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Frère JM, Verlaine O, Matagne A. The measurement of true initial rates is not always absolutely necessary to estimate enzyme kinetic parameters. Sci Rep 2023; 13:15053. [PMID: 37699921 PMCID: PMC10497622 DOI: 10.1038/s41598-023-41805-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 08/31/2023] [Indexed: 09/14/2023] Open
Abstract
In the chapters dealing with enzyme reactions, the authors of all Biochemistry textbooks and of even more specialized texts consider that the characteristic parameters (kcat and Km) must be determined under initial or steady-state rate conditions. This implies the transformation of a very limited proportion of substrate (at most 10-20%) or a continuous recording of the product or substrate concentration vs. time. Both options can present practical difficulties. Is it possible to get around these very stringent conditions? Here we show that in the most favourable cases up to 70% of the substrate can be converted resulting in systematic errors on the parameters (that can easily be taken account of) if the simple Henri-Michaelis-Menten equation is utilised. Alternatively, the integrated form of the same equation directly yields excellent estimates of the same parameters. Our observations should greatly facilitate the task of researchers who study systems in which measurements of the reaction progress are painstaking or when substrate concentrations close to the detection limit must be used. The general conclusion is that it is not always absolutely necessary to determine initial or steady-state rates to obtain reliable estimations of the enzyme kinetic parameters..
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Affiliation(s)
- Jean-Marie Frère
- Enzymology and Protein Folding Laboratory, University of Liège, Building B6C, Quartier Agora, Allée du 6 Août, 13, 4000, Liège (Sart-Tilman), Belgium.
- Centre for Protein Engineering, InBioS, University of Liège, Building B6C, Quartier Agora, Allée du 6 Août, 13, 4000, Liège (Sart-Tilman), Belgium.
| | - Olivier Verlaine
- Centre for Protein Engineering, InBioS, University of Liège, Building B6C, Quartier Agora, Allée du 6 Août, 13, 4000, Liège (Sart-Tilman), Belgium
| | - André Matagne
- Enzymology and Protein Folding Laboratory, University of Liège, Building B6C, Quartier Agora, Allée du 6 Août, 13, 4000, Liège (Sart-Tilman), Belgium.
- Centre for Protein Engineering, InBioS, University of Liège, Building B6C, Quartier Agora, Allée du 6 Août, 13, 4000, Liège (Sart-Tilman), Belgium.
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2
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Crystal structure of AmpC BER and molecular docking lead to the discovery of broad inhibition activities of halisulfates against β-lactamases. Comput Struct Biotechnol J 2020; 19:145-152. [PMID: 33425247 PMCID: PMC7773887 DOI: 10.1016/j.csbj.2020.12.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 12/08/2020] [Accepted: 12/13/2020] [Indexed: 11/23/2022] Open
Abstract
AmpC BER is an extended-spectrum (ES) class C β-lactamase with a two-amino-acid insertion in the H10 helix region located at the boundary of the active site compared with its narrow spectrum progenitor. The crystal structure of the wild-type AmpC BER revealed that the insertion widens the active site by restructuring the flexible H10 helix region, which is the structural basis for its ES activity. Besides, two sulfates originated from the crystallization solution were observed in the active site. The presence of sulfate-binding subsites, together with the recognition of ring-structured chemical scaffolds by AmpC BER, led us to perform in silico molecular docking experiments with halisulfates, natural products isolated from marine sponge. Inspired by the snug fit of halisulfates within the active site, we demonstrated that halisulfate 3 and 5 significantly inhibit ES class C β-lactamases. Especially, halisulfate 5 is comparable to avibactam in terms of inhibition efficiency; it inhibits the nitrocefin-hydrolyzing activity of AmpC BER with a Ki value of 5.87 μM in a competitive manner. Furthermore, halisulfate 5 displayed moderate and weak inhibition activities against class A and class B/D enzymes, respectively. The treatment of β-lactamase inhibitors (BLIs) in combination with β-lactam antibiotics is a working strategy to cope with infections by pathogens producing ES β-lactamases. Considering the emergence and dissemination of enzymes insensitive to clinically-used BLIs, the broad inhibition spectrum and structural difference of halisulfates would be used to develop novel BLIs that can escape the bacterial resistance mechanism mediated by β-lactamases.
