1
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Drago VN, Campos C, Hooper M, Collins A, Gerlits O, Weiss KL, Blakeley MP, Phillips RS, Kovalevsky A. Revealing protonation states and tracking substrate in serine hydroxymethyltransferase with room-temperature X-ray and neutron crystallography. Commun Chem 2023; 6:162. [PMID: 37532884 PMCID: PMC10397204 DOI: 10.1038/s42004-023-00964-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 07/25/2023] [Indexed: 08/04/2023] Open
Abstract
Pyridoxal 5'-phosphate (PLP)-dependent enzymes utilize a vitamin B6-derived cofactor to perform a myriad of chemical transformations on amino acids and other small molecules. Some PLP-dependent enzymes, such as serine hydroxymethyltransferase (SHMT), are promising drug targets for the design of small-molecule antimicrobials and anticancer therapeutics, while others have been used to synthesize pharmaceutical building blocks. Understanding PLP-dependent catalysis and the reaction specificity is crucial to advance structure-assisted drug design and enzyme engineering. Here we report the direct determination of the protonation states in the active site of Thermus thermophilus SHMT (TthSHMT) in the internal aldimine state using room-temperature joint X-ray/neutron crystallography. Conserved active site architecture of the model enzyme TthSHMT and of human mitochondrial SHMT (hSHMT2) were compared by obtaining a room-temperature X-ray structure of hSHMT2, suggesting identical protonation states in the human enzyme. The amino acid substrate serine pathway through the TthSHMT active site cavity was tracked, revealing the peripheral and cationic binding sites that correspond to the pre-Michaelis and pseudo-Michaelis complexes, respectively. At the peripheral binding site, the substrate is bound in the zwitterionic form. By analyzing the observed protonation states, Glu53, but not His residues, is proposed as the general base catalyst, orchestrating the retro-aldol transformation of L-serine into glycine.
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Affiliation(s)
- Victoria N Drago
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Claudia Campos
- Department of Natural Sciences, Tennessee Wesleyan University, Athens, TN, 37303, USA
| | - Mattea Hooper
- Department of Natural Sciences, Tennessee Wesleyan University, Athens, TN, 37303, USA
| | - Aliyah Collins
- Department of Natural Sciences, Tennessee Wesleyan University, Athens, TN, 37303, USA
| | - Oksana Gerlits
- Department of Natural Sciences, Tennessee Wesleyan University, Athens, TN, 37303, USA
| | - Kevin L Weiss
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Matthew P Blakeley
- Large Scale Structures Group, Institut Laue-Langevin, 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Robert S Phillips
- Department of Chemistry, University of Georgia, Athens, GA, 30602, USA
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, 30602, USA
| | - Andrey Kovalevsky
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
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2
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Demchenko AP. Proton transfer reactions: from photochemistry to biochemistry and bioenergetics. BBA ADVANCES 2023. [DOI: 10.1016/j.bbadva.2023.100085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023] Open
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3
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Schröder GC, O'Dell WB, Webb SP, Agarwal PK, Meilleur F. Capture of activated dioxygen intermediates at the copper-active site of a lytic polysaccharide monooxygenase. Chem Sci 2022; 13:13303-13320. [PMID: 36507176 PMCID: PMC9683017 DOI: 10.1039/d2sc05031e] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 10/19/2022] [Indexed: 11/24/2022] Open
Abstract
Metalloproteins perform a diverse array of redox-related reactions facilitated by the increased chemical functionality afforded by their metallocofactors. Lytic polysaccharide monooxygenases (LPMOs) are a class of copper-dependent enzymes that are responsible for the breakdown of recalcitrant polysaccharides via oxidative cleavage at the glycosidic bond. The activated copper-oxygen intermediates and their mechanism of formation remains to be established. Neutron protein crystallography which permits direct visualization of protonation states was used to investigate the initial steps of oxygen activation directly following active site copper reduction in Neurospora crassa LPMO9D. Herein, we cryo-trap an activated dioxygen intermediate in a mixture of superoxo and hydroperoxo states, and we identify the conserved second coordination shell residue His157 as the proton donor. Density functional theory calculations indicate that both superoxo and hydroperoxo active site states are stable. The hydroperoxo formed is potentially an early LPMO catalytic reaction intermediate or the first step in the mechanism of hydrogen peroxide formation in the absence of substrate. We observe that the N-terminal amino group of the copper coordinating His1 remains doubly protonated directly following molecular oxygen reduction by copper. Aided by molecular dynamics and mining minima free energy calculations we establish that the conserved second-shell His161 in MtPMO3* displays conformational flexibility in solution and that this flexibility is also observed, though to a lesser extent, in His157 of NcLPMO9D. The imidazolate form of His157 observed in our structure following oxygen intermediate protonation can be attributed to abolished His157 flexibility due steric hindrance in the crystal as well as the solvent-occluded active site environment due to crystal packing. A neutron crystal structure of NcLPMO9D at low pH further supports occlusion of the active site since His157 remains singly protonated even at acidic conditions.
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Affiliation(s)
- Gabriela C. Schröder
- Department of Molecular and Structural Biochemistry, North Carolina State UniversityRaleighNC 27695USA,Neutron Scattering Division, Oak Ridge National LaboratoryOak RidgeTN 37831USA
| | - William B. O'Dell
- Department of Molecular and Structural Biochemistry, North Carolina State UniversityRaleighNC 27695USA,Neutron Scattering Division, Oak Ridge National LaboratoryOak RidgeTN 37831USA
| | - Simon P. Webb
- VeraChem LLC12850 Middlebrook Rd. Ste 205GermantownMD 20874-5244USA
| | - Pratul K. Agarwal
- Department of Physiological Sciences and High-Performance Computing Center, Oklahoma State UniversityStillwaterOK 74078USA
| | - Flora Meilleur
- Department of Molecular and Structural Biochemistry, North Carolina State UniversityRaleighNC 27695USA,Neutron Scattering Division, Oak Ridge National LaboratoryOak RidgeTN 37831USA
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4
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Taguchi M, Oyama R, Kaneso M, Hayashi S. Hybrid QM/MM Free-Energy Evaluation of Drug-Resistant Mutational Effect on the Binding of an Inhibitor Indinavir to HIV-1 Protease. J Chem Inf Model 2022; 62:1328-1344. [PMID: 35212226 DOI: 10.1021/acs.jcim.1c01193] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A human immunodeficiency virus-1 (HIV-1) protease is a homodimeric aspartic protease essential for the replication of HIV. The HIV-1 protease is a target protein in drug discovery for antiretroviral therapy, and various inhibitor molecules of transition state analogues have been developed. However, serious drug-resistant mutants have emerged. For understanding the molecular mechanism of the drug resistance, an accurate examination of the impacts of the mutations on ligand binding and enzymatic activity is necessary. Here, we present a molecular simulation study on the ligand binding of indinavir, a potent transition state analogue inhibitor, to the wild-type protein and a V82T/I84V drug-resistant mutant of the HIV-1 protease. We employed a hybrid ab initio quantum mechanical/molecular mechanical (QM/MM) free-energy optimization technique which combines a highly accurate QM description of the ligand molecule and its interaction with statistically ample conformational sampling of the MM protein environment by long-time molecular dynamics simulations. Through the free-energy calculations of protonation states of catalytic groups at the binding pocket and of the ligand-binding affinity changes upon the mutations, we successfully reproduced the experimentally observed significant reduction of the binding affinity upon the drug-resistant mutations and elucidated the underlying molecular mechanism. The present study opens the way for understanding the molecular mechanism of drug resistance through the direct quantitative comparison of ligand binding and enzymatic reaction with the same accuracy.
