisar A, Habib U, Ahmad B. A comparative evaluation of antibacterial activities of imidazolium-, pyridinium-, and phosphonium-based ionic liquids containing octyl side chains. Heliyon 2022; 8:e09533. [PMID: 35663730 PMCID: PMC9160493 DOI: 10.1016/j.heliyon.2022.e09533] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/14/2022] [Accepted: 05/19/2022] [Indexed: 11/27/2022] Open
Abstract
Antibacterial activity is an essential property of ionic liquids. In this work, a comprehensive study has been performed on the antibacterial activity of ionic liquids to be utilized for further research and applications. Eighteen ionic liquids viz. Octyl Imidazolium, octyl Pyridinium, quaternary phosphonium-based cations containing bromide, sodium methane sulphonates, bis(trifluoromethane sulfonyl) imide, dichloroacetate, tetrafluoroborate, hydrogen sulfate were prepared and characterized with the help of different spectroscopic techniques. All these samples of ionic liquids were tested for their antibacterial activity against the most commonly occurring bacteria in the environment, i.e., Enterobacter aerogenes (E. aerogenes), Proteus vulgaris (P. vulgaris), Klebsiella pneumoniae (K. pneumoniae), Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), and Streptococcus pyogenes (S. pyogenes). Most of the ionic liquids show good antibacterial properties, and imidazolium-based ionic liquids were even more antibacterial as compared to positive control. It was observed that a unique combination of cation and anion is essential to achieve desired antibacterial properties. The mechanism of antibacterial activity was further investigated using density functional theory calculations. A good correlation was found between experimental and theoretical studies.
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Affiliation(s)
- Rabia Hassan
- Department of Chemistry, School of Natural Sciences (SNS), National University of Sciences & Technology (NUST), H-12, Islamabad, 44000, Pakistan
| | - Muhammad Asad Asghar
- Department of Chemistry, School of Natural Sciences (SNS), National University of Sciences & Technology (NUST), H-12, Islamabad, 44000, Pakistan
| | - Mudassir Iqbal
- Department of Chemistry, School of Natural Sciences (SNS), National University of Sciences & Technology (NUST), H-12, Islamabad, 44000, Pakistan
| | - Arshemah Qaisar
- Research Center for Modeling and Simulation (RCMS), National University of Sciences & Technology (NUST), H-12, Islamabad, 44000, Pakistan
| | - Uzma Habib
- Research Center for Modeling and Simulation (RCMS), National University of Sciences & Technology (NUST), H-12, Islamabad, 44000, Pakistan
| | - Bashir Ahmad
- Department of Biological Sciences, International Islamic University, Islamabad, Pakistan
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3
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Ahmadvand P, Avillan JJ, Lewis JA, Call DR, Kang C. Characterization of Interactions between CTX-M-15 and Clavulanic Acid, Desfuroylceftiofur, Ceftiofur, Ampicillin, and Nitrocefin. Int J Mol Sci 2022; 23:ijms23095229. [PMID: 35563620 PMCID: PMC9100253 DOI: 10.3390/ijms23095229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 05/02/2022] [Accepted: 05/03/2022] [Indexed: 11/16/2022] Open
Abstract
Cefotaximase-Munich (CTX-M) extended-spectrum beta-lactamases (ESBLs) are commonly associated with Gram-negative, hospital-acquired infections worldwide. Several beta-lactamase inhibitors, such as clavulanate, are used to inhibit the activity of these enzymes. To understand the mechanism of CTX-M-15 activity, we have determined the crystal structures of CTX-M-15 in complex with two specific classes of beta-lactam compounds, desfuroylceftiofur (DFC) and ampicillin, and an inhibitor, clavulanic acid. The crystal structures revealed that Ser70 and five other residues (Lys73, Tyr105, Glu166, Ser130, and Ser237) participate in catalysis and binding of those compounds. Based on analysis of steady-state kinetics, thermodynamic data, and molecular docking to both wild-type and S70A mutant structures, we determined that CTX-M-15 has a similar affinity for all beta-lactam compounds (ceftiofur, nitrocefin, DFC, and ampicillin), but with lower affinity for clavulanic acid. A catalytic mechanism for tested β-lactams and two-step inhibition mechanism of clavulanic acid were proposed. CTX-M-15 showed a higher activity toward DFC and nitrocefin, but significantly lower activity toward ampicillin and ceftiofur. The interaction between CTX-M-15 and both ampicillin and ceftiofur displayed a higher entropic but lower enthalpic effect, compared with DFC and nitrocefin. DFC, a metabolite of ceftiofur, displayed lower entropy and higher enthalpy than ceftiofur. This finding suggests that compounds containing amine moiety (e.g., ampicillin) and the furfural moiety (e.g., ceftiofur) could hinder the hydrolytic activity of CTX-M-15.
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Affiliation(s)
- Parvaneh Ahmadvand
- Department of Chemistry, Washington State University, Pullman, WA 99164, USA; (P.A.); (J.A.L.)
| | - Johannetsy J. Avillan
- Paul G Allen School for Global Health, Washington State University, Pullman, WA 99164, USA; (J.J.A.); (D.R.C.)
| | - Jacob A. Lewis
- Department of Chemistry, Washington State University, Pullman, WA 99164, USA; (P.A.); (J.A.L.)
| | - Douglas R. Call
- Paul G Allen School for Global Health, Washington State University, Pullman, WA 99164, USA; (J.J.A.); (D.R.C.)
| | - ChulHee Kang
- Department of Chemistry, Washington State University, Pullman, WA 99164, USA; (P.A.); (J.A.L.)
- Correspondence:
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4
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Steinert RM, Kasireddy C, Heikes ME, Mitchell-Koch KR. Newly identified C–H⋯O hydrogen bond in histidine. Phys Chem Chem Phys 2022; 24:19233-19251. [DOI: 10.1039/d2cp02048c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Histidine C–H bonds observed in protein structures include (clockwise from top left): myoglobin, β-lactamase, and photoactive yellow protein; calculations indicate that tautomeric/protonation state influences H-bonding ability (bottom left).
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Affiliation(s)
- Ryan M. Steinert
- Department of Chemistry and Biochemistry, Wichita State University, 1845 Fairmount Street, Wichita, KS 67260-0051, USA
| | - Chandana Kasireddy
- Department of Chemistry and Biochemistry, Wichita State University, 1845 Fairmount Street, Wichita, KS 67260-0051, USA
| | - Micah E. Heikes
- Department of Chemistry and Biochemistry, Wichita State University, 1845 Fairmount Street, Wichita, KS 67260-0051, USA
| | - Katie R. Mitchell-Koch
- Department of Chemistry and Biochemistry, Wichita State University, 1845 Fairmount Street, Wichita, KS 67260-0051, USA
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5
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Song Z, Trozzi F, Palzkill T, Tao P. QM/MM modeling of class A β-lactamases reveals distinct acylation pathways for ampicillin and cefalexin. Org Biomol Chem 2021; 19:9182-9189. [PMID: 34647114 PMCID: PMC8613693 DOI: 10.1039/d1ob01593a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Efficient mechanism-based design of antibiotics that are not susceptible to β-lactamases is hindered by the lack of comprehensive knowledge on the energetic landscapes for the hydrolysis of various β-lactams. Herein, we adopted efficient quantum mechanics/molecular mechanics simulations to explore the acylation reaction catalyzed by CTX-M-44 (Toho-1) β-lactamase. We show that the catalytic pathways for β-lactam hydrolysis are correlated to substrate scaffolds: using Glu166 as the only general base for acylation is viable for ampicillin but prohibitive for cefalexin. The present computational workflow provides quantitative insights to facilitate the optimization of future β-lactam antibiotics.