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Decuyper L, Magdalenić K, Verstraete M, Jukič M, Sosič I, Sauvage E, Amoroso AM, Verlaine O, Joris B, Gobec S, D'hooghe M. α-Unsaturated 3-Amino-1-carboxymethyl-β-lactams as Bacterial PBP Inhibitors: Synthesis and Biochemical Assessment. Chemistry 2019; 25:16128-16140. [PMID: 31596974 DOI: 10.1002/chem.201904139] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/08/2019] [Indexed: 01/24/2023]
Abstract
Innovative monocyclic β-lactam entities create opportunities in the battle against resistant bacteria because of their PBP acylation potential, intrinsically high β-lactamase stability and compact scaffold. α-Benzylidene-substituted 3-amino-1-carboxymethyl-β-lactams were recently shown to be potent PBP inhibitors and constitute eligible anchor points for synthetic elaboration of the chemical space around the central β-lactam ring. The present study discloses a 12-step synthesis of ten α-arylmethylidenecarboxylates using a microwave-assisted Wittig olefination as the crucial reaction step. The library was designed aiming at enhanced β-lactam electrophilicity and extended electron flow after enzymatic attack. Additionally, increased β-lactamase stability and intermolecular target interaction were envisioned by tackling both the substitution pattern of the aromatic ring and the β-lactam C4-position. The significance of α-unsaturation was validated and the R39/PBP3 inhibitory potency shown to be augmented the most through decoration of the aromatic ring with electron-withdrawing groups. Furthermore, ring cleavage by representative β-lactamases was ruled out, providing new insights in the SAR landscape of monocyclic β-lactams as eligible PBP or β-lactamase inhibitors.
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Affiliation(s)
- Lena Decuyper
- SynBioC Research Group, Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Katarina Magdalenić
- SynBioC Research Group, Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Marie Verstraete
- SynBioC Research Group, Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Marko Jukič
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000, Ljubljana, Slovenia
| | - Izidor Sosič
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000, Ljubljana, Slovenia
| | - Eric Sauvage
- Centre for Protein Engineering, Faculty of Sciences, University of Liège, Quartier Agora, Allée du 6 Août 13, Bât B6a, 4000, Liège Sart-Tilman, Belgium
| | - Ana Maria Amoroso
- Centre for Protein Engineering, Faculty of Sciences, University of Liège, Quartier Agora, Allée du 6 Août 13, Bât B6a, 4000, Liège Sart-Tilman, Belgium
| | - Olivier Verlaine
- Centre for Protein Engineering, Faculty of Sciences, University of Liège, Quartier Agora, Allée du 6 Août 13, Bât B6a, 4000, Liège Sart-Tilman, Belgium
| | - Bernard Joris
- Centre for Protein Engineering, Faculty of Sciences, University of Liège, Quartier Agora, Allée du 6 Août 13, Bât B6a, 4000, Liège Sart-Tilman, Belgium
| | - Stanislav Gobec
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000, Ljubljana, Slovenia
| | - Matthias D'hooghe
- SynBioC Research Group, Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
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Decuyper L, Deketelaere S, Vanparys L, Jukič M, Sosič I, Sauvage E, Amoroso AM, Verlaine O, Joris B, Gobec S, D'hooghe M. In Silico Design and Enantioselective Synthesis of Functionalized Monocyclic 3-Amino-1-carboxymethyl-β-lactams as Inhibitors of Penicillin-Binding Proteins of Resistant Bacteria. Chemistry 2018; 24:15254-15266. [PMID: 29882610 DOI: 10.1002/chem.201801868] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 06/07/2018] [Indexed: 01/20/2023]
Abstract
As a complement to the renowned bicyclic β-lactam antibiotics, monocyclic analogues provide a breath of fresh air in the battle against resistant bacteria. In that framework, the present study discloses the in silico design and unprecedented ten-step synthesis of eleven nocardicin-like enantiomerically pure 2-{3-[2-(2-aminothiazol-4-yl)-2-(methoxyimino)acetamido]-2-oxoazetidin-1-yl}acetic acids starting from serine as a readily accessible precursor. The capability of this novel class of monocyclic 3-amino-β-lactams to inhibit penicillin-binding proteins (PBPs) of various (resistant) bacteria was assessed, revealing the potential of α-benzylidenecarboxylates as interesting leads in the pursuit of novel PBP inhibitors. No deactivation by representative enzymes belonging to the four β-lactamase classes was observed, while weak inhibition of class C β-lactamase P99 was demonstrated.