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Affiliation(s)
- Masahiko Taguchi
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.,Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, Kizugawa, Kyoto 619-0215, Japan
| | - Ryo Oyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Masahiro Kaneso
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Shigehiko Hayashi
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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5
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Kneller DW, Gerlits O, Daemen LL, Pavlova A, Gumbart JC, Cheng Y, Kovalevsky A. Joint neutron/molecular dynamics vibrational spectroscopy reveals softening of HIV-1 protease upon binding of a tight inhibitor. Phys Chem Chem Phys 2022; 24:3586-3597. [PMID: 35089990 PMCID: PMC8940534 DOI: 10.1039/d1cp05487b] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Biomacromolecules are inherently dynamic, and their dynamics are interwoven into function. The fast collective vibrational dynamics in proteins occurs in the low picosecond timescale corresponding to frequencies of ∼5-50 cm-1. This sub-to-low THz frequency regime covers the low-amplitude collective breathing motions of a whole protein and vibrations of the constituent secondary structure elements, such as α-helices, β-sheets and loops. We have used inelastic neutron scattering experiments in combination with molecular dynamics simulations to demonstrate the vibrational dynamics softening of HIV-1 protease, a target of HIV/AIDS antivirals, upon binding of a tight clinical inhibitor darunavir. Changes in the vibrational density of states of matching structural elements in the two monomers of the homodimeric protein are not identical, indicating asymmetric effects of darunavir on the vibrational dynamics. Three of the 11 major secondary structure elements contribute over 40% to the overall changes in the vibrational density of states upon darunavir binding. Molecular dynamics simulations informed by experiments allowed us to estimate that the altered vibrational dynamics of the protease would contribute -3.6 kcal mol-1 at 300 K, or 25%, to the free energy of darunavir binding. As HIV-1 protease drug resistance remains a concern, our results open a new avenue to help establish a direct quantitative link between protein vibrational dynamics and drug resistance.
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Affiliation(s)
- Daniel W. Kneller
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.A
| | - Oksana Gerlits
- Department of Natural Sciences, Tennessee Wesleyan University, Athens, TN 37303, U.S.A
| | - Luke L. Daemen
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.A
| | - Anna Pavlova
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A
| | - James C. Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A
| | - Yongqiang Cheng
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Andrey Kovalevsky
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
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6
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Drago VN, Dajnowicz S, Parks JM, Blakeley MP, Keen DA, Coquelle N, Weiss KL, Gerlits O, Kovalevsky A, Mueser TC. An N⋯H⋯N low-barrier hydrogen bond preorganizes the catalytic site of aspartate aminotransferase to facilitate the second half-reaction. Chem Sci 2022; 13:10057-10065. [PMID: 36128223 PMCID: PMC9430417 DOI: 10.1039/d2sc02285k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 07/20/2022] [Indexed: 11/21/2022] Open
Abstract
Pyridoxal 5′-phosphate (PLP)-dependent enzymes have been extensively studied for their ability to fine-tune PLP cofactor electronics to promote a wide array of chemistries. Neutron crystallography offers a straightforward approach to studying the electronic states of PLP and the electrostatics of enzyme active sites, responsible for the reaction specificities, by enabling direct visualization of hydrogen atom positions. Here we report a room-temperature joint X-ray/neutron structure of aspartate aminotransferase (AAT) with pyridoxamine 5′-phosphate (PMP), the cofactor product of the first half reaction catalyzed by the enzyme. Between PMP NSB and catalytic Lys258 Nζ amino groups an equally shared deuterium is observed in an apparent low-barrier hydrogen bond (LBHB). Density functional theory calculations were performed to provide further evidence of this LBHB interaction. The structural arrangement and the juxtaposition of PMP and Lys258, facilitated by the LBHB, suggests active site preorganization for the incoming ketoacid substrate that initiates the second half-reaction. The neutron structure of pyridoxal 5′-phosphate-dependent enzyme aspartate aminotransferase with pyridoxamine 5′-phosphate (PMP) reveals a low-barrier hydrogen bond between the amino groups of PMP and catalytic Lys258, preorganizing the active site for catalysis![]()
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Affiliation(s)
- Victoria N. Drago
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH 43606, USA
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Steven Dajnowicz
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH 43606, USA
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Jerry M. Parks
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Matthew P. Blakeley
- Large Scale Structures Group, Institut Laue–Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - David A. Keen
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0QX, UK
| | - Nicolas Coquelle
- Large Scale Structures Group, Institut Laue–Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Kevin L. Weiss
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Oksana Gerlits
- Department of Natural Sciences, Tennessee Wesleyan University, Athens, TN 37303, USA
| | - Andrey Kovalevsky
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Timothy C. Mueser
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH 43606, USA
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7
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Wan Q, Bennett BC, Wymore T, Li Z, Wilson MA, Brooks CL, Langan P, Kovalevsky A, Dealwis CG. Capturing the Catalytic Proton of Dihydrofolate Reductase: Implications for General Acid-Base Catalysis. ACS Catal 2021; 11:5873-5884. [PMID: 34055457 PMCID: PMC8154319 DOI: 10.1021/acscatal.1c00417] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 04/19/2021] [Indexed: 02/04/2023]
Abstract
![]()
Acid–base
catalysis, which involves one or more proton transfer
reactions, is a chemical mechanism commonly employed by many enzymes.
The molecular basis for catalysis is often derived from structures
determined at the optimal pH for enzyme activity. However, direct
observation of protons from experimental structures is quite difficult;
thus, a complete mechanistic description for most enzymes remains
lacking. Dihydrofolate reductase (DHFR) exemplifies general acid–base
catalysis, requiring hydride transfer and protonation of its substrate,
DHF, to form the product, tetrahydrofolate (THF). Previous X-ray and
neutron crystal structures coupled with theoretical calculations have
proposed that solvent mediates the protonation step. However, visualization
of a proton transfer has been elusive. Based on a 2.1 Å resolution
neutron structure of a pseudo-Michaelis complex of E. coli DHFR determined at acidic pH, we report the
direct observation of the catalytic proton and its parent solvent
molecule. Comparison of X-ray and neutron structures elucidated at
acidic and neutral pH reveals dampened dynamics at acidic pH, even
for the regulatory Met20 loop. Guided by the structures and calculations,
we propose a mechanism where dynamics are crucial for solvent entry
and protonation of substrate. This mechanism invokes the release of
a sole proton from a hydronium (H3O+) ion, its
pathway through a narrow channel that sterically hinders the passage
of water, and the ultimate protonation of DHF at the N5 atom.
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Affiliation(s)
| | - Brad C. Bennett
- Biological and Environmental Science Department, Samford University, Birmingham, Alabama 35229, United States
| | - Troy Wymore
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | | | - Mark A. Wilson
- Department of Biochemistry and Redox Biology Center, University of Nebraska, Lincoln, Nebraska 68588, United States
| | - Charles L. Brooks
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Paul Langan
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Andrey Kovalevsky
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
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8
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Schröder GC, O’Dell WB, Swartz PD, Meilleur F. Preliminary results of neutron and X-ray diffraction data collection on a lytic polysaccharide monooxygenase under reduced and acidic conditions. Acta Crystallogr F Struct Biol Commun 2021; 77:128-133. [PMID: 33830078 PMCID: PMC8034432 DOI: 10.1107/s2053230x21002399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 03/02/2021] [Indexed: 11/10/2022] Open
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are copper-center enzymes that are involved in the oxidative cleavage of the glycosidic bond in crystalline cellulose and other polysaccharides. The LPMO reaction is initiated by the addition of a reductant and oxygen to ultimately form an unknown activated copper-oxygen species that is responsible for polysaccharide-substrate H-atom abstraction. Given the sensitivity of metalloproteins to radiation damage, neutron protein crystallography provides a nondestructive technique for structural characterization while also informing on the positions of H atoms. Neutron cryo-crystallography permits the trapping of catalytic intermediates, thereby providing insight into the protonation states and chemical nature of otherwise short-lived species in the reaction mechanism. To characterize the reaction-mechanism intermediates of LPMO9D from Neurospora crassa, a cryo-neutron diffraction data set was collected from an ascorbate-reduced crystal. A second neutron diffraction data set was collected at room temperature from an LPMO9D crystal exposed to low-pH conditions to probe the protonation states of ionizable groups involved in catalysis under acidic conditions.