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Affiliation(s)
- Zilin Song
- Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, Texas 75205, USA.
| | - Francesco Trozzi
- Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, Texas 75205, USA.
| | - Timothy Palzkill
- The Verna and Marrs McLean Department of Biochemistry and Molecular Biology and Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Peng Tao
- Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, Texas 75205, USA.
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6
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Sakhrani VV, Ghosh RK, Hilario E, Weiss KL, Coates L, Mueller LJ. Toho-1 β-lactamase: backbone chemical shift assignments and changes in dynamics upon binding with avibactam. JOURNAL OF BIOMOLECULAR NMR 2021; 75:303-318. [PMID: 34218390 PMCID: PMC9122098 DOI: 10.1007/s10858-021-00375-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 06/23/2021] [Indexed: 06/13/2023]
Abstract
Backbone chemical shift assignments for the Toho-1 β-lactamase (263 amino acids, 28.9 kDa) are reported based on triple resonance solution-state NMR experiments performed on a uniformly 2H,13C,15N-labeled sample. These assignments allow for subsequent site-specific characterization at the chemical, structural, and dynamical levels. At the chemical level, titration with the non-β-lactam β-lactamase inhibitor avibactam is found to give chemical shift perturbations indicative of tight covalent binding that allow for mapping of the inhibitor binding site. At the structural level, protein secondary structure is predicted based on the backbone chemical shifts and protein residue sequence using TALOS-N and found to agree well with structural characterization from X-ray crystallography. At the dynamical level, model-free analysis of 15N relaxation data at a single field of 16.4 T reveals well-ordered structures for the ligand-free and avibactam-bound enzymes with generalized order parameters of ~ 0.85. Complementary relaxation dispersion experiments indicate that there is an escalation in motions on the millisecond timescale in the vicinity of the active site upon substrate binding. The combination of high rigidity on short timescales and active site flexibility on longer timescales is consistent with hypotheses for achieving both high catalytic efficiency and broad substrate specificity: the induced active site dynamics allows variously sized substrates to be accommodated and increases the probability that the optimal conformation for catalysis will be sampled.
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Affiliation(s)
- Varun V Sakhrani
- Department of Chemistry, University of California Riverside, Riverside, CA, 92521, USA
| | - Rittik K Ghosh
- Department of Biochemistry, University of California Riverside, Riverside, CA, 92521, USA
| | - Eduardo Hilario
- Department of Chemistry, University of California Riverside, Riverside, CA, 92521, USA
| | - Kevin L Weiss
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37831, USA
| | - Leighton Coates
- Second Target Station, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37831, USA.
| | - Leonard J Mueller
- Department of Chemistry, University of California Riverside, Riverside, CA, 92521, USA.
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7
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Bahr G, González LJ, Vila AJ. Metallo-β-lactamases in the Age of Multidrug Resistance: From Structure and Mechanism to Evolution, Dissemination, and Inhibitor Design. Chem Rev 2021; 121:7957-8094. [PMID: 34129337 PMCID: PMC9062786 DOI: 10.1021/acs.chemrev.1c00138] [Citation(s) in RCA: 96] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Antimicrobial resistance is one of the major problems in current practical medicine. The spread of genes coding for resistance determinants among bacteria challenges the use of approved antibiotics, narrowing the options for treatment. Resistance to carbapenems, last resort antibiotics, is a major concern. Metallo-β-lactamases (MBLs) hydrolyze carbapenems, penicillins, and cephalosporins, becoming central to this problem. These enzymes diverge with respect to serine-β-lactamases by exhibiting a different fold, active site, and catalytic features. Elucidating their catalytic mechanism has been a big challenge in the field that has limited the development of useful inhibitors. This review covers exhaustively the details of the active-site chemistries, the diversity of MBL alleles, the catalytic mechanism against different substrates, and how this information has helped developing inhibitors. We also discuss here different aspects critical to understand the success of MBLs in conferring resistance: the molecular determinants of their dissemination, their cell physiology, from the biogenesis to the processing involved in the transit to the periplasm, and the uptake of the Zn(II) ions upon metal starvation conditions, such as those encountered during an infection. In this regard, the chemical, biochemical and microbiological aspects provide an integrative view of the current knowledge of MBLs.
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Affiliation(s)
- Guillermo Bahr
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Universidad Nacional de Rosario, Ocampo y Esmeralda S/N, 2000 Rosario, Argentina
- Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
| | - Lisandro J. González
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Universidad Nacional de Rosario, Ocampo y Esmeralda S/N, 2000 Rosario, Argentina
- Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
| | - Alejandro J. Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Universidad Nacional de Rosario, Ocampo y Esmeralda S/N, 2000 Rosario, Argentina
- Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
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8
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Lizana I, Uribe EA, Delgado EJ. A theoretical approach for the acylation/deacylation mechanisms of avibactam in the reversible inhibition of KPC-2. J Comput Aided Mol Des 2021; 35:943-952. [PMID: 34236545 PMCID: PMC8264174 DOI: 10.1007/s10822-021-00408-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 06/30/2021] [Indexed: 11/28/2022]
Abstract
Klebsiella pneumoniae carbapenemase (KPC-2) is the most commonly encountered class A β-lactamase variant worldwide, which confer high-level resistance to most available antibiotics. In this article we address the issue by a combined approach involving molecular dynamics simulations and hybrid quantum mechanics/molecular mechanics calculations. The study contributes to improve the understanding, at molecular level, of the acylation and deacylation stages of avibactam involved in the inhibition of KPC-2. The results show that both mechanisms, acylation and deacylation, the reaction occur via the formation of a tetrahedral intermediate. The formation of this intermediate corresponds to the rate limiting stage. The activation barriers are 19.5 kcal/mol and 23.0 kcal/mol for the acylation and deacylation stages, respectively. The associated rate constants calculated, using the Eyring equation, are 1.2 × 10−1 and 3.9 × 10−4 (s−1). These values allow estimating a value of 3.3 × 10−3 for the inhibition constant, in good agreement with the experimental value.
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Affiliation(s)
- Ignacio Lizana
- Grupo QTC, Departamento de Físico-Química, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile.,Millennium Nucleus on Catalytic Processes Towards Sustainable Chemistry, 4070386, Santiago, Chile
| | - Elena A Uribe
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Eduardo J Delgado
- Grupo QTC, Departamento de Físico-Química, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile. .,Millennium Nucleus on Catalytic Processes Towards Sustainable Chemistry, 4070386, Santiago, Chile.
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9
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Soeung V, Lu S, Hu L, Judge A, Sankaran B, Prasad BVV, Palzkill T. A drug-resistant β-lactamase variant changes the conformation of its active-site proton shuttle to alter substrate specificity and inhibitor potency. J Biol Chem 2020; 295:18239-18255. [PMID: 33109613 DOI: 10.1074/jbc.ra120.016103] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/22/2020] [Indexed: 11/06/2022] Open
Abstract
Lys234 is one of the residues present in class A β-lactamases that is under selective pressure due to antibiotic use. Located adjacent to proton shuttle residue Ser130, it is suggested to play a role in proton transfer during catalysis of the antibiotics. The mechanism underpinning how substitutions in this position modulate inhibitor efficiency and substrate specificity leading to drug resistance is unclear. The K234R substitution identified in several inhibitor-resistant β-lactamase variants is associated with decreased potency of the inhibitor clavulanic acid, which is used in combination with amoxicillin to overcome β-lactamase-mediated antibiotic resistance. Here we show that for CTX-M-14 β-lactamase, whereas Lys234 is required for hydrolysis of cephalosporins such as cefotaxime, either lysine or arginine is sufficient for hydrolysis of ampicillin. Further, by determining the acylation and deacylation rates for cefotaxime hydrolysis, we show that both rates are fast, and neither is rate-limiting. The K234R substitution causes a 1500-fold decrease in the cefotaxime acylation rate but a 5-fold increase in kcat for ampicillin, suggesting that the K234R enzyme is a good penicillinase but a poor cephalosporinase due to slow acylation. Structural results suggest that the slow acylation by the K234R enzyme is due to a conformational change in Ser130, and this change also leads to decreased inhibition potency of clavulanic acid. Because other inhibitor resistance mutations also act through changes at Ser130 and such changes drastically reduce cephalosporin but not penicillin hydrolysis, we suggest that clavulanic acid paired with an oxyimino-cephalosporin rather than penicillin would impede the evolution of resistance.
