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Fröhlich C, Bunzel HA, Buda K, Mulholland AJ, van der Kamp MW, Johnsen PJ, Leiros HKS, Tokuriki N. Epistasis arises from shifting the rate-limiting step during enzyme evolution of a β-lactamase. Nat Catal 2024; 7:499-509. [PMID: 38828429 PMCID: PMC11136654 DOI: 10.1038/s41929-024-01117-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 01/25/2024] [Indexed: 06/05/2024]
Abstract
Epistasis, the non-additive effect of mutations, can provide combinatorial improvements to enzyme activity that substantially exceed the gains from individual mutations. Yet the molecular mechanisms of epistasis remain elusive, undermining our ability to predict pathogen evolution and engineer biocatalysts. Here we reveal how directed evolution of a β-lactamase yielded highly epistatic activity enhancements. Evolution selected four mutations that increase antibiotic resistance 40-fold, despite their marginal individual effects (≤2-fold). Synergistic improvements coincided with the introduction of super-stochiometric burst kinetics, indicating that epistasis is rooted in the enzyme's conformational dynamics. Our analysis reveals that epistasis stemmed from distinct effects of each mutation on the catalytic cycle. The initial mutation increased protein flexibility and accelerated substrate binding, which is rate-limiting in the wild-type enzyme. Subsequent mutations predominantly boosted the chemical steps by fine-tuning substrate interactions. Our work identifies an overlooked cause for epistasis: changing the rate-limiting step can result in substantial synergy that boosts enzyme activity.
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Affiliation(s)
| | - H. Adrian Bunzel
- Department of Biosystem Science and Engineering, ETH Zurich, Basel, Switzerland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, UK
- School of Biochemistry, University of Bristol, Bristol, UK
| | - Karol Buda
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia Canada
| | - Adrian J. Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, UK
| | - Marc W. van der Kamp
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, UK
- School of Biochemistry, University of Bristol, Bristol, UK
| | - Pål J. Johnsen
- Department of Pharmacy, UiT The Arctic University of Norway, Tromsø, Norway
| | | | - Nobuhiko Tokuriki
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia Canada
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2
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C6 Hydroxymethyl-Substituted Carbapenem MA-1-206 Inhibits the Major Acinetobacter baumannii Carbapenemase OXA-23 by Impeding Deacylation. mBio 2022; 13:e0036722. [PMID: 35420470 PMCID: PMC9239083 DOI: 10.1128/mbio.00367-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Acinetobacter baumannii has become a major nosocomial pathogen, as it is often multidrug-resistant, which results in infections characterized by high mortality rates. The bacterium achieves high levels of resistance to β-lactam antibiotics by producing β-lactamases, enzymes which destroy these valuable agents. Historically, the carbapenem family of β-lactam antibiotics have been the drugs of choice for treating A. baumannii infections. However, their effectiveness has been significantly diminished due to the pathogen’s production of carbapenem-hydrolyzing class D β-lactamases (CHDLs); thus, new antibiotics and inhibitors of these enzymes are urgently needed. Here, we describe a new carbapenem antibiotic, MA-1-206, in which the canonical C6 hydroxyethyl group has been replaced with hydroxymethyl. The antimicrobial susceptibility studies presented here demonstrated that this compound is more potent than meropenem and imipenem against A. baumannii producing OXA-23, the most prevalent CHDL of this pathogen, and also against strains producing the CHDL OXA-24/40 and the class B metallo-β-lactamase VIM-2. Our kinetic and mass spectrometry studies revealed that this drug is a reversible inhibitor of OXA-23, where inhibition takes place through a branched pathway. X-ray crystallographic studies, molecular docking, and molecular dynamics simulations of the OXA-23-MA-1-206 complex show that the C6 hydroxymethyl group forms a hydrogen bond with the carboxylated catalytic lysine of OXA-23, effectively preventing deacylation. These results provide a promising strategy for designing a new generation of CHDL-resistant carbapenems to restore their efficacy against deadly A. baumannii infections.
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Suhandynata RT, Lund K, Caraballo-Rodríguez AM, Reed SL, Dorrestein PC, Fitzgerald RL, Bevins NJ. Mass Spectrometry-Based Detection of Beta Lactam Hydrolysis Enables Rapid Detection of Beta Lactamase Mediated Antibiotic Resistance. Lab Med 2022; 53:128-137. [PMID: 34403464 PMCID: PMC8900932 DOI: 10.1093/labmed/lmab068] [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] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVE Antibiotic resistance by beta lactamase expression is a serious and growing threat. We aimed to determine whether beta-lactamase activity is detectable in urine specimens to enable faster identification of resistance. METHODS Urine specimens from patients with extended spectrum beta lactamase (ESBL)-expressing urinary infections were incubated with beta lactam antibiotics. Beta lactam hydrolysis was determined by mass spectrometry methods. RESULTS Ceftriaxone hydrolysis was observed in 45 of 45 ESBL-containing specimens from patients not treated with a beta lactamase inhibitor before specimen collection. Ceftriaxone hydrolysis was not observed in 108 of 108 non-ESBL-containing specimens. Spiking studies show that beta lactam hydrolysis can be observed within 30 minutes. Beta lactam hydrolysis is evidenced by mass spectrometry preceded by either liquid chromatography or matrix-assisted laser desorption ionization specimen processing methods. CONCLUSION Clinically significant beta lactamase activity is detectable directly from urine specimens. The described methods would enable the detection of beta lactam resistance 24 to 48 hours sooner than culture based methods.
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Affiliation(s)
| | - Kyle Lund
- Department of Pathology, UC San Diego Health, San Diego, California, US
| | - Andrés M Caraballo-Rodríguez
- Collaborative Mass Spectrometry Innovation Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, US
| | - Sharon L Reed
- Department of Pathology, UC San Diego Health, San Diego, California, US
| | - Pieter C Dorrestein
- Collaborative Mass Spectrometry Innovation Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, US
| | | | - Nicholas J Bevins
- Department of Pathology, UC San Diego Health, San Diego, California, US
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4
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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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5
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Tooke CL, Hinchliffe P, Bonomo RA, Schofield CJ, Mulholland AJ, Spencer J. Natural variants modify Klebsiella pneumoniae carbapenemase (KPC) acyl-enzyme conformational dynamics to extend antibiotic resistance. J Biol Chem 2021; 296:100126. [PMID: 33257320 PMCID: PMC7949053 DOI: 10.1074/jbc.ra120.016461] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 11/21/2020] [Accepted: 11/30/2020] [Indexed: 12/11/2022] Open
Abstract
Class A serine β-lactamases (SBLs) are key antibiotic resistance determinants in Gram-negative bacteria. SBLs neutralize β-lactams via a hydrolytically labile covalent acyl-enzyme intermediate. Klebsiella pneumoniae carbapenemase (KPC) is a widespread SBL that hydrolyzes carbapenems, the most potent β-lactams; known KPC variants differ in turnover of expanded-spectrum oxyimino-cephalosporins (ESOCs), for example, cefotaxime and ceftazidime. Here, we compare ESOC hydrolysis by the parent enzyme KPC-2 and its clinically observed double variant (P104R/V240G) KPC-4. Kinetic analyses show that KPC-2 hydrolyzes cefotaxime more efficiently than the bulkier ceftazidime, with improved ESOC turnover by KPC-4 resulting from enhanced turnover (kcat), rather than altered KM values. High-resolution crystal structures of ESOC acyl-enzyme complexes with deacylation-deficient (E166Q) KPC-2 and KPC-4 mutants show that ceftazidime acylation causes rearrangement of three loops; the Ω, 240, and 270 loops, which border the active site. However, these rearrangements are less pronounced in the KPC-4 than the KPC-2 ceftazidime acyl-enzyme and are not observed in the KPC-2:cefotaxime acyl-enzyme. Molecular dynamics simulations of KPC:ceftazidime acyl-enyzmes reveal that the deacylation general base E166, located on the Ω loop, adopts two distinct conformations in KPC-2, either pointing "in" or "out" of the active site; with only the "in" form compatible with deacylation. The "out" conformation was not sampled in the KPC-4 acyl-enzyme, indicating that efficient ESOC breakdown is dependent upon the ordering and conformation of the KPC Ω loop. The results explain how point mutations expand the activity spectrum of the clinically important KPC SBLs to include ESOCs through their effects on the conformational dynamics of the acyl-enzyme intermediate.