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Affiliation(s)
- Lena Decuyper
- SynBioC Research Group, Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Sari Deketelaere
- SynBioC Research Group, Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Lore Vanparys
- SynBioC Research Group, Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Marko Jukič
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000, Ljubljana, Slovenia
| | - Izidor Sosič
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000, Ljubljana, Slovenia
| | - Eric Sauvage
- Center for Protein Engineering, Faculty of Sciences, University of Liège, Quartier Agora, Allée du 6 Août 13, Bât B6a, 4000, Liège-Sart Tilman, Belgium
| | - Ana Maria Amoroso
- Center for Protein Engineering, Faculty of Sciences, University of Liège, Quartier Agora, Allée du 6 Août 13, Bât B6a, 4000, Liège-Sart Tilman, Belgium
| | - Olivier Verlaine
- Center for Protein Engineering, Faculty of Sciences, University of Liège, Quartier Agora, Allée du 6 Août 13, Bât B6a, 4000, Liège-Sart Tilman, Belgium
| | - Bernard Joris
- Center for Protein Engineering, Faculty of Sciences, University of Liège, Quartier Agora, Allée du 6 Août 13, Bât B6a, 4000, Liège-Sart Tilman, Belgium
| | - Stanislav Gobec
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000, Ljubljana, Slovenia
| | - Matthias D'hooghe
- SynBioC Research Group, Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
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Application of Nanoparticle Technology to Reduce the Anti-Microbial Resistance through β-Lactam Antibiotic-Polymer Inclusion Nano-Complex. Pharmaceuticals (Basel) 2018; 11:ph11010019. [PMID: 29439391 PMCID: PMC5874715 DOI: 10.3390/ph11010019] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 02/07/2018] [Accepted: 02/07/2018] [Indexed: 11/16/2022] Open
Abstract
Biocompatible polymeric materials with potential to form functional structures in association with different therapeutic molecules have a high potential for biological, medical and pharmaceutical applications. Therefore, the capability of the inclusion of nano-Complex formed between the sodium salt of poly(maleic acid-alt-octadecene) and a β-lactam drug (ampicillin trihydrate) to avoid the chemical and enzymatic degradation and enhance the biological activity were evaluated. PAM-18Na was produced and characterized, as reported previously. The formation of polymeric hydrophobic aggregates in aqueous solution was determined, using pyrene as a fluorescent probe. Furthermore, the formation of polymer-drug nano-complexes was characterized by Differential Scanning Calorimetry-DSC, viscometric, ultrafiltration/centrifugation assays, zeta potential and size measurements were determined by dynamic light scattering-DLS. The PAM-18Na capacity to avoid the chemical degradation was studied through stress stability tests. The enzymatic degradation was evaluated from a pure β-lactamase, while the biological degradation was determined by different β-lactamase producing Staphylococcus aureus strains. When ampicillin was associated with PAM-18Na, the half-life time in acidic conditions increased, whereas both the enzymatic degradation and the minimum inhibitory concentration decreased to a 90 and 75%, respectively. These results suggest a promissory capability of this polymer to protect the β-lactam drugs against chemical, enzymatic and biological degradation.
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Piens N, De Craene S, Franceus J, Mollet K, Van Hecke K, Desmet T, D'hooghe M. Diastereoselective synthesis of 3-acetoxy-4-(3-aryloxiran-2-yl)azetidin-2-ones and their transformation into 3,4-oxolane-fused bicyclic β-lactams. Org Biomol Chem 2016; 14:11279-11288. [PMID: 27853806 DOI: 10.1039/c6ob02221a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
cis-3-Acetoxy-4-(3-aryloxiran-2-yl)azetidin-2-ones were prepared through a Staudinger [2+2]-cyclocondensation between acetoxyketene and the appropriate epoxyimines in a highly diastereoselective way. Subsequent potassium carbonate-mediated acetate hydrolysis, followed by intramolecular ring closure through epoxide ring opening, afforded stereodefined 3-aryl-4-hydroxy-2-oxa-6-azabicyclo[3.2.0]heptan-7-ones as a novel class of C-fused bicyclic β-lactams. Selective benzylic oxidation of bicyclic N-(4-methoxybenzyl)-β-lactams with potassium persulfate and potassium dihydrogen phosphate provided the corresponding N-aroyl derivatives as interesting leads for further β-lactamase inhibitor development.
