1
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Radojković M, Ubbink M. Positive epistasis drives clavulanic acid resistance in double mutant libraries of BlaC β-lactamase. Commun Biol 2024; 7:197. [PMID: 38368480 PMCID: PMC10874438 DOI: 10.1038/s42003-024-05868-5] [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: 10/06/2023] [Accepted: 01/26/2024] [Indexed: 02/19/2024] Open
Abstract
Phenotypic effects of mutations are highly dependent on the genetic backgrounds in which they occur, due to epistatic effects. To test how easily the loss of enzyme activity can be compensated for, we screen mutant libraries of BlaC, a β-lactamase from Mycobacterium tuberculosis, for fitness in the presence of carbenicillin and the inhibitor clavulanic acid. Using a semi-rational approach and deep sequencing, we prepare four double-site saturation libraries and determine the relative fitness effect for 1534/1540 (99.6%) of the unique library members at two temperatures. Each library comprises variants of a residue known to be relevant for clavulanic acid resistance as well as residue 105, which regulates access to the active site. Variants with greatly improved fitness were identified within each library, demonstrating that compensatory mutations for loss of activity can be readily found. In most cases, the fittest variants are a result of positive epistasis, indicating strong synergistic effects between the chosen residue pairs. Our study sheds light on a role of epistasis in the evolution of functional residues and underlines the highly adaptive potential of BlaC.
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Affiliation(s)
- Marko Radojković
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands
| | - Marcellus Ubbink
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands.
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2
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van Alen I, Aguirre García MA, Maaskant JJ, Kuijl CP, Bitter W, Meijer AH, Ubbink M. Mycobacterium tuberculosis β-lactamase variant reduces sensitivity to ampicillin/avibactam in a zebrafish-Mycobacterium marinum model of tuberculosis. Sci Rep 2023; 13:15406. [PMID: 37717068 PMCID: PMC10505137 DOI: 10.1038/s41598-023-42152-8] [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: 05/12/2023] [Accepted: 09/06/2023] [Indexed: 09/18/2023] Open
Abstract
The β-lactamase of Mycobacterium tuberculosis, BlaC, hydrolyzes β-lactam antibiotics, hindering the use of these antibiotics for the treatment of tuberculosis. Inhibitors, such as avibactam, can reversibly inhibit the enzyme, allowing for the development of combination therapies using both antibiotic and inhibitor. However, laboratory evolution studies using Escherichia coli resulted in the discovery of single amino acid variants of BlaC that reduce the sensitivity for inhibitors or show higher catalytic efficiency against antibiotics. Here, we tested these BlaC variants under more physiological conditions using the M. marinum infection model of zebrafish, which recapitulates hallmark features of tuberculosis, including the intracellular persistence of mycobacteria in macrophages and the induction of granuloma formation. To this end, the M. tuberculosis blaC gene was integrated into the chromosome of a blaC frameshift mutant of M. marinum. Subsequently, the resulting strains were used to infect zebrafish embryos in order to test the combinatorial effect of ampicillin and avibactam. The results show that embryos infected with an M. marinum strain producing BlaC show lower infection levels after treatment than untreated embryos. Additionally, BlaC K234R showed higher infection levels after treatment than those infected with bacteria producing the wild-type enzyme, demonstrating that the zebrafish host is less sensitive to the combinatorial therapy of β-lactam antibiotic and inhibitor. These findings are of interest for future development of combination therapies to treat tuberculosis.
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Affiliation(s)
- Ilona van Alen
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC, Leiden, The Netherlands
| | - Mayra A Aguirre García
- Institute of Biology Leiden, Leiden University, Einsteinweg 55, 2333CC, Leiden, The Netherlands
| | - Janneke J Maaskant
- Department of Medical Microbiology and Infection Control, Amsterdam UMC, Location VUmc, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
| | - Coenraad P Kuijl
- Department of Medical Microbiology and Infection Control, Amsterdam UMC, Location VUmc, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
| | - Wilbert Bitter
- Department of Medical Microbiology and Infection Control, Amsterdam UMC, Location VUmc, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
- Section of Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
| | - Annemarie H Meijer
- Institute of Biology Leiden, Leiden University, Einsteinweg 55, 2333CC, Leiden, The Netherlands
| | - Marcellus Ubbink
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC, Leiden, The Netherlands.