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Affiliation(s)
- Gabriela C. Schröder
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - William B. O’Dell
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Paul D. Swartz
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Flora Meilleur
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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9
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Elsässer B, Goettig P. Mechanisms of Proteolytic Enzymes and Their Inhibition in QM/MM Studies. Int J Mol Sci 2021; 22:3232. [PMID: 33810118 PMCID: PMC8004986 DOI: 10.3390/ijms22063232] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/24/2021] [Accepted: 02/26/2021] [Indexed: 12/11/2022] Open
Abstract
Experimental evidence for enzymatic mechanisms is often scarce, and in many cases inadvertently biased by the employed methods. Thus, apparently contradictory model mechanisms can result in decade long discussions about the correct interpretation of data and the true theory behind it. However, often such opposing views turn out to be special cases of a more comprehensive and superior concept. Molecular dynamics (MD) and the more advanced molecular mechanical and quantum mechanical approach (QM/MM) provide a relatively consistent framework to treat enzymatic mechanisms, in particular, the activity of proteolytic enzymes. In line with this, computational chemistry based on experimental structures came up with studies on all major protease classes in recent years; examples of aspartic, metallo-, cysteine, serine, and threonine protease mechanisms are well founded on corresponding standards. In addition, experimental evidence from enzyme kinetics, structural research, and various other methods supports the described calculated mechanisms. One step beyond is the application of this information to the design of new and powerful inhibitors of disease-related enzymes, such as the HIV protease. In this overview, a few examples demonstrate the high potential of the QM/MM approach for sophisticated pharmaceutical compound design and supporting functions in the analysis of biomolecular structures.
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Affiliation(s)
| | - Peter Goettig
- Structural Biology Group, Department of Biosciences, University of Salzburg, Billrothstrasse 11, 5020 Salzburg, Austria;
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10
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Kumar P, Agarwal PK, Cuneo MJ. On the Case of the Misplaced Hydrogens. Chembiochem 2021; 22:288-297. [PMID: 32706524 PMCID: PMC7952024 DOI: 10.1002/cbic.202000376] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 07/21/2020] [Indexed: 12/30/2022]
Abstract
Few other elements play a more central role in biology than hydrogen. The interactions, bonding and movement of hydrogen atoms are central to biological catalysis, structure and function. Yet owing to the elusive nature of a single hydrogen atom few experimental and computational techniques can precisely determine its location. This is exemplified in short hydrogen bonds (SHBs) where the location of the hydrogen atom is indicative of the underlying strength of the bonds, which can vary from 1-5 kcal/mol in canonical hydrogen bonds, to an almost covalent nature in single-well hydrogen bonds. Owing to the often-times inferred position of hydrogen, the role of SHBs in biology has remained highly contested and debated. This has also led to discrepancies in computational, biochemical and structural studies of proteins thought to use SHBs in performing chemistry and stabilizing interactions. Herein, we discuss in detail two distinct examples, namely the conserved catalytic triad and the photoreceptor, photoactive yellow protein, where studies of these SHB-containing systems have permitted contextualization of the role these unique hydrogen bonds play in biology.
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Affiliation(s)
- Prashasti Kumar
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Pratul K Agarwal
- Arium BioLabs LLC, Knoxville, TN, 37932, USA
- Department of Physiological Sciences and High-Performance Computing Center, Oklahoma State University, Stillwater, OK 74078, USA
| | - Matthew J Cuneo
- Department of Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Pl, Memphis, TN, 38103, USA
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11
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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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12
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Rusere LN, Lockbaum GJ, Henes M, Lee SK, Spielvogel E, Rao DN, Kosovrasti K, Nalivaika EA, Swanstrom R, Kurt Yilmaz N, Schiffer CA, Ali A. Structural Analysis of Potent Hybrid HIV-1 Protease Inhibitors Containing Bis-tetrahydrofuran in a Pseudosymmetric Dipeptide Isostere. J Med Chem 2020; 63:8296-8313. [PMID: 32672965 DOI: 10.1021/acs.jmedchem.0c00529] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The design, synthesis, and X-ray structural analysis of hybrid HIV-1 protease inhibitors (PIs) containing bis-tetrahydrofuran (bis-THF) in a pseudo-C2-symmetric dipeptide isostere are described. A series of PIs were synthesized by incorporating bis-THF of darunavir on either side of the Phe-Phe isostere of lopinavir in combination with hydrophobic amino acids on the opposite P2/P2' position. Structure-activity relationship studies indicated that the bis-THF moiety can be attached at either the P2 or P2' position without significantly affecting potency. However, the group on the opposite P2/P2' position had a dramatic effect on potency depending on the size and shape of the side chain. Cocrystal structures of inhibitors with wild-type HIV-1 protease revealed that the bis-THF moiety retained similar interactions as observed in the darunavir-protease complex regardless of the position on the Phe-Phe isostere. Analyses of cocrystal structures and molecular dynamics simulations provide insights into optimizing HIV-1 PIs containing bis-THF in non-sulfonamide dipeptide isosteres.
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Affiliation(s)
- Linah N Rusere
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, United States
| | - Gordon J Lockbaum
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, United States
| | - Mina Henes
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, United States
| | - Sook-Kyung Lee
- Department of Biochemistry and Biophysics, and the UNC Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Ean Spielvogel
- Department of Biochemistry and Biophysics, and the UNC Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Desaboini Nageswara Rao
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, United States
| | - Klajdi Kosovrasti
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, United States
| | - Ellen A Nalivaika
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, United States
| | - Ronald Swanstrom
- Department of Biochemistry and Biophysics, and the UNC Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Nese Kurt Yilmaz
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, United States
| | - Celia A Schiffer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, United States
| | - Akbar Ali
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, United States
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13
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Kneller DW, Agniswamy J, Harrison RW, Weber IT. Highly drug-resistant HIV-1 protease reveals decreased intra-subunit interactions due to clusters of mutations. FEBS J 2020; 287:3235-3254. [PMID: 31920003 PMCID: PMC7343616 DOI: 10.1111/febs.15207] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 11/16/2019] [Accepted: 01/08/2020] [Indexed: 01/07/2023]
Abstract
Drug-resistance is a serious problem for treatment of the HIV/AIDS pandemic. Potent clinical inhibitors of HIV-1 protease show several orders of magnitude worse inhibition of highly drug-resistant variants. Hence, the structure and enzyme activities were analyzed for HIV protease mutant HIV-1 protease (EC 3.4.23.16) (PR) with 22 mutations (PRS5B) from a clinical isolate that was selected by machine learning to represent high-level drug-resistance. PRS5B has 22 mutations including only one (I84V) in the inhibitor binding site; however, clinical inhibitors had poor inhibition of PRS5B activity with kinetic inhibition value (Ki ) values of 4-1000 nm or 18- to 8000-fold worse than for wild-type PR. High-resolution crystal structures of PRS5B complexes with the best inhibitors, amprenavir (APV) and darunavir (DRV) (Ki ~ 4 nm), revealed only minor changes in protease-inhibitor interactions. Instead, two distinct clusters of mutations in distal regions induce coordinated conformational changes that decrease favorable internal interactions across the entire protein subunit. The largest structural rearrangements are described and compared to other characterized resistant mutants. In the protease hinge region, the N83D mutation eliminates a hydrogen bond connecting the hinge and core of the protease and increases disorder compared to highly resistant mutants PR with 17 mutations and PR with 20 mutations with similar hinge mutations. In a distal β-sheet, mutations G73T and A71V coordinate with accessory mutations to bring about shifts that propagate throughout the subunit. Molecular dynamics simulations of ligand-free dimers show differences consistent with loss of interactions in mutant compared to wild-type PR. Clusters of mutations exhibit both coordinated and antagonistic effects, suggesting PRS5B may represent an intermediate stage in the evolution of more highly resistant variants. DATABASES: Structural data are available in Protein Data Bank under the accession codes 6P9A and 6P9B for PRS5B/DRV and PRS5B/APV, respectively.
