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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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Meller A, Kelly D, Smith LG, Bowman GR. Toward physics-based precision medicine: Exploiting protein dynamics to design new therapeutics and interpret variants. Protein Sci 2024; 33:e4902. [PMID: 38358129 PMCID: PMC10868452 DOI: 10.1002/pro.4902] [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: 09/01/2023] [Revised: 12/01/2023] [Accepted: 01/04/2024] [Indexed: 02/16/2024]
Abstract
The goal of precision medicine is to utilize our knowledge of the molecular causes of disease to better diagnose and treat patients. However, there is a substantial mismatch between the small number of food and drug administration (FDA)-approved drugs and annotated coding variants compared to the needs of precision medicine. This review introduces the concept of physics-based precision medicine, a scalable framework that promises to improve our understanding of sequence-function relationships and accelerate drug discovery. We show that accounting for the ensemble of structures a protein adopts in solution with computer simulations overcomes many of the limitations imposed by assuming a single protein structure. We highlight studies of protein dynamics and recent methods for the analysis of structural ensembles. These studies demonstrate that differences in conformational distributions predict functional differences within protein families and between variants. Thanks to new computational tools that are providing unprecedented access to protein structural ensembles, this insight may enable accurate predictions of variant pathogenicity for entire libraries of variants. We further show that explicitly accounting for protein ensembles, with methods like alchemical free energy calculations or docking to Markov state models, can uncover novel lead compounds. To conclude, we demonstrate that cryptic pockets, or cavities absent in experimental structures, provide an avenue to target proteins that are currently considered undruggable. Taken together, our review provides a roadmap for the field of protein science to accelerate precision medicine.
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Affiliation(s)
- Artur Meller
- Department of Biochemistry and Molecular BiophysicsWashington University in St. LouisSt. LouisMissouriUSA
- Medical Scientist Training ProgramWashington University in St. LouisSt. LouisMissouriUSA
- Departments of Biochemistry & Biophysics and BioengineeringUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Devin Kelly
- Departments of Biochemistry & Biophysics and BioengineeringUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Louis G. Smith
- Departments of Biochemistry & Biophysics and BioengineeringUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Gregory R. Bowman
- Departments of Biochemistry & Biophysics and BioengineeringUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
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3
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Lu S, Montoya M, Hu L, Neetu N, Sankaran B, Prasad BVV, Palzkill T. Mutagenesis and structural analysis reveal the CTX-M β-lactamase active site is optimized for cephalosporin catalysis and drug resistance. J Biol Chem 2023; 299:104630. [PMID: 36963495 PMCID: PMC10139949 DOI: 10.1016/j.jbc.2023.104630] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 03/17/2023] [Accepted: 03/19/2023] [Indexed: 03/26/2023] Open
Abstract
CTX-M β-lactamases are a widespread source of resistance to β-lactam antibiotics in Gram-negative bacteria. These enzymes readily hydrolyze penicillins and cephalosporins, including oxyimino-cephalosporins such as cefotaxime. To investigate the preference of CTX-M enzymes for cephalosporins, we examined eleven active-site residues in the CTX-M-14 β-lactamase model system by alanine mutagenesis to assess the contribution of the residues to catalysis and specificity for the hydrolysis of the penicillin, ampicillin, and the cephalosporins cephalothin and cefotaxime. Key active site residues for class A β-lactamases, including Lys73, Ser130, Asn132, Lys234, Thr216, and Thr235, contribute significantly to substrate binding and catalysis of penicillin and cephalosporin substrates in that alanine substitutions decrease both kcat and kcat/KM. A second group of residues, including Asn104, Tyr105, Asn106, Thr215, and Thr216, contribute only to substrate binding, with the substitutions decreasing only kcat/KM. Importantly, calculating the average effect of a substitution across the 11 active-site residues shows that the most significant impact is on cefotaxime hydrolysis while ampicillin hydrolysis is least affected, suggesting the active site is highly optimized for cefotaxime catalysis. Furthermore, we determined X-ray crystal structures for the apo-enzymes of the mutants N106A, S130A, N132A, N170A, T215A, and T235A. Surprisingly, in the structures of some mutants, particularly N106A and T235A, the changes in structure propagate from the site of substitution to other regions of the active site, suggesting that the impact of substitutions is due to more widespread changes in structure and illustrating the interconnected nature of the active site.