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Affiliation(s)
- Catherine L Tooke
- School of Cellular and Molecular Medicine, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom; Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - Philip Hinchliffe
- School of Cellular and Molecular Medicine, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom
| | - Robert A Bonomo
- Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio, USA; Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, and Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA; CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES) Cleveland, Ohio, USA
| | - Christopher J Schofield
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Adrian J Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - James Spencer
- School of Cellular and Molecular Medicine, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom.
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6
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Cao TP, Yi H, Dhanasingh I, Ghosh S, Choi JM, Lee KH, Ryu S, Kim HS, Lee SH. Non-catalytic-Region Mutations Conferring Transition of Class A β-Lactamases Into ESBLs. Front Mol Biosci 2020; 7:598998. [PMID: 33335913 PMCID: PMC7737660 DOI: 10.3389/fmolb.2020.598998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 10/28/2020] [Indexed: 12/03/2022] Open
Abstract
Despite class A ESBLs carrying substitutions outside catalytic regions, such as Cys69Tyr or Asn136Asp, have emerged as new clinical threats, the molecular mechanisms underlying their acquired antibiotics-hydrolytic activity remains unclear. We discovered that this non-catalytic-region (NCR) mutations induce significant dislocation of β3-β4 strands, conformational changes in critical residues associated with ligand binding to the lid domain, dynamic fluctuation of Ω-loop and β3-β4 elements. Such structural changes increase catalytic regions’ flexibility, enlarge active site, and thereby accommodate third-generation cephalosporin antibiotics, ceftazidime (CAZ). Notably, the electrostatic property around the oxyanion hole of Cys69Tyr ESBL is significantly changed, resulting in possible additional stabilization of the acyl-enzyme intermediate. Interestingly, the NCR mutations are as effective for antibiotic resistance by altering the structure and dynamics in regions mediating substrate recognition and binding as single amino-acid substitutions in the catalytic region of the canonical ESBLs. We believe that our findings are crucial in developing successful therapeutic strategies against diverse class A ESBLs, including the new NCR-ESBLs.
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Affiliation(s)
- Thinh-Phat Cao
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, Gwangju, South Korea.,Department of Biomedical Sciences, Gwangju Alzheimer's Disease and Related Dementia Cohort Research Center, College of Natural Sciences and Public Health and Safety, Chosun University, Gwangju, South Korea
| | - Hyojeong Yi
- Division of Biosystems & Biomedical Sciences, College of Health Sciences, Korea University, Seoul, South Korea
| | - Immanuel Dhanasingh
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, Gwangju, South Korea
| | - Suparna Ghosh
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, Gwangju, South Korea
| | - Jin Myung Choi
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, Gwangju, South Korea
| | - Kun Ho Lee
- Department of Biomedical Sciences, Gwangju Alzheimer's Disease and Related Dementia Cohort Research Center, College of Natural Sciences and Public Health and Safety, Chosun University, Gwangju, South Korea.,Aging Neuroscience Research Group, Korea Brain Research Institute, Daegu, South Korea
| | - Seol Ryu
- Department of Chemistry, Chosun University, Gwangju, South Korea
| | - Heenam Stanley Kim
- Division of Biosystems & Biomedical Sciences, College of Health Sciences, Korea University, Seoul, South Korea
| | - Sung Haeng Lee
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, Gwangju, South Korea.,Department of Biomedical Sciences, Gwangju Alzheimer's Disease and Related Dementia Cohort Research Center, College of Natural Sciences and Public Health and Safety, Chosun University, Gwangju, South Korea
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7
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Cheng Q, Xu C, Chai J, Zhang R, Wai chi Chan E, Chen S. Structural Insight into the Mechanism of Inhibitor Resistance in CTX-M-199, a CTX-M-64 Variant Carrying the S 130T Substitution. ACS Infect Dis 2020; 6:577-587. [PMID: 31709791 DOI: 10.1021/acsinfecdis.9b00345] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The smart design of β-lactamase inhibitors allowed us to combat extended-spectrum β-lactamase (ESBL)-producing organisms for many years without developing resistance to these inhibitors. However, novel resistant variants have emerged recently, and notable examples are the CTX-M-190 and CTX-M-199 variants, which carried a S130T amino acid substitution and exhibited resistance to inhibitors such as sulbactam and tazobactam. Using mass spectrometric and crystallographic approaches, this study depicted the mechanisms of inhibitor resistance. Our data showed that CTX-M-64 (S130T) did not cause any conformational change or exert any effect on its ability to hydrolyze β-lactam substrates. However, binding of sulbactam, but not clavulanic acid, to the active site of CTX-M-64 (S130T) led to the conformational changes in such active site, which comprised the key residues involved in substrate catalysis, namely, Thr130, Lys73, Lys234, Asn104, and Asn132. This conformational change weakened the binding of the sulbactam trans-enamine intermediate (TSL) to the active site and rendered the formation of the inhibitor-enzyme complex, which features a covalent acrylic acid (AKR)-T130 bond, inefficient, thereby resulting in inhibitor resistance in CTX-M-64 (S130T). Understanding the mechanisms of inhibitor resistance provided structural insight for the future development of new inhibitors against inhibitor-resistant β-lactamases.