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Affiliation(s)
- Victoria Soeung
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Shuo Lu
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Liya Hu
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Allison Judge
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Banumathi Sankaran
- Department of Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - B V Venkataram Prasad
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA; Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Timothy Palzkill
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA; Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA; Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA.
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10
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Kneller DW, Phillips G, Kovalevsky A, Coates L. Room-temperature neutron and X-ray data collection of 3CL M pro from SARS-CoV-2. Acta Crystallogr F Struct Biol Commun 2020; 76:483-487. [PMID: 33006576 PMCID: PMC7531248 DOI: 10.1107/s2053230x20011814] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 08/27/2020] [Indexed: 01/16/2023] Open
Abstract
The replication of SARS-CoV-2 produces two large polyproteins, pp1a and pp1ab, that are inactive until cleavage by the viral chymotrypsin-like cysteine protease enzyme (3CL Mpro) into a series of smaller functional proteins. At the heart of 3CL Mpro is an unusual catalytic dyad formed by the side chains of His41 and Cys145 and a coordinated water molecule. The catalytic mechanism by which the enzyme operates is still unknown, as crucial information on the protonation states within the active site is unclear. To experimentally determine the protonation states of the catalytic site and of the other residues in the substrate-binding cavity, and to visualize the hydrogen-bonding networks throughout the enzyme, room-temperature neutron and X-ray data were collected from a large H/D-exchanged crystal of ligand-free (apo) 3CL Mpro.
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Affiliation(s)
- Daniel W. Kneller
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
- National Virtual Biotechnology Laboratory, US Department of Energy, USA
| | - Gwyndalyn Phillips
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
- National Virtual Biotechnology Laboratory, US Department of Energy, USA
| | - Andrey Kovalevsky
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
- National Virtual Biotechnology Laboratory, US Department of Energy, USA
| | - Leighton Coates
- National Virtual Biotechnology Laboratory, US Department of Energy, USA
- Second Target Station, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37830, USA
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11
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He Y, Lei J, Pan X, Huang X, Zhao Y. The hydrolytic water molecule of Class A β-lactamase relies on the acyl-enzyme intermediate ES* for proper coordination and catalysis. Sci Rep 2020; 10:10205. [PMID: 32576842 PMCID: PMC7311446 DOI: 10.1038/s41598-020-66431-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 01/06/2020] [Indexed: 11/16/2022] Open
Abstract
Serine-based β-lactamases of Class A, C and D all rely on a key water molecule to hydrolyze and inactivate β-lactam antibiotics. This process involves two conserved catalytic steps. In the first acylation step, the β-lactam antibiotic forms an acyl-enzyme intermediate (ES*) with the catalytic serine residue. In the second deacylation step, an activated water molecule serves as nucleophile (WAT_Nu) to attack ES* and release the inactivated β-lactam. The coordination and activation of WAT_Nu is not fully understood. Using time-resolved x-ray crystallography and QM/MM simulations, we analyzed three intermediate structures of Class A β-lactamase PenP as it slowly hydrolyzed cephaloridine. WAT_Nu is centrally located in the apo structure but becomes slightly displaced away by ES* in the post-acylation structure. In the deacylation structure, WAT_Nu moves back and is positioned along the Bürgi–Dunitz trajectory with favorable energetic profile to attack ES*. Unexpectedly, WAT_Nu is also found to adopt a catalytically incompetent conformation in the deacylation structure forming a hydrogen bond with ES*. Our results reveal that ES* plays a significant role in coordinating and activating WAT_Nu through subtle yet distinct interactions at different stages of the catalytic process. These interactions may serve as potential targets to circumvent β-lactamase-mediated antibiotic resistance.
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Affiliation(s)
- Yunjiao He
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, P. R. China.,Department of Applied Biology and Chemical Technology, State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
| | - Jinping Lei
- Department of Chemistry, Center of Systems Biology and Human Health, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China.,School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, P. R. China
| | - Xuehua Pan
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, P. R. China.,Department of Applied Biology and Chemical Technology, State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
| | - Xuhui Huang
- Department of Chemistry, Center of Systems Biology and Human Health, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China.
| | - Yanxiang Zhao
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, P. R. China. .,Department of Applied Biology and Chemical Technology, State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China.
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12
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Cheng Q, Xu C, Chai J, Zhang R, Wai chi Chan E, Chen S. Structural Insight into the Mechanism of Inhibitor Resistance in CTX-M-199, a CTX-M-64 Variant Carrying the S 130T Substitution. ACS Infect Dis 2020; 6:577-587. [PMID: 31709791 DOI: 10.1021/acsinfecdis.9b00345] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The smart design of β-lactamase inhibitors allowed us to combat extended-spectrum β-lactamase (ESBL)-producing organisms for many years without developing resistance to these inhibitors. However, novel resistant variants have emerged recently, and notable examples are the CTX-M-190 and CTX-M-199 variants, which carried a S130T amino acid substitution and exhibited resistance to inhibitors such as sulbactam and tazobactam. Using mass spectrometric and crystallographic approaches, this study depicted the mechanisms of inhibitor resistance. Our data showed that CTX-M-64 (S130T) did not cause any conformational change or exert any effect on its ability to hydrolyze β-lactam substrates. However, binding of sulbactam, but not clavulanic acid, to the active site of CTX-M-64 (S130T) led to the conformational changes in such active site, which comprised the key residues involved in substrate catalysis, namely, Thr130, Lys73, Lys234, Asn104, and Asn132. This conformational change weakened the binding of the sulbactam trans-enamine intermediate (TSL) to the active site and rendered the formation of the inhibitor-enzyme complex, which features a covalent acrylic acid (AKR)-T130 bond, inefficient, thereby resulting in inhibitor resistance in CTX-M-64 (S130T). Understanding the mechanisms of inhibitor resistance provided structural insight for the future development of new inhibitors against inhibitor-resistant β-lactamases.
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Affiliation(s)
- Qipeng Cheng
- State Key Lab of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Chen Xu
- State Key Lab of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Jiachang Chai
- Department of Clinical Medicine, Second Affiliated Hospital of Zhejiang University, Hangzhou 310009, China
| | - Rong Zhang
- Department of Clinical Medicine, Second Affiliated Hospital of Zhejiang University, Hangzhou 310009, China
| | - Edward Wai chi Chan
- State Key Lab of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Sheng Chen
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong
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13
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Coates L. Ion permeation in potassium ion channels. Acta Crystallogr D Struct Biol 2020; 76:326-331. [PMID: 32254056 PMCID: PMC7137105 DOI: 10.1107/s2059798320003599] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 03/10/2020] [Indexed: 11/11/2022] Open
Abstract
The study of ion channels dates back to the 1950s and the groundbreaking electrophysiology work of Hodgin and Huxley, who used giant squid axons to probe how action potentials in neurons were initiated and propagated. More recently, several experiments using different structural biology techniques and approaches have been conducted to try to understand how potassium ions permeate through the selectivity filter of potassium ion channels. Two mechanisms of permeation have been proposed, and each of the two mechanisms is supported by different experiments. The key structural biology experiments conducted so far to try to understand how ion permeation takes place in potassium ion channels are reviewed and discussed. Protein crystallography has made, and continues to make, key contributions in this field, often through the use of anomalous scattering. Other structural biology techniques used to study the contents of the selectivity filter include solid-state nuclear magnetic resonance and two-dimensional infrared spectroscopy, both of which make clever use of isotopic labeling techniques, while molecular-dynamics simulations of ion flow through the selectivity filter have been enabled by the growing number of potassium ion channel structures deposited in the Protein Data Bank.