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Affiliation(s)
- Nicola Piens
- SynBioC Research Group, Department of Sustainable Organic Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
| | - Sven De Craene
- SynBioC Research Group, Department of Sustainable Organic Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
| | - Jorick Franceus
- Department of Biochemical and Microbial Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
| | - Karen Mollet
- SynBioC Research Group, Department of Sustainable Organic Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
| | - Kristof Van Hecke
- XStruct, Department of Inorganic and Physical Chemistry, Faculty of Sciences, Ghent University, Krijgslaan 281-S3, B-9000 Ghent, Belgium
| | - Tom Desmet
- Department of Biochemical and Microbial Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
| | - Matthias D'hooghe
- SynBioC Research Group, Department of Sustainable Organic Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
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Crystal structure of EstSRT1, a family VIII carboxylesterase displaying hydrolytic activity toward oxyimino cephalosporins. Biochem Biophys Res Commun 2016; 478:818-24. [DOI: 10.1016/j.bbrc.2016.08.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 08/04/2016] [Indexed: 11/20/2022]
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Jeon JH, Lee HS, Lee JH, Koo BS, Lee CM, Lee SH, Kang SG, Lee JH. A novel family VIII carboxylesterase hydrolysing third- and fourth-generation cephalosporins. SPRINGERPLUS 2016; 5:525. [PMID: 27186489 PMCID: PMC4844572 DOI: 10.1186/s40064-016-2172-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 04/15/2016] [Indexed: 11/21/2022]
Abstract
A metagenomic library was constructed from a soil sample of spindle tree-rhizosphere. From this library, one clone with esterase activity was selected. The sequence analysis revealed an open reading frame (EstSTR1) encoded protein of 390 amino acids. EstSTR1 is a family VIII carboxylesterase and retains the S-X-X-K motif conserved in both family VIII carboxylesterases and class C β-lactamases. The estSTR1 gene was overexpressed in E. coli and the recombinant protein was purified by purified by metal chelating affinity chromatography and size-exclusion chromatography. EstSTR1 hydrolysed p-nitrophenyl esters, exhibited the highest activity toward p-nitrophenyl butyrate. Furthermore, EstSTR1 could hydrolyse third- and fourth-generation cephalosporins (cefotaxime and cefepime) as well as first-generation cephalosporin (cephalothin). Site-directed mutagenesis studies revealed that a catalytic residue, Ser71, of EstSTR1 plays an essential role in hydrolysing both antibiotics and p-nitrophenyl esters. We demonstrate that a metagenome-derived carboxylesterase displays β-lactam-hydrolysing activities toward third- and fourth-generation cephalosporins.
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Affiliation(s)
- Jeong Ho Jeon
- Marine Biotechnology Research Division, Korea Institute of Ocean Science and Technology, Ansan, 15627 Republic of Korea ; National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University, 116 Myongjiro, Yongin, Gyeonggido, 17058 Republic of Korea
| | - Hyun Sook Lee
- Marine Biotechnology Research Division, Korea Institute of Ocean Science and Technology, Ansan, 15627 Republic of Korea ; Department of Marine Biotechnology, University of Science and Technology, Daejeon, 34113 Republic of Korea
| | - Jung Hun Lee
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University, 116 Myongjiro, Yongin, Gyeonggido, 17058 Republic of Korea
| | - Bon-Sung Koo
- Department of Agricultural Biotechnology, National Academy of Agricultural Science, RDA, Jeonju, 54875 Republic of Korea
| | - Chang-Muk Lee
- Department of Agricultural Biotechnology, National Academy of Agricultural Science, RDA, Jeonju, 54875 Republic of Korea
| | - Sang Hee Lee
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University, 116 Myongjiro, Yongin, Gyeonggido, 17058 Republic of Korea
| | - Sung Gyun Kang
- Marine Biotechnology Research Division, Korea Institute of Ocean Science and Technology, Ansan, 15627 Republic of Korea ; Department of Marine Biotechnology, University of Science and Technology, Daejeon, 34113 Republic of Korea
| | - Jung-Hyun Lee
- Marine Biotechnology Research Division, Korea Institute of Ocean Science and Technology, Ansan, 15627 Republic of Korea ; Department of Marine Biotechnology, University of Science and Technology, Daejeon, 34113 Republic of Korea
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Characterization of a Carbapenem-Hydrolyzing Enzyme, PoxB, in Pseudomonas aeruginosa PAO1. Antimicrob Agents Chemother 2015; 60:936-45. [PMID: 26621621 DOI: 10.1128/aac.01807-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 11/18/2015] [Indexed: 12/15/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen often associated with severe and life-threatening infections that are highly impervious to treatment. This microbe readily exhibits intrinsic and acquired resistance to varied antimicrobial drugs. Resistance to penicillin-like compounds is commonplace and provided by the chromosomal AmpC β-lactamase. A second, chromosomally encoded β-lactamase, PoxB, has previously been reported in P. aeruginosa. In the present work, the contribution of this class D enzyme was investigated using a series of clean in-frame ampC, poxB, and oprD deletions, as well as complementation by expression under the control of an inducible promoter. While poxB deletions failed to alter β-lactam sensitivities, expression of poxB in ampC-deficient backgrounds decreased susceptibility to both meropenem and doripenem but had no effect on imipenem, penicillin, and cephalosporin MICs. However, when expressed in an ampCpoxB-deficient background, that additionally lacked the outer membrane porin-encoding gene oprD, PoxB significantly increased the imipenem as well as the meropenem and doripenem MICs. Like other class D carbapenem-hydrolyzing β-lactamases, PoxB was only poorly inhibited by class A enzyme inhibitors, but a novel non-β-lactam compound, avibactam, was a slightly better inhibitor of PoxB activity. In vitro susceptibility testing with a clinical concentration of avibactam, however, failed to reduce PoxB activity against the carbapenems. In addition, poxB was found to be cotranscribed with an upstream open reading frame, poxA, which itself was shown to encode a 32-kDa protein of yet unknown function.