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Affiliation(s)
- Shuo Lu
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Miranda Montoya
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Liya Hu
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Neetu Neetu
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Banumathi Sankaran
- Department of Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - B V Venkataram Prasad
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Timothy Palzkill
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA; Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA.
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4
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Mehrabi P, Sung S, von Stetten D, Prester A, Hatton CE, Kleine-Döpke S, Berkes A, Gore G, Leimkohl JP, Schikora H, Kollewe M, Rohde H, Wilmanns M, Tellkamp F, Schulz EC. Millisecond cryo-trapping by the spitrobot crystal plunger simplifies time-resolved crystallography. Nat Commun 2023; 14:2365. [PMID: 37185266 PMCID: PMC10130016 DOI: 10.1038/s41467-023-37834-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 04/01/2023] [Indexed: 05/17/2023] Open
Abstract
We introduce the spitrobot, a protein crystal plunger, enabling reaction quenching via cryo-trapping with a time-resolution in the millisecond range. Protein crystals are mounted on canonical micromeshes on an electropneumatic piston, where the crystals are kept in a humidity and temperature-controlled environment, then reactions are initiated via the liquid application method (LAMA) and plunging into liquid nitrogen is initiated after an electronically set delay time to cryo-trap intermediate states. High-magnification images are automatically recorded before and after droplet deposition, prior to plunging. The SPINE-standard sample holder is directly plunged into a storage puck, enabling compatibility with high-throughput infrastructure. Here we demonstrate binding of glucose and 2,3-butanediol in microcrystals of xylose isomerase, and of avibactam and ampicillin in microcrystals of the extended spectrum beta-lactamase CTX-M-14. We also trap reaction intermediates and conformational changes in macroscopic crystals of tryptophan synthase to demonstrate that the spitrobot enables insight into catalytic events.
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Affiliation(s)
- Pedram Mehrabi
- Institute for Nanostructure and Solid-State Physics, Universität Hamburg, Hamburg, Germany.
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany.
| | - Sihyun Sung
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - David von Stetten
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Andreas Prester
- University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Caitlin E Hatton
- Institute for Nanostructure and Solid-State Physics, Universität Hamburg, Hamburg, Germany
| | - Stephan Kleine-Döpke
- Institute for Nanostructure and Solid-State Physics, Universität Hamburg, Hamburg, Germany
| | - Alexander Berkes
- Institute for Nanostructure and Solid-State Physics, Universität Hamburg, Hamburg, Germany
| | - Gargi Gore
- Institute for Nanostructure and Solid-State Physics, Universität Hamburg, Hamburg, Germany
| | | | - Hendrik Schikora
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany
| | - Martin Kollewe
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany
| | - Holger Rohde
- University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Matthias Wilmanns
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
- University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Friedjof Tellkamp
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany.
| | - Eike C Schulz
- Institute for Nanostructure and Solid-State Physics, Universität Hamburg, Hamburg, Germany.
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany.
- University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany.
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5
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Ren H, Lu Z, Sun R, Wang X, Zhong J, Su T, He Q, Liao X, Liu Y, Lian X, Sun J. Functional metagenomics reveals wildlife as natural reservoirs of novel β-lactamases. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 868:161505. [PMID: 36626997 DOI: 10.1016/j.scitotenv.2023.161505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 12/21/2022] [Accepted: 01/05/2023] [Indexed: 06/17/2023]
Abstract
The antibiotic resistances in bacteria are believed to rapidly evolve over time in the anthropogenic environments which enriched with selection pressures. However, the knowledge regarding the development of antibiotic resistance in wildlife and their habitats is scarce. It is, therefore, of great interest and significance to unveil the yet-unknown antibiotic resistances in wildlife in accordance with One Health concept. To this end, we analyzed the samples taken from wildlife and surrounding environments using a functional metagenomics approach. By functional screening in combination with Illumina sequencing, a total of 32 candidate genes which encoding putative novel β-lactamase were identified. These putative β-lactamase were taxonomically assigned into bacteria of 23 genera from 7 phyla, where Proteobacteria, Actinobacteria and Firmicutes were dominant. The following functional assessment demonstrated that 4 novel β-lactamases, namely blaSSA, blaSSB1, blaSSB2 and blaSSD, were functionally active to confer the phenotypical resistance to bacteria by increasing MICs up to 128-fold. Further analysis indicated that the novel β-lactamases identified in the current study were able to hydrolyze a broad spectrum of β-lactams including cephalosporins, and they were genetically unique comparing with known β-lactamases. The plausible transmission of some novel β-lactamase genes was supported by our results as the same gene was detected in different samples from different sites. This study shed the light on the active role of wildlife and associated environments as natural reservoirs of novel β-lactamases, implying that the antibiotic resistances might evolve in absence of selection pressure and threaten public health once spread into clinically important pathogens.
