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Judge A, Sankaran B, Hu L, Palaniappan M, Birgy A, Prasad BVV, Palzkill T. Network of epistatic interactions in an enzyme active site revealed by large-scale deep mutational scanning. Proc Natl Acad Sci U S A 2024; 121:e2313513121. [PMID: 38483989 PMCID: PMC10962969 DOI: 10.1073/pnas.2313513121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Accepted: 02/14/2024] [Indexed: 03/19/2024] Open
Abstract
Cooperative interactions between amino acids are critical for protein function. A genetic reflection of cooperativity is epistasis, which is when a change in the amino acid at one position changes the sequence requirements at another position. To assess epistasis within an enzyme active site, we utilized CTX-M β-lactamase as a model system. CTX-M hydrolyzes β-lactam antibiotics to provide antibiotic resistance, allowing a simple functional selection for rapid sorting of modified enzymes. We created all pairwise mutations across 17 active site positions in the β-lactamase enzyme and quantitated the function of variants against two β-lactam antibiotics using next-generation sequencing. Context-dependent sequence requirements were determined by comparing the antibiotic resistance function of double mutations across the CTX-M active site to their predicted function based on the constituent single mutations, revealing both positive epistasis (synergistic interactions) and negative epistasis (antagonistic interactions) between amino acid substitutions. The resulting trends demonstrate that positive epistasis is present throughout the active site, that epistasis between residues is mediated through substrate interactions, and that residues more tolerant to substitutions serve as generic compensators which are responsible for many cases of positive epistasis. Additionally, we show that a key catalytic residue (Glu166) is amenable to compensatory mutations, and we characterize one such double mutant (E166Y/N170G) that acts by an altered catalytic mechanism. These findings shed light on the unique biochemical factors that drive epistasis within an enzyme active site and will inform enzyme engineering efforts by bridging the gap between amino acid sequence and catalytic function.
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Affiliation(s)
- Allison Judge
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX77030
| | - Banumathi Sankaran
- Department of Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology Lawrence Berkeley National Laboratory, Berkeley, CA94720
| | - Liya Hu
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX77030
| | - Murugesan Palaniappan
- Department of Pathology and Immunology, Center for Drug Discovery, Baylor College of Medicine, Houston, TX77030
| | - André Birgy
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX77030
- Infections, Antimicrobials, Modelling, Evolution, UMR 1137, French Insitute for Medical Research (INSERM), Faculty of Health, Université Paris Cité, Paris75006, France
| | - B. V. Venkataram Prasad
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX77030
| | - Timothy Palzkill
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX77030
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2
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Chen S, Mack AR, Hujer AM, Bethel CR, Bonomo RA, Haider S. Ω-Loop mutations control the dynamics of the active site by modulating a network of hydrogen bonds in PDC-3 β-lactamase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.04.578824. [PMID: 38370743 PMCID: PMC10871217 DOI: 10.1101/2024.02.04.578824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
The expression of antibiotic-inactivating enzymes, such as Pseudomonas-derived cephalosporinase-3 (PDC-3), is a major mechanism of intrinsic resistance in bacteria. To explore the relationships between structural dynamics and altered substrate specificity as a result of amino acid substitutions in PDC-3, innovative computational methods like machine learning driven adaptive bandit molecular dynamics simulations and markov state modeling of the wild-type PDC-3 and nine clinically identified variants were conducted. Our analysis reveals that structural changes in the Ω loop controls the dynamics of the active site. The E219K and Y221A substitutions have the most pronounced effects. The modulation of three key hydrogen bonds K67(sc)-G220(bb), Y150(bb)-A292(bb) and N287(sc)-N314(sc) were found to result in an expansion of the active site, which could have implications for the binding and inactivation of cephalosporins. Overall, the findings highlight the importance of understanding the structural dynamics of PDC-3 in the development of new treatments for antibiotic-resistant infections.
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Affiliation(s)
| | - Andrew R Mack
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Andrea M Hujer
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Christopher R Bethel
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA
| | - Robert A Bonomo
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, USA
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, USA
- Clinician Scientist Investigator, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA
- Departments of Pharmacology, Biochemistry, and Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES) Cleveland, OH, USA
| | - Shozeb Haider
- UCL School of Pharmacy, London UK
- UCL Centre for Advanced Research Computing, London UK
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3
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Kar R, Mandal S, Thakkur V, Meyer B, Nair NN. Speeding-up Hybrid Functional-Based Ab Initio Molecular Dynamics Using Multiple Time-stepping and Resonance-Free Thermostat. J Chem Theory Comput 2023; 19:8351-8364. [PMID: 37933121 DOI: 10.1021/acs.jctc.3c00964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Abstract
Ab initio molecular dynamics (AIMD) based on density functional theory (DFT) has become a workhorse for studying the structure, dynamics, and reactions in condensed matter systems. Currently, AIMD simulations are primarily carried out at the level of generalized gradient approximation (GGA), which is at the second rung of DFT functionals in terms of accuracy. Hybrid DFT functionals, which form the fourth rung in the accuracy ladder, are not commonly used in AIMD simulations as the computational cost involved is 100 times or higher. To facilitate AIMD simulations with hybrid functionals, we propose here an approach using multiple time stepping with adaptively compressed exchange operator and resonance-free thermostat, that could speed up the calculations by ∼30 times or more for systems with a few hundred of atoms. We demonstrate that by achieving this significant speed up and making the compute time of hybrid functional-based AIMD simulations at par with that of GGA functionals, we are able to study several complex condensed matter systems and model chemical reactions in solution with hybrid functionals that were earlier unthinkable to be performed.
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Affiliation(s)
- Ritama Kar
- Department of Chemistry, Indian Institute of Technology Kanpur (IITK), Kanpur 208016, India
| | - Sagarmoy Mandal
- Interdisciplinary Center for Molecular Materials and Computer Chemistry Center, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nägelsbachstr. 25, Erlangen 91052, Germany
- Erlangen National High Performance Computing Center (NHR@FAU), Friedrich-Alexander-Universität Erlangen-Nürnberg, Martensstr. 1, Erlangen 91058, Germany
| | - Vaishali Thakkur
- Department of Chemistry, Indian Institute of Technology Kanpur (IITK), Kanpur 208016, India
| | - Bernd Meyer
- Interdisciplinary Center for Molecular Materials and Computer Chemistry Center, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nägelsbachstr. 25, Erlangen 91052, Germany
- Erlangen National High Performance Computing Center (NHR@FAU), Friedrich-Alexander-Universität Erlangen-Nürnberg, Martensstr. 1, Erlangen 91058, Germany
| | - Nisanth N Nair
- Department of Chemistry, Indian Institute of Technology Kanpur (IITK), Kanpur 208016, India
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4
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Tripathi S, Nair NN. Temperature Accelerated Sliced Sampling to Probe Ligand Dissociation from Protein. J Chem Inf Model 2023; 63:5182-5191. [PMID: 37540828 DOI: 10.1021/acs.jcim.3c00376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/06/2023]
Abstract
Modeling ligand unbinding in proteins to estimate the free energy of binding and probing the mechanism presents several challenges. They primarily pertain to the entropic bottlenecks resulting from protein and solvent conformations. While exploring the unbinding processes using enhanced sampling techniques, very long simulations are required to sample all of the conformational states as the system gets trapped in local free energy minima along transverse coordinates. Here, we demonstrate that temperature accelerated sliced sampling (TASS) is an ideal approach to overcome some of the difficulties faced by conventional sampling methods in studying ligand unbinding. Using TASS, we study the unbinding of avibactam inhibitor molecules from the Class C β-lactamase (CBL) active site. Extracting CBL-avibactam unbinding free energetics, unbinding pathways, and identifying critical interactions from the TASS simulations are demonstrated.