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Jeon JH, Hong MK, Lee JH, Lee JJ, Park KS, Karim AM, Jo JY, Kim JH, Ko KS, Kang LW, Lee SH. Structure of ADC-68, a novel carbapenem-hydrolyzing class C extended-spectrum β-lactamase isolated from Acinetobacter baumannii. ACTA ACUST UNITED AC 2014; 70:2924-36. [PMID: 25372683 DOI: 10.1107/s1399004714019543] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 08/28/2014] [Indexed: 11/10/2022]
Abstract
Outbreaks of multidrug-resistant bacterial infections have become more frequent worldwide owing to the emergence of several different classes of β-lactamases. In this study, the molecular, biochemical and structural characteristics of an Acinetobacter-derived cephalosporinase (ADC)-type class C β-lactamase, ADC-68, isolated from the carbapenem-resistant A. baumannii D015 were investigated. The blaADC-68 gene which encodes ADC-68 was confirmed to exist on the chromosome via Southern blot analysis and draft genome sequencing. The catalytic kinetics of β-lactams and their MICs (minimum inhibitory concentrations) for A. baumannii D015 and purified ADC-68 (a carbapenemase obtained from this strain) were assessed: the strain was resistant to penicillins, narrow-spectrum and extended-spectrum cephalosporins, and carbapenems, which were hydrolyzed by ADC-68. The crystal structure of ADC-68 was determined at a resolution of 1.8 Å. The structure of ADC-68 was compared with that of ADC-1 (a non-carbapenemase); differences were found in the central part of the Ω-loop and the C-loop constituting the edge of the R1 and R2 subsites and are close to the catalytic serine residue Ser66. The ADC-68 C-loop was stabilized in the open conformation of the upper R2 subsite and could better accommodate carbapenems with larger R2 side chains. Furthermore, a wide-open conformation of the R2-loop allowed ADC-68 to bind to and hydrolyze extended-spectrum cephalosporins. Therefore, ADC-68 had enhanced catalytic efficiency against these clinically important β-lactams (extended-spectrum cephalosporins and carbapenems). ADC-68 is the first reported enzyme among the chromosomal class C β-lactamases to possess class C extended-spectrum β-lactamase and carbapenemase activities.
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Affiliation(s)
- Jeong Ho Jeon
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University, 116 Myongjiro, Yongin, Gyeonggido 449-728, Republic of Korea
| | - Myoung Ki Hong
- Institute for Cellular and Structural Biology of Sun Yat-Sen University, Guangzhou, Peoples Republic of China
| | - Jung Hun Lee
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University, 116 Myongjiro, Yongin, Gyeonggido 449-728, Republic of Korea
| | - Jae Jin Lee
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University, 116 Myongjiro, Yongin, Gyeonggido 449-728, Republic of Korea
| | - Kwang Seung Park
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University, 116 Myongjiro, Yongin, Gyeonggido 449-728, Republic of Korea
| | - Asad Mustafa Karim
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University, 116 Myongjiro, Yongin, Gyeonggido 449-728, Republic of Korea
| | - Jeong Yeon Jo
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University, 116 Myongjiro, Yongin, Gyeonggido 449-728, Republic of Korea
| | - Ji Hwan Kim
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University, 116 Myongjiro, Yongin, Gyeonggido 449-728, Republic of Korea
| | - Kwan Soo Ko
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Lin Woo Kang
- Institute for Cellular and Structural Biology of Sun Yat-Sen University, Guangzhou, Peoples Republic of China
| | - Sang Hee Lee
- National Leading Research Laboratory of Drug Resistance Proteomics, Department of Biological Sciences, Myongji University, 116 Myongjiro, Yongin, Gyeonggido 449-728, Republic of Korea
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Tsang MW, So PK, Liu SY, Tsang CW, Chan PH, Wong KY, Leung YC. Catalytically impaired fluorescent Class C β-lactamase enables rapid and sensitive cephalosporin detection by stabilizing fluorescence signals: Implications for biosensor design. Biotechnol J 2014; 10:126-35. [PMID: 25181520 DOI: 10.1002/biot.201400140] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 07/17/2014] [Accepted: 08/29/2014] [Indexed: 01/06/2023]
Affiliation(s)
- Man-Wah Tsang
- Department of Applied Biology and Chemical Technology, and State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hong Kong, China
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12
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Permeation rates of penicillins indicate that Escherichia coli porins function principally as nonspecific channels. Proc Natl Acad Sci U S A 2013; 110:E2629-34. [PMID: 23798411 DOI: 10.1073/pnas.1310333110] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Small, hydrophilic compounds such as β-lactams diffuse across the outer membrane of Gram-negative bacteria through porin channels, which were originally thought to be nonspecific channels devoid of any specificity. However, since the discovery of an ampicillin-binding site within the OmpF channel in 2002, much attention has been focused on the potential specificity of the channel, where the binding site was assumed either to facilitate or to retard the penetration of β-lactams. Since the earlier studies on porin permeability were done without the knowledge of the contribution of multidrug efflux pumps in the overall flux process across the cell envelope, in this study we have carefully studied both the porin permeability and active efflux of ampicillin and benzylpenicillin. We found that the influx occurs apparently by a spontaneous passive diffusion without any indication of specific binding within the concentration range relevant to the antibiotic action of these drugs, and that the higher permeability for ampicillin is totally as expected from the gross property of this drug as a zwitterionic compound. The active efflux by AcrAB was more effective for benzylpenicillin due to the stronger affinity and high degree of positive cooperativity. Our data now give a complete quantitative picture of the influx, efflux, and periplasmic degradation (catalyzed by AmpC β-lactamase) of these two compounds, and correlate closely with the susceptibility of Escherichia coli strains used here, thus validating not only our model but also the parameters obtained in this study.