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Affiliation(s)
- Daniel W. Kneller
- Department of Biology, Georgia State University, Atlanta, Georgia 30303, United States of America
| | - Johnson Agniswamy
- Department of Biology, Georgia State University, Atlanta, Georgia 30303, United States of America
| | - Robert W. Harrison
- Department of Computer Science, Georgia State University, Atlanta, Georgia 30303, United States of America
| | - Irene T. Weber
- Department of Biology, Georgia State University, Atlanta, Georgia 30303, United States of America,Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, United States of America,Author of correspondence:
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14
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Lawal MM, Sanusi ZK, Govender T, Maguire GE, Honarparvar B, Kruger HG. From Recognition to Reaction Mechanism: An Overview on the Interactions between HIV-1 Protease and its Natural Targets. Curr Med Chem 2020; 27:2514-2549. [DOI: 10.2174/0929867325666181113122900] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 11/04/2018] [Accepted: 11/07/2018] [Indexed: 12/28/2022]
Abstract
Current investigations on the Human Immunodeficiency Virus Protease (HIV-1
PR) as a druggable target towards the treatment of AIDS require an update to facilitate further
development of promising inhibitors with improved inhibitory activities. For the past two
decades, up to 100 scholarly reports appeared annually on the inhibition and catalytic mechanism
of HIV-1 PR. A fundamental literature review on the prerequisite of HIV-1 PR action
leading to the release of the infectious virion is absent. Herein, recent advances (both computationally
and experimentally) on the recognition mode and reaction mechanism of HIV-1 PR
involving its natural targets are provided. This review features more than 80 articles from
reputable journals. Recognition of the natural Gag and Gag-Pol cleavage junctions by this
enzyme and its mutant analogs was first addressed. Thereafter, a comprehensive dissect of
the enzymatic mechanism of HIV-1 PR on its natural polypeptide sequences from literature
was put together. In addition, we highlighted ongoing research topics in which in silico
methods could be harnessed to provide deeper insights into the catalytic mechanism of the
HIV-1 protease in the presence of its natural substrates at the molecular level. Understanding
the recognition and catalytic mechanism of HIV-1 PR leading to the release of an infective
virion, which advertently affects the immune system, will assist in designing mechanismbased
inhibitors with improved bioactivity.
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Affiliation(s)
- Monsurat M. Lawal
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa
| | - Zainab K. Sanusi
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa
| | - Thavendran Govender
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa
| | - Glenn E.M. Maguire
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa
| | - Bahareh Honarparvar
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa
| | - Hendrik G. Kruger
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa
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15
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Kumar M, Mandal K, Blakeley MP, Wymore T, Kent SBH, Louis JM, Das A, Kovalevsky A. Visualizing Tetrahedral Oxyanion Bound in HIV-1 Protease Using Neutrons: Implications for the Catalytic Mechanism and Drug Design. ACS OMEGA 2020; 5:11605-11617. [PMID: 32478251 PMCID: PMC7254801 DOI: 10.1021/acsomega.0c00835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 04/30/2020] [Indexed: 06/11/2023]
Abstract
HIV-1 protease is indispensable for virus propagation and an important therapeutic target for antiviral inhibitors to treat AIDS. As such inhibitors are transition-state mimics, a detailed understanding of the enzyme mechanism is crucial for the development of better anti-HIV drugs. Here, we used room-temperature joint X-ray/neutron crystallography to directly visualize hydrogen atoms and map hydrogen bonding interactions in a protease complex with peptidomimetic inhibitor KVS-1 containing a reactive nonhydrolyzable ketomethylene isostere, which, upon reacting with the catalytic water molecule, is converted into a tetrahedral intermediate state, KVS-1TI. We unambiguously determined that the resulting tetrahedral intermediate is an oxyanion, rather than the gem-diol, and both catalytic aspartic acid residues are protonated. The oxyanion tetrahedral intermediate appears to be unstable, even though the negative charge on the oxyanion is delocalized through a strong n → π* hyperconjugative interaction into the nearby peptidic carbonyl group of the inhibitor. To better understand the influence of the ketomethylene isostere as a protease inhibitor, we have also examined the protease structure and binding affinity with keto-darunavir (keto-DRV), which similar to KVS-1 includes the ketomethylene isostere. We show that keto-DRV is a significantly less potent protease inhibitor than DRV. These findings shed light on the reaction mechanism of peptide hydrolysis catalyzed by HIV-1 protease and provide valuable insights into further improvements in the design of protease inhibitors.
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Affiliation(s)
- Mukesh Kumar
- Protein Crystallography
Section, Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Kalyaneswar Mandal
- Departments of Chemistry, and Biochemistry and Molecular Biology,
Institute for Biophysical Dynamics, University
of Chicago, Chicago, Illinois 60637, United States
| | - Matthew P. Blakeley
- Large Scale Structures Group, Institut Laue−Langevin, 38000 Grenoble, France
| | - Troy Wymore
- Department of Chemistry, University
of Michigan, Ann Arbor, Michigan 48109, United States
| | - Stephen B. H. Kent
- Departments of Chemistry, and Biochemistry and Molecular Biology,
Institute for Biophysical Dynamics, University
of Chicago, Chicago, Illinois 60637, United States
| | - John M. Louis
- Laboratory of Chemical Physics, National
Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, DHHS, Bethesda, Maryland 20892-0520, United States
| | - Amit Das
- Protein Crystallography
Section, Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Andrey Kovalevsky
- Neutron Scattering
Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
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16
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Neutron crystallography of copper amine oxidase reveals keto/enolate interconversion of the quinone cofactor and unusual proton sharing. Proc Natl Acad Sci U S A 2020; 117:10818-10824. [PMID: 32371483 DOI: 10.1073/pnas.1922538117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recent advances in neutron crystallographic studies have provided structural bases for quantum behaviors of protons observed in enzymatic reactions. Thus, we resolved the neutron crystal structure of a bacterial copper (Cu) amine oxidase (CAO), which contains a prosthetic Cu ion and a protein-derived redox cofactor, topa quinone (TPQ). We solved hitherto unknown structures of the active site, including a keto/enolate equilibrium of the cofactor with a nonplanar quinone ring, unusual proton sharing between the cofactor and the catalytic base, and metal-induced deprotonation of a histidine residue that coordinates to the Cu. Our findings show a refined active-site structure that gives detailed information on the protonation state of dissociable groups, such as the quinone cofactor, which are critical for catalytic reactions.
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17
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Mueser TC, Drago V, Kovalevsky A, Dajnowicz S. Pyridoxal 5'-phosphate dependent reactions: Analyzing the mechanism of aspartate aminotransferase. Methods Enzymol 2020; 634:333-359. [PMID: 32093839 DOI: 10.1016/bs.mie.2020.01.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Enzyme catalysis is the primary activity in energy and information metabolism and enzyme cofactors are key to the catalytic ability of most enzymes. Pyridoxal 5'-phosphate (PLP) cofactor, derived from Vitamin B6, is widely distributed in nature and has significant latitude in catalytic diversity. X-ray crystallography has revealed the structures of diverse PLP dependent enzymes from multiple families. But these structures are incomplete, lacking the positions of protons essential for understanding enzymatic mechanisms. Here, we review the diversity of PLP and discuss the use of neutron crystallography and joint X-ray/neutron refinement of Fold Type I aspartate aminotransferase to visualize the positions of protons in both the internal and external aldimine forms. Strategies used to prepare extremely large crystals required for neutron diffraction and the approach to data refinement including the PLP cofactor are discussed. The observed positions of protons, including one located in a previously unknown low-barrier hydrogen bond, have been used to create more accurate models for computational analysis. The results revealed a new mechanism for the transaminase reaction where hyperconjugation is key to reducing the energy barrier which finally provides a clear explanation of the Dunathan alignment.
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Affiliation(s)
- Timothy C Mueser
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH, United States.
| | - Victoria Drago
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH, United States
| | - Andrey Kovalevsky
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Steven Dajnowicz
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH, United States; Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
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18
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Shibazaki C, Shimizu R, Kagotani Y, Ostermann A, Schrader TE, Adachi M. Direct Observation of the Protonation States in the Mutant Green Fluorescent Protein. J Phys Chem Lett 2020; 11:492-496. [PMID: 31880458 DOI: 10.1021/acs.jpclett.9b03252] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Neutron crystallography has been used to elucidate the protonation states for the enhanced green fluorescent protein, which has revolutionized imaging technologies. The structure has a deprotonated hydroxyl group in the fluorescent chromophore. Also, the protonation states of His148 and Thr203, as well as the orientation of a critical water molecule in direct contact with the chromophore, could be determined. The results demonstrate that the deprotonated hydroxyl group in the chromophore and the nitrogen atom ND1 in His148 are charged negatively and positively, respectively, forming an ion pair. The position of the two deuterium atoms in the critical water molecule appears to be displaced slightly toward the acceptor oxygen atoms according to their omit maps. This displacement implies the formation of an intriguing electrostatic potential realized inside of the protein. Our findings provide new insights into future protein design strategies along with developments in quantum chemical calculations.