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Affiliation(s)
- Shubhandra Tripathi
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Nisanth N Nair
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
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5
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Dutta S, Chandra A. A Multiple Proton Transfer Mechanism for the Charging Step of the Aminoacylation Reaction at the Active Site of Aspartyl tRNA Synthetase. J Chem Inf Model 2023; 63:1819-1832. [PMID: 36893463 DOI: 10.1021/acs.jcim.2c01332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
Abstract
Aspartyl-tRNA synthetase catalyzes the attachment of aspartic acid to its cognate tRNA by the aminoacylation reaction during the initiation of the protein biosynthesis process. In the second step of the aminoacylation reaction, known as the charging step, the aspartate moiety is transferred from aspartyl-adenylate to the 3'-OH of A76 of tRNA through a proton transfer process. We have investigated different pathways for the charging step through three separate QM/MM simulations combined with the enhanced sampling method of well-sliced metadynamics and found out the most feasible pathway for the reaction at the active site of the enzyme. In the charging reaction, both the phosphate group and the ammonium group after deprotonation can potentially act as a base for proton transfer in the substrate-assisted mechanism. We have considered three possible mechanisms involving different pathways of proton transfer, and only one of them is determined to be enzymatically feasible. The free energy landscape along reaction coordinates where the phosphate group acts as the general base showed that, in the absence of water, the barrier height is 52.6 kcal/mol. The free energy barrier is reduced to 39.7 kcal/mol when the active site water molecules are also treated quantum mechanically, thus allowing a water mediated proton transfer. The charging reaction involving the ammonium group of the aspartyl adenylate is found to follow a path where first a proton from the ammonium group moves to a water in the vicinity forming a hydronium ion (H3O+) and NH2 group. The hydronium ion subsequently passes the proton to the Asp233 residue, thus minimizing the chance of back proton transfer from hydronium to the NH2 group. The neutral NH2 group subsequently takes the proton from the O3' of A76 with a free energy barrier of 10.7 kcal/mol. In the next step, the deprotonated O3' makes a nucleophilic attack to the carbonyl carbon forming a tetrahedral transition state with a free energy barrier of 24.8 kcal/mol. Thus, the present work shows that the charging step proceeds through a multiple proton transfer mechanism where the amino group formed after deprotonation acts as the base to capture a proton from O3' of A76 rather than the phosphate group. The current study also shows the important role played by Asp233 in the proton transfer process.
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Affiliation(s)
- Saheb Dutta
- Department of Chemistry, Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Amalendu Chandra
- Department of Chemistry, Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
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6
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Affiliation(s)
- Vaishali Thakkur
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Chandan Kumar Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Nisanth N. Nair
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
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7
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Dutta S, Chandra A. Free Energy Landscape of the Adenylation Reaction of the Aminoacylation Process at the Active Site of Aspartyl tRNA Synthetase. J Phys Chem B 2022; 126:5821-5831. [PMID: 35895864 DOI: 10.1021/acs.jpcb.2c03843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The process of protein biosynthesis is initiated by the aminoacylation process where a transfer ribonucleic acid (tRNA) is charged by the attachment of its cognate amino acid at the active site of the corresponding aminoacyl tRNA synthetase enzyme. The first step of the aminoacylation process, known as the adenylation reaction, involves activation of the cognate amino acid where it reacts with a molecule of adenosine triphosphate (ATP) at the active site of the enzyme to form the aminoacyl adenylate and inorganic pyrophosphate. In the current work, we have investigated the adenylation reaction between aspartic acid and ATP at the active site of the fully solvated aspartyl tRNA synthetase (AspRS) from Escherichia coli in aqueous medium at room temperature through hybrid quantum mechanical/molecular mechanical (QM/MM) simulations combined with enhanced sampling methods of well-tempered and well-sliced metadynamics. The objective of the present work is to study the associated free energy landscape and reaction barrier and also to explore the effects of active site mutation on the free energy surface of the reaction. The current calculations include finite temperature effects on free energy profiles. In particular, apart from contributions of interaction energies, the current calculations also include contributions of conformational, vibrational, and translational entropy of active site residues, substrates, and also the rest of the solvated protein and surrounding water into the free energy calculations. The present QM/MM metadynamics simulations predict a free energy barrier of 23.35 and 23.5 kcal/mol for two different metadynamics methods used to perform the reaction at the active site of the wild type enzyme. The free energy barrier increases to 30.6 kcal/mol when Arg217, which is an important conserved residue of the wild type enzyme at its active site, is mutated by alanine. These free energy results including the effect of mutation compare reasonably well with those of kinetic experiments that are available in the literature. The current work also provides molecular details of structural changes of the reactants and surroundings as the system dynamically evolves along the reaction pathway from reactant to the product state through QM/MM metadynamics simulations.
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Affiliation(s)
- Saheb Dutta
- Department of Chemistry, Indian Institute of Technology Kanpur, Uttar Pradesh, India 208016
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Uttar Pradesh, India 208016
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8
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Soniya K, Chandra A. Free Energy Landscape and Proton Transfer Pathways of the Transimination Reaction at the Active site of the Serine Hydroxymethyltransferase Enzyme in Aqueous Medium. J Phys Chem B 2021; 125:11848-11856. [PMID: 34696588 DOI: 10.1021/acs.jpcb.1c05864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Serine hydroxymethyltransferase (SHMT) is a ubiquitous enzyme belonging to the fold type I or aspartate aminotransferase (AspAT) family of the pyridoxal 5'-phosphate (PLP)-dependent enzymes. Like other PLP-dependent enzymes, SHMT also undergoes the so-called transimination reaction before exhibiting its enzymatic activity. The transimination process constitutes an important pre-step for all PLP-dependent enzymes, where an internal aldimine of the PLP-enzyme complex gets converted to an external aldimine of the substrate-PLP complex at the active site of the enzyme. In case of the transimination reaction involving SHMT, the PLP molecule bound to the active site lysine residue of SHMT (internal aldimine) gets detached from the enzyme by a serine substrate to produce an external aldimine complex, where the PLP is now bound to the serine substrate. In the current study, the free energy surfaces and reaction pathways of different steps of the transimination reaction at the active site of SHMT are investigated by employing hybrid quantum mechanical/molecular mechanical (QM/MM) simulations combined with metadynamics methods of rare event sampling. It is found that the process of transimination involving serine and PLP at the active site of the SHMT enzyme takes place through different elementary steps such as the formation of the first geminal diamine intermediate (GDI1), transfer of a proton from the substrate serine to the phenolic oxygen of PLP, followed by another proton transfer from PLP to the amine nitrogen of lysine with the formation of the second geminal diamine intermediate (GDI2), and finally, detachment of the active site lysine residue from PLP to produce the external aldimine.