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Affiliation(s)
- Hao Ren
- Guangdong Laboratory for Lingnan Modern Agriculture, National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics, Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China
| | - Zhaoxiang Lu
- Guangdong Laboratory for Lingnan Modern Agriculture, National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics, Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China
| | - Ruanyang Sun
- Guangdong Laboratory for Lingnan Modern Agriculture, National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics, Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China
| | - Xiran Wang
- Guangdong Laboratory for Lingnan Modern Agriculture, National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics, Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China
| | - Jiahao Zhong
- Guangdong Laboratory for Lingnan Modern Agriculture, National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics, Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China
| | - Tiantian Su
- Guangdong Laboratory for Lingnan Modern Agriculture, National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics, Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China
| | - Qian He
- Guangdong Laboratory for Lingnan Modern Agriculture, National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics, Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China
| | - Xiaoping Liao
- Guangdong Laboratory for Lingnan Modern Agriculture, National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics, Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China; Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonoses, Yangzhou University, Yangzhou 225009, China
| | - Yahong Liu
- Guangdong Laboratory for Lingnan Modern Agriculture, National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics, Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China; Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonoses, Yangzhou University, Yangzhou 225009, China
| | - Xinlei Lian
- Guangdong Laboratory for Lingnan Modern Agriculture, National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics, Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China
| | - Jian Sun
- Guangdong Laboratory for Lingnan Modern Agriculture, National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics, Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China; Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonoses, Yangzhou University, Yangzhou 225009, China.
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6
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Judge A, Hu L, Sankaran B, Van Riper J, Venkataram Prasad BV, Palzkill T. Mapping the determinants of catalysis and substrate specificity of the antibiotic resistance enzyme CTX-M β-lactamase. Commun Biol 2023; 6:35. [PMID: 36635385 PMCID: PMC9837174 DOI: 10.1038/s42003-023-04422-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 01/04/2023] [Indexed: 01/14/2023] Open
Abstract
CTX-M β-lactamases are prevalent antibiotic resistance enzymes and are notable for their ability to rapidly hydrolyze the extended-spectrum cephalosporin, cefotaxime. We hypothesized that the active site sequence requirements of CTX-M-mediated hydrolysis differ between classes of β-lactam antibiotics. Accordingly, we use codon randomization, antibiotic selection, and deep sequencing to determine the CTX-M active-site residues required for hydrolysis of cefotaxime and the penicillin, ampicillin. The study reveals positions required for hydrolysis of all β-lactams, as well as residues controlling substrate specificity. Further, CTX-M enzymes poorly hydrolyze the extended-spectrum cephalosporin, ceftazidime. We further show that the sequence requirements for ceftazidime hydrolysis follow those of cefotaxime, with the exception that key active-site omega loop residues are not required, and may be detrimental, for ceftazidime hydrolysis. These results provide insights into cephalosporin hydrolysis and demonstrate that changes to the active-site omega loop are likely required for the evolution of CTX-M-mediated ceftazidime resistance.
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Affiliation(s)
- Allison Judge
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Liya Hu
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Banumathi Sankaran
- Department of Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Justin Van Riper
- Graduate Program in Chemical, Physical, and Structural Biology, Baylor College of Medicine, Houston, TX, USA
| | - B V Venkataram Prasad
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Timothy Palzkill
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA.
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX, USA.