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Affiliation(s)
- Qipeng Cheng
- State Key Lab of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Chen Xu
- State Key Lab of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Jiachang Chai
- Department of Clinical Medicine, Second Affiliated Hospital of Zhejiang University, Hangzhou 310009, China
| | - Rong Zhang
- Department of Clinical Medicine, Second Affiliated Hospital of Zhejiang University, Hangzhou 310009, China
| | - Edward Wai chi Chan
- State Key Lab of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Sheng Chen
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong
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8
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Philippon A, Jacquier H, Ruppé E, Labia R. Structure-based classification of class A beta-lactamases, an update. Curr Res Transl Med 2019; 67:115-122. [PMID: 31155436 DOI: 10.1016/j.retram.2019.05.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 05/21/2019] [Accepted: 05/21/2019] [Indexed: 02/06/2023]
Abstract
Beta-lactamase (EC 3.5.2.6) synthesis, particularly in Gram-negative bacilli, is a major mechanism of natural and acquired resistance to beta-lactams, sometimes accompanied by impermeability and/or active efflux. These enzymes have been classified into four molecular classes (A-D). The serine enzymes of class A, which may be encoded by the bacterial chromosome or transferable elements and are susceptible to clinically available inhibitors (clavulanic acid, sulbactam, tazobactam, avibactam), are prevalent considering other molecular classes (B,C,D). The continual rapid development of genomic approaches and tremendous progress in automatic sequencer technology have resulted in the accumulation of massive amounts of data. A structure-based classification of class A beta-lactamases based on specific conserved motifs involved in catalytic mechanisms and/or substrate binding (S70XXK, S130DN, K234TG), together with E166 (Ambler numbering) and at least 24 other amino-acid residues or analogs such as G45, F66, V80, L81, L91, L101, P107, A134, L138, G143, G144, G156, L169, T181, T182, P183, was validated on 700 amino-acid sequences, including 132 representative types, but mostly probable enzyme sequences, many produced by environmental bacteria. Two subclasses (A1, A2), six major clusters or groups (e.g. natural limited-spectrum beta-lactamases (LSBL), wider spectrum beta-lactamases (WSBL), and various other clusters were identified on the basis of conserved (> 90%) and specific motifs, and residues such as S70TFKAL, S130DNTAANL, R164XEXXLN, V231GDKTG for subclass A1, S70VFKFH, S130DNNACDI,E166XXM, and V231AHKTG for subclass A2, a probable disulfide bridge C77-C123 and G236, A237, G238, and R244 for the LSBL group. This great diversity of primary structures was used as the basis for a structure-based and phylogenetic classification.
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Affiliation(s)
- Alain Philippon
- Faculté de Médecine Paris Descartes, Service de Bactériologie, Paris, France.
| | - Hervé Jacquier
- AP-HP, Hôpital Lariboisière, Laboratoire de Bactériologie, Paris, France; INSERM, IAME, UMR 1137, Université Paris Diderot, IAME, UMR 1137, Sorbonne Paris Cité, France
| | - Etienne Ruppé
- INSERM, IAME, UMR 1137, Université Paris Diderot, IAME, UMR 1137, Sorbonne Paris Cité, France; AP-HP, Hôpital Bichat, Laboratoire de Bactériologie, F-75018 Paris, France
| | - Roger Labia
- Laboratoire Universitaire de Biodiversité et d'Ecologie Microbienne, 6 Rue de l'Université, Quimper, France
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9
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Abrar S, Ain NU, Liaqat H, Hussain S, Rasheed F, Riaz S. Distribution of bla CTX - M , bla TEM , bla SHV and bla OXA genes in Extended-spectrum- β-lactamase-producing Clinical isolates: A three-year multi-center study from Lahore, Pakistan. Antimicrob Resist Infect Control 2019; 8:80. [PMID: 31139363 PMCID: PMC6530043 DOI: 10.1186/s13756-019-0536-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/09/2019] [Indexed: 01/05/2023] Open
Abstract
Background Frequency of extended-spectrum-β-lactamase-producing clinical isolates is increasing worldwide. This is a multi-center study which was aimed to check the frequency of third-generation cephalosporin resistance and distribution of the key genetic determinants of Extended-spectrum-β-lactamase-producing Clinical isolates in Pakistan. Methods A total of 2372 samples were processed in three tertiary care hospitals and one diagnostic research center of Lahore, Pakistan during Aug-2014 to Sep-2017. Analytical profile index (API 20-E) was used for biochemical characterization of isolates. Antibiotic susceptibility testing (AST) and third generation cephalosporin resistant (3GC-R) isolates were subjected to: double disc synergism test (DDST), combination disc test (CDST) and epsilometric test (E-test) for confirmation of ESBL-production. PCR amplification of isolates with plasmid and genomic DNA was performed. Amplicon sequences were checked for gene-variants and statistical analyses were performed to check the significance of data. Results A total of 497/995 (50%) isolates including Escherichia coli 65% (n = 321), Klebsiella spp. 25% (n = 124) and Pseudomonas. 5% (n = 24), Enterobacter spp. 4% (n = 20) and Acinetobacter spp. 2% (n = 8) were screened as third generation cephalosporin resistant (3GC-R). Urine 56% (n = 278) followed by pus 20% (n = 99) and wound swab 6% (n = 29) were frequent sources. Incidence of ESBL-producers detected by combination disc test was 79% (n = 392). PCR revealed blaCTX − M (76%) gene followed by blaOXA (52%), blaTEM (28%) and blaSHV (21%) were most prevalent among ESBL-producers detected by CDST. blaCTX − M − 1(65%), blaOXA (78%) and blaTEM (57%) genes were carried on plasmids. Amplicon sequencing revealed blaCTX − M − 15 (75%), blaOXA − 1 (49%) and blaTEM − 1B (34%) and 21 (n = 28) isolates carried three genes in them. Conclusion Prevalence of ESBL-producing isolates has increased 1.13 folds during study years. Isolates had high prevalence of ESBL-encoding blaCTXM − 15 gene and narrow spectrum blaOXA − 1 and blaTEM − 1B were also prevalent.
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Affiliation(s)
- Samyyia Abrar
- 1Department of Microbiology and Molecular genetics, University of the Punjab, Lahore, Pakistan
| | - Noor Ul Ain
- 1Department of Microbiology and Molecular genetics, University of the Punjab, Lahore, Pakistan
| | - Huma Liaqat
- 1Department of Microbiology and Molecular genetics, University of the Punjab, Lahore, Pakistan
| | - Shahida Hussain
- 1Department of Microbiology and Molecular genetics, University of the Punjab, Lahore, Pakistan
| | - Farhan Rasheed
- Allama Iqbal Medical College, Jinnah Hospital Lahore, Lahore, Pakistan
| | - Saba Riaz
- 1Department of Microbiology and Molecular genetics, University of the Punjab, Lahore, Pakistan.,Citilab and Research Center, Lahore, Pakistan
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10
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Low-cost and user-friendly biosensor to test the integrity of mRNA molecules suitable for field applications. Biosens Bioelectron 2019; 137:199-206. [PMID: 31100599 DOI: 10.1016/j.bios.2019.05.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 04/17/2019] [Accepted: 05/03/2019] [Indexed: 12/15/2022]
Abstract
The use of mRNA in biotechnology has expanded with novel applications such as vaccines and therapeutic mRNA delivery recently demonstrated. For mRNA to be used in patients, quality control assays will need to be routinely established. Currently, there is a gap between the highly sophisticated RNA integrity tests available and broader application of mRNA-based products by non-specialist users, e.g. in mass vaccination campaigns. Therefore, the aim of this work was to develop a low-cost biosensor able to test the integrity of a mRNA molecule with low technological requirements and easy end-user application. The biosensor is based on a bi-functional fusion protein, composed by the λN peptide that recognizes its cognate aptamer encoded on the 5' end of the RNA under study and β-lactamase, which is able to produce a colorimetric response through a simple test. We propose two different mechanisms for signal processing adapted to two levels of technological sophistication, one based on spectrophotometric measurements and other on visual inspection. We show that the proposed λN-βLac chimeric protein specifically targets its cognate RNA aptamer, boxB, using both gel shift and biolayer interferometry assays. More importantly, the results presented confirm the biosensor performs reliably, with a wide dynamic range and a proportional response at different percentages of full-length RNA, even when gene-sized mRNAs were used. Thus, the features of the proposed biosensor would allow to end-users of products such as mRNA vaccines to test the integrity of the product before its application in a low-cost fashion, enabling a more reliable application of these products.