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Affiliation(s)
- Leighton Coates
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
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14
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Mechanism of proton transfer in class A β-lactamase catalysis and inhibition by avibactam. Proc Natl Acad Sci U S A 2020; 117:5818-5825. [PMID: 32123084 DOI: 10.1073/pnas.1922203117] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Gram-negative bacteria expressing class A β-lactamases pose a serious health threat due to their ability to inactivate all β-lactam antibiotics. The acyl-enzyme intermediate is a central milestone in the hydrolysis reaction catalyzed by these enzymes. However, the protonation states of the catalytic residues in this complex have never been fully analyzed experimentally due to inherent difficulties. To help unravel the ambiguity surrounding class A β-lactamase catalysis, we have used ultrahigh-resolution X-ray crystallography and the recently approved β-lactamase inhibitor avibactam to trap the acyl-enzyme complex of class A β-lactamase CTX-M-14 at varying pHs. A 0.83-Å-resolution CTX-M-14 complex structure at pH 7.9 revealed a neutral state for both Lys73 and Glu166. Furthermore, the avibactam hydroxylamine-O-sulfonate group conformation varied according to pH, and this conformational switch appeared to correspond to a change in the Lys73 protonation state at low pH. In conjunction with computational analyses, our structures suggest that Lys73 has a perturbed acid dissociation constant (pKa) compared with acyl-enzyme complexes with β-lactams, hindering its function to deprotonate Glu166 and the initiation of the deacylation reaction. Further NMR analysis demonstrated Lys73 pKa to be ∼5.2 to 5.6. Together with previous ultrahigh-resolution crystal structures, these findings enable us to follow the proton transfer process of the entire acylation reaction and reveal the critical role of Lys73. They also shed light on the stability and reversibility of the avibactam carbamoyl acyl-enzyme complex, highlighting the effect of substrate functional groups in influencing the protonation states of catalytic residues and subsequently the progression of the reaction.
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15
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β-Lactamase of Mycobacterium tuberculosis Shows Dynamics in the Active Site That Increase upon Inhibitor Binding. Antimicrob Agents Chemother 2020; 64:AAC.02025-19. [PMID: 31871087 DOI: 10.1128/aac.02025-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 12/19/2019] [Indexed: 12/11/2022] Open
Abstract
The Mycobacterium tuberculosis β-lactamase BlaC is a broad-spectrum β-lactamase that can convert a range of β-lactam antibiotics. Enzymes with low specificity are expected to exhibit active-site flexibility. To probe the motions in BlaC, we studied the dynamic behavior in solution using nuclear magnetic resonance (NMR) spectroscopy. 15N relaxation experiments show that BlaC is mostly rigid on the pico- to nanosecond timescale. Saturation transfer experiments indicate that also on the high-millisecond timescale BlaC is not dynamic. Using relaxation dispersion experiments, clear evidence was obtained for dynamics in the low-millisecond range, with an exchange rate of ca. 860 s-1 The dynamic amide groups are localized in the active site. Upon formation of an adduct with the inhibitor avibactam, extensive line broadening occurs, indicating an increase in magnitude of the active-site dynamics. Furthermore, the rate of the motions increases significantly. Upon reaction with the inhibitor clavulanic acid, similar line broadening is accompanied by duplication of NMR signals, indicative of at least one additional, slower exchange process (exchange rate, k ex, of <100 s-1), while for this inhibitor also loss of pico- to nanosecond timescale rigidity is observed for some amides in the α domain. Possible sources of the observed dynamics, such as motions in the omega loop and rearrangements of active-site residues, are discussed. The increase in dynamics upon ligand binding argues against a model of inhibitor binding through conformational selection. Rather, the induced dynamics may serve to maximize the likelihood of sampling the optimal conformation for hydrolysis of the bound ligand.
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16
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Langan PS, Sullivan B, Weiss KL, Coates L. Probing the role of the conserved residue Glu166 in a class A β-lactamase using neutron and X-ray protein crystallography. Acta Crystallogr D Struct Biol 2020; 76:118-123. [PMID: 32038042 PMCID: PMC7008513 DOI: 10.1107/s2059798319016334] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 12/03/2019] [Indexed: 11/10/2022] Open
Abstract
The amino-acid sequence of the Toho-1 β-lactamase contains several conserved residues in the active site, including Ser70, Lys73, Ser130 and Glu166, some of which coordinate a catalytic water molecule. This catalytic water molecule is essential in the acylation and deacylation parts of the reaction mechanism through which Toho-1 inactivates specific antibiotics and provides resistance to its expressing bacterial strains. To investigate the function of Glu166 in the acylation part of the catalytic mechanism, neutron and X-ray crystallographic studies were performed on a Glu166Gln mutant. The structure of this class A β-lactamase mutant provides several insights into its previously reported reduced drug-binding kinetic rates. A joint refinement of both X-ray and neutron diffraction data was used to study the effects of the Glu166Gln mutation on the active site of Toho-1. This structure reveals that while the Glu166Gln mutation has a somewhat limited impact on the positions of the conserved amino acids within the active site, it displaces the catalytic water molecule from the active site. These subtle changes offer a structural explanation for the previously observed decreases in the binding of non-β-lactam inhibitors such as the recently developed diazobicyclooctane inhibitor avibactam.
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Affiliation(s)
- Patricia S. Langan
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Brendan Sullivan
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Kevin L. Weiss
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Leighton Coates
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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17
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18
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Dynamical Behavior of β-Lactamases and Penicillin- Binding Proteins in Different Functional States and Its Potential Role in Evolution. ENTROPY 2019. [PMCID: PMC7514474 DOI: 10.3390/e21111130] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
β-Lactamases are enzymes produced by bacteria to hydrolyze β-lactam-based antibiotics, and pose serious threat to public health through related antibiotic resistance. Class A β-lactamases are structurally and functionally related to penicillin-binding proteins (PBPs). Despite the extensive studies of the structures, catalytic mechanisms and dynamics of both β-lactamases and PBPs, the potentially different dynamical behaviors of these proteins in different functional states still remain elusive in general. In this study, four evolutionarily related proteins, including TEM-1 and TOHO-1 as class A β-lactamases, PBP-A and DD-transpeptidase as two PBPs, are subjected to molecular dynamics simulations and various analyses to characterize their dynamical behaviors in different functional states. Penicillin G and its ring opening product serve as common ligands for these four proteins of interest. The dynamic analyses of overall structures, the active sites with penicillin G, and three catalytically important residues commonly shared by all four proteins reveal unexpected cross similarities between Class A β-lactamases and PBPs. These findings shed light on both the hidden relations among dynamical behaviors of these proteins and the functional and evolutionary relations among class A β-lactamases and PBPs.