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Affiliation(s)
- Kumari Soniya
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
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9
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Mora-Ochomogo M, Lohans CT. β-Lactam antibiotic targets and resistance mechanisms: from covalent inhibitors to substrates. RSC Med Chem 2021; 12:1623-1639. [PMID: 34778765 PMCID: PMC8528271 DOI: 10.1039/d1md00200g] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 07/25/2021] [Indexed: 12/24/2022] Open
Abstract
The β-lactams are the most widely used antibacterial agents worldwide. These antibiotics, a group that includes the penicillins and cephalosporins, are covalent inhibitors that target bacterial penicillin-binding proteins and disrupt peptidoglycan synthesis. Bacteria can achieve resistance to β-lactams in several ways, including the production of serine β-lactamase enzymes. While β-lactams also covalently interact with serine β-lactamases, these enzymes are capable of deacylating this complex, treating the antibiotic as a substrate. In this tutorial-style review, we provide an overview of the β-lactam antibiotics, focusing on their covalent interactions with their target proteins and resistance mechanisms. We begin by describing the structurally diverse range of β-lactam antibiotics and β-lactamase inhibitors that are currently used as therapeutics. Then, we introduce the penicillin-binding proteins, describing their functions and structures, and highlighting their interactions with β-lactam antibiotics. We next describe the classes of serine β-lactamases, exploring some of the mechanisms by which they achieve the ability to degrade β-lactams. Finally, we introduce the l,d-transpeptidases, a group of bacterial enzymes involved in peptidoglycan synthesis which are also targeted by β-lactam antibiotics. Although resistance mechanisms are now prevalent for all antibiotics in this class, past successes in antibiotic development have at least delayed this onset of resistance. The β-lactams continue to be an essential tool for the treatment of infectious disease, and recent advances (e.g., β-lactamase inhibitor development) will continue to support their future use.
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Affiliation(s)
| | - Christopher T Lohans
- Department of Biomedical and Molecular Sciences, Queen's University Kingston ON K7L 3N6 Canada
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10
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Bahr G, González LJ, Vila AJ. Metallo-β-lactamases in the Age of Multidrug Resistance: From Structure and Mechanism to Evolution, Dissemination, and Inhibitor Design. Chem Rev 2021; 121:7957-8094. [PMID: 34129337 PMCID: PMC9062786 DOI: 10.1021/acs.chemrev.1c00138] [Citation(s) in RCA: 96] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Antimicrobial resistance is one of the major problems in current practical medicine. The spread of genes coding for resistance determinants among bacteria challenges the use of approved antibiotics, narrowing the options for treatment. Resistance to carbapenems, last resort antibiotics, is a major concern. Metallo-β-lactamases (MBLs) hydrolyze carbapenems, penicillins, and cephalosporins, becoming central to this problem. These enzymes diverge with respect to serine-β-lactamases by exhibiting a different fold, active site, and catalytic features. Elucidating their catalytic mechanism has been a big challenge in the field that has limited the development of useful inhibitors. This review covers exhaustively the details of the active-site chemistries, the diversity of MBL alleles, the catalytic mechanism against different substrates, and how this information has helped developing inhibitors. We also discuss here different aspects critical to understand the success of MBLs in conferring resistance: the molecular determinants of their dissemination, their cell physiology, from the biogenesis to the processing involved in the transit to the periplasm, and the uptake of the Zn(II) ions upon metal starvation conditions, such as those encountered during an infection. In this regard, the chemical, biochemical and microbiological aspects provide an integrative view of the current knowledge of MBLs.
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Affiliation(s)
- Guillermo Bahr
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Universidad Nacional de Rosario, Ocampo y Esmeralda S/N, 2000 Rosario, Argentina
- Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
| | - Lisandro J. González
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Universidad Nacional de Rosario, Ocampo y Esmeralda S/N, 2000 Rosario, Argentina
- Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
| | - Alejandro J. Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Universidad Nacional de Rosario, Ocampo y Esmeralda S/N, 2000 Rosario, Argentina
- Area Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina
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Mandal S, Thakkur V, Nair NN. Achieving an Order of Magnitude Speedup in Hybrid-Functional- and Plane-Wave-Based Ab Initio Molecular Dynamics: Applications to Proton-Transfer Reactions in Enzymes and in Solution. J Chem Theory Comput 2021; 17:2244-2255. [PMID: 33740375 DOI: 10.1021/acs.jctc.1c00009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ab initio molecular dynamics (MD) with hybrid density functionals and a plane wave basis is computationally expensive due to the high computational cost of exact exchange energy evaluation. Recently, we proposed a strategy to combine adaptively compressed exchange (ACE) operator formulation and a multiple time step integration scheme to reduce the computational cost significantly [J. Chem. Phys. 2019, 151, 151102 ]. However, it was found that the construction of the ACE operator, which has to be done at least once in every MD time step, is computationally expensive. In the present work, systematic improvements are introduced to further speed up by employing localized orbitals for the construction of the ACE operator. By this, we could achieve a computational speedup of an order of magnitude for a periodic system containing 32 water molecules. Benchmark calculations were carried out to show the accuracy and efficiency of the method in predicting the structural and dynamical properties of bulk water. To demonstrate the applicability, computationally intensive free-energy computations at the level of hybrid density functional theory were performed to investigate (a) methyl formate hydrolysis reaction in neutral aqueous media and (b) proton-transfer reaction within the active-site residues of the class C β-lactamase enzyme.
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Affiliation(s)
- Sagarmoy Mandal
- Department of Chemistry, Indian Institute of Technology Kanpur (IITK), Kanpur 208016, India.,Interdisciplinary Center for Molecular Materials and Computer Chemistry Center, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nägelsbachstr. 25, Erlangen 91052, Germany
| | - Vaishali Thakkur
- Department of Chemistry, Indian Institute of Technology Kanpur (IITK), Kanpur 208016, India
| | - Nisanth N Nair
- Department of Chemistry, Indian Institute of Technology Kanpur (IITK), Kanpur 208016, India
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12
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Dutta Banik S, Bankura A, Chandra A. A QM/MM simulation study of transamination reaction at the active site of aspartate aminotransferase: Free energy landscape and proton transfer pathways. J Comput Chem 2020; 41:2684-2694. [PMID: 32932551 DOI: 10.1002/jcc.26422] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 08/08/2020] [Accepted: 09/03/2020] [Indexed: 11/10/2022]
Abstract
Transaminase is a key enzyme for amino acid metabolism, which reversibly catalyzes the transamination reaction with the help of PLP (pyridoxal 5' -phosphate) as its cofactor. Here we have investigated the mechanism and free energy landscape of the transamination reaction involving the aspartate transaminase (AspTase) enzyme and aspartate-PLP (Asp-PLP) complex using QM/MM simulation and metadynamics methods. The reaction is found to follow a stepwise mechanism where the active site residue Lys258 acts as a base to shuttle a proton from α-carbon (CA) to imine carbon (C4A) of the PLP-Asp Schiff base. In the first step, the Lys258 abstracts the CA proton of the substrate leading to the formation of a carbanionic intermediate which is followed by the reprotonation of the Asp-PLP Schiff base at C4A atom by Lys258. It is found that the free energy barrier for the proton abstraction by Lys258 and that for the reprotonation are 17.85 and 3.57 kcal/mol, respectively. The carbanionic intermediate is 7.14 kcal/mol higher in energy than the reactant. Hence, the first step acts as the rate limiting step. The present calculations also show that the Lys258 residue undergoes a conformational change after the first step of transamination reaction and becomes proximal to C4A atom of the Asp-PLP Schiff base to favor the second step. The active site residues Tyr70* and Gly38 anchor the Lys258 in proper position and orientation during the first step of the reaction and stabilize the positive charge over Lys258 generated at the intermediate step.