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3
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Chikunova A, Ubbink M. The roles of highly conserved, non‐catalytic residues in class A β‐lactamases. Protein Sci 2022; 31:e4328. [PMID: 35634774 PMCID: PMC9112487 DOI: 10.1002/pro.4328] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/03/2022] [Accepted: 04/20/2022] [Indexed: 11/12/2022]
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4
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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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5
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White DS, Choy CJ, Moural TW, Martin SE, Wang J, Gargaro S, Kang C, Berkman CE. Bis(benzoyl) phosphate inactivators of beta-lactamase C from Mtb. Bioorg Med Chem Lett 2019; 29:2116-2118. [PMID: 31281019 DOI: 10.1016/j.bmcl.2019.07.002] [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: 05/08/2019] [Revised: 06/27/2019] [Accepted: 07/01/2019] [Indexed: 11/26/2022]
Abstract
The class A β-lactamase BlaC is a cell surface expressed serine hydrolase of Mycobacterium tuberculosis (Mtb), one of the causative agents for Tuberculosis in humans. Mtb has demonstrated increased susceptibility to β-lactam antibiotics upon inactivation of BlaC; thus, making BlaC a rational enzyme target for therapeutic agents. Herein, we present the synthesis and structure-activity-relationship data for the 1st-generation library of bis(benzoyl) phosphates (1-10). Substituent effects ranged from σp = -0.27 to 0.78 for electronic and π = -0.41 to 1.98 for hydrophobic parameters. Compounds 1, 4 and 5 demonstrated the greatest inhibitory potency against BlaC in a time-dependent manner (kobs = 0.212, 0.324, and 0.450 mn-1 respectively). Combined crystal structure data and mass spectrometric analysis of a tryptic digest for BlaC inactivated with 4 provided evidence that the mechanism of inactivation by this bis(benzoyl) phosphate scaffold occurs via phosphorylation of the active-site Ser-70, ultimately leading to an aged form of the enzyme.
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Affiliation(s)
- Dawanna S White
- Washington State University, Department of Chemistry, Pullman, WA 99164-6340, United States
| | - Cindy J Choy
- Washington State University, Department of Chemistry, Pullman, WA 99164-6340, United States
| | - Timothy W Moural
- Washington State University, Department of Chemistry, Pullman, WA 99164-6340, United States
| | - Stacy E Martin
- Washington State University, Department of Chemistry, Pullman, WA 99164-6340, United States
| | - Jing Wang
- Washington State University, Tissue Imaging and Proteomics Laboratory, Pullman, WA 99164-4630, United States
| | - Samantha Gargaro
- Washington State University, Department of Chemistry, Pullman, WA 99164-6340, United States
| | - ChulHee Kang
- Washington State University, Department of Chemistry, Pullman, WA 99164-6340, United States
| | - Clifford E Berkman
- Washington State University, Department of Chemistry, Pullman, WA 99164-6340, United States.
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Kashyap A, Singh PK, Silakari O. Mechanistic investigation of resistance via drug-inactivating enzymes in Mycobacterium tuberculosis. Drug Metab Rev 2018; 50:448-465. [PMID: 30343607 DOI: 10.1080/03602532.2018.1533966] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Tuberculosis (TB) is a serious major health concern that has existed from millennia. According to annual WHO report 2016, it is considered as world's ninth highest killer disease by single infectious agent, ranking above HIV/AIDS. To worsen the scenario the development of multi-drug resistant tuberculosis (MDR-TB) and extremely drug-resistant tuberculosis (XDR-TB) have significantly reduced the success rate of TB treatment. Several efforts are being made to handle pharmacodynamic resistance (MDR and XDR-TB) involving designing of new inhibitors, targeting mutated target or by multi-targeting agents. However, the issue of pharmacokinetic resistance in TB is not being addressed appropriately till date. Pharmacokinetic mode of resistance involves an intrinsic mechanism of bacterial drug resistance via expression of various enzymes and efflux pumps that are responsible for the loss of activity of the therapeutic agents. Mycobacterium tuberculosis is also intrinsically resistant to various approved agents via pharmacokinetic mechanism of resistance. Several bacterial enzymes are encoded that either degrade or modifies the drugs and renders them ineffective. Targeting such inactivating bacterial enzymes provides a novel approach to make the current therapy effective and combat the problem of resistance. This review provides an insight into different bacterial enzymes which are responsible for pharmacokinetic drug resistance in TB. The structure attributes and mechanism of catalysis employed by these enzymes to inactivate drug have also been discussed which may provide basis for developing novel therapeutic agents for resistant TB.