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11
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The Structural Dynamics of Engineered β-Lactamases Vary Broadly on Three Timescales yet Sustain Native Function. Sci Rep 2019; 9:6656. [PMID: 31040324 PMCID: PMC6491436 DOI: 10.1038/s41598-019-42866-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 04/10/2019] [Indexed: 12/20/2022] Open
Abstract
Understanding the principles of protein dynamics will help guide engineering of protein function: altering protein motions may be a barrier to success or may be an enabling tool for protein engineering. The impact of dynamics on protein function is typically reported over a fraction of the full scope of motional timescales. If motional patterns vary significantly at different timescales, then only by monitoring motions broadly will we understand the impact of protein dynamics on engineering functional proteins. Using an integrative approach combining experimental and in silico methodologies, we elucidate protein dynamics over the entire span of fast to slow timescales (ps to ms) for a laboratory-engineered system composed of five interrelated β-lactamases: two natural homologs and three laboratory-recombined variants. Fast (ps-ns) and intermediate (ns-µs) dynamics were mostly conserved. However, slow motions (µs-ms) were few and conserved in the natural homologs yet were numerous and widely dispersed in their recombinants. Nonetheless, modified slow dynamics were functionally tolerated. Crystallographic B-factors from high-resolution X-ray structures were partly predictive of the conserved motions but not of the new slow motions captured in our solution studies. Our inspection of protein dynamics over a continuous range of timescales vividly illustrates the complexity of dynamic impacts of protein engineering as well as the functional tolerance of an engineered enzyme system to new slow motions.
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12
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Beleva Guthrie V, Masica DL, Fraser A, Federico J, Fan Y, Camps M, Karchin R. Network Analysis of Protein Adaptation: Modeling the Functional Impact of Multiple Mutations. Mol Biol Evol 2019. [PMID: 29522102 PMCID: PMC5967520 DOI: 10.1093/molbev/msy036] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The evolution of new biochemical activities frequently involves complex dependencies between mutations and rapid evolutionary radiation. Mutation co-occurrence and covariation have previously been used to identify compensating mutations that are the result of physical contacts and preserve protein function and fold. Here, we model pairwise functional dependencies and higher order interactions that enable evolution of new protein functions. We use a network model to find complex dependencies between mutations resulting from evolutionary trade-offs and pleiotropic effects. We present a method to construct these networks and to identify functionally interacting mutations in both extant and reconstructed ancestral sequences (Network Analysis of Protein Adaptation). The time ordering of mutations can be incorporated into the networks through phylogenetic reconstruction. We apply NAPA to three distantly homologous β-lactamase protein clusters (TEM, CTX-M-3, and OXA-51), each of which has experienced recent evolutionary radiation under substantially different selective pressures. By analyzing the network properties of each protein cluster, we identify key adaptive mutations, positive pairwise interactions, different adaptive solutions to the same selective pressure, and complex evolutionary trajectories likely to increase protein fitness. We also present evidence that incorporating information from phylogenetic reconstruction and ancestral sequence inference can reduce the number of spurious links in the network, whereas preserving overall network community structure. The analysis does not require structural or biochemical data. In contrast to function-preserving mutation dependencies, which are frequently from structural contacts, gain-of-function mutation dependencies are most commonly between residues distal in protein structure.
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Affiliation(s)
- Violeta Beleva Guthrie
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD
| | - David L Masica
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD
| | - Andrew Fraser
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD
| | - Joseph Federico
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD
| | - Yunfan Fan
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD
| | - Manel Camps
- Department of Environmental Toxicology, University of California Santa Cruz, Santa Cruz, CA
| | - Rachel Karchin
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD.,Department of Oncology, Johns Hopkins University Medicine, Baltimore, MD
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13
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Cortina GA, Hays JM, Kasson PM. Conformational Intermediate That Controls KPC-2 Catalysis and Beta-Lactam Drug Resistance. ACS Catal 2018; 8:2741-2747. [PMID: 30637173 DOI: 10.1021/acscatal.7b03832] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The KPC-2 carbapenemase enzyme is responsible for drug resistance in the majority of carbapenem-resistant gram-negative bacterial infections in the United States. A better understanding of what permits KPC-2 to hydrolyze carbapenem antibiotics and how this might be inhibited is thus of fundamental interest and great practical importance to development of better anti-infectives. By correlating molecular dynamics simulations with experimental enzyme kinetics, we have identified conformational changes that control KPC-2's ability to hydrolyze carbapenem antibiotics. Related beta-lactamase enzymes can interconvert between catalytically permissive and catalytically nonpermissive forms of an acylenzyme intermediate critical to drug hydrolysis. Using molecular dynamics simulations, we identify a similar equilibrium in KPC-2 and analyze the determinants of this conformational change. Because the conformational dynamics of KPC-2 are complex and sensitive to allosteric changes, we develop an information-theoretic approach to identify key determinants of this change. We measure unbiased estimators of the reaction coordinate between catalytically permissive and nonpermissive states, perform information-theoretic feature selection and, using restrained molecular dynamics simulations, validate the protein conformational changes predicted to control catalytically permissive geometry. We identify two binding-pocket residues that control the conformational transitions between catalytically active and inactive forms of KPC-2. Mutations to one of these residues, Trp105, lower the stability of the catalytically permissive state in simulations and have reduced experimental k cat values that show a strong linear correlation with the simulated catalytically permissive state lifetimes. This understanding can be leveraged to predict the drug resistance of further KPC-2 mutants and help design inhibitors to combat extreme drug resistance.