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19
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Structural Insights into the Inhibition of the Extended-Spectrum β-Lactamase PER-2 by Avibactam. Antimicrob Agents Chemother 2019; 63:AAC.00487-19. [PMID: 31235626 DOI: 10.1128/aac.00487-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 06/17/2019] [Indexed: 02/07/2023] Open
Abstract
The diazabicyclooctane (DBO) avibactam (AVI) reversibly inactivates most serine-β-lactamases. Previous investigations showed that inhibition constants of AVI toward class A PER-2 are reminiscent of values observed for class C and D β-lactamases (i.e., k 2/K of ≈103 M-1 s-1) but lower than other class A β-lactamases (i.e., k 2/K = 104 to 105 M-1 s-1). Herein, biochemical and structural studies were conducted with PER-2 and AVI to explore these differences. Furthermore, biochemical studies on Arg220 and Thr237 variants with AVI were conducted to gain deeper insight into the mechanism of PER-2 inactivation. The main biochemical and structural observations revealed the following: (i) both amino-acid substitutions in Arg220 and the rich hydrophobic content in the active site hinder the binding of catalytic waters and acylation, impairing AVI inhibition; (ii) movement of Ser130 upon binding of AVI favors the formation of a hydrogen bond with the sulfate group of AVI; and (iii) the Thr237Ala substitution alters the AVI inhibition constants. The acylation constant (k 2/K) of PER-2 by AVI is primarily influenced by stabilizing hydrogen bonds involving AVI and important residues such as Thr237 and Arg220. (Variants in Arg220 demonstrate a dramatic reduction in k 2/K) We also observed that displacement of Ser130 side chain impairs AVI acylation, an observation not made in other extended-spectrum β-lactamases (ESBLs). Comparatively, relebactam combined with a β-lactam is more potent against Escherichia coli producing PER-2 variants than β-lactam-AVI combinations. Our findings provide a rationale for evaluating the utility of the currently available DBO inhibitors against unique ESBLs like PER-2 and anticipate the effectiveness of these inhibitors toward variants that may eventually be selected upon AVI usage.
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20
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Moural TW, White DSD, Choy CJ, Kang C, Berkman CE. Crystal Structure of Phosphoserine BlaC from Mycobacterium tuberculosis Inactivated by Bis(Benzoyl) Phosphate. Int J Mol Sci 2019; 20:E3247. [PMID: 31269656 PMCID: PMC6650796 DOI: 10.3390/ijms20133247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 06/28/2019] [Accepted: 06/29/2019] [Indexed: 11/16/2022] Open
Abstract
Mycobacterium tuberculosis, the pathogen responsible for tuberculosis (TB), is the leading cause of death from infectious disease worldwide. The class A serine β-lactamase BlaC confers Mycobacterium tuberculosis resistance to conventional β-lactam antibiotics. As the primary mechanism of bacterial resistance to β-lactam antibiotics, the expression of a β-lactamase by Mycobacterium tuberculosis results in hydrolysis of the β-lactam ring and deactivation of these antibiotics. In this study, we conducted protein X-ray crystallographic analysis of the inactivation of BlaC, upon exposure to the inhibitor bis(benzoyl) phosphate. Crystal structure data confirms that serine β-lactamase is phosphorylated at the catalytic serine residue (Ser-70) by this phosphate-based inactivator. This new crystallographic evidence suggests a mechanism for phosphorylation of BlaC inhibition by bis(benzoyl) phosphate over acylation. Additionally, we confirmed that bis(benzoyl) phosphate inactivated BlaC in a time-dependent manner.
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Affiliation(s)
- Timothy W Moural
- Department of Chemistry, Washington State University, Pullman, WA 99164, USA
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
| | | | - Cindy J Choy
- Department of Chemistry, Washington State University, Pullman, WA 99164, USA
| | - Chulhee Kang
- Department of Chemistry, Washington State University, Pullman, WA 99164, USA.
| | - Clifford E Berkman
- Department of Chemistry, Washington State University, Pullman, WA 99164, USA.
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21
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Srivastava SK, King KS, AbuSara NF, Malayny CJ, Piercey BM, Wilson JA, Tahlan K. In vivo functional analysis of a class A β-lactamase-related protein essential for clavulanic acid biosynthesis in Streptomyces clavuligerus. PLoS One 2019; 14:e0215960. [PMID: 31013337 PMCID: PMC6478378 DOI: 10.1371/journal.pone.0215960] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 04/12/2019] [Indexed: 11/23/2022] Open
Abstract
In Streptomyces clavuligerus, the gene cluster involved in the biosynthesis of the clinically used β-lactamase inhibitor clavulanic acid contains a gene (orf12 or cpe) encoding a protein with a C-terminal class A β-lactamase-like domain. The cpe gene is essential for clavulanic acid production, and the recent crystal structure of its product (Cpe) was shown to also contain an N-terminal isomerase/cyclase-like domain, but the function of the protein remains unknown. In the current study, we show that Cpe is a cytoplasmic protein and that both its N- and C-terminal domains are required for in vivo clavulanic acid production in S. clavuligerus. Our results along with those from previous studies allude towards a biosynthetic role for Cpe during the later stages of clavulanic acid production in S. clavuligerus. Amino acids from Cpe essential for biosynthesis were also identified, including one (Lys89) from the recently described N-terminal isomerase-like domain of unknown function. Homologues of Cpe from other clavulanic acid-producing Streptomyces spp. were shown to be functionally equivalent to the S. clavuligerus protein, whereas those from non-producers containing clavulanic acid-like gene clusters were not. The suggested in vivo involvement of an isomerase-like domain recruited by an ancestral β-lactamase related protein, supports a previous hypothesis that Cpe could be involved in a step requiring the opening and modification of the clavulanic acid core during its biosynthesis from 5S precursors.
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Affiliation(s)
| | - Kelcey S. King
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Nader F. AbuSara
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Chelsea J. Malayny
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Brandon M. Piercey
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Jaime A. Wilson
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Kapil Tahlan
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
- * E-mail:
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22
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Lizana I, Delgado EJ. Molecular Insights on the Release of Avibactam from the Acyl-Enzyme Complex. Biophys J 2019; 116:1650-1657. [PMID: 31010666 DOI: 10.1016/j.bpj.2019.03.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 02/13/2019] [Accepted: 03/06/2019] [Indexed: 02/06/2023] Open
Abstract
Avibactam is a non-β-lactam β-lactamase inhibitor for treating complicated urinary tract and respiratory infections caused by multidrug-resistant bacterial pathogens, a serious public health threat. Despite its importance, the release mechanism of avibactam from the enzyme-inhibitor complex has been scarcely studied from first principles, considering the total protein environment. This information at the molecular level is essential for the rational design of new antibiotics and inhibitors. In this article, we addressed the release of avibactam from the complex CTX-M-15 by means of molecular dynamics simulations and quantum mechanics/molecular mechanics calculations. This study provides molecular information not available earlier, including exploration of the potential energy surfaces, characterization of the observed intermediate, and their critical points, as well. Our results show that unlike that observed in the acylation reaction, the residues Glu166 and Lys73 would be in their neutral forms. Release of avibactam follows a stepwise mechanism in which the first stage corresponds to the formation of a tetrahedral intermediate, whereas the second stage corresponds to the cleavage of the Ser70-C7 bond, mediated by Lys73, either directly or through Ser130.
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Affiliation(s)
- Ignacio Lizana
- Departament of Physical Chemistry, Universidad de Concepción, Concepción, Chile
| | - Eduardo J Delgado
- Departament of Physical Chemistry, Universidad de Concepción, Concepción, Chile; Millenium Nucleus on Catalytic Processes toward Sustainable Chemistry, Santiago, Chile.
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23
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Yano N, Yamada T, Hosoya T, Ohhara T, Tanaka I, Niimura N, Kusaka K. Status of the neutron time-of-flight single-crystal diffraction data-processing software STARGazer. Acta Crystallogr D Struct Biol 2018; 74:1041-1052. [PMID: 30387763 PMCID: PMC6213574 DOI: 10.1107/s2059798318012081] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 08/24/2018] [Indexed: 11/10/2022] Open
Abstract
The STARGazer data-processing software is used for neutron time-of-flight (TOF) single-crystal diffraction data collected using the IBARAKI Biological Crystal Diffractometer (iBIX) at the Japan Proton Accelerator Research Complex (J-PARC). This software creates hkl intensity data from three-dimensional (x, y, TOF) diffraction data. STARGazer is composed of a data-processing component and a data-visualization component. The former is used to calculate the hkl intensity data. The latter displays the three-dimensional diffraction data with searched or predicted peak positions and is used to determine and confirm integration regions. STARGazer has been developed to make it easier to use and to obtain more accurate intensity data. For example, a profile-fitting method for peak integration was developed and the data statistics were improved. STARGazer and its manual, containing installation and data-processing components, have been prepared and provided to iBIX users. This article describes the status of the STARGazer data-processing software and its data-processing algorithms.