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Affiliation(s)
- Chie Shibazaki
- Institute for Quantum Life Science , National Institutes for Quantum and Radiological Science and Technology (QST) , 2-4 Shirakata , Tokai , Ibaraki 319-1106 , Japan
| | - Rumi Shimizu
- Institute for Quantum Life Science , National Institutes for Quantum and Radiological Science and Technology (QST) , 2-4 Shirakata , Tokai , Ibaraki 319-1106 , Japan
| | - Yuji Kagotani
- Institute for Quantum Life Science , National Institutes for Quantum and Radiological Science and Technology (QST) , 2-4 Shirakata , Tokai , Ibaraki 319-1106 , Japan
| | - Andreas Ostermann
- Heinz Maier-Leibnitz Zentrum (MLZ) , Technische Universität München , Lichtenbergstrasse 1 , 85748 Garching , Germany
| | - Tobias E Schrader
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ) , Forschungszentrum Jülich GmbH , Lichtenbergstrasse 1 , 85748 Garching , Germany
| | - Motoyasu Adachi
- Institute for Quantum Life Science , National Institutes for Quantum and Radiological Science and Technology (QST) , 2-4 Shirakata , Tokai , Ibaraki 319-1106 , Japan
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19
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Kovalevsky A, Gerlits O, Beltran K, Weiss KL, Keen DA, Blakeley MP, Louis JM, Weber IT. Proton transfer and drug binding details revealed in neutron diffraction studies of wild-type and drug resistant HIV-1 protease. Methods Enzymol 2020; 634:257-279. [PMID: 32093836 DOI: 10.1016/bs.mie.2019.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
HIV-1 protease is an essential therapeutic target for the design and development of antiviral inhibitors to treat AIDS. We used room temperature neutron crystallography to accurately determine hydrogen atom positions in several protease complexes with clinical drugs, amprenavir and darunavir. Hydrogen bonding interactions were carefully mapped to provide an unprecedented picture of drug binding to the protease target. We demonstrate that hydrogen atom positions within the enzyme catalytic site can be altered by introducing drug resistant mutations and by protonating surface residues that trigger proton transfer reactions between the catalytic Asp residues and the hydroxyl group of darunavir. When protein perdeuteration is not feasible, we validate the use of initial H/D exchange with unfolded protein and partial deuteration in pure D2O with hydrogenous glycerol to maximize deuterium incorporation into the protein, with no detrimental effects on the growth of quality crystals suitable for neutron diffraction experiments.
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Affiliation(s)
- Andrey Kovalevsky
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States.
| | - Oksana Gerlits
- Department of Natural Sciences, Tennessee Wesleyan University, Athens, TN, United States
| | - Kaira Beltran
- Department of Natural Sciences, Tennessee Wesleyan University, Athens, TN, United States
| | - Kevin L Weiss
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - David A Keen
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, United Kingdom
| | | | - John M Louis
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, DHHS, Bethesda, MD, United States
| | - Irene T Weber
- Department of Biology, Georgia State University, Atlanta, GA, United States; Department of Chemistry, Georgia State University, Atlanta, GA, United States
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20
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Knihtila R, Volmar AY, Meilleur F, Mattos C. Titration of ionizable groups in proteins using multiple neutron data sets from a single crystal: application to the small GTPase Ras. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2019; 75:111-115. [PMID: 30713162 DOI: 10.1107/s2053230x18018125] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 12/20/2018] [Indexed: 11/11/2022]
Abstract
Neutron protein crystallography (NPC) reveals the three-dimensional structures of proteins, including the positions of H atoms. The technique is particularly suited to elucidate ambiguous catalytic steps in complex biochemical reactions. While NPC uniquely complements biochemical assays and X-ray structural analyses by revealing the protonation states of ionizable groups at and around the active site of enzymes, the technique suffers from a major drawback: large single crystals must be grown to compensate for the relatively low flux of neutron beams. However, in addition to revealing the positions of hydrogens involved in enzyme catalysis, NPC has the advantage over X-ray crystallography that the crystals do not suffer radiation damage. The lack of radiation damage can be exploited to conduct in crystallo parametric studies. Here, the use of a single crystal of the small GTPase Ras to collect three neutron data sets at pD 8.4, 9.0 and 9.4 is reported, enabling an in crystallo titration study using NPC. In addition to revealing the behavior of titratable groups in the active site, the data sets will allow the analysis of allosteric water-mediated communication networks across the molecule, particularly regarding Cys118 and three tyrosine residues central to these networks, Tyr32, Tyr96 and Tyr137, with pKa values expected to be in the range sampled in our experiments.
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Affiliation(s)
- Ryan Knihtila
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA
| | - Alicia Y Volmar
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA
| | - Flora Meilleur
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Carla Mattos
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA
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21
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Ashkar R, Bilheux HZ, Bordallo H, Briber R, Callaway DJE, Cheng X, Chu XQ, Curtis JE, Dadmun M, Fenimore P, Fushman D, Gabel F, Gupta K, Herberle F, Heinrich F, Hong L, Katsaras J, Kelman Z, Kharlampieva E, Kneller GR, Kovalevsky A, Krueger S, Langan P, Lieberman R, Liu Y, Losche M, Lyman E, Mao Y, Marino J, Mattos C, Meilleur F, Moody P, Nickels JD, O'Dell WB, O'Neill H, Perez-Salas U, Peters J, Petridis L, Sokolov AP, Stanley C, Wagner N, Weinrich M, Weiss K, Wymore T, Zhang Y, Smith JC. Neutron scattering in the biological sciences: progress and prospects. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2018; 74:1129-1168. [PMID: 30605130 DOI: 10.1107/s2059798318017503] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/12/2018] [Indexed: 12/11/2022]
Abstract
The scattering of neutrons can be used to provide information on the structure and dynamics of biological systems on multiple length and time scales. Pursuant to a National Science Foundation-funded workshop in February 2018, recent developments in this field are reviewed here, as well as future prospects that can be expected given recent advances in sources, instrumentation and computational power and methods. Crystallography, solution scattering, dynamics, membranes, labeling and imaging are examined. For the extraction of maximum information, the incorporation of judicious specific deuterium labeling, the integration of several types of experiment, and interpretation using high-performance computer simulation models are often found to be particularly powerful.