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7
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Lu S, Hu L, Lin H, Judge A, Rivera P, Palaniappan M, Sankaran B, Wang J, Prasad BVV, Palzkill T. An active site loop toggles between conformations to control antibiotic hydrolysis and inhibition potency for CTX-M β-lactamase drug-resistance enzymes. Nat Commun 2022; 13:6726. [PMID: 36344533 PMCID: PMC9640584 DOI: 10.1038/s41467-022-34564-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 10/27/2022] [Indexed: 11/09/2022] Open
Abstract
β-lactamases inactivate β-lactam antibiotics leading to drug resistance. Consequently, inhibitors of β-lactamases can combat this resistance, and the β-lactamase inhibitory protein (BLIP) is a naturally occurring inhibitor. The widespread CTX-M-14 and CTX-M-15 β-lactamases have an 83% sequence identity. In this study, we show that BLIP weakly inhibits CTX-M-14 but potently inhibits CTX-M-15. The structure of the BLIP/CTX-M-15 complex reveals that binding is associated with a conformational change of an active site loop of β-lactamase. Surprisingly, the loop structure in the complex is similar to that in a drug-resistant variant (N106S) of CTX-M-14. We hypothesized that the pre-established favorable loop conformation of the N106S mutant would facilitate binding. The N106S substitution results in a ~100- and 10-fold increase in BLIP inhibition potency for CTX-M-14 and CTX-M-15, respectively. Thus, this indicates that an active site loop in β-lactamase toggles between conformations that control antibiotic hydrolysis and inhibitor susceptibility. These findings highlight the role of accessible active site conformations in controlling enzyme activity and inhibitor susceptibility as well as the influence of mutations in selectively stabilizing discrete conformations.
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Affiliation(s)
- Shuo Lu
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX, USA
| | - Liya Hu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Hanfeng Lin
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX, USA
| | - Allison Judge
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Paola Rivera
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX, USA
| | - Murugesan Palaniappan
- Center for Drug Discovery, Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Banumathi Sankaran
- Department of Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jin Wang
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX, USA
| | - B V Venkataram Prasad
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Timothy Palzkill
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX, USA.
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA.
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8
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Klebsiella pneumoniae Carbapenemase Variants Resistant to Ceftazidime-Avibactam: an Evolutionary Overview. Antimicrob Agents Chemother 2022; 66:e0044722. [PMID: 35980232 PMCID: PMC9487638 DOI: 10.1128/aac.00447-22] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
First variants of the Klebsiella pneumoniae carbapenemase (KPC), KPC-2 and KPC-3, have encountered a worldwide success, particularly in K. pneumoniae isolates. These beta-lactamases conferred resistance to most beta-lactams including carbapenems but remained susceptible to new beta-lactam/beta-lactamase inhibitors, such as ceftazidime-avibactam. After the marketing of ceftazidime-avibactam, numerous variants of KPC resistant to this association have been described among isolates recovered from clinical samples or derived from experimental studies. In KPC variants resistant to ceftazidime-avibactam, point mutations, insertions and/or deletions have been described in various hot spots. Deciphering the impact of these mutations is crucial, not only from a therapeutic point of view, but also to follow the evolution in time and space of KPC variants resistant to ceftazidime-avibactam. In this review, we describe the mutational landscape of the KPC beta-lactamase toward ceftazidime-avibactam resistance based on a multidisciplinary approach including epidemiology, microbiology, enzymology, and thermodynamics. We show that resistance is associated with three hot spots, with a high representation of insertions and deletions compared with other class A beta-lactamases. Moreover, extension of resistance to ceftazidime-avibactam is associated with a trade-off in the resistance to other beta-lactams and a decrease in enzyme stability. Nevertheless, the high natural stability of KPC could underlay the propensity of this enzyme to acquire in vivo mutations conferring resistance to ceftazidime-avibactam (CAZavi), particularly via insertions and deletions.