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Affiliation(s)
| | | | - Peter M. Kasson
- Laboratory of Molecular Biophysics, Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Box 596, Uppsala 75124, Sweden
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14
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Cecchini T, Yoon EJ, Charretier Y, Bardet C, Beaulieu C, Lacoux X, Docquier JD, Lemoine J, Courvalin P, Grillot-Courvalin C, Charrier JP. Deciphering Multifactorial Resistance Phenotypes in Acinetobacter baumannii by Genomics and Targeted Label-free Proteomics. Mol Cell Proteomics 2017; 17:442-456. [PMID: 29259044 DOI: 10.1074/mcp.ra117.000107] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 09/22/2017] [Indexed: 12/19/2022] Open
Abstract
Resistance to β-lactams in Acinetobacter baumannii involves various mechanisms. To decipher them, whole genome sequencing (WGS) and real-time quantitative polymerase chain reaction (RT-qPCR) were complemented by mass spectrometry (MS) in selected reaction monitoring mode (SRM) in 39 clinical isolates. The targeted label-free proteomic approach enabled, in one hour and using a single method, the quantitative detection of 16 proteins associated with antibiotic resistance: eight acquired β-lactamases (i.e. GES, NDM-1, OXA-23, OXA-24, OXA-58, PER, TEM-1, and VEB), two resident β-lactamases (i.e. ADC and OXA-51-like) and six components of the two major efflux systems (i.e. AdeABC and AdeIJK). Results were normalized using "bacterial quantotypic peptides," i.e. peptide markers of the bacterial quantity, to obtain precise protein quantitation (on average 8.93% coefficient of variation for three biological replicates). This allowed to correlate the levels of resistance to β-lactam with those of the production of acquired as well as resident β-lactamases or of efflux systems. SRM detected enhanced ADC or OXA-51-like production and absence or increased efflux pump production. Precise protein quantitation was particularly valuable to detect resistance mechanisms mediated by regulated genes or by overexpression of chromosomal genes. Combination of WGS and MS, two orthogonal and complementary techniques, allows thereby interpretation of the resistance phenotypes at the molecular level.
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Affiliation(s)
- Tiphaine Cecchini
- From the ‡Technology Research Department, Innovation Unit, bioMérieux SA, Marcy l'Etoile, France.,§UMR 5280, Institut des Sciences Analytiques, Université de Lyon, Lyon 1, Villeurbanne, France
| | - Eun-Jeong Yoon
- ¶Institut Pasteur, Unité des Agents Antibactériens, Paris, France
| | - Yannick Charretier
- From the ‡Technology Research Department, Innovation Unit, bioMérieux SA, Marcy l'Etoile, France.,§UMR 5280, Institut des Sciences Analytiques, Université de Lyon, Lyon 1, Villeurbanne, France
| | - Chloé Bardet
- From the ‡Technology Research Department, Innovation Unit, bioMérieux SA, Marcy l'Etoile, France.,§UMR 5280, Institut des Sciences Analytiques, Université de Lyon, Lyon 1, Villeurbanne, France
| | - Corinne Beaulieu
- From the ‡Technology Research Department, Innovation Unit, bioMérieux SA, Marcy l'Etoile, France
| | - Xavier Lacoux
- ‖R&D ImmunoAssays, bioMérieux SA, Marcy l'Etoile, France
| | | | - Jerome Lemoine
- §UMR 5280, Institut des Sciences Analytiques, Université de Lyon, Lyon 1, Villeurbanne, France
| | | | | | - Jean-Philippe Charrier
- From the ‡Technology Research Department, Innovation Unit, bioMérieux SA, Marcy l'Etoile, France;
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15
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High adaptability of the omega loop underlies the substrate-spectrum-extension evolution of a class A β-lactamase, PenL. Sci Rep 2016; 6:36527. [PMID: 27827433 PMCID: PMC5101513 DOI: 10.1038/srep36527] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 10/18/2016] [Indexed: 01/11/2023] Open
Abstract
The omega loop in β-lactamases plays a pivotal role in substrate recognition and catalysis, and some mutations in this loop affect the adaptability of the enzymes to new antibiotics. Various mutations, including substitutions, deletions, and intragenic duplications resulting in tandem repeats (TRs), have been associated with β-lactamase substrate spectrum extension. TRs are unique among the mutations as they cause severe structural perturbations in the enzymes. We explored the process by which TRs are accommodated in order to test the adaptability of the omega loop. Structures of the mutant enzymes showed that the extra amino acid residues in the omega loop were freed outward from the enzyme, thereby maintaining the overall enzyme integrity. This structural adjustment was accompanied by disruptions of the internal α-helix and hydrogen bonds that originally maintained the conformation of the omega loop and the active site. Consequently, the mutant enzymes had a relaxed binding cavity, allowing for access of new substrates, which regrouped upon substrate binding in an induced-fit manner for subsequent hydrolytic reactions. Together, the data demonstrate that the design of the binding cavity, including the omega loop with its enormous adaptive capacity, is the foundation of the continuous evolution of β-lactamases against new drugs.
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16
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A Structure-Based Classification of Class A β-Lactamases, a Broadly Diverse Family of Enzymes. Clin Microbiol Rev 2016; 29:29-57. [PMID: 26511485 DOI: 10.1128/cmr.00019-15] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
For medical biologists, sequencing has become a commonplace technique to support diagnosis. Rapid changes in this field have led to the generation of large amounts of data, which are not always correctly listed in databases. This is particularly true for data concerning class A β-lactamases, a group of key antibiotic resistance enzymes produced by bacteria. Many genomes have been reported to contain putative β-lactamase genes, which can be compared with representative types. We analyzed several hundred amino acid sequences of class A β-lactamase enzymes for phylogenic relationships, the presence of specific residues, and cluster patterns. A clear distinction was first made between dd-peptidases and class A enzymes based on a small number of residues (S70, K73, P107, 130SDN132, G144, E166, 234K/R, 235T/S, and 236G [Ambler numbering]). Other residues clearly separated two main branches, which we named subclasses A1 and A2. Various clusters were identified on the major branch (subclass A1) on the basis of signature residues associated with catalytic properties (e.g., limited-spectrum β-lactamases, extended-spectrum β-lactamases, and carbapenemases). For subclass A2 enzymes (e.g., CfxA, CIA-1, CME-1, PER-1, and VEB-1), 43 conserved residues were characterized, and several significant insertions were detected. This diversity in the amino acid sequences of β-lactamases must be taken into account to ensure that new enzymes are accurately identified. However, with the exception of PER types, this diversity is poorly represented in existing X-ray crystallographic data.
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17
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Identification of Novel VEB β-Lactamase Enzymes and Their Impact on Avibactam Inhibition. Antimicrob Agents Chemother 2016; 60:3183-6. [PMID: 26926646 DOI: 10.1128/aac.00047-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 02/21/2016] [Indexed: 11/20/2022] Open
Abstract
Ceftazidime-avibactam has activity against Pseudomonas aeruginosa and Enterobacteriaceae expressing numerous class A and class C β-lactamases, although the ability to inhibit many minor enzyme variants has not been established. Novel VEB class A β-lactamases were identified during characterization of surveillance isolates. The cloned novel VEB β-lactamases possessed an extended-spectrum β-lactamase phenotype and were inhibited by avibactam in a concentration-dependent manner. The residues that comprised the avibactam binding pocket were either identical or functionally conserved. These data demonstrate that avibactam can inhibit VEB β-lactamases.