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Schwartz T, Kohnen W, Jansen B, Obst U. Detection of antibiotic-resistant bacteria and their resistance genes in wastewater, surface water, and drinking water biofilms. FEMS Microbiol Ecol 2012; 43:325-35. [PMID: 19719664 DOI: 10.1111/j.1574-6941.2003.tb01073.x] [Citation(s) in RCA: 594] [Impact Index Per Article: 49.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Abstract In view of the increasing interest in the possible role played by hospital and municipal wastewater systems in the selection of antibiotic-resistant bacteria, biofilms were investigated using enterococci, staphylococci, Enterobacteriaceae, and heterotrophic bacteria as indicator organisms. In addition to wastewater, biofilms were also investigated in drinking water from river bank filtrate to estimate the occurrence of resistant bacteria and their resistance genes, thus indicating possible transfer from wastewater and surface water to the drinking water distribution network. Vancomycin-resistant enterococci were characterized by antibiograms, and the vanA resistance gene was detected by molecular biology methods, including PCR. The vanA gene was found not only in wastewater biofilms but also in drinking water biofilms in the absence of enterococci, indicating possible gene transfer to autochthonous drinking water bacteria. The mecA gene encoding methicillin resistance in staphylococci was detected in hospital wastewater biofilms but not in any other compartment. Enterobacterial ampC resistance genes encoding beta-lactamase activities were amplified by PCR from wastewater, surface water and drinking water biofilms.
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Affiliation(s)
- Thomas Schwartz
- Forschungszentrum Karlsruhe GmbH, Department of Environmental Microbiology, ITC-WGT, P.O. Box 3640, D-76021 Karlsruhe, Germany
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Functional characterization of a putative β-lactamase gene in the genome of Zymomonas mobilis. Biotechnol Lett 2011; 33:2425-30. [PMID: 21796435 DOI: 10.1007/s10529-011-0704-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2011] [Accepted: 07/08/2011] [Indexed: 10/17/2022]
Abstract
Zymomonas mobilis ZM4 is resistant to β-lactam antibiotics but there are no reports of a β-lactam resistance gene and its regulation. A putative β-lactamase gene sequence (ZMO0103) in the genome of Z. mobilis showed a 55% amino acid sequence identity with class C β-lactamase genes. qPCR analysis of the β-lactamase transcript indicated a higher level expression of the β-lactamase compared to the relative transcript quantities in antibiotic-susceptible bacteria. The putative β-lactamase gene was cloned, expressed in Escherichia coli BL21 and the product, AmpC, was purified to homogeneity. Its optimal activity was at pH 6 and 30 °C. Further, the β-lactamase had a higher affinity towards penicillins than cephalosporin antibiotics.
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15
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Nottingham M, Bethel CR, Pagadala SRR, Harry E, Pinto A, Lemons ZA, Drawz SM, Akker FVD, Carey PR, Bonomo RA, Buynak JD. Modifications of the C6-substituent of penicillin sulfones with the goal of improving inhibitor recognition and efficacy. Bioorg Med Chem Lett 2010; 21:387-93. [PMID: 21129961 DOI: 10.1016/j.bmcl.2010.10.134] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2010] [Revised: 10/26/2010] [Accepted: 10/27/2010] [Indexed: 11/27/2022]
Abstract
In order to evaluate the importance of a hydrogen-bond donating substituent in the design of β-lactamase inhibitors, a series of C6-substituted penicillin sulfones, lacking a C2' substituent, and having an sp(3) hybridized C6, was prepared and evaluated against a representative classes A and C β-lactamases. It was found that a C6 hydrogen-bond donor is necessary for good inhibitory activity, but that this feature alone is not sufficient in this series of C6β-substituted penicillin sulfones. Other factors which may impact the potency of the inhibitor include the steric bulk of the C6 substituent (e.g., methicillin sulfone) which may hinder recognition in the class A β-lactamases, and also high similarity to the natural substrates (e.g., penicillin G sulfone) which may render the prospective inhibitor a good substrate of both classes of enzyme. The best inhibitors had non-directional hydrogen-bonding substituents, such as hydroxymethyl, which may allow sufficient conformational flexibility of the acyl-enzyme for abstraction of the C6 proton by E166 (class A), thus promoting isomerization to the β-aminoacrylate as a stabilized acyl-enzyme.