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Affiliation(s)
- Aanchal Kashyap
- a Molecular Modeling Lab (MML), Department of Pharmaceutical Sciences and Drug Research , Punjabi University , Patiala , India
| | - Pankaj Kumar Singh
- a Molecular Modeling Lab (MML), Department of Pharmaceutical Sciences and Drug Research , Punjabi University , Patiala , India
| | - Om Silakari
- a Molecular Modeling Lab (MML), Department of Pharmaceutical Sciences and Drug Research , Punjabi University , Patiala , India
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7
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Enhanced catalytic activities and modified substrate preferences for taxoid 10β-O-acetyl transferase mutants by engineering catalytic histidine residues. Biotechnol Lett 2018; 40:1245-1251. [PMID: 29869304 DOI: 10.1007/s10529-018-2573-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Accepted: 05/18/2018] [Indexed: 12/14/2022]
Abstract
OBJECTIVES Taxoid 10β-O-acetyl transferase (DBAT) was redesigned to enhance its catalytic activity and substrate preference for baccatin III and taxol biosynthesis. RESULTS Residues H162, D166 and R363 were determined as potential sites within the catalytic pocket of DBAT for molecular docking and site-directed mutagenesis to modify the activity of DBAT. Enzymatic activity assays revealed that the kcat/KM values of mutant H162A/R363H, D166H, R363H, D166H/R363H acting on 10-deacetylbaccatin III were about 3, 15, 26 and 60 times higher than that of the wild type of DBAT, respectively. Substrate preference assays indicated that these mutants (H162A/R363H, D166H, R363H, D166H/R363H) could transfer acetyl group from unnatural acetyl donor (e.g. vinyl acetate, sec-butyl acetate, isobutyl acetate, amyl acetate and isoamyl acetate) to 10-deacetylbaccatin III. CONCLUSION Taxoid 10β-O-acetyl transferase mutants with redesigned active sites displayed increased catalytic activities and modified substrate preferences, indicating their possible application in the enzymatic synthesis of baccatin III and taxol.
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8
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Fisher JF, Mobashery S. β-Lactam Resistance Mechanisms: Gram-Positive Bacteria and Mycobacterium tuberculosis. Cold Spring Harb Perspect Med 2016; 6:cshperspect.a025221. [PMID: 27091943 DOI: 10.1101/cshperspect.a025221] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The value of the β-lactam antibiotics for the control of bacterial infection has eroded with time. Three Gram-positive human pathogens that were once routinely susceptible to β-lactam chemotherapy-Streptococcus pneumoniae, Enterococcus faecium, and Staphylococcus aureus-now are not. Although a fourth bacterium, the acid-fast (but not Gram-positive-staining) Mycobacterium tuberculosis, has intrinsic resistance to earlier β-lactams, the emergence of strains of this bacterium resistant to virtually all other antibiotics has compelled the evaluation of newer β-lactam combinations as possible contributors to the multidrug chemotherapy required to control tubercular infection. The emerging molecular-level understanding of these resistance mechanisms used by these four bacteria provides the conceptual framework for bringing forward new β-lactams, and new β-lactam strategies, for the future control of their infections.