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Affiliation(s)
- Naomine Yano
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Taro Yamada
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Takaaki Hosoya
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
- College of Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan
| | - Takashi Ohhara
- Neutron Science Section, J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Ibaraki 319-1195, Japan
| | - Ichiro Tanaka
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
- College of Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan
| | - Nobuo Niimura
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Katsuhiro Kusaka
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
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24
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The Neutron Macromolecular Crystallography Instruments at Oak Ridge National Laboratory: Advances, Challenges, and Opportunities. CRYSTALS 2018. [DOI: 10.3390/cryst8100388] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The IMAGINE and MaNDi instruments, located at Oak Ridge National Laboratory High Flux Isotope Reactor and Spallation Neutron Source, respectively, are powerful tools for determining the positions of hydrogen atoms in biological macromolecules and their ligands, orienting water molecules, and for differentiating chemical states in macromolecular structures. The possibility to model hydrogen and deuterium atoms in neutron structures arises from the strong interaction of neutrons with the nuclei of these isotopes. Positions can be unambiguously assigned from diffraction studies at the 1.5–2.5 Å resolutions, which are typical for protein crystals. Neutrons have the additional benefit for structural biology of not inducing radiation damage to protein crystals, which can be critical in the study of metalloproteins. Here we review the specifications of the IMAGINE and MaNDi beamlines and illustrate their complementarity. IMAGINE is suitable for crystals with unit cell edges up to 150 Å using a quasi-Laue technique, whereas MaNDi provides neutron crystallography resources for large unit cell samples with unit cell edges up to 300 Å using the time of flight (TOF) Laue technique. The microbial culture and crystal growth facilities which support the IMAGINE and MaNDi user programs are also described.
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25
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Patel MP, Hu L, Brown CA, Sun Z, Adamski CJ, Stojanoski V, Sankaran B, Prasad BVV, Palzkill T. Synergistic effects of functionally distinct substitutions in β-lactamase variants shed light on the evolution of bacterial drug resistance. J Biol Chem 2018; 293:17971-17984. [PMID: 30275013 DOI: 10.1074/jbc.ra118.003792] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 09/26/2018] [Indexed: 11/06/2022] Open
Abstract
The CTX-M β-lactamases have emerged as the most widespread extended-spectrum β-lactamases (ESBLs) in Gram-negative bacteria. These enzymes rapidly hydrolyze cefotaxime, but not the related cephalosporin, ceftazidime. ESBL variants have evolved, however, that provide enhanced ceftazidime resistance. We show here that a natural variant at a nonactive site, i.e. second-shell residue N106S, enhances enzyme stability but reduces catalytic efficiency for cefotaxime and ceftazidime and decreases resistance levels. However, when the N106S variant was combined with an active-site variant, D240G, that enhances enzyme catalytic efficiency, but decreases stability, the resultant double mutant exhibited higher resistance levels than predicted on the basis of the phenotypes of each variant. We found that this epistasis is due to compensatory effects, whereby increased stability provided by N106S overrides its cost of decreased catalytic activity. X-ray structures of the variant enzymes in complex with cefotaxime revealed conformational changes in the active-site loop spanning residues 103-106 that were caused by the N106S substitution and relieve steric strain to stabilize the enzyme, but also alter contacts with cefotaxime and thereby reduce catalytic activity. We noted that the 103-106 loop conformation in the N106S-containing variants is different from that of WT CTX-M but nearly identical to that of the non-ESBL, TEM-1 β-lactamase, having a serine at the 106 position. Therefore, residue 106 may serve as a "switch" that toggles the conformations of the 103-106 loop. When it is serine, the loop is in the non-ESBL, TEM-like conformation, and when it is asparagine, the loop is in a CTX-M-like, cefotaximase-favorable conformation.
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Affiliation(s)
- Meha P Patel
- From the Interdepartmental Graduate Program in Translational Biology and Molecular Medicine; Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Liya Hu
- Verna Marrs McLean Department of Biochemistry and Molecular Biology
| | - Cameron A Brown
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Zhizeng Sun
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Carolyn J Adamski
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas 77030; Verna Marrs McLean Department of Biochemistry and Molecular Biology
| | - Vlatko Stojanoski
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas 77030; Verna Marrs McLean Department of Biochemistry and Molecular Biology
| | - Banumathi Sankaran
- Department of Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | | | - Timothy Palzkill
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas 77030; Verna Marrs McLean Department of Biochemistry and Molecular Biology.
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26
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Kwon H, Langan PS, Coates L, Raven EL, Moody PCE. The rise of neutron cryo-crystallography. Acta Crystallogr D Struct Biol 2018; 74:792-799. [PMID: 30082515 PMCID: PMC6079629 DOI: 10.1107/s205979831800640x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 04/25/2018] [Indexed: 11/10/2022] Open
Abstract
The use of boiled-off liquid nitrogen to maintain protein crystals at 100 K during X-ray data collection has become almost universal. Applying this to neutron protein crystallography offers the opportunity to significantly broaden the scope of biochemical problems that can be addressed, although care must be taken in assuming that direct extrapolation to room temperature is always valid. Here, the history to date of neutron protein cryo-crystallography and the particular problems and solutions associated with the mounting and cryocooling of the larger crystals needed for neutron crystallography are reviewed. Finally, the outlook for further cryogenic neutron studies using existing and future neutron instrumentation is discussed.
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Affiliation(s)
- Hanna Kwon
- Henry Wellcome Laboratories for Structural Biology, Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Lancaster Road, Leicester LE1 7RH, England
| | - Patricia S. Langan
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Leighton Coates
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Emma L. Raven
- Leicester Institute of Structural and Chemical Biology, Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, England
| | - Peter C. E. Moody
- Henry Wellcome Laboratories for Structural Biology, Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Lancaster Road, Leicester LE1 7RH, England
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27
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Neutron macromolecular crystallography. Emerg Top Life Sci 2018; 2:39-55. [DOI: 10.1042/etls20170083] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 12/12/2017] [Accepted: 12/19/2017] [Indexed: 01/02/2023]
Abstract
Neutron diffraction techniques permit direct determination of the hydrogen (H) and deuterium (D) positions in crystal structures of biological macromolecules at resolutions of ∼1.5 and 2.5 Å, respectively. In addition, neutron diffraction data can be collected from a single crystal at room temperature without radiation damage issues. By locating the positions of H/D-atoms, protonation states and water molecule orientations can be determined, leading to a more complete understanding of many biological processes and drug-binding. In the last ca. 5 years, new beamlines have come online at reactor neutron sources, such as BIODIFF at Heinz Maier-Leibnitz Zentrum and IMAGINE at Oak Ridge National Laboratory (ORNL), and at spallation neutron sources, such as MaNDi at ORNL and iBIX at the Japan Proton Accelerator Research Complex. In addition, significant improvements have been made to existing beamlines, such as LADI-III at the Institut Laue-Langevin. The new and improved instrumentations are allowing sub-mm3 crystals to be regularly used for data collection and permitting the study of larger systems (unit-cell edges >100 Å). Owing to this increase in capacity and capability, many more studies have been performed and for a wider range of macromolecules, including enzymes, signalling proteins, transport proteins, sugar-binding proteins, fluorescent proteins, hormones and oligonucleotides; of the 126 structures deposited in the Protein Data Bank, more than half have been released since 2013 (65/126, 52%). Although the overall number is still relatively small, there are a growing number of examples for which neutron macromolecular crystallography has provided the answers to questions that otherwise remained elusive.