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Affiliation(s)
- Rana Ashkar
- Department of Physics, Virginia Polytechnic Institute and State University, 850 West Campus Drive, Blacksburg, VA 24061, USA
| | - Hassina Z Bilheux
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | | | - Robert Briber
- Materials Science and Engineeering, University of Maryland, 1109 Chemical and Nuclear Engineering Building, College Park, MD 20742, USA
| | - David J E Callaway
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Xiaolin Cheng
- Department of Medicinal Chemistry and Pharmacognosy, Ohio State University College of Pharmacy, 642 Riffe Building, Columbus, OH 43210, USA
| | - Xiang Qiang Chu
- Graduate School of China Academy of Engineering Physics, Beijing, 100193, People's Republic of China
| | - Joseph E Curtis
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - Mark Dadmun
- Department of Chemistry, University of Tennessee Knoxville, Knoxville, TN 37996, USA
| | - Paul Fenimore
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - David Fushman
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742, USA
| | - Frank Gabel
- Institut Laue-Langevin, Université Grenoble Alpes, CEA, CNRS, IBS, 38042 Grenoble, France
| | - Kushol Gupta
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Frederick Herberle
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Frank Heinrich
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - Liang Hong
- Department of Physics and Astronomy, Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - John Katsaras
- Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Zvi Kelman
- Institute for Bioscience and Biotechnology Research, National Institute of Standards and Technology and the University of Maryland, Rockville, MD 20850, USA
| | - Eugenia Kharlampieva
- Department of Chemistry, University of Alabama at Birmingham, 901 14th Street South, Birmingham, AL 35294, USA
| | - Gerald R Kneller
- Centre de Biophysique Moléculaire, CNRS, Université d'Orléans, Chateau de la Source, Avenue du Parc Floral, Orléans, France
| | - Andrey Kovalevsky
- Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Susan Krueger
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - Paul Langan
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Raquel Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Yun Liu
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - Mathias Losche
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Edward Lyman
- Department of Physics and Astrophysics, University of Delaware, Newark, DE 19716, USA
| | - Yimin Mao
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - John Marino
- Institute for Bioscience and Biotechnology Research, National Institute of Standards and Technology and the University of Maryland, Rockville, MD 20850, USA
| | - Carla Mattos
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts, USA
| | - Flora Meilleur
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Peter Moody
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN, England
| | - Jonathan D Nickels
- Department of Physics, Virginia Polytechnic Institute and State University, 850 West Campus Drive, Blacksburg, VA 24061, USA
| | - William B O'Dell
- Institute for Bioscience and Biotechnology Research, National Institute of Standards and Technology and the University of Maryland, Rockville, MD 20850, USA
| | - Hugh O'Neill
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Ursula Perez-Salas
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | | | - Loukas Petridis
- Materials Science and Engineeering, University of Maryland, 1109 Chemical and Nuclear Engineering Building, College Park, MD 20742, USA
| | - Alexei P Sokolov
- Department of Chemistry, University of Tennessee Knoxville, Knoxville, TN 37996, USA
| | - Christopher Stanley
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Norman Wagner
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Michael Weinrich
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - Kevin Weiss
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Troy Wymore
- Graduate School of China Academy of Engineering Physics, Beijing, 100193, People's Republic of China
| | - Yang Zhang
- NIST Center for Neutron Research, National Institutes of Standard and Technology, 100 Bureau Drive, Mail Stop 6102, Gaithersburg, MD 20899, USA
| | - Jeremy C Smith
- Department of Medicinal Chemistry and Pharmacognosy, Ohio State University College of Pharmacy, 642 Riffe Building, Columbus, OH 43210, USA
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22
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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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23
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Wong-Sam A, Wang YF, Zhang Y, Ghosh AK, Harrison RW, Weber IT. Drug Resistance Mutation L76V Alters Nonpolar Interactions at the Flap-Core Interface of HIV-1 Protease. ACS OMEGA 2018; 3:12132-12140. [PMID: 30288468 PMCID: PMC6167001 DOI: 10.1021/acsomega.8b01683] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 09/13/2018] [Indexed: 06/08/2023]
Abstract
Four HIV-1 protease (PR) inhibitors, clinical inhibitors lopinavir and tipranavir, and two investigational compounds 4 and 5, were studied for their effect on the structure and activity of PR with drug-resistant mutation L76V (PRL76V). Compound 5 exhibited the best K i value of 1.9 nM for PRL76V, whereas the other three inhibitors had K i values of 4.5-7.6 nM, 2-3 orders of magnitude worse than for wild-type enzymes. Crystal structures showed only minor differences in interactions of inhibitors with PRL76V compared to wild-type complexes. The shorter side chain of Val76 in the mutant lost hydrophobic interactions with Lys45 and Ile47 in the flap, and with Asp30 and Thr74 in the protein core, consistent with decreased stability. Inhibitors forming additional polar interactions with the flaps or dimer interface of PRL76V were unable to compensate for the decrease in internal hydrophobic contacts. These structures provide insights for inhibitor design.
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Affiliation(s)
- Andres Wong-Sam
- Department
of Biology, Molecular Basis of Disease Program, Department of Computer Science, and Department of
Chemistry, Georgia State University, Atlanta, Georgia 30303, United States
| | - Yuan-Fang Wang
- Department
of Biology, Molecular Basis of Disease Program, Department of Computer Science, and Department of
Chemistry, Georgia State University, Atlanta, Georgia 30303, United States
| | - Ying Zhang
- Department
of Biology, Molecular Basis of Disease Program, Department of Computer Science, and Department of
Chemistry, Georgia State University, Atlanta, Georgia 30303, United States
- RNA Therapeutics Institute and Department of Biochemistry and Molecular
Pharmacology, University of Massachusetts
Medical School, Worcester, Massachusetts 01605, United States
| | - Arun K. Ghosh
- Department of Chemistry and Department
of Medicinal Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Robert W. Harrison
- Department
of Biology, Molecular Basis of Disease Program, Department of Computer Science, and Department of
Chemistry, Georgia State University, Atlanta, Georgia 30303, United States
| | - Irene T. Weber
- Department
of Biology, Molecular Basis of Disease Program, Department of Computer Science, and Department of
Chemistry, Georgia State University, Atlanta, Georgia 30303, United States
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Li Z, Zhang X, Wang Q, Li C, Zhang N, Zhang X, Xu B, Ma B, Schrader TE, Coates L, Kovalevsky A, Huang Y, Wan Q. Understanding the pH-Dependent Reaction Mechanism of a Glycoside Hydrolase Using High-Resolution X-ray and Neutron Crystallography. ACS Catal 2018. [DOI: 10.1021/acscatal.8b01472] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zhihong Li
- College of Science, Nanjing Agricultural University, Nanjing 210095, People’s Republic of China
| | - Xiaoshuai Zhang
- College of Science, Nanjing Agricultural University, Nanjing 210095, People’s Republic of China
| | - Qingqing Wang
- College of Science, Nanjing Agricultural University, Nanjing 210095, People’s Republic of China
| | - Chunran Li
- College of Science, Nanjing Agricultural University, Nanjing 210095, People’s Republic of China
| | - Nianying Zhang
- College of Science, Nanjing Agricultural University, Nanjing 210095, People’s Republic of China
| | - Xinkai Zhang
- College of Science, Nanjing Agricultural University, Nanjing 210095, People’s Republic of China
| | - Birui Xu
- College of Science, Nanjing Agricultural University, Nanjing 210095, People’s Republic of China
| | - Baoliang Ma
- College of Science, Nanjing Agricultural University, Nanjing 210095, People’s Republic of China
| | - Tobias E. Schrader
- Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Forschungszentrum Jülich GmbH, Garching 85747, Germany
| | - Leighton Coates
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Andrey Kovalevsky
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Yandong Huang
- College of Computer Engineering, Jimei University, Xiamen 361021, People’s Republic of China
| | - Qun Wan
- College of Science, Nanjing Agricultural University, Nanjing 210095, People’s Republic of China
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25
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Schröder GC, O'Dell WB, Myles DAA, Kovalevsky A, Meilleur F. IMAGINE: neutrons reveal enzyme chemistry. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2018; 74:778-786. [DOI: 10.1107/s2059798318001626] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 01/26/2018] [Indexed: 11/10/2022]
Abstract
Neutron diffraction is exquisitely sensitive to the positions of H atoms in protein crystal structures. IMAGINE is a high-intensity, quasi-Laue neutron crystallography beamline developed at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. This state-of-the-art facility for neutron diffraction has enabled detailed structural analysis of macromolecules. IMAGINE is especially suited to resolve individual H atoms in protein structures, enabling neutron protein structures to be determined at or near atomic resolutions from crystals with volumes of less than 1 mm3 and unit-cell edges of less than 150 Å. Beamline features include elliptical focusing mirrors that deliver neutrons into a 2.0 × 3.2 mm focal spot at the sample position, and variable short- and long-wavelength cutoff optics that provide automated exchange between multiple wavelength configurations. This review gives an overview of the IMAGINE beamline at the HFIR, presents examples of the scientific questions being addressed at this beamline, and highlights important findings in enzyme chemistry that have been made using the neutron diffraction capabilities offered by IMAGINE.
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Bastys T, Gapsys V, Doncheva NT, Kaiser R, de Groot BL, Kalinina OV. Consistent Prediction of Mutation Effect on Drug Binding in HIV-1 Protease Using Alchemical Calculations. J Chem Theory Comput 2018; 14:3397-3408. [PMID: 29847122 DOI: 10.1021/acs.jctc.7b01109] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Despite a large number of antiretroviral drugs targeting HIV-1 protease for inhibition, mutations in this protein during the course of patient treatment can render them inefficient. This emerging resistance inspired numerous computational studies of the HIV-1 protease aimed at predicting the effect of mutations on drug binding in terms of free binding energy Δ G, as well as in mechanistic terms. In this study, we analyze ten different protease-inhibitor complexes carrying major resistance-associated mutations (RAMs) G48V, I50V, and L90M using molecular dynamics simulations. We demonstrate that alchemical free energy calculations can consistently predict the effect of mutations on drug binding. By explicitly probing different protonation states of the catalytic aspartic dyad, we reveal the importance of the correct choice of protonation state for the accuracy of the result. We also provide insight into how different mutations affect drug binding in their specific ways, with the unifying theme of how all of them affect the crucial drug binding regions of the protease.