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9
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Excreted Antibiotics May Be Key to Emergence of Increasingly Efficient Antibiotic Resistance in Food Animal Production. Appl Environ Microbiol 2022; 88:e0079122. [PMID: 35867586 PMCID: PMC9361830 DOI: 10.1128/aem.00791-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
At a time when antibiotic resistance is seemingly ubiquitous worldwide, understanding the mechanisms responsible for successful emergence of new resistance genes may provide insights into the persistence and pathways of dissemination for antibiotic-resistant organisms in general. For example, Escherichia coli strains harboring a class A β-lactamase-encoding gene (blaCTX-M-15) appear to be displacing strains that harbor a class C β-lactamase gene (blaCMY-2) in Washington State dairy cattle. We cloned these genes with native promoters into low-copy-number plasmids that were then transformed into isogenic strains of E. coli, and growth curves were generated for two commonly administered antibiotics (ampicillin and ceftiofur). Both strains met the definition of resistance for ampicillin (≥32 μg/mL) and ceftiofur (≥16 μg/mL). Growth of the CMY-2-producing strain was compromised at 1,000 μg/mL ampicillin, whereas the CTX-M-15-producing strain was not inhibited in the presence of 3,000 μg/mL ampicillin or with most concentrations of ceftiofur, although there were mixed outcomes with ceftiofur metabolites. Consequently, in the absence of competing genes, E. coli harboring either gene would experience a selective advantage if exposed to these antibiotics. Successful emergence of CTX-M-15-producing strains where CMY-2-producing strains are already established, however, requires high concentrations of antibiotics that can only be found in the urine of treated animals (e.g., >2,000 μg/mL for ampicillin, based on literature). This ex vivo selection pressure may be important for the emergence of new and more efficient antibiotic resistance genes and likely for persistence of antibiotic-resistant bacteria in food animal populations. IMPORTANCE We studied the relative fitness benefits of a cephalosporin resistance enzyme (CTX-M-15) that is displacing a similar enzyme (CMY-2), which is extant in E. coli from dairy cattle in Washington State. In vitro experiments demonstrated that CTX-M-15 provides a significant fitness advantage, but only in the presence of very high concentrations of antibiotic that are only found when the antibiotic ampicillin, and to a lesser extent ceftiofur, is excreted in urine from treated animals. As such, the increasing prevalence of bacteria with blaCTX-M-15 is likely occurring ex vivo. Interventions should focus on controlling waste from treated animals and, when possible, selecting antibiotics that are less likely to impact the proximal environment of treated animals.
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10
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Three new inhibitors of class A β-lactamases evaluated by molecular docking and dynamics simulations methods: relebactam, enmetazobactam, and QPX7728. J Mol Model 2022; 28:76. [PMID: 35243556 DOI: 10.1007/s00894-022-05073-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 02/26/2022] [Indexed: 10/18/2022]
Abstract
Antibiotic-resistant Acinetobacter baumannii, Pseudomonas aeruginosa, Mycobacterium tuberculosis, Staphylococcus aureus, and Enterobacterales infections are serious global health problems, and class A β-lactamases are one mechanism that leads to antibiotic resistance. QPX7728, relebactam, and enmetazobactam are new β-lactamase inhibitors to combat β-lactam resistance. in silico approach was used in the current study to find which of the three inhibitors would be more effective for all class A β-lactamases and to reveal molecular insights into the differences between their binding energies. The mutations in conserved residues of the active sites of β-lactamases were defined using BLDB and Clustal Omega. FastME and MMseq2 were used for cluster and phylogeny analysis. 3D protein structure models for β-lactamases were built using SWISS-MODEL. ERRAT and Galaxy Web Server were used to verify 42 β-lactamase protein structures. QPX7728, relebactam, and enmetazobactam were docked to β-lactamases by using AutoDock 4.2. The TEM76-relebactam, CTX-M-81-relebactam, TEM-76-enmetazobactam, and CTX-M-200-enmetazobactam complexes were simulated by molecular dynamics method for 500 ns. Based on molecular docking results, relebactam and QPX7728 were more favorable inhibitors for serine A β-lactamases. A 2D representation of the interactions between ligands and β-lactamases showed that S235, hydrogen bonded with TEM-76, might play a role in inhibitor design. A 500-ns MD analysis of complexes indicated that distance from S70, stability in the enzyme active cavity, and high atomic displacement would account for a significant difference in inhibitor binding affinity.