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Affiliation(s)
- Sindrila Dutta Banik
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, India
| | - Arindam Bankura
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, India
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, India
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13
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Song Z, Zhou H, Tian H, Wang X, Tao P. Unraveling the energetic significance of chemical events in enzyme catalysis via machine-learning based regression approach. Commun Chem 2020; 3:134. [PMID: 36703376 PMCID: PMC9814854 DOI: 10.1038/s42004-020-00379-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 09/11/2020] [Indexed: 01/29/2023] Open
Abstract
The bacterial enzyme class of β-lactamases are involved in benzylpenicillin acylation reactions, which are currently being revisited using hybrid quantum mechanical molecular mechanical (QM/MM) chain-of-states pathway optimizations. Minimum energy pathways are sampled by reoptimizing pathway geometry under different representative protein environments obtained through constrained molecular dynamics simulations. Predictive potential energy surface models in the reaction space are trained with machine-learning regression techniques. Herein, using TEM-1/benzylpenicillin acylation reaction as the model system, we introduce two model-independent criteria for delineating the energetic contributions and correlations in the predicted reaction space. Both methods are demonstrated to effectively quantify the energetic contribution of each chemical process and identify the rate limiting step of enzymatic reaction with high degrees of freedom. The consistency of the current workflow is tested under seven levels of quantum chemistry theory and three non-linear machine-learning regression models. The proposed approaches are validated to provide qualitative compliance with experimental mutagenesis studies.
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Affiliation(s)
- Zilin Song
- grid.263864.d0000 0004 1936 7929Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, TX 75275 USA
| | - Hongyu Zhou
- grid.263864.d0000 0004 1936 7929Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, TX 75275 USA
| | - Hao Tian
- grid.263864.d0000 0004 1936 7929Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, TX 75275 USA
| | - Xinlei Wang
- grid.263864.d0000 0004 1936 7929Department of Statistical Science, Southern Methodist University, Dallas, TX 75275 USA
| | - Peng Tao
- grid.263864.d0000 0004 1936 7929Department of Chemistry, Center for Research Computing, Center for Drug Discovery, Design, and Delivery (CD4), Southern Methodist University, Dallas, TX 75275 USA
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14
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Das CK, Nair NN. Elucidating the Molecular Basis of Avibactam‐Mediated Inhibition of Class A β‐Lactamases. Chemistry 2020; 26:9639-9651. [DOI: 10.1002/chem.202001261] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/10/2020] [Indexed: 12/25/2022]
Affiliation(s)
- Chandan Kumar Das
- Department of ChemistryIndian Institute of Technology Kanpur Kanpur 208016 India
- Current Address: Lehrstuhl für Theoretische ChemieRuhr Universität Bochum 44780 Bochum Germany
| | - Nisanth N. Nair
- Department of ChemistryIndian Institute of Technology Kanpur Kanpur 208016 India
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15
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Cheng Q, DeYonker NJ. Acylation and deacylation mechanism and kinetics of penicillin G reaction with Streptomyces R61 DD-peptidase. J Comput Chem 2020; 41:1685-1697. [PMID: 32323874 DOI: 10.1002/jcc.26210] [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] [Received: 11/15/2019] [Revised: 02/26/2020] [Accepted: 04/05/2020] [Indexed: 12/20/2022]
Abstract
Two quantum mechanical (QM)-cluster models are built for studying the acylation and deacylation mechanism and kinetics of Streptomyces R61 DD-peptidase with the penicillin G at atomic level detail. DD-peptidases are bacterial enzymes involved in the cross-linking of peptidoglycan to form the cell wall, necessary for bacterial survival. The cross-linking can be inhibited by antibiotic beta-lactam derivatives through acylation, preventing the acyl-enzyme complex from undergoing further deacylation. The deacylation step was predicted to be rate-limiting. Transition state and intermediate structures are found using density functional theory in this study, and thermodynamic and kinetic properties of the proposed mechanism are evaluated. The acyl-enzyme complex is found lying in a deep thermodynamic sink, and deacylation is indeed the severely rate-limiting step, leading to suicide inhibition of the peptidoglycan cross-linking. The usage of QM-cluster models is a promising technique to understand, improve, and design antibiotics to disrupt function of the Streptomyces R61 DD-peptidase.
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Affiliation(s)
- Qianyi Cheng
- Department of Chemistry, University of Memphis, Memphis, Tennessee, USA
| | - Nathan J DeYonker
- Department of Chemistry, University of Memphis, Memphis, Tennessee, USA
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16
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Gimenez-Dejoz J, Tsuchiya K, Tateishi A, Motoda Y, Kigawa T, Asano Y, Numata K. Computational study on the polymerization reaction of d-aminopeptidase for the synthesis of d-peptides. RSC Adv 2020; 10:17582-17592. [PMID: 35515590 PMCID: PMC9053604 DOI: 10.1039/d0ra01138j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/28/2020] [Indexed: 02/02/2023] Open
Abstract
Almost all natural proteins are composed exclusively of l-amino acids, and this chirality influences their properties, functions, and selectivity. Proteases can recognize proteins composed of l-amino acids but display lower selectivity for their stereoisomers, d-amino acids. Taking this as an advantage, d-amino acids can be used to develop polypeptides or biobased materials with higher biostability. Chemoenzymatic peptide synthesis is a technique that uses proteases as biocatalysts to synthesize polypeptides, and d-stereospecific proteases can be used to synthesize polypeptides incorporating d-amino acids. However, engineered proteases with modified catalytic activities are required to allow the incorporation of d-amino acids with increased efficiency. To understand the stereospecificity presented by proteases and their involvement in polymerization reactions, we studied d-aminopeptidase. This enzyme displays the ability to efficiently synthesize poly d-alanine-based peptides under mild conditions. To elucidate the mechanisms involved in the unique specificity of d-aminopeptidase, we performed quantum mechanics/molecular mechanics simulations of its polymerization reaction and determined the energy barriers presented by the chiral substrates. The enzyme faces higher activation barriers for the acylation and aminolysis reactions with the l-stereoisomer than with the d-substrate (10.7 and 17.7 kcal mol−1 higher, respectively). The simulation results suggest that changes in the interaction of the substrate with Asn155 influence the stereospecificity of the polymerization reaction. We studied the molecular mechanism of d-aminopeptidase for the synthesis of polypeptides incorporating d-amino acids.![]()
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Affiliation(s)
- Joan Gimenez-Dejoz
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science 2-1 Hirosawa Wako-shi Saitama 351-0198 Japan
| | - Kousuke Tsuchiya
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science 2-1 Hirosawa Wako-shi Saitama 351-0198 Japan
| | - Ayaka Tateishi
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science 2-1 Hirosawa Wako-shi Saitama 351-0198 Japan
| | - Yoko Motoda
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science 2-1 Hirosawa Wako-shi Saitama 351-0198 Japan
| | - Takanori Kigawa
- Laboratory for Cellular Structural Biology, RIKEN Center for Biosystems Dynamics Research 1-7-22 Suehiro-cho, Tsurumi Yokohama 230-0045 Japan
| | - Yasuhisa Asano
- Biotechnology Research Center, Department of Biotechnology, Toyama Prefectural University 5180 Kurokawa Imizu Toyama 939-0398 Japan
| | - Keiji Numata
- Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science 2-1 Hirosawa Wako-shi Saitama 351-0198 Japan
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17