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18
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Naas T, Dortet L, Iorga BI. Structural and Functional Aspects of Class A Carbapenemases. Curr Drug Targets 2016; 17:1006-28. [PMID: 26960341 PMCID: PMC5405625 DOI: 10.2174/1389450117666160310144501] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 07/02/2015] [Accepted: 03/05/2016] [Indexed: 01/28/2023]
Abstract
The fight against infectious diseases is probably one of the greatest public health challenges faced by our society, especially with the emergence of carbapenem-resistant gram-negatives that are in some cases pan-drug resistant. Currently,β-lactamase-mediated resistance does not spare even the newest and most powerful β-lactams (carbapenems), whose activity is challenged by carbapenemases. The worldwide dissemination of carbapenemases in gram-negative organisms threatens to take medicine back into the pre-antibiotic era since the mortality associated with infections caused by these "superbugs" is very high, due to limited treatment options. Clinically-relevant carbapenemases belong either to metallo-β- lactamases (MBLs) of Ambler class B or to serine-β-lactamases (SBLs) of Ambler class A and D enzymes. Class A carbapenemases may be chromosomally-encoded (SME, NmcA, SFC-1, BIC-1, PenA, FPH-1, SHV-38), plasmid-encoded (KPC, GES, FRI-1) or both (IMI). The plasmid-encoded enzymes are often associated with mobile elements responsible for their mobilization. These enzymes, even though weakly related in terms of sequence identities, share structural features and a common mechanism of action. They variably hydrolyse penicillins, cephalosporins, monobactams, carbapenems, and are inhibited by clavulanate and tazobactam. Three-dimensional structures of class A carbapenemases, in the apo form or in complex with substrates/inhibitors, together with site-directed mutagenesis studies, provide essential input for identifying the structural factors and subtle conformational changes that influence the hydrolytic profile and inhibition of these enzymes. Overall, these data represent the building blocks for understanding the structure-function relationships that define the phenotypes of class A carbapenemases and can guide the design of new molecules of therapeutic interest.
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Affiliation(s)
- Thierry Naas
- Service de Bactériologie- Hygiène, Hôpital de Bicêtre, APHP, EA7361, Faculté de Médecine Paris- Sud, LabEx LERMIT, Le Kremlin-Bicêtre, France.
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19
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Stojanoski V, Chow DC, Hu L, Sankaran B, Gilbert HF, Prasad BVV, Palzkill T. A triple mutant in the Ω-loop of TEM-1 β-lactamase changes the substrate profile via a large conformational change and an altered general base for catalysis. J Biol Chem 2015; 290:10382-94. [PMID: 25713062 DOI: 10.1074/jbc.m114.633438] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Indexed: 11/06/2022] Open
Abstract
β-Lactamases are bacterial enzymes that hydrolyze β-lactam antibiotics. TEM-1 is a prevalent plasmid-encoded β-lactamase in Gram-negative bacteria that efficiently catalyzes the hydrolysis of penicillins and early cephalosporins but not oxyimino-cephalosporins. A previous random mutagenesis study identified a W165Y/E166Y/P167G triple mutant that displays greatly altered substrate specificity with increased activity for the oxyimino-cephalosporin, ceftazidime, and decreased activity toward all other β-lactams tested. Surprisingly, this mutant lacks the conserved Glu-166 residue critical for enzyme function. Ceftazidime contains a large, bulky side chain that does not fit optimally in the wild-type TEM-1 active site. Therefore, it was hypothesized that the substitutions in the mutant expand the binding site in the enzyme. To investigate structural changes and address whether there is an enlargement in the active site, the crystal structure of the triple mutant was solved to 1.44 Å. The structure reveals a large conformational change of the active site Ω-loop structure to create additional space for the ceftazidime side chain. The position of the hydroxyl group of Tyr-166 and an observed shift in the pH profile of the triple mutant suggests that Tyr-166 participates in the hydrolytic mechanism of the enzyme. These findings indicate that the highly conserved Glu-166 residue can be substituted in the mechanism of serine β-lactamases. The results reveal that the robustness of the overall β-lactamase fold coupled with the plasticity of an active site loop facilitates the evolution of enzyme specificity and mechanism.
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Affiliation(s)
- Vlatko Stojanoski
- From the Verna and Marrs McLean Department of Biochemistry and Molecular Biology and the Department of Pharmacology, Baylor College of Medicine, Houston, Texas 77030 and
| | - Dar-Chone Chow
- the Department of Pharmacology, Baylor College of Medicine, Houston, Texas 77030 and
| | - Liya Hu
- From the Verna and Marrs McLean Department of Biochemistry and Molecular Biology and
| | - Banumathi Sankaran
- the Berkeley Center for Structural Biology, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Hiram F Gilbert
- From the Verna and Marrs McLean Department of Biochemistry and Molecular Biology and
| | - B V Venkataram Prasad
- From the Verna and Marrs McLean Department of Biochemistry and Molecular Biology and
| | - Timothy Palzkill
- From the Verna and Marrs McLean Department of Biochemistry and Molecular Biology and the Department of Pharmacology, Baylor College of Medicine, Houston, Texas 77030 and
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20
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In vitro prediction of the evolution of GES-1 β-lactamase hydrolytic activity. Antimicrob Agents Chemother 2015; 59:1664-70. [PMID: 25561336 DOI: 10.1128/aac.04450-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Resistance to β-lactams is constantly increasing due to the emergence of totally new enzymes but also to the evolution of preexisting β-lactamases. GES-1 is a clinically relevant extended-spectrum β-lactamase (ESBL) that hydrolyzes penicillins and broad-spectrum cephalosporins but spares monobactams and carbapenems. However, several GES-1 variants (i.e., GES-2 and GES-5) previously identified among clinical isolates display an extended spectrum of activity toward carbapenems. To study the evolution potential of the GES-1 β-lactamase, this enzyme was submitted to in vitro-directed evolution, with selection on increasing concentrations of the cephalosporin cefotaxime, the monobactam aztreonam, or the carbapenem imipenem. The highest resistance levels were conferred by a combination of up to four substitutions. The A6T-E104K-G243A variant selected on cefotaxime and the A6T-E104K-T237A-G243A variant selected on aztreonam conferred high resistance to cefotaxime, ceftazidime, and aztreonam. Conversely, the A6T-G170S variant selected on imipenem conferred high resistance to imipenem and cefoxitin. Of note, the A6T substitution involved in higher MICs for all β-lactams is located in the leader peptide of the GES enzyme and therefore is not present in the mature protein. Acquired cross-resistance was not observed, since selection with cefotaxime or aztreonam did not select for resistance to imipenem, and vice versa. Here, we demonstrate that the β-lactamase GES-1 exhibits peculiar properties, with a significant potential to gain activity against broad-spectrum cephalosporins, monobactams, and carbapenems.