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Affiliation(s)
- Jed F Fisher
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670
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9
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Boulton S, Melacini G. Advances in NMR Methods To Map Allosteric Sites: From Models to Translation. Chem Rev 2016; 116:6267-304. [PMID: 27111288 DOI: 10.1021/acs.chemrev.5b00718] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The last five years have witnessed major developments in the understanding of the allosteric phenomenon, broadly defined as coupling between remote molecular sites. Such advances have been driven not only by new theoretical models and pharmacological applications of allostery, but also by progress in the experimental approaches designed to map allosteric sites and transitions. Among these techniques, NMR spectroscopy has played a major role given its unique near-atomic resolution and sensitivity to the dynamics that underlie allosteric couplings. Here, we highlight recent progress in the NMR methods tailored to investigate allostery with the goal of offering an overview of which NMR approaches are best suited for which allosterically relevant questions. The picture of the allosteric "NMR toolbox" is provided starting from one of the simplest models of allostery (i.e., the four-state thermodynamic cycle) and continuing to more complex multistate mechanisms. We also review how such an "NMR toolbox" has assisted the elucidation of the allosteric molecular basis for disease-related mutations and the discovery of novel leads for allosteric drugs. From this overview, it is clear that NMR plays a central role not only in experimentally validating transformative theories of allostery, but also in tapping the full translational potential of allosteric systems.
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Affiliation(s)
- Stephen Boulton
- Department of Chemistry and Chemical Biology Department of Biochemistry and Biomedical Sciences, McMaster University , 1280 Main St. W., Hamilton L8S 4M1, Canada
| | - Giuseppe Melacini
- Department of Chemistry and Chemical Biology Department of Biochemistry and Biomedical Sciences, McMaster University , 1280 Main St. W., Hamilton L8S 4M1, Canada
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10
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Iannazzo L, Soroka D, Triboulet S, Fonvielle M, Compain F, Dubée V, Mainardi JL, Hugonnet JE, Braud E, Arthur M, Etheve-Quelquejeu M. Routes of Synthesis of Carbapenems for Optimizing Both the Inactivation of l,d-Transpeptidase LdtMt1 of Mycobacterium tuberculosis and the Stability toward Hydrolysis by β-Lactamase BlaC. J Med Chem 2016; 59:3427-38. [DOI: 10.1021/acs.jmedchem.6b00096] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Laura Iannazzo
- Laboratoire
de Chimie et de Biochimie Pharmacologiques et Toxicologiques, team
CBNIT, Université Paris Descartes, CNRS UMR 8601, Paris F-75006, France
| | | | | | | | | | - Vincent Dubée
- Assistance
Publique-Hôpitaux de Paris, Service de Réanimation Médicale, Hôpital Saint-Antoine, Paris F-75012,France
| | - Jean-Luc Mainardi
- Assistance
Publique-Hôpitaux de Paris, Service de Microbiologie, Hôpital Européen Georges Pompidou, Paris F-75015, France
| | | | - Emmanuelle Braud
- Laboratoire
de Chimie et de Biochimie Pharmacologiques et Toxicologiques, team
CBNIT, Université Paris Descartes, CNRS UMR 8601, Paris F-75006, France
| | | | - Mélanie Etheve-Quelquejeu
- Laboratoire
de Chimie et de Biochimie Pharmacologiques et Toxicologiques, team
CBNIT, Université Paris Descartes, CNRS UMR 8601, Paris F-75006, France
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11
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Exposing a β-Lactamase "Twist": the Mechanistic Basis for the High Level of Ceftazidime Resistance in the C69F Variant of the Burkholderia pseudomallei PenI β-Lactamase. Antimicrob Agents Chemother 2015; 60:777-88. [PMID: 26596949 DOI: 10.1128/aac.02073-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 11/08/2015] [Indexed: 12/31/2022] Open
Abstract