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Affiliation(s)
- Tomas Bastys
- Department for Computational Biology and Applied Algorithmics , Max Planck Institute for Informatics , D-66123 Saarbrücken , Germany.,Saarbrücken Graduate School of Computer Science , University of Saarland , D-66123 Saarbrücken , Germany
| | - Vytautas Gapsys
- Computational Biomolecular Dynamics Group, Department of Theoretical and Computational Biophysics , Max Planck Institute for Biophysical Chemistry , D-37077 Göttingen , Germany
| | - Nadezhda T Doncheva
- Department for Computational Biology and Applied Algorithmics , Max Planck Institute for Informatics , D-66123 Saarbrücken , Germany.,Faculty of Health and Medical Sciences , University of Copenhagen , 2200 Copenhagen , Denmark
| | - Rolf Kaiser
- Institute for Virology , University Clinic of Cologne , D-50935 Köln , Germany
| | - Bert L de Groot
- Computational Biomolecular Dynamics Group, Department of Theoretical and Computational Biophysics , Max Planck Institute for Biophysical Chemistry , D-37077 Göttingen , Germany
| | - Olga V Kalinina
- Department for Computational Biology and Applied Algorithmics , Max Planck Institute for Informatics , D-66123 Saarbrücken , Germany
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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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Kumar V, Pilati T, Quici S, Chierotti MR, Nervi C, Gobetto R, Resnati G. Proton in a Confined Space: Structural Studies of H + ⊂Crypt-111 Iodide and Some Halogen-Bonded Derivatives. Chemistry 2017; 23:14462-14468. [PMID: 28657685 DOI: 10.1002/chem.201701699] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Revised: 06/27/2017] [Indexed: 11/06/2022]
Abstract
Experimental observations and modeling data are reported on the solid-state structural features of crypt- 111⋅HI (1) and the three-component co-crystals that 1 forms with α,ω-diiodoperfluoroalkanes 2 a-d. X-ray analyses indicate that, in all five systems and at low temperature, the caged proton is covalently bonded to a single nitrogen atom and is involved in a network of intramolecular hydrogen bonds. In contrast, room-temperature, solid-state 15 N NMR spectroscopy suggests magnetic equivalency of the two N atoms of crypt-111 in both 1 and co-crystals of 1 with diiodoperfluoroalkanes. Computational modelling confirms that the acidic hydrogen inside the cavity preferentially sits along the internitrogen axis and is covalently bonded to one nitrogen. The computed energy barriers suggest that the hopping of the encapsulated proton between the two N atoms of the cage can occur in the halogen-bonded co-crystals of 1⋅2, but it is hardly possible in the pure H+ ⊂crypt-111 iodide 1. These different pictures of the proton position and dynamics obtained by using different techniques and conditions confirm the unique characteristics of the confined space within the cavity of crypr-111 and the distinctive features of processes occurring therein.
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Affiliation(s)
- Vijith Kumar
- Nanostructured Fluorinated Materials Laboratory (NFMLab), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Via L. Mancinelli 7, 20131, Milan, Italy
| | - Tullio Pilati
- Nanostructured Fluorinated Materials Laboratory (NFMLab), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Via L. Mancinelli 7, 20131, Milan, Italy
| | - Silvio Quici
- CNR, Istituto di Scienze e Tecnologie Molecolari, Via C. Golgi 19, 20133, Milan, Italy
| | - Michele R Chierotti
- Department of Chemistry and NIS, University of Turin, Via P. Giuria 7, 10125, Turin, Italy
| | - Carlo Nervi
- Department of Chemistry and NIS, University of Turin, Via P. Giuria 7, 10125, Turin, Italy
| | - Roberto Gobetto
- Department of Chemistry and NIS, University of Turin, Via P. Giuria 7, 10125, Turin, Italy
| | - Giuseppe Resnati
- Nanostructured Fluorinated Materials Laboratory (NFMLab), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Via L. Mancinelli 7, 20131, Milan, Italy
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29
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Direct visualization of critical hydrogen atoms in a pyridoxal 5'-phosphate enzyme. Nat Commun 2017; 8:955. [PMID: 29038582 PMCID: PMC5643538 DOI: 10.1038/s41467-017-01060-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 08/15/2017] [Indexed: 11/13/2022] Open
Abstract
Enzymes dependent on pyridoxal 5′-phosphate (PLP, the active form of vitamin B6) perform a myriad of diverse chemical transformations. They promote various reactions by modulating the electronic states of PLP through weak interactions in the active site. Neutron crystallography has the unique ability of visualizing the nuclear positions of hydrogen atoms in macromolecules. Here we present a room-temperature neutron structure of a homodimeric PLP-dependent enzyme, aspartate aminotransferase, which was reacted in situ with α-methylaspartate. In one monomer, the PLP remained as an internal aldimine with a deprotonated Schiff base. In the second monomer, the external aldimine formed with the substrate analog. We observe a deuterium equidistant between the Schiff base and the C-terminal carboxylate of the substrate, a position indicative of a low-barrier hydrogen bond. Quantum chemical calculations and a low-pH room-temperature X-ray structure provide insight into the physical phenomena that control the electronic modulation in aspartate aminotransferase. Pyridoxal 5’-phosphate (PLP) is a ubiquitous co factor for diverse enzymes, among them aspartate aminotransferase. Here the authors use neutron crystallography, which allows the visualization of the positions of hydrogen atoms, and computation to characterize the catalytic mechanism of the enzyme.
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30
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High Pressure Spectroscopic Investigation on Proton Transfer in Squaric Acid and 4,4'-Bipyridine Co-crystal. Sci Rep 2017; 7:4677. [PMID: 28680044 PMCID: PMC5498627 DOI: 10.1038/s41598-017-04980-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 05/23/2017] [Indexed: 11/09/2022] Open
Abstract
In attempt to the obtain detailed geometric information of proton transfer compound (subsequently denote as SQBP) formed between squaric acid (SQ)and 4,4′-bipyridine(BP), and to investigate the mechanisms of pressure-induced double proton transfer and related structural phase transition, we carried out in-situ high pressure Raman spectroscopy of SQBP up to 20 GPa. A solid-solid phase transition together with double proton transfer phenomenon was confirmed by Raman spectroscopy at about 1.5 GPa, and the activation of C = O stretching mode in Raman spectra indicates a square-ring structure of SQ with four symmetric C = O bond formation. These results are further supported by first-principals calculations and in-situ high pressure infrared absorption spectroscopy. Additionally, Raman intensity analysis suggests that a higher-order phase transition with planar BP molecular structure occurred in the pressure range of 3~6 GPa. As a result, the π electron delocalization effect in BP dominated the intensity enhancement of C = O stretching mode in SQ. To the best of our knowledge, this is the first time observation of the intensity enhancement of proton donor’s normal modes induced by proton acceptor’s π electron delocalization.
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31
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Yee AW, Blakeley MP, Moulin M, Haertlein M, Mitchell E, Forsyth VT. Back-exchange of deuterium in neutron crystallography: characterization by IR spectroscopy. J Appl Crystallogr 2017; 50:660-664. [PMID: 28381984 PMCID: PMC5377354 DOI: 10.1107/s1600576717003624] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 03/07/2017] [Indexed: 01/02/2023] Open
Abstract
The application of IR spectroscopy to the characterization and quality control of samples used in neutron crystallography is described. While neutron crystallography is a growing field, the limited availability of neutron beamtime means that there may be a delay between crystallogenesis and data collection. Since essentially all neutron crystallographic work is carried out using D2O-based solvent buffers, a particular concern for these experiments is the possibility of H2O back-exchange across reservoir or capillary sealants. This may limit the quality of neutron scattering length density maps and of the associated analysis. Given the expense of central facility beamtime and the effort that goes into the production of suitably sized (usually perdeuterated) crystals, a systematic method of exploiting IR spectroscopy for the analysis of back-exchange phenomena in the reservoirs used for crystal growth is valuable. Examples are given in which the characterization of D2O/H2O back-exchange in transthyretin crystals is described.