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21
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Characterization of the inhibitor-resistant SHV β-lactamase SHV-107 in a clinical Klebsiella pneumoniae strain coproducing GES-7 enzyme. Antimicrob Agents Chemother 2011; 56:1042-6. [PMID: 22083476 DOI: 10.1128/aac.01444-10] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The clinical Klebsiella pneumoniae INSRA6884 strain exhibited nonsusceptibility to all penicillins tested (MICs of 64 to >2,048 μg/ml). The MICs of penicillins were weakly reduced by clavulanate (from 2,048 to 512 μg/ml), and tazobactam restored piperacillin susceptibility. Molecular characterization identified the genes bla(GES-7) and a new β-lactamase gene, bla(SHV-107), which encoded an enzyme that differed from SHV-1 by the amino acid substitutions Leu35Gln and Thr235Ala. The SHV-107-producing Escherichia coli strain exhibited only a β-lactam resistance phenotype with respect to amoxicillin, ticarcillin, and amoxicillin-clavulanate combination. The kinetic parameters of the purified SHV-107 enzyme revealed a high affinity for penicillins. However, catalytic efficiency for these antibiotics was lower for SHV-107 than for SHV-1. No hydrolysis was detected against oxyimino-β-lactams. The 50% inhibitory concentration (IC(50)) for clavulanic acid was 9-fold higher for SHV-107 than for SHV-1, but the inhibitory effects of tazobactam were unchanged. Molecular dynamics simulation suggested that the Thr235Ala substitution affects the accommodation of clavulanate in the binding site and therefore its inhibitory activity.
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22
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Kanj SS, Kanafani ZA. Current concepts in antimicrobial therapy against resistant gram-negative organisms: extended-spectrum beta-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and multidrug-resistant Pseudomonas aeruginosa. Mayo Clin Proc 2011; 86:250-9. [PMID: 21364117 PMCID: PMC3046948 DOI: 10.4065/mcp.2010.0674] [Citation(s) in RCA: 178] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The development of antimicrobial resistance among gram-negative pathogens has been progressive and relentless. Pathogens of particular concern include extended-spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and multidrug-resistant Pseudomonas aeruginosa. Classic agents used to treat these pathogens have become outdated. Of the few new drugs available, many have already become targets for bacterial mechanisms of resistance. This review describes the current approach to infections due to these resistant organisms and elaborates on the available treatment options.
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Affiliation(s)
- Souha S Kanj
- Division of Infectious Diseases, American University of Beirut Medical Center, Cairo Street, PO Box 11-0236, Riad El Solh, Beirut 1107 2020, Lebanon.
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23
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Abstract
Over the past decade, resistance to antibiotics has emerged as a crisis of global proportion. Microbes resistant to many and even all clinically approved antibiotics are increasingly common and easily spread across continents. At the same time there are fewer new antibiotic drugs coming to market. We are reaching a point where we are no longer able to confidently treat a growing number of bacterial infections. The molecular mechanisms of drug resistance provide the essential knowledge on new drug development and clinical use. These mechanisms include enzyme catalyzed antibiotic modifications, bypass of antibiotic targets and active efflux of drugs from the cell. Understanding the chemical rationale and underpinnings of resistance is an essential component of our response to this clinical challenge.
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Affiliation(s)
- Gerard D Wright
- M.G. DeGroote Institute for Infectious Disease Research, McMaster University, 1200 Main St W, Hamilton, ON, Canada.
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24
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Salverda MLM, De Visser JAGM, Barlow M. Natural evolution of TEM-1 β-lactamase: experimental reconstruction and clinical relevance. FEMS Microbiol Rev 2011; 34:1015-36. [PMID: 20412308 DOI: 10.1111/j.1574-6976.2010.00222.x] [Citation(s) in RCA: 193] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
TEM-1 β-lactamase is one of the most well-known antibiotic resistance determinants around. It confers resistance to penicillins and early cephalosporins and has shown an astonishing functional plasticity in response to the introduction of novel drugs derived from these antibiotics. Since its discovery in the 1960s, over 170 variants of TEM-1 - with different amino acid sequences and often resistance phenotypes - have been isolated in hospitals and clinics worldwide. Next to this well-documented 'natural' evolution, the in vitro evolution of TEM-1 has been the focus of attention of many experimental studies. In this review, we compare the natural and laboratory evolution of TEM-1 in order to address the question to what extent the evolution of antibiotic resistance can be repeated, and hence might have been predicted, under laboratory conditions. We also use the comparison to gain an insight into the adaptive relevance of hitherto uncharacterized substitutions present in clinical isolates and to predict substitutions not yet observed in nature. Based on new structural insights, we review what is known about substitutions in TEM-1 that contribute to the extension of its resistance phenotype. Finally, we address the clinical relevance of TEM alleles during the past decade, which has been dominated by the emergence of another β-lactamase, CTX-M.
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25
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De Pascale G, Wright GD. Antibiotic resistance by enzyme inactivation: from mechanisms to solutions. Chembiochem 2010; 11:1325-34. [PMID: 20564281 DOI: 10.1002/cbic.201000067] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Gianfranco De Pascale
- DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, 1200 Main Street W, Hamilton, ON L8N 3Z5 Canada
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26
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Alfaresi MS, Elkoush AA. Real-time polymerase chain reaction for rapid detection of genes encoding SHV extended-spectrum β-lactamases. Indian J Med Microbiol 2010; 28:332-6. [DOI: 10.4103/0255-0857.71827] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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27
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Comparative biochemical and computational study of the role of naturally occurring mutations at Ambler positions 104 and 170 in GES β-lactamases. Antimicrob Agents Chemother 2010; 54:4864-71. [PMID: 20696873 DOI: 10.1128/aac.00771-10] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In GES-type β-lactamases, positions 104 and 170 are occupied by Glu or Lys and by Gly, Asn, or Ser, respectively. Previous studies have indicated an important role of these amino acids in the interaction with β-lactams, although their precise role, especially that of residue 104, remains uncertain. In this study, we constructed GES-1 (Glu104, Gly170), GES-2 (Glu104, Asn170), GES-5 (Glu104, Ser170), GES-6 (Lys104, Ser170), GES-7 (Lys104, Gly170), and GES-13 (Lys104, Asn170) by site-specific mutagenesis and compared their hydrolytic properties. Isogenic comparisons of β-lactam resistance levels conferred by these GES variants were also performed. Data indicated the following patterns: (i) Lys104-containing enzymes exhibited enhanced hydrolysis of oxyimino-cephalosporins and reduced efficiency against imipenem in relation to enzymes possessing Glu104, (ii) Asn170-containing enzymes showed reduced hydrolysis rates of penicillins and older cephalosporins, (iii) Ser170 enabled GES to hydrolyze cefoxitin efficiently, and (iv) Asn170 and Ser170 increased the carbapenemase character of GES enzymes but reduced their activity against ceftazidime. Molecular dynamic simulations of GES apoenzyme models, as well as construction of GES structures complexed with cefoxitin and an achiral ceftazidime-like boronic acid, provided insights into the catalytic behavior of the studied mutants. There were indications that an increased stability of the hydrogen bonding network of Glu166-Lys73-Ser70 and an altered positioning of Trp105 correlated with the substrate spectra, especially with acylation of GES by imipenem. Furthermore, likely effects of Ser170 on GES interactions with cefoxitin and of Lys104 on interactions with oxyimino-cephalosporins were revealed. Overall, the data unveiled the importance of residues 104 and 170 in the function of GES enzymes.