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Tripathi R, Forbert H, Marx D. Settling the Long-Standing Debate on the Proton Storage Site of the Prototype Light-Driven Proton Pump Bacteriorhodopsin. J Phys Chem B 2019; 123:9598-9608. [DOI: 10.1021/acs.jpcb.9b09608] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Tooke CL, Hinchliffe P, Bragginton EC, Colenso CK, Hirvonen VHA, Takebayashi Y, Spencer J. β-Lactamases and β-Lactamase Inhibitors in the 21st Century. J Mol Biol 2019; 431:3472-3500. [PMID: 30959050 PMCID: PMC6723624 DOI: 10.1016/j.jmb.2019.04.002] [Citation(s) in RCA: 437] [Impact Index Per Article: 87.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 03/27/2019] [Accepted: 04/01/2019] [Indexed: 12/31/2022]
Abstract
The β-lactams retain a central place in the antibacterial armamentarium. In Gram-negative bacteria, β-lactamase enzymes that hydrolyze the amide bond of the four-membered β-lactam ring are the primary resistance mechanism, with multiple enzymes disseminating on mobile genetic elements across opportunistic pathogens such as Enterobacteriaceae (e.g., Escherichia coli) and non-fermenting organisms (e.g., Pseudomonas aeruginosa). β-Lactamases divide into four classes; the active-site serine β-lactamases (classes A, C and D) and the zinc-dependent or metallo-β-lactamases (MBLs; class B). Here we review recent advances in mechanistic understanding of each class, focusing upon how growing numbers of crystal structures, in particular for β-lactam complexes, and methods such as neutron diffraction and molecular simulations, have improved understanding of the biochemistry of β-lactam breakdown. A second focus is β-lactamase interactions with carbapenems, as carbapenem-resistant bacteria are of grave clinical concern and carbapenem-hydrolyzing enzymes such as KPC (class A) NDM (class B) and OXA-48 (class D) are proliferating worldwide. An overview is provided of the changing landscape of β-lactamase inhibitors, exemplified by the introduction to the clinic of combinations of β-lactams with diazabicyclooctanone and cyclic boronate serine β-lactamase inhibitors, and of progress and strategies toward clinically useful MBL inhibitors. Despite the long history of β-lactamase research, we contend that issues including continuing unresolved questions around mechanism; opportunities afforded by new technologies such as serial femtosecond crystallography; the need for new inhibitors, particularly for MBLs; the likely impact of new β-lactam:inhibitor combinations and the continuing clinical importance of β-lactams mean that this remains a rewarding research area.
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Affiliation(s)
- Catherine L Tooke
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Philip Hinchliffe
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Eilis C Bragginton
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Charlotte K Colenso
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Viivi H A Hirvonen
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Yuiko Takebayashi
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - James Spencer
- School of Cellular and Molecular Medicine, University of Bristol Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom.
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19
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Dik DA, Fisher JF, Mobashery S. Cell-Wall Recycling of the Gram-Negative Bacteria and the Nexus to Antibiotic Resistance. Chem Rev 2018; 118:5952-5984. [PMID: 29847102 PMCID: PMC6855303 DOI: 10.1021/acs.chemrev.8b00277] [Citation(s) in RCA: 121] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The importance of the cell wall to the viability of the bacterium is underscored by the breadth of antibiotic structures that act by blocking key enzymes that are tasked with cell-wall creation, preservation, and regulation. The interplay between cell-wall integrity, and the summoning forth of resistance mechanisms to deactivate cell-wall-targeting antibiotics, involves exquisite orchestration among cell-wall synthesis and remodeling and the detection of and response to the antibiotics through modulation of gene regulation by specific effectors. Given the profound importance of antibiotics to the practice of medicine, the assertion that understanding this interplay is among the most fundamentally important questions in bacterial physiology is credible. The enigmatic regulation of the expression of the AmpC β-lactamase, a clinically significant and highly regulated resistance response of certain Gram-negative bacteria to the β-lactam antibiotics, is the exemplar of this challenge. This review gives a current perspective to this compelling, and still not fully solved, 35-year enigma.
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Affiliation(s)
- David A. Dik
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jed F. Fisher
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
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20
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Awasthi S, Gupta S, Tripathi R, Nair NN. Mechanism and Kinetics of Aztreonam Hydrolysis Catalyzed by Class-C β-Lactamase: A Temperature-Accelerated Sliced Sampling Study. J Phys Chem B 2018; 122:4299-4308. [DOI: 10.1021/acs.jpcb.8b01287] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Shalini Awasthi
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Shalini Gupta
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Ravi Tripathi
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Nisanth N. Nair
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
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21
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Das CK, Nair NN. Molecular insights into avibactam mediated class C β-lactamase inhibition: competition between reverse acylation and hydrolysis through desulfation. Phys Chem Chem Phys 2018; 20:14482-14490. [DOI: 10.1039/c8cp01670d] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The spatial water probability density plots show that the axial –NHOSO3 group of avibactam impedes the deacylating water molecule(s) to enter the active site, while the –NHSO3 group in aztreonam is unable to prevent the water molecule(s) to diffuse into the active site.
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Affiliation(s)
- Chandan Kumar Das
- Department of Chemistry
- Indian Institute of Technology Kanpur
- Kanpur
- India
| | - Nisanth N. Nair
- Department of Chemistry
- Indian Institute of Technology Kanpur
- Kanpur
- India
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22
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Fakhar Z, Govender T, Maguire GEM, Lamichhane G, Walker RC, Kruger HG, Honarparvar B. Differential flap dynamics in l,d-transpeptidase2 from mycobacterium tuberculosis revealed by molecular dynamics. MOLECULAR BIOSYSTEMS 2017; 13:1223-1234. [PMID: 28480928 DOI: 10.1039/c7mb00110j] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Despite the advances in tuberculosis treatment, TB is still one the most deadly infectious diseases and remains a major global health quandary. Mycobacterium tuberculosis (Mtb) is the only known mycobacterium with a high content of 3→3 crosslinks in the biosynthesis of peptidoglycan, which is negligible in most bacterial species. An Mtb lacking LdtMt2 leads to alteration of the colony morphology and loss of virulence which makes this enzyme an attractive target. Regardless of the vital role of LdtMt2 for cell wall survival, the impact of ligand binding on the dynamics of the β-hairpin flap is still unknown. Understanding the structural and dynamical behaviour of the flap regions provides clear insight into the design of the effective inhibitors against LdtMt2. Carbapenems, an specific class of β-lactam family, have been shown to inactivate this enzyme. Herein a comprehensive investigation of the flap dynamics of LdtMt2 complex with substrate and three carbapenems namely, ertapenem, imipenem and meropenem is discussed and analyzed for the first account using 140 ns molecular dynamics simulations. The structural features (RMSD, RMSF and Rg) derived by MD trajectories were analyzed. Distance analysis, particularly tip-tip SER135-ASN167 index, identified conformational changes in terms of flap opening and closure within binding process. Principal component analysis (PCA) was employed to qualitatively understand the divergent effects of different inhibitors on the dominant motion of each residue. To probe different internal dynamics induced by ligand binding, dynamic cross-correlation marix (DCCM) analysis was used. The binding free energies of the selected complexes were assessed using MM-GBSA method and per residue free energy decomposition analysis were performed to characterize the contribution of the key residues to the total binding free energies.