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Langan PS, Vandavasi VG, Cooper CJ, Weiss KL, Ginell SL, Parks JM, Coates L. Substrate Binding Induces Conformational Changes in a Class A β-lactamase That Prime It for Catalysis. ACS Catal 2018. [DOI: 10.1021/acscatal.7b04114] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Patricia S. Langan
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Venu Gopal Vandavasi
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Connor J. Cooper
- Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Kevin L. Weiss
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Stephan L. Ginell
- Structural Biology Center, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States
| | - Jerry M. Parks
- Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6309, United States
| | - Leighton Coates
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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Saravanan M, Ramachandran B, Barabadi H. The prevalence and drug resistance pattern of extended spectrum β–lactamases (ESBLs) producing Enterobacteriaceae in Africa. Microb Pathog 2018; 114:180-192. [DOI: 10.1016/j.micpath.2017.11.061] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 11/27/2017] [Accepted: 11/27/2017] [Indexed: 10/18/2022]
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Lewandowski EM, Lethbridge KG, Sanishvili R, Skiba J, Kowalski K, Chen Y. Mechanisms of proton relay and product release by Class A β-lactamase at ultrahigh resolution. FEBS J 2017; 285:87-100. [PMID: 29095570 DOI: 10.1111/febs.14315] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 09/15/2017] [Accepted: 10/28/2017] [Indexed: 01/25/2023]
Abstract
The β-lactam antibiotics inhibit penicillin-binding proteins (PBPs) by forming a stable, covalent, acyl-enzyme complex. During the evolution from PBPs to Class A β-lactamases, the β-lactamases acquired Glu166 to activate a catalytic water and cleave the acyl-enzyme bond. Here we present three product complex crystal structures of CTX-M-14 Class A β-lactamase with a ruthenocene-conjugated penicillin-a 0.85 Å resolution structure of E166A mutant complexed with the penilloate product, a 1.30 Å resolution complex structure of the same mutant with the penicilloate product, and a 1.18 Å resolution complex structure of S70G mutant with a penicilloate product epimer-shedding light on the catalytic mechanisms and product inhibition of PBPs and Class A β-lactamases. The E166A-penilloate complex captured the hydrogen bonding network following the protonation of the leaving group and, for the first time, unambiguously show that the ring nitrogen donates a proton to Ser130, which in turn donates a proton to Lys73. These observations indicate that in the absence of Glu166, the equivalent lysine would be neutral in PBPs and therefore capable of serving as the general base to activate the catalytic serine. Together with previous results, this structure suggests a common proton relay network shared by Class A β-lactamases and PBPs, from the catalytic serine to the lysine, and ultimately to the ring nitrogen. Additionally, the E166A-penicilloate complex reveals previously unseen conformational changes of key catalytic residues during the release of the product, and is the first structure to capture the hydrolyzed product in the presence of an unmutated catalytic serine. DATABASE Structural data are available in the PDB database under the accession numbers 5TOP, 5TOY, and 5VLE.
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Affiliation(s)
- Eric M Lewandowski
- Department of Molecular Medicine, University of South Florida College of Medicine, Tampa, FL, USA
| | - Kathryn G Lethbridge
- Department of Molecular Medicine, University of South Florida College of Medicine, Tampa, FL, USA
| | - Ruslan Sanishvili
- GMCA@APS, X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, IL, USA
| | - Joanna Skiba
- Department of Organic Chemistry, Faculty of Chemistry, University of Lodz, Poland
| | - Konrad Kowalski
- Department of Organic Chemistry, Faculty of Chemistry, University of Lodz, Poland
| | - Yu Chen
- Department of Molecular Medicine, University of South Florida College of Medicine, Tampa, FL, USA
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31
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Calvopiña K, Hinchliffe P, Brem J, Heesom KJ, Johnson S, Cain R, Lohans CT, Fishwick CWG, Schofield CJ, Spencer J, Avison MB. Structural/mechanistic insights into the efficacy of nonclassical β-lactamase inhibitors against extensively drug resistantStenotrophomonas maltophiliaclinical isolates. Mol Microbiol 2017; 106:492-504. [DOI: 10.1111/mmi.13831] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2017] [Indexed: 01/23/2023]
Affiliation(s)
- Karina Calvopiña
- School of Cellular & Molecular Medicine; University of Bristol; Bristol UK
| | - Philip Hinchliffe
- School of Cellular & Molecular Medicine; University of Bristol; Bristol UK
| | - Jürgen Brem
- Department of Chemistry; University of Oxford; Oxford UK
| | | | - Samar Johnson
- School of Cellular & Molecular Medicine; University of Bristol; Bristol UK
| | - Ricky Cain
- School of Chemistry; University of Leeds; Leeds UK
| | | | | | | | - James Spencer
- School of Cellular & Molecular Medicine; University of Bristol; Bristol UK
| | - Matthew B. Avison
- School of Cellular & Molecular Medicine; University of Bristol; Bristol UK
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Oksanen E, Chen JCH, Fisher SZ. Neutron Crystallography for the Study of Hydrogen Bonds in Macromolecules. Molecules 2017; 22:molecules22040596. [PMID: 28387738 PMCID: PMC6154725 DOI: 10.3390/molecules22040596] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Revised: 03/29/2017] [Accepted: 04/01/2017] [Indexed: 11/21/2022] Open
Abstract
The hydrogen bond (H bond) is one of the most important interactions that form the foundation of secondary and tertiary protein structure. Beyond holding protein structures together, H bonds are also intimately involved in solvent coordination, ligand binding, and enzyme catalysis. The H bond by definition involves the light atom, H, and it is very difficult to study directly, especially with X-ray crystallographic techniques, due to the poor scattering power of H atoms. Neutron protein crystallography provides a powerful, complementary tool that can give unambiguous information to structural biologists on solvent organization and coordination, the electrostatics of ligand binding, the protonation states of amino acid side chains and catalytic water species. The method is complementary to X-ray crystallography and the dynamic data obtainable with NMR spectroscopy. Also, as it gives explicit H atom positions, it can be very valuable to computational chemistry where exact knowledge of protonation and solvent orientation can make a large difference in modeling. This article gives general information about neutron crystallography and shows specific examples of how the method has contributed to structural biology, structure-based drug design; and the understanding of fundamental questions of reaction mechanisms.
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Affiliation(s)
- Esko Oksanen
- Science Directorate, European Spallation Source ERIC, Tunavägen 24, 22100 Lund, Sweden.
- Department of Biochemistry and Structural Biology, Lund University, Sölvegatan 39, 22362 Lund, Sweden.
| | - Julian C-H Chen
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - Suzanne Zoë Fisher
- Science Directorate, European Spallation Source ERIC, Tunavägen 24, 22100 Lund, Sweden.
- Department of Biology, Lund University, Sölvegatan 35, 22362 Lund, Sweden.