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28
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Endimiani A, Doi Y, Bethel CR, Taracila M, Adams-Haduch JM, O'Keefe A, Hujer AM, Paterson DL, Skalweit MJ, Page MGP, Drawz SM, Bonomo RA. Enhancing resistance to cephalosporins in class C beta-lactamases: impact of Gly214Glu in CMY-2. Biochemistry 2010; 49:1014-23. [PMID: 19938877 DOI: 10.1021/bi9015549] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The biochemical properties of CMY-32, a class C enzyme possessing a single-amino acid substitution in the Omega loop (Gly214Glu), were compared to those of the parent enzyme, CMY-2, a widespread class C beta-lactamase. In parallel with our microbiological characterization, the Gly214Glu substitution in CMY-32 reduced catalytic efficiency (k(cat)/K(m)) by 50-70% against "good" substrates (i.e., cephalothin) while increasing k(cat)/K(m) against "poor" substrates (i.e., cefotaxime). Additionally, CMY-32 was more susceptible to inactivation by sulfone beta-lactamase inhibitors (i.e., sulbactam and tazobactam) than CMY-2. Timed electrospray ionization mass spectrometry (ESI-MS) analysis of the reaction of CMY-2 and CMY-32 with different substrates and inhibitors suggested that both beta-lactamases formed similar intermediates during catalysis and inactivation. We next showed that the carbapenems (imipenem, meropenem, and doripenem) form long-lived acyl-enzyme intermediates and present evidence that there is beta-lactamase-catalyzed elimination of the C(6) hydroxyethyl substituent. Furthermore, we discovered that the monobactam aztreonam and BAL29880, a new beta-lactamase inhibitor of the monobactam class, inactivate CMY-2 and CMY-32 by forming an acyl-enzyme intermediate that undergoes elimination of SO(3)(2-). Molecular modeling and dynamics simulations suggest that the Omega loop is more constrained in CMY-32 than CMY-2. Our model also proposes that Gln120 adopts a novel conformation in the active site while new interactions form between Glu214 and Tyr221, thus explaining the increased level of cefotaxime hydrolysis. When it is docked in the active site, we observe that BAL29880 exploits contacts with highly conserved residues Lys67 and Asn152 in CMY-2 and CMY-32. These findings highlight (i) the impact of single-amino acid substitutions on protein evolution in clinically important AmpC enzymes and (ii) the novel insights into the mechanisms by which carbapenems and monobactams interact with CMY-2 and CMY-32 beta-lactamases.
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Affiliation(s)
- Andrea Endimiani
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio 44106, USA
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Frase H, Shi Q, Testero SA, Mobashery S, Vakulenko SB. Mechanistic basis for the emergence of catalytic competence against carbapenem antibiotics by the GES family of beta-lactamases. J Biol Chem 2009; 284:29509-13. [PMID: 19656947 DOI: 10.1074/jbc.m109.011262] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A major mechanism of bacterial resistance to beta-lactam antibiotics (penicillins, cephalosporins, carbapenems, etc.) is the production of beta-lactamases. A handful of class A beta-lactamases have been discovered that have acquired the ability to turn over carbapenem antibiotics. This is a disconcerting development, as carbapenems are often considered last resort antibiotics in the treatment of difficult infections. The GES family of beta-lactamases constitutes a group of extended spectrum resistance enzymes that hydrolyze penicillins and cephalosporins avidly. A single amino acid substitution at position 170 has expanded the breadth of activity to include carbapenems. The basis for this expansion of activity is investigated in this first report of detailed steady-state and pre-steady-state kinetics of carbapenem hydrolysis, performed with a class A carbapenemase. Monitoring the turnover of imipenem (a carbapenem) by GES-1 (Gly-170) revealed the acylation step as rate-limiting. GES-2 (Asn-170) has an enhanced rate of acylation, compared with GES-1, and no longer has a single rate-determining step. Both the acylation and deacylation steps are of equal magnitude. GES-5 (Ser-170) exhibits an enhancement of the rate constant for acylation by a remarkable 5000-fold, whereby the enzyme acylation event is no longer rate-limiting. This carbapenemase exhibits k(cat)/K(m) of 3 x 10(5) m(-1)s(-1), which is sufficient for manifestation of resistance against imipenem.
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Affiliation(s)
- Hilary Frase
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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Pyrosequencing using the single-nucleotide polymorphism protocol for rapid determination of TEM- and SHV-type extended-spectrum beta-lactamases in clinical isolates and identification of the novel beta-lactamase genes blaSHV-48, blaSHV-105, and blaTEM-155. Antimicrob Agents Chemother 2008; 53:977-86. [PMID: 19075050 DOI: 10.1128/aac.01155-08] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
TEM- and SHV-type extended-spectrum beta-lactamases (ESBLs) are the most common ESBLs found in the United States and are prevalent throughout the world. Amino acid substitutions at a number of positions in TEM-1 lead to the ESBL phenotype, although substitutions at residues 104 (E to K), 164 (R to S or H), 238 (G to S), and 240 (E to K) appear to be particularly important in modifying the spectrum of activity of the enzyme. The SHV-1-derived ESBLs are a less diverse collection of enzymes; however, the majority of amino acid substitutions resulting in an ESBL mirror those seen in the TEM-1-derived enzymes. Pyrosequencing by use of the single-nucleotide polymorphism (SNP) protocol was applied to provide sequence data at positions critical for the ESBL phenotype spanning the bla(TEM) and bla(SHV) genes. Three novel beta-lactamases are described: the ESBLs TEM-155 (Q39K, R164S, E240K) and SHV-105 (I8F, R43S, G156D, G238S, E240K) and a non-ESBL, SHV-48 (V119I). The ceftazidime, ceftriaxone, and aztreonam MICs for an Escherichia coli isolate expressing bla(SHV-105) were >128, 128, and >128 microg/ml, respectively. Likewise, the ceftazidime, ceftriaxone, and aztreonam MICs for an E. coli isolate expressing bla(TEM-155) were >128, 64, and > 128 microg/ml, respectively. Pyrosequence analysis determined the true identity of the beta-lactamase on plasmid R1010 to be SHV-11 rather than SHV-1, as previously reported. Pyrosequencing is a real-time sequencing-by-synthesis approach that was applied to SNP detection for TEM- and SHV-type ESBL identification and represents a robust tool for rapid sequence determination that may have a place in the clinical setting.
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