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Affiliation(s)
- Zeynab Fakhar
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, 4001, South Africa.
| | - Thavendran Govender
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, 4001, South Africa.
| | - Glenn E M Maguire
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, 4001, South Africa. and School of Chemistry and Physics, University of KwaZulu-Natal, 4001, Durban, South Africa
| | - Gyanu Lamichhane
- Center for Tuberculosis Research, Division of Infectious Diseases, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Ross C Walker
- GlaxoSmithKline PLC, 1250 S. Collegeville Rd., Collegeville, PA 19426, USA and Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Hendrik G Kruger
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, 4001, South Africa.
| | - Bahareh Honarparvar
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, 4001, South Africa.
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23
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Wang J, Zheng S, Liu Y, Zhang Z, Lin Z, Li J, Zhang G, Wang X, Li J, Chen PR. Palladium-Triggered Chemical Rescue of Intracellular Proteins via Genetically Encoded Allene-Caged Tyrosine. J Am Chem Soc 2016; 138:15118-15121. [PMID: 27797486 DOI: 10.1021/jacs.6b08933] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Chemical de-caging has emerged as an attractive strategy for gain-of-function study of proteins via small-molecule reagents. The previously reported chemical de-caging reactions have been largely centered on liberating the side chain of lysine on a given protein. Herein, we developed an allene-based caging moiety and the corresponding palladium de-caging reagents for chemical rescue of tyrosine (Tyr) activity on intracellular proteins. This bioorthogonal de-caging pair has been successfully applied to unmask enzymatic Tyr sites (e.g., Y671 on Taq polymerase and Y728 on Anthrax lethal factor) as well as the post-translational Tyr modification site (Y416 on Src kinase) in vitro and in living cells. Our strategy provides a general platform for chemical rescue of Tyr-dependent protein activity inside cells.
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Affiliation(s)
- Jie Wang
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China.,Academy for Advanced Interdisciplinary Studies, Peking University , Beijing 100871, China
| | - Siqi Zheng
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
| | - Yanjun Liu
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
| | - Zhaoyue Zhang
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
| | - Zhi Lin
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
| | - Jiaofeng Li
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
| | - Gong Zhang
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China.,Academy for Advanced Interdisciplinary Studies, Peking University , Beijing 100871, China
| | - Xin Wang
- Academy for Advanced Interdisciplinary Studies, Peking University , Beijing 100871, China.,Peking-Tsinghua Center for Life Sciences, Peking University , Beijing 100871, China
| | - Jie Li
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
| | - Peng R Chen
- Synthetic and Functional Biomolecules Center, Beijing National Laboratory for Molecular Sciences, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China.,Peking-Tsinghua Center for Life Sciences, Peking University , Beijing 100871, China
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24
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Asada T, Ando K, Bandyopadhyay P, Koseki S. Free Energy Contribution Analysis Using Response Kernel Approximation: Insights into the Acylation Reaction of a Beta-Lactamase. J Phys Chem B 2016; 120:9338-46. [PMID: 27501066 DOI: 10.1021/acs.jpcb.6b06104] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A widely applicable free energy contribution analysis (FECA) method based on the quantum mechanical/molecular mechanical (QM/MM) approximation using response kernel approaches has been proposed to investigate the influences of environmental residues and/or atoms in the QM region on the free energy profile. This method can evaluate atomic contributions to the free energy along the reaction path including polarization effects on the QM region within a dramatically reduced computational time. The rate-limiting step in the deactivation of the β-lactam antibiotic cefalotin (CLS) by β-lactamase was studied using this method. The experimentally observed activation barrier was successfully reproduced by free energy perturbation calculations along the optimized reaction path that involved activation by the carboxylate moiety in CLS. It was found that the free energy profile in the QM region was slightly higher than the isolated energy and that two residues, Lys67 and Lys315, as well as water molecules deeply influenced the QM atoms associated with the bond alternation reaction in the acyl-enzyme intermediate. These facts suggested that the surrounding residues are favorable for the reactant complex and prevent the intermediate from being too stabilized to proceed to the following deacylation reaction. We have demonstrated that the free energy contribution analysis should be a useful method to investigate enzyme catalysis and to facilitate intelligent molecular design.
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Affiliation(s)
- Toshio Asada
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University , 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan.,The Research Institute for Molecular Electronic Devices (RIMED), Osaka Prefecture University , 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan
| | - Kanta Ando
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University , 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan
| | - Pradipta Bandyopadhyay
- School of Computational and Integrative Sciences, Jawaharlal Nehru University , New Delhi, India 110067
| | - Shiro Koseki
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University , 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan.,The Research Institute for Molecular Electronic Devices (RIMED), Osaka Prefecture University , 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan
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25
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Arora P, Narang R, Nayak SK, Singh SK, Judge V. 2,4-Disubstituted thiazoles as multitargated bioactive molecules. Med Chem Res 2016. [DOI: 10.1007/s00044-016-1610-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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26
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Bhattacharjee N, Field MJ, Simorre JP, Arthur M, Bougault CM. Hybrid Potential Simulation of the Acylation of Enterococcus faecium l,d-Transpeptidase by Carbapenems. J Phys Chem B 2016; 120:4767-81. [DOI: 10.1021/acs.jpcb.6b02836] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nicholus Bhattacharjee
- DYNAMO/DYNAMOP,
UMR 5075, Université Grenoble 1, CNRS, CEA, Institut de Biologie
Structurale, 71 Avenue des Martyrs,
CS 10090, 38044 Grenoble Cedex 9, France
| | - Martin J. Field
- DYNAMO/DYNAMOP,
UMR 5075, Université Grenoble 1, CNRS, CEA, Institut de Biologie
Structurale, 71 Avenue des Martyrs,
CS 10090, 38044 Grenoble Cedex 9, France
| | - Jean-Pierre Simorre
- RMN, UMR 5075,
Université Grenoble 1, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des Martyrs, CS 10090, 38044 Grenoble Cedex 9, France
| | - Michel Arthur
- Centre de Recherche
des Cordeliers, Equipe 12, UMR S 872, Université Pierre et
Marie Curie-Paris 6, INSERM, Université Paris Descartes, Sorbonne
Paris Cité, 15 rue de l’Ecole
de Médecine, 75006 Paris, France
| | - Catherine M. Bougault
- RMN, UMR 5075,
Université Grenoble 1, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des Martyrs, CS 10090, 38044 Grenoble Cedex 9, France
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27
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Choi H, Paton RS, Park H, Schofield CJ. Investigations on recyclisation and hydrolysis in avibactam mediated serine β-lactamase inhibition. Org Biomol Chem 2016; 14:4116-28. [PMID: 27072755 PMCID: PMC4847122 DOI: 10.1039/c6ob00353b] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 04/04/2016] [Indexed: 01/13/2023]
Abstract
β-Lactams inhibit penicillin-binding proteins (PBPs) and serine β-lactamases by acylation of a nucleophilic active site serine. Avibactam is approved for clinical use in combination with ceftazidime, and is a breakthrough non β-lactam β-lactamase inhibitor also reacting via serine acylation. Molecular dynamics (MD) and quantum chemical calculations on avibactam-mediated inhibition of a clinically relevant cephalosporinase reveal that recyclisation of the avibactam derived carbamoyl complex is favoured over hydrolysis. In contrast, we show that analogous recyclisation in β-lactam mediated inhibition is disfavoured. Avibactam recyclisation is promoted by a proton shuttle, a 'structural' water protonating the nucleophilic serine, and stabilization of the negative charge developed on aminocarbonyl oxygen. The results imply the potential of calculations for distinguishing between bifurcating pathways during inhibition and in generating hypotheses for predicting resistance. The inability of β-lactams to undergo recyclisation may be an Achilles heel, but one that can be addressed by suitably functionalized reversibly binding inhibitors.