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Affiliation(s)
- Micheal Nottingham
- Department of Chemistry, Southern Methodist University, Dallas, TX 75275-0314, USA
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16
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Kinetic parameters of efflux of penicillins by the multidrug efflux transporter AcrAB-TolC of Escherichia coli. Antimicrob Agents Chemother 2010; 54:1800-6. [PMID: 20160052 DOI: 10.1128/aac.01714-09] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The multidrug efflux transporter AcrAB-TolC is known to pump out a diverse range of antibiotics, including beta-lactams. However, the kinetic constants of the efflux process, needed for the quantitative understanding of resistance, were not available until those accompanying the efflux of some cephalosporins were recently determined by combining efflux with the hydrolysis of drugs by the periplasmic beta-lactamase. In the present study we extended this approach to the study of a wide range of penicillins, from ampicillin and penicillin V to ureidopenicillins and isoxazolylpenicillins, by combining efflux with hydrolysis with the OXA-7 penicillinase. We found that the penicillins had a much stronger apparent affinity to AcrB and higher maximum rates of efflux than the cephalosporins. All penicillins showed strong positive cooperativity kinetics for export. The kinetic constants obtained were validated, as the MICs theoretically predicted on the basis of efflux and hydrolysis kinetics were remarkably similar to the observed MICs (except for the isoxazolylpenicillins). Surprisingly, however, the efflux kinetics of cloxacillin, for example, whose MIC decreased 512-fold in Escherichia coli upon the genetic deletion of the acrB gene, were quite similar to those of ampicillin, whose MIC decreased only 2-fold with the same treatment. Analysis of this phenomenon showed that the extensive decrease in the MIC for the acrB mutant is primarily due to the low permeation of the drug and that comparison of the MICs between the parent and the acrB strains is a very poor measure of the ability of AcrB to pump a drug out.
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17
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Genetic and biochemical characterization of TRU-1, the endogenous class C beta-lactamase from Aeromonas enteropelogenes. Antimicrob Agents Chemother 2010; 54:1547-54. [PMID: 20124004 DOI: 10.1128/aac.01252-09] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Aeromonas enteropelogenes (formerly A. tructi) was described to be an ampicillin-susceptible and cephalothin-resistant Aeromonas species, which suggests the production of a cephalosporinase. Strain ATCC 49803 was susceptible to amoxicillin, cefotaxime, and imipenem but resistant to cefazolin (MICs of 2, 0.032, 0.125, and >256 microg/ml, respectively) and produced an inducible beta-lactamase. Cefotaxime-resistant mutants (MIC, 32 microg/ml) that showed constitutive beta-lactamase production could be selected in vitro. The gene coding for the cephalosporinase of A. enteropelogenes ATCC 49803 was cloned, and its biochemical properties were investigated. Escherichia coli transformants showing resistance to various beta-lactams carried a 3.5-kb plasmid insert whose sequence revealed a 1,146-bp open reading frame (ORF) encoding a class C beta-lactamase, named TRU-1, showing the highest identity scores with A. punctata CAV-1 (75%), A. salmonicida AmpC (75%), and A. hydrophila CepH (71%). The bla(TRU-1) locus includes open reading frames (ORFs) showing significant homology with genes found in the genomes of other Aeromonas species, although it exhibits a different organization, as reflected by the presence of additional ORFs located downstream of the beta-lactamase gene in the A. hydrophila and A. salmonicida genomes. Specific PCR assays were negative for cphA-like and bla(OXA-12)-like genes in three A. enteropelogenes ATCC strains. Purified TRU-1 showed a broad substrate profile, efficiently hydrolyzing benzylpenicillin, cephalothin, cefoxitin, and, although with significantly lower turnover rates, oxyiminocephalosporins. Cephaloridine and cefepime were poorly recognized by the enzyme, as reflected by the high K(m) values observed with these substrates. Thus far, A. enteropelogenes represents the only known example of an Aeromonas species that produces only one beta-lactamase belonging to molecular class C.