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Elings W, Chikunova A, van Zanten DB, Drenth R, Ahmad MUD, Blok AJ, Timmer M, Perrakis A, Ubbink M. Two β-Lactamase Variants with Reduced Clavulanic Acid Inhibition Display Different Millisecond Dynamics. Antimicrob Agents Chemother 2021; 65:e0262820. [PMID: 34031049 PMCID: PMC8284444 DOI: 10.1128/aac.02628-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 05/07/2021] [Indexed: 11/20/2022] Open
Abstract
The β-lactamase of Mycobacterium tuberculosis, BlaC, is susceptible to inhibition by clavulanic acid. The ability of this enzyme to escape inhibition through mutation was probed using error-prone PCR combined with functional screening in Escherichia coli. The variant that was found to confer the most inhibitor resistance, K234R, as well as variant G132N that was found previously were characterized using X-ray crystallography and nuclear magnetic resonance (NMR) relaxation experiments to probe structural and dynamic properties. The G132N mutant exists in solution in two almost equally populated conformations that exchange with a rate of ca. 88 s-1. The conformational change affects a broad region of the enzyme. The crystal structure reveals that the Asn132 side chain forces the peptide bond between Ser104 and Ile105 in a cis-conformation. The crystal structure suggests multiple conformations for several side chains (e.g., Ser104 and Ser130) and a short loop (positions 214 to 216). In the K234R mutant, the active-site dynamics are significantly diminished with respect to the wild-type enzyme. These results show that multiple evolutionary routes are available to increase inhibitor resistance in BlaC and that active-site dynamics on the millisecond time scale are not required for catalytic function.
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Affiliation(s)
- Wouter Elings
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | | | | | - Ralphe Drenth
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - Misbha Ud Din Ahmad
- Division of Biochemistry, the Netherlands Cancer Institute, Amsterdam, The Netherlands
- Oncode Institute, Amsterdam, The Netherlands
| | - Anneloes J. Blok
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - Monika Timmer
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - Anastassis Perrakis
- Division of Biochemistry, the Netherlands Cancer Institute, Amsterdam, The Netherlands
- Oncode Institute, Amsterdam, The Netherlands
| | - Marcellus Ubbink
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
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Furey IM, Mehta SC, Sankaran B, Hu L, Prasad BVV, Palzkill T. Local interactions with the Glu166 base and the conformation of an active site loop play key roles in carbapenem hydrolysis by the KPC-2 β-lactamase. J Biol Chem 2021; 296:100799. [PMID: 34022225 PMCID: PMC8189571 DOI: 10.1016/j.jbc.2021.100799] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 05/06/2021] [Accepted: 05/17/2021] [Indexed: 01/05/2023] Open
Abstract
The Klebsiella pneumoniae carbapenemase-2 (KPC-2) is a common source of antibiotic resistance in Gram-negative bacterial infections. KPC-2 is a class A β-lactamase that exhibits a broad substrate profile and hydrolyzes most β-lactam antibiotics including carbapenems owing to rapid deacylation of the covalent acyl-enzyme intermediate. However, the features that allow KPC-2 to deacylate substrates more rapidly than non-carbapenemase enzymes are not clear. The active-site residues in KPC-2 are largely conserved in sequence and structure compared with non-carbapenemases, suggesting that subtle alterations may collectively facilitate hydrolysis of carbapenems. We utilized a nonbiased genetic approach to identify mutants deficient in carbapenem hydrolysis but competent for ampicillin hydrolysis. Subsequent pre–steady-state enzyme kinetics analyses showed that the substitutions slow the rate of deacylation of carbapenems. Structure determination via X-ray diffraction indicated that a F72Y mutant forms a hydrogen bond between the tyrosine hydroxyl group and Glu166, which may lower basicity and impair the activation of the catalytic water for deacylation, whereas several mutants impact the structure of the Q214-R220 active site loop. A T215P substitution lowers the deacylation rate and drastically alters the conformation of the loop, thereby disrupting interactions between the enzyme and the carbapenem acyl-enzyme intermediate. Thus, the environment of the Glu166 general base and the precise placement and conformational stability of the Q214-R220 loop are critical for efficient deacylation of carbapenems by the KPC-2 enzyme. Therefore, the design of carbapenem antibiotics that interact with Glu166 or alter the Q214-R220 loop conformation may disrupt enzyme function and overcome resistance.
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Affiliation(s)
- Ian M Furey
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Shrenik C Mehta
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Banumathi Sankaran
- Department of Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Liya Hu
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston Texas, USA
| | - B V Venkataram Prasad
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston Texas, USA
| | - Timothy Palzkill
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, USA; Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston Texas, USA.
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