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Affiliation(s)
- Hwanho Choi
- Department of Bioscience and Biotechnology, Sejong University, 209 Neungdong-ro, Kwangjin-gu, Seoul 143-747, Korea. and Chemical Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK
| | - Robert S Paton
- Chemical Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK
| | - Hwangseo Park
- Department of Bioscience and Biotechnology, Sejong University, 209 Neungdong-ro, Kwangjin-gu, Seoul 143-747, Korea.
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28
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Tripathi R, Nair NN. Deacylation Mechanism and Kinetics of Acyl-Enzyme Complex of Class C β-Lactamase and Cephalothin. J Phys Chem B 2016; 120:2681-90. [PMID: 26918257 DOI: 10.1021/acs.jpcb.5b11623] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Understanding the molecular details of antibiotic resistance by the bacterial enzymes β-lactamases is vital for the development of novel antibiotics and inhibitors. In this spirit, the detailed mechanism of deacylation of the acyl-enzyme complex formed by cephalothin and class C β-lactamase is investigated here using hybrid quantum-mechanical/molecular-mechanical molecular dynamics methods. The roles of various active-site residues and substrate in the deacylation reaction are elucidated. We identify the base that activates the hydrolyzing water molecule and the residue that protonates the catalytic serine (Ser64). Conformational changes in the active sites and proton transfers that potentiate the efficiency of the deacylation reaction are presented. We have also characterized the oxyanion holes and other H-bonding interactions that stabilize the reaction intermediates. Together with the kinetic and mechanistic details of the acylation reaction, we analyze the complete mechanism and the overall kinetics of the drug hydrolysis. Finally, the apparent rate-determining step in the drug hydrolysis is scrutinized.
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Affiliation(s)
- Ravi Tripathi
- Department of Chemistry, Indian Institute of Technology Kanpur , Kanpur 208016, India
| | - Nisanth N Nair
- Department of Chemistry, Indian Institute of Technology Kanpur , Kanpur 208016, India
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29
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Meziane-Cherif D, Bonnet R, Haouz A, Courvalin P. Structural insights into the loss of penicillinase and the gain of ceftazidimase activities by OXA-145 β-lactamase in Pseudomonas aeruginosa. J Antimicrob Chemother 2015; 71:395-402. [PMID: 26568564 DOI: 10.1093/jac/dkv375] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 10/13/2015] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES We previously described extended-spectrum oxacillinase OXA-145 from Pseudomonas aeruginosa, which differs from narrow-spectrum OXA-35 by loss of Leu-155. The deletion results in loss of benzylpenicillin hydrolysis and acquisition of activity against ceftazidime. We report the crystal structure of OXA-145 and provide the basis of its switch in substrate specificity. METHODS OXA-145 variants were generated by site-directed mutagenesis and purified to homogeneity. The crystal structure of OXA-145 was determined and molecular dynamics simulations were performed. Kinetic parameters were investigated in the absence and in the presence of sodium hydrogen carbonate (NaHCO3) for representative substrates. RESULTS The structure of OXA-145 was obtained at a resolution of 2.3 Å and its superposition with that of OXA-10 showed that Trp-154 was shifted by 1.8 Å away from the catalytic Lys-70, which was not N-carboxylated. Addition of NaHCO3 significantly increased the catalytic efficiency against penicillins, but not against ceftazidime. The active-site cavity of OXA-145 was larger than that of OXA-10, which may favour the accommodation of large molecules such as ceftazidime. Molecular dynamics simulations of OXA-145 in complex with ceftazidime revealed two highly coordinated water molecules on the α- or β-face of the acyl ester bond, between Ser-67 and ceftazidime, which could be involved in the catalytic process. CONCLUSIONS Deletion of Leu-155 resulted in inefficient positioning of Trp-154, leading to a non-carboxylated Lys-70 and thus to loss of hydrolysis of the penicillins. Ceftazidime hydrolysis could be attributed to enlargement of the active site and to a catalytic mechanism independent of the carboxylated Lys-70.
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Affiliation(s)
- D Meziane-Cherif
- Institut Pasteur, Unité des Agents Antibactériens, 25 rue du Docteur Roux, 75724 Paris cedex 15, France
| | - R Bonnet
- Laboratoire de bactériologie mycologie et parasitologie, Pôle de biologie médicale et d'anatomie pathologique, CHU de Clermont Ferrand - Hôpital Gabriel Montpied, 58 rue Montalembert, 63003 Clermont-Ferrand cedex 1, France
| | - A Haouz
- Institut Pasteur, Plateforme de cristallographie, CNRS-UMR3528, 25 rue du Docteur Roux, 75724 Paris cedex 15, France
| | - P Courvalin
- Institut Pasteur, Unité des Agents Antibactériens, 25 rue du Docteur Roux, 75724 Paris cedex 15, France
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Silva JRA, Bishai WR, Govender T, Lamichhane G, Maguire GEM, Kruger HG, Lameira J, Alves CN. Targeting the cell wall of Mycobacterium tuberculosis: a molecular modeling investigation of the interaction of imipenem and meropenem with L,D-transpeptidase 2. J Biomol Struct Dyn 2015; 34:304-17. [PMID: 25762064 DOI: 10.1080/07391102.2015.1029000] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The single crystal X-ray structure of the extracellular portion of the L,D-transpeptidase (ex-LdtMt2 - residues 120-408) enzyme was recently reported. It was observed that imipenem and meropenem inhibit activity of this enzyme, responsible for generating L,D-transpeptide linkages in the peptidoglycan layer of Mycobacterium tuberculosis. Imipenem is more active and isothermal titration calorimetry experiments revealed that meropenem is subjected to an entropy penalty upon binding to the enzyme. Herein, we report a molecular modeling approach to obtain a molecular view of the inhibitor/enzyme interactions. The average binding free energies for nine commercially available inhibitors were calculated using MM/GBSA and Solvation Interaction Energy (SIE) approaches and the calculated energies corresponded well with the available experimentally observed results. The method reproduces the same order of binding energies as experimentally observed for imipenem and meropenem. We have also demonstrated that SIE is a reasonably accurate and cost-effective free energy method, which can be used to predict carbapenem affinities for this enzyme. A theoretical explanation was offered for the experimental entropy penalty observed for meropenem, creating optimism that this computational model can serve as a potential computational model for other researchers in the field.