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Chiu W, Holton J, Langan P, Sauter NK, Schlichting I, Terwilliger T, Martin JL, Read RJ, Wakatsuki S. Responses to `Atomic resolution': a badly abused term in structural biology. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2017; 73:381-383. [PMID: 28375150 DOI: 10.1107/s205979831700417x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Wah Chiu
- The Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, Texas, USA
| | - James Holton
- Molecular Biophysics & Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, USA
| | - Paul Langan
- Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Nicholas K Sauter
- Molecular Biophysics & Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, USA
| | - Ilme Schlichting
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Tom Terwilliger
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - Jennifer L Martin
- The Eskitis Drug Discovery Institute, N27, Griffith University, Nathan, Australia
| | - Randy J Read
- Cambridge Institute for Medical Research, Department of Haematology, University of Cambridge, Wellcome Trust/MRC Building, Hills Road, Cambridge, United Kingdom
| | - Soichi Wakatsuki
- Photon Science, SLAC and Structural Biology, School of Medicine, Stanford University, Menlo Park, USA
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Pan X, He Y, Lei J, Huang X, Zhao Y. Crystallographic Snapshots of Class A β-Lactamase Catalysis Reveal Structural Changes That Facilitate β-Lactam Hydrolysis. J Biol Chem 2017; 292:4022-4033. [PMID: 28100776 DOI: 10.1074/jbc.m116.764340] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 12/22/2016] [Indexed: 11/06/2022] Open
Abstract
β-Lactamases confer resistance to β-lactam-based antibiotics. There is great interest in understanding their mechanisms to enable the development of β-lactamase-specific inhibitors. The mechanism of class A β-lactamases has been studied extensively, revealing Lys-73 and Glu-166 as general bases that assist the catalytic residue Ser-70. However, the specific roles of these two residues within the catalytic cycle remain not fully understood. To help resolve this, we first identified an E166H mutant that is functional but is kinetically slow. We then carried out time-resolved crystallographic study of a full cycle of the catalytic reaction. We obtained structures that represent apo, ES*-acylation, and ES*-deacylation states and analyzed the conformational changes of His-166. The "in" conformation in the apo structure allows His-166 to form a hydrogen bond with Lys-73. The unexpected "flipped-out" conformation of His-166 in the ES*-acylation structure was further examined by molecular dynamics simulations, which suggested deprotonated Lys-73 serving as the general base for acylation. The "revert-in" conformation in the ES*-deacylation structure aligns His-166 toward the water molecule that hydrolyzes the acyl adduct. Finally, when the acyl adduct is fully hydrolyzed, His-166 rotates back to the "in" conformation of the apo-state, restoring the Lys-73/His-166 interaction. Using His-166 as surrogate, our study identifies distinct conformational changes within the active site during catalysis. We suggest that the native Glu-166 executes similar changes in a less constricted way. Taken together, this structural series improves our understanding of β-lactam hydrolysis in this important class of enzymes.
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Affiliation(s)
- Xuehua Pan
- From the Department of Applied Biology and Chemical Technology, State Key Laboratory of Chirosciences, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.,the Shenzhen Research Institute, Hong Kong Polytechnic University, Shenzhen, and
| | - Yunjiao He
- From the Department of Applied Biology and Chemical Technology, State Key Laboratory of Chirosciences, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Jinping Lei
- the Department of Chemistry, Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xuhui Huang
- the Department of Chemistry, Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Yanxiang Zhao
- From the Department of Applied Biology and Chemical Technology, State Key Laboratory of Chirosciences, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong,
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35
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Biological Structures. NEUTRON SCATTERING - APPLICATIONS IN BIOLOGY, CHEMISTRY, AND MATERIALS SCIENCE 2017. [DOI: 10.1016/b978-0-12-805324-9.00001-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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36
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Active-Site Protonation States in an Acyl-Enzyme Intermediate of a Class A β-Lactamase with a Monobactam Substrate. Antimicrob Agents Chemother 2016; 61:AAC.01636-16. [PMID: 27795378 PMCID: PMC5192116 DOI: 10.1128/aac.01636-16] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 09/29/2016] [Indexed: 11/20/2022] Open
Abstract
The monobactam antibiotic aztreonam is used to treat cystic fibrosis patients with chronic pulmonary infections colonized by Pseudomonas aeruginosa strains expressing CTX-M extended-spectrum β-lactamases. The protonation states of active-site residues that are responsible for hydrolysis have been determined previously for the apo form of a CTX-M β-lactamase but not for a monobactam acyl-enzyme intermediate. Here we used neutron and high-resolution X-ray crystallography to probe the mechanism by which CTX-M extended-spectrum β-lactamases hydrolyze monobactam antibiotics. In these first reported structures of a class A β-lactamase in an acyl-enzyme complex with aztreonam, we directly observed most of the hydrogen atoms (as deuterium) within the active site. Although Lys 234 is fully protonated in the acyl intermediate, we found that Lys 73 is neutral. These findings are consistent with Lys 73 being able to serve as a general base during the acylation part of the catalytic mechanism, as previously proposed.
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37
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Yano N, Yamada T, Hosoya T, Ohhara T, Tanaka I, Kusaka K. Application of profile fitting method to neutron time-of-flight protein single crystal diffraction data collected at the iBIX. Sci Rep 2016; 6:36628. [PMID: 27905404 PMCID: PMC5131355 DOI: 10.1038/srep36628] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 10/17/2016] [Indexed: 12/13/2022] Open
Abstract
We developed and employed a profile fitting method for the peak integration of neutron time-of-flight diffraction data collected by the IBARAKI Biological Crystal Diffractometer (iBIX) at the Japan Proton Accelerator Research Complex (J-PARC) for protein ribonuclease A and α-thrombin single crystals. In order to determine proper fitting functions, four asymmetric functions were evaluated using strong intensity peaks. A Gaussian convolved with two back-to-back exponentials was selected as the most suitable fitting function, and a profile fitting algorithm for the integration method was developed. The intensity and structure refinement data statistics of the profile fitting method were compared to those of the summation integration method. It was clearly demonstrated that the profile fitting method provides more accurate integrated intensities and model structures than the summation integration method at higher resolution shells. The integration component with the profile fitting method has already been implemented in the iBIX data processing software STARGazer and its user manual has been prepared.
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Affiliation(s)
- Naomine Yano
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Taro Yamada
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Takaaki Hosoya
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan.,College of Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki, 316-8511, Japan
| | - Takashi Ohhara
- Neutron Science Section, J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Ibaraki 319-1195, Japan
| | - Ichiro Tanaka
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan.,College of Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki, 316-8511, Japan
| | - Katsuhiro Kusaka
- Frontier Research Center for Applied Atomic Sciences, Ibaraki University, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
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Langan PS, Vandavasi VG, Weiss KL, Cooper JB, Ginell SL, Coates L. The structure of Toho1 β-lactamase in complex with penicillin reveals the role of Tyr105 in substrate recognition. FEBS Open Bio 2016; 6:1170-1177. [PMID: 28255534 PMCID: PMC5324766 DOI: 10.1002/2211-5463.12132] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 09/26/2016] [Accepted: 09/28/2016] [Indexed: 11/06/2022] Open
Abstract
The role of the conserved residue Tyr105 in class A β‐lactamases has been the subject of investigation using both structural studies and saturation mutagenesis. Both have shown that while it does not need to be strictly conserved for activity, it is important for substrate recognition. With this in mind we determined the crystal structure of Toho1 β‐lactamase at 15 K to 1.10 Å resolution in complex with penicillin. As expected a ring‐opened penicillin molecule bound to Ser70 the catalytic nucleophile, can clearly be seen in electron density in the active site. In addition to the trapped penicillin, however, are two additional intact ring‐closed penicillin molecules, captured by the enzyme through noncovalent interactions at the edge of the active site.
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Affiliation(s)
- Patricia S Langan
- Biology and Soft Matter Division Oak Ridge National Laboratory TN USA
| | | | - Kevin L Weiss
- Biology and Soft Matter Division Oak Ridge National Laboratory TN USA
| | | | | | - Leighton Coates
- Biology and Soft Matter Division Oak Ridge National Laboratory TN USA
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Abstract
Since drugs bind to their targets through directional H bonding and non-directional hydrophobic and electrostatic interactions, neutron crystallography can help guide structure-based drug design. This is illustrated by McKenna and co-workers [Aggarwal et al. (2016), IUCrJ, 3, 319-325] who describe the room-temperature neutron structure of human carbonic anyhydrase II in complex with the clinical inhibitor methazolamide to 2.2 Å resolution, and compare this with the previously determined room-temperature neutron structure of human carbonic anyhydrase II in complex with the clinical inhibitor acetazolamide to 2.0 Å resolution [Fisher et al. (2012). J. Am. Chem. Soc.134, 14726-14729].
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Affiliation(s)
- M. P. Blakeley
- Large-Scale Structures Group, Institut Laue-Langevin, 71 Avenue des Martyrs, Grenoble, 38000, France
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