Around the world, Burkholderia spp. are emerging as pathogens highly resistant to β-lactam antibiotics, especially ceftazidime. Clinical variants of Burkholderia pseudomallei possessing the class A β-lactamase PenI with substitutions at positions C69 and P167 are known to demonstrate ceftazidime resistance. However, the biochemical basis for ceftazidime resistance in class A β-lactamases in B. pseudomallei is largely undefined. Here, we performed site saturation mutagenesis of the C69 position and investigated the kinetic properties of the C69F variant of PenI from B. pseudomallei that results in a high level of ceftazidime resistance (2 to 64 mg/liter) when expressed in Escherichia coli. Surprisingly, quantitative immunoblotting showed that the steady-state protein levels of the C69F variant β-lactamase were ∼4-fold lower than those of wild-type PenI (0.76 fg of protein/cell versus 4.1 fg of protein/cell, respectively). However, growth in the presence of ceftazidime increases the relative amount of the C69F variant to greater than wild-type PenI levels. The C69F variant exhibits a branched kinetic mechanism for ceftazidime hydrolysis, suggesting there are two different conformations of the enzyme. When incubated with an anti-PenI antibody, one conformation of the C69F variant rapidly hydrolyzes ceftazidime and most likely contributes to the higher levels of ceftazidime resistance observed in cell-based assays. Molecular dynamics simulations suggest that the electrostatic characteristics of the oxyanion hole are altered in the C69F variant. When ceftazidime was positioned in the active site, the C69F variant is predicted to form a greater number of hydrogen-bonding interactions than PenI with ceftazidime. In conclusion, we propose "a new twist" for enhanced ceftazidime resistance mediated by the C69F variant of the PenI β-lactamase based on conformational changes in the C69F variant. Our findings explain the biochemical basis of ceftazidime resistance in B. pseudomallei, a pathogen of considerable importance, and suggest that the full repertoire of conformational states of a β-lactamase profoundly affects β-lactam resistance.
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12
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Hydrolysis of clavulanate by Mycobacterium tuberculosis β-lactamase BlaC harboring a canonical SDN motif. Antimicrob Agents Chemother 2015; 59:5714-20. [PMID: 26149997 DOI: 10.1128/aac.00598-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 06/30/2015] [Indexed: 01/28/2023] Open
Abstract
Combinations of β-lactams with clavulanate are currently being investigated for tuberculosis treatment. Since Mycobacterium tuberculosis produces a broad spectrum β-lactamase, BlaC, the success of this approach could be compromised by the emergence of clavulanate-resistant variants, as observed for inhibitor-resistant TEM variants in enterobacteria. Previous analyses based on site-directed mutagenesis of BlaC have led to the conclusion that this risk was limited. Here, we used a different approach based on determination of the crystal structure of β-lactamase BlaMAb of Mycobacterium abscessus, which efficiently hydrolyzes clavulanate. Comparison of BlaMAb and BlaC allowed for structure-assisted site-directed mutagenesis of BlaC and identification of the G(132)N substitution that was sufficient to switch the interaction of BlaC with clavulanate from irreversible inactivation to efficient hydrolysis. The substitution, which restored the canonical SDN motif (SDG→SDN), allowed for efficient hydrolysis of clavulanate, with a more than 10(4)-fold increase in k cat (0.41 s(-1)), without affecting the hydrolysis of other β-lactams. Mass spectrometry revealed that acylation of BlaC and of its G(132)N variant by clavulanate follows similar paths, involving sequential formation of two acylenzymes. Decarboxylation of the first acylenzyme results in a stable secondary acylenzyme in BlaC, whereas hydrolysis occurs in the G(132)N variant. The SDN/SDG polymorphism defines two mycobacterial lineages comprising rapidly and slowly growing species, respectively. Together, these results suggest that the efficacy of β-lactam-clavulanate combinations may be limited by the emergence of resistance. β-Lactams active without clavulanate, such as faropenem, should be prioritized for the development of new therapies.
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13
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Chica RA. Protein engineering in the 21st century. Protein Sci 2015; 24:431-3. [PMID: 25644972 DOI: 10.1002/pro.2656] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 01/30/2015] [Indexed: 12/24/2022]
Affiliation(s)
- Roberto A Chica
- Department of Chemistry, University of Ottawa, Ottawa, Ontario, Canada, K1N 6N5
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