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Affiliation(s)
- Ai Woon Yee
- Life Sciences Group, Institut Laue–Langevin, 71 avenue des Martyrs, Grenoble 38042, France
- Faculty of Natural Sciences, Keele University, Keele ST5 5BG, UK
| | - Matthew P. Blakeley
- Large-Scale Structures Group, Institut Laue–Langevin, 71 avenue des Martyrs, Grenoble 38042, France
| | - Martine Moulin
- Life Sciences Group, Institut Laue–Langevin, 71 avenue des Martyrs, Grenoble 38042, France
- Faculty of Natural Sciences, Keele University, Keele ST5 5BG, UK
| | - Michael Haertlein
- Life Sciences Group, Institut Laue–Langevin, 71 avenue des Martyrs, Grenoble 38042, France
| | - Edward Mitchell
- Faculty of Natural Sciences, Keele University, Keele ST5 5BG, UK
- European Synchrotron Research Facility, 71 avenue des Martyrs, Grenoble 38043, France
| | - V. Trevor Forsyth
- Life Sciences Group, Institut Laue–Langevin, 71 avenue des Martyrs, Grenoble 38042, France
- Faculty of Natural Sciences, Keele University, Keele ST5 5BG, UK
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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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33
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Gerlits O, Keen DA, Blakeley MP, Louis JM, Weber IT, Kovalevsky A. Room Temperature Neutron Crystallography of Drug Resistant HIV-1 Protease Uncovers Limitations of X-ray Structural Analysis at 100 K. J Med Chem 2017; 60:2018-2025. [PMID: 28195728 DOI: 10.1021/acs.jmedchem.6b01767] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
HIV-1 protease inhibitors are crucial for treatment of HIV-1/AIDS, but their effectiveness is thwarted by rapid emergence of drug resistance. To better understand binding of clinical inhibitors to resistant HIV-1 protease, we used room-temperature joint X-ray/neutron (XN) crystallography to obtain an atomic-resolution structure of the protease triple mutant (V32I/I47V/V82I) in complex with amprenavir. The XN structure reveals a D+ ion located midway between the inner Oδ1 oxygen atoms of the catalytic aspartic acid residues. Comparison of the current XN structure with our previous XN structure of the wild-type HIV-1 protease-amprenavir complex suggests that the three mutations do not significantly alter the drug-enzyme interactions. This is in contrast to the observations in previous 100 K X-ray structures of these complexes that indicated loss of interactions by the drug with the triple mutant protease. These findings, thus, uncover limitations of structural analysis of drug binding using X-ray structures obtained at 100 K.
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Affiliation(s)
- Oksana Gerlits
- UT/ORNL Joint Institute of Biological Sciences, University of Tennessee , Knoxville, Tennessee 37996, United States
| | - David A Keen
- ISIS Facility, Rutherford Appleton Laboratory , Harwell Campus, Didcot, OX11 0QX, U.K
| | - Matthew P Blakeley
- Large-Scale Structures Group, Institut Laue Langevin , 71 avenue des Martyrs, 38000 Grenoble, France
| | - John M Louis
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , DHHS, Bethesda, Maryland 20892-0520, United States
| | - Irene T Weber
- Departments of Chemistry and Biology, Georgia State University , Atlanta, Georgia 30302, United States
| | - Andrey Kovalevsky
- Biology and Soft Matter Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
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Chen JCH, Unkefer CJ. Fifteen years of the Protein Crystallography Station: the coming of age of macromolecular neutron crystallography. IUCRJ 2017; 4:72-86. [PMID: 28250943 PMCID: PMC5331467 DOI: 10.1107/s205225251601664x] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 10/17/2016] [Indexed: 06/06/2023]
Abstract
The Protein Crystallography Station (PCS), located at the Los Alamos Neutron Scattering Center (LANSCE), was the first macromolecular crystallography beamline to be built at a spallation neutron source. Following testing and commissioning, the PCS user program was funded by the Biology and Environmental Research program of the Department of Energy Office of Science (DOE-OBER) for 13 years (2002-2014). The PCS remained the only dedicated macromolecular neutron crystallography station in North America until the construction and commissioning of the MaNDi and IMAGINE instruments at Oak Ridge National Laboratory, which started in 2012. The instrument produced a number of research and technical outcomes that have contributed to the field, clearly demonstrating the power of neutron crystallo-graphy in helping scientists to understand enzyme reaction mechanisms, hydrogen bonding and visualization of H-atom positions, which are critical to nearly all chemical reactions. During this period, neutron crystallography became a technique that increasingly gained traction, and became more integrated into macromolecular crystallography through software developments led by investigators at the PCS. This review highlights the contributions of the PCS to macromolecular neutron crystallography, and gives an overview of the history of neutron crystallography and the development of macromolecular neutron crystallography from the 1960s to the 1990s and onwards through the 2000s.
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Affiliation(s)
- Julian C.-H. Chen
- Bioscience Division, Protein Crystallography Station, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Clifford J. Unkefer
- Bioscience Division, Protein Crystallography Station, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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Laucirica G, Marmisollé WA, Azzaroni O. Dangerous liaisons: anion-induced protonation in phosphate–polyamine interactions and their implications for the charge states of biologically relevant surfaces. Phys Chem Chem Phys 2017; 19:8612-8620. [DOI: 10.1039/c6cp08793k] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The specific binding of phosphates on surface amino groups has complex consequences on the protonation equilibriums and effective surface charges with serious implications for further biochemically relevant interactions.
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Affiliation(s)
- Gregorio Laucirica
- Instituto de Investigaciones Fisicoquímica Teóricas y Aplicadas (INIFTA)
- Departamento de Química
- Facultad de Ciencias Exactas
- Universidad Nacional de La Plata (UNLP)
- La Plata
| | - Waldemar A. Marmisollé
- Instituto de Investigaciones Fisicoquímica Teóricas y Aplicadas (INIFTA)
- Departamento de Química
- Facultad de Ciencias Exactas
- Universidad Nacional de La Plata (UNLP)
- La Plata
| | - Omar Azzaroni
- Instituto de Investigaciones Fisicoquímica Teóricas y Aplicadas (INIFTA)
- Departamento de Química
- Facultad de Ciencias Exactas
- Universidad Nacional de La Plata (UNLP)
- La Plata
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Neutron structures of the Helicobacter pylori 5'-methylthioadenosine nucleosidase highlight proton sharing and protonation states. Proc Natl Acad Sci U S A 2016; 113:13756-13761. [PMID: 27856757 DOI: 10.1073/pnas.1609718113] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
MTAN (5'-methylthioadenosine nucleosidase) catalyzes the hydrolysis of the N-ribosidic bond of a variety of adenosine-containing metabolites. The Helicobacter pylori MTAN (HpMTAN) hydrolyzes 6-amino-6-deoxyfutalosine in the second step of the alternative menaquinone biosynthetic pathway. Substrate binding of the adenine moiety is mediated almost exclusively by hydrogen bonds, and the proposed catalytic mechanism requires multiple proton-transfer events. Of particular interest is the protonation state of residue D198, which possesses a pKa above 8 and functions as a general acid to initiate the enzymatic reaction. In this study we present three corefined neutron/X-ray crystal structures of wild-type HpMTAN cocrystallized with S-adenosylhomocysteine (SAH), Formycin A (FMA), and (3R,4S)-4-(4-Chlorophenylthiomethyl)-1-[(9-deaza-adenin-9-yl)methyl]-3-hydroxypyrrolidine (p-ClPh-Thio-DADMe-ImmA) as well as one neutron/X-ray crystal structure of an inactive variant (HpMTAN-D198N) cocrystallized with SAH. These results support a mechanism of D198 pKa elevation through the unexpected sharing of a proton with atom N7 of the adenine moiety possessing unconventional hydrogen-bond geometry. Additionally, the neutron structures also highlight active site features that promote the stabilization of the transition state and slight variations in these interactions that result in 100-fold difference in binding affinities between the DADMe-ImmA and ImmA analogs.
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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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