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Affiliation(s)
- José Rogério A Silva
- a Laboratório de Planejamento e Desenvolvimento de Fármacos, Instituto de Ciências Exatas e Naturais , Universidade Federal do Pará , CP 11101, Belém , PA 66075-110 , Brazil
| | - William R Bishai
- b Department of Medicine, Division of Infectious Diseases , Johns Hopkins University School of Medicine , Baltimore , MD 21205 , USA
| | - Thavendran Govender
- c Catalysis and Peptide Research Unit, School of Health Sciences , University of KwaZulu-Natal , Durban 4001 , South Africa
| | - Gyanu Lamichhane
- c Catalysis and Peptide Research Unit, School of Health Sciences , University of KwaZulu-Natal , Durban 4001 , South Africa
| | - Glenn E M Maguire
- d Taskforce to study Resistance Emergence & Antimicrobial Development Technology , Johns Hopkins University School of Medicine , Baltimore , MD 21205 , USA
| | - Hendrik G Kruger
- d Taskforce to study Resistance Emergence & Antimicrobial Development Technology , Johns Hopkins University School of Medicine , Baltimore , MD 21205 , USA
| | - Jeronimo Lameira
- a Laboratório de Planejamento e Desenvolvimento de Fármacos, Instituto de Ciências Exatas e Naturais , Universidade Federal do Pará , CP 11101, Belém , PA 66075-110 , Brazil
| | - Cláudio N Alves
- a Laboratório de Planejamento e Desenvolvimento de Fármacos, Instituto de Ciências Exatas e Naturais , Universidade Federal do Pará , CP 11101, Belém , PA 66075-110 , Brazil
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Affiliation(s)
- Ravi Tripathi
- Department
of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Nisanth N. Nair
- Department
of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
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32
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Antunes NT, Fisher JF. Acquired Class D β-Lactamases. Antibiotics (Basel) 2014; 3:398-434. [PMID: 27025753 PMCID: PMC4790369 DOI: 10.3390/antibiotics3030398] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 07/31/2014] [Accepted: 08/08/2014] [Indexed: 12/21/2022] Open
Abstract
The Class D β-lactamases have emerged as a prominent resistance mechanism against β-lactam antibiotics that previously had efficacy against infections caused by pathogenic bacteria, especially by Acinetobacter baumannii and the Enterobacteriaceae. The phenotypic and structural characteristics of these enzymes correlate to activities that are classified either as a narrow spectrum, an extended spectrum, or a carbapenemase spectrum. We focus on Class D β-lactamases that are carried on plasmids and, thus, present particular clinical concern. Following a historical perspective, the susceptibility and kinetics patterns of the important plasmid-encoded Class D β-lactamases and the mechanisms for mobilization of the chromosomal Class D β-lactamases are discussed.
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Affiliation(s)
- Nuno T Antunes
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Jed F Fisher
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
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Sgrignani J, Grazioso G, De Amici M, Colombo G. Inactivation of TEM-1 by Avibactam (NXL-104): Insights from Quantum Mechanics/Molecular Mechanics Metadynamics Simulations. Biochemistry 2014; 53:5174-85. [DOI: 10.1021/bi500589x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Jacopo Sgrignani
- Istituto di Chimica
del Riconscimento Molecolare, CNR, Via Mario Bianco 9, 20131 Milan, Italy
| | - Giovanni Grazioso
- Dipartimento
di Scienze Farmaceutiche, Sezione di Chimica Farmaceutica “Pietro
Pratesi”, Università degli Studi di Milano, Via
Mangiagalli 25, 20133, Milan, Italy
| | - Marco De Amici
- Dipartimento
di Scienze Farmaceutiche, Sezione di Chimica Farmaceutica “Pietro
Pratesi”, Università degli Studi di Milano, Via
Mangiagalli 25, 20133, Milan, Italy
| | - Giorgio Colombo
- Istituto di Chimica
del Riconscimento Molecolare, CNR, Via Mario Bianco 9, 20131 Milan, Italy
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34
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Zheng S, Pfaendtner J. Enhanced sampling of chemical and biochemical reactions with metadynamics. MOLECULAR SIMULATION 2014. [DOI: 10.1080/08927022.2014.923574] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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35
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Bai Q, Shen Y, Jin N, Liu H, Yao X. Molecular modeling study on the dynamical structural features of human smoothened receptor and binding mechanism of antagonist LY2940680 by metadynamics simulation and free energy calculation. Biochim Biophys Acta Gen Subj 2014; 1840:2128-38. [PMID: 24637074 DOI: 10.1016/j.bbagen.2014.03.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 02/26/2014] [Accepted: 03/10/2014] [Indexed: 02/02/2023]
Abstract
BACKGROUND The smoothened (SMO) receptor, one of the Class F G protein coupled receptors (GPCRs), is an essential component of the canonical hedgehog signaling pathway which plays a key role in the regulation of embryonic development in animals. The function of the SMO receptor can be modulated by small-molecule agonists and antagonists, some of which are potential antitumour agents. Understanding the binding mode of an antagonist in the SMO receptor is crucial for the rational design of new antitumour agents. METHODS Molecular dynamics (MD) simulation and dynamical network analysis are used to study the dynamical structural features of SMO receptor. Metadynamics simulation and free energy calculation are employed to explore the binding mechanism between the antagonist and SMO receptor. RESULTS The MD simulation results and dynamical network analysis show that the conserved KTXXXW motif in helix VIII has strong interaction with helix I. The α-helical extension of transmembrane 6 (TM6) is detected as part of the ligand-binding pocket and dissociation pathway of the antagonist. The metadynamics simulation results illustrate the binding mechanism of the antagonist in the pocket of SMO receptor, and free energy calculation shows the antagonist needs to overcome about 38kcal/mol of energy barrier to leave the binding pocket of SMO receptor. CONCLUSIONS The unusually long TM6 plays an important role on the binding behavior of the antagonist in the pocket of SMO receptor. GENERAL SIGNIFICANCE The results can not only profile the binding mechanism between the antagonist and Class F GPCRs, but also supply the useful information for the rational design of a more potential small molecule antagonist bound to SMO receptor.
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Affiliation(s)
- Qifeng Bai
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, PR China
| | - Yulin Shen
- Gansu Computing Center, Lanzhou, Gansu 730000, PR China
| | - Nengzhi Jin
- Gansu Computing Center, Lanzhou, Gansu 730000, PR China
| | - Huanxiang Liu
- School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, PR China
| | - Xiaojun Yao
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, PR China; State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Taipa, Macau, PR China.
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Bhattacharya M, Toth M, Antunes NT, Smith CA, Vakulenko SB. Structure of the extended-spectrum class C β-lactamase ADC-1 from Acinetobacter baumannii. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:760-71. [PMID: 24598745 PMCID: PMC3949520 DOI: 10.1107/s1399004713033014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 12/05/2013] [Indexed: 11/10/2022]
Abstract
ADC-type class C β-lactamases comprise a large group of enzymes that are encoded by genes located on the chromosome of Acinetobacter baumannii, a causative agent of serious bacterial infections. Overexpression of these enzymes renders A. baumannii resistant to various β-lactam antibiotics and thus severely compromises the ability to treat infections caused by this deadly pathogen. Here, the high-resolution crystal structure of ADC-1, the first member of this clinically important family of antibiotic-resistant enzymes, is reported. Unlike the narrow-spectrum class C β-lactamases, ADC-1 is capable of producing resistance to the expanded-spectrum cephalosporins, rendering them inactive against A. baumannii. The extension of the substrate profile of the enzyme is likely to be the result of structural differences in the R2-loop, primarily the deletion of three residues and subsequent rearrangement of the A10a and A10b helices. These structural rearrangements result in the enlargement of the R2 pocket of ADC-1, allowing it to accommodate the bulky R2 substituents of the third-generation cephalosporins, thus enhancing the catalytic efficiency of the enzyme against these clinically important antibiotics.
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Affiliation(s)
- Monolekha Bhattacharya
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Marta Toth
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Nuno Tiago Antunes
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Clyde A. Smith
- Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California USA
| | - Sergei B. Vakulenko
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
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