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Abstract
SUMMARY AmpC beta-lactamases are clinically important cephalosporinases encoded on the chromosomes of many of the Enterobacteriaceae and a few other organisms, where they mediate resistance to cephalothin, cefazolin, cefoxitin, most penicillins, and beta-lactamase inhibitor-beta-lactam combinations. In many bacteria, AmpC enzymes are inducible and can be expressed at high levels by mutation. Overexpression confers resistance to broad-spectrum cephalosporins including cefotaxime, ceftazidime, and ceftriaxone and is a problem especially in infections due to Enterobacter aerogenes and Enterobacter cloacae, where an isolate initially susceptible to these agents may become resistant upon therapy. Transmissible plasmids have acquired genes for AmpC enzymes, which consequently can now appear in bacteria lacking or poorly expressing a chromosomal bla(AmpC) gene, such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. Resistance due to plasmid-mediated AmpC enzymes is less common than extended-spectrum beta-lactamase production in most parts of the world but may be both harder to detect and broader in spectrum. AmpC enzymes encoded by both chromosomal and plasmid genes are also evolving to hydrolyze broad-spectrum cephalosporins more efficiently. Techniques to identify AmpC beta-lactamase-producing isolates are available but are still evolving and are not yet optimized for the clinical laboratory, which probably now underestimates this resistance mechanism. Carbapenems can usually be used to treat infections due to AmpC-producing bacteria, but carbapenem resistance can arise in some organisms by mutations that reduce influx (outer membrane porin loss) or enhance efflux (efflux pump activation).
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Michaux C, Massant J, Kerff F, Frère JM, Docquier JD, Vandenberghe I, Samyn B, Pierrard A, Feller G, Charlier P, Van Beeumen J, Wouters J. Crystal structure of a cold-adapted class C beta-lactamase. FEBS J 2008; 275:1687-97. [PMID: 18312599 DOI: 10.1111/j.1742-4658.2008.06324.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In this study, the crystal structure of a class C beta-lactamase from a psychrophilic organism, Pseudomonas fluorescens, has been refined to 2.2 A resolution. It is one of the few solved crystal structures of psychrophilic proteins. The structure was compared with those of homologous mesophilic enzymes and of another, modeled, psychrophilic protein. The elucidation of the 3D structure of this enzyme provides additional insights into the features involved in cold adaptation. Structure comparison of the psychrophilic and mesophilic beta-lactamases shows that electrostatics seems to play a major role in low-temperature adaptation, with a lower total number of ionic interactions for cold enzymes. The psychrophilic enzymes are also characterized by a decreased number of hydrogen bonds, a lower content of prolines, and a lower percentage of arginines in comparison with lysines. All these features make the structure more flexible so that the enzyme can behave as an efficient catalyst at low temperatures.
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Affiliation(s)
- Catherine Michaux
- Chimie Biologique Structurale Laboratory, CPTS group, FUNDP, 61 rue de Bruxelles, Namur, Belgium.
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20
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Lefurgy ST, de Jong RM, Cornish VW. Saturation mutagenesis of Asn152 reveals a substrate selectivity switch in P99 cephalosporinase. Protein Sci 2008; 16:2636-46. [PMID: 18029418 DOI: 10.1110/ps.073092407] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
In class C beta-lactamases, the strictly conserved Asn152 forms part of an extended active-site hydrogen-bonding network. To probe its role in catalysis, all 19 mutants of Enterobacter cloacae P99 cephalosporinase Asn152 were simultaneously constructed and screened in Escherichia coli for their in vivo activity. The screen identified the previously uncharacterized mutants Asn152Ser, Asn152Thr, and Asn152Gly, which possess significant activity and altered substrate selectivity. In vitro measurement of Michaelis-Menten kinetic constants revealed that the Asn152Ser mutation causes a selectivity switch for penicillin G versus cefoxitin. Asn152Thr showed a 63-fold increase in k (cat) for oxacillin, a slow substrate for wild-type cephalosporinase. The results contribute to a growing body of data showing that mutation of highly conserved residues in the active site can result in substrate selectivity changes. The library screening method presented here would be applicable to substrate selectivity determination in other readily screenable enzymes.
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Affiliation(s)
- Scott T Lefurgy
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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21
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Bush K. The Evolution of β-Lactamases. CIBA FOUNDATION SYMPOSIUM 207 - ANTIBIOTIC RESISTANCE: ORIGINS, EVOLUTION, SELECTION AND SPREAD 2007. [DOI: 10.1002/9780470515358.ch10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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22
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Gangoué-Piéboji J, Baurin S, Frère JM, Ngassam P, Ngameni B, Azebaze A, Pegnyemb DE, Watchueng J, Goffin C, Galleni M. Screening of some medicinal plants from cameroon forβ-Lactamase inhibitory activity. Phytother Res 2007; 21:284-7. [PMID: 17221939 DOI: 10.1002/ptr.2001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In efforts to find new bioactive beta-lactamase inhibitors, this study investigated 16 Cameroonian plants belonging to 10 families which were evaluated for anti-beta-lactamase activity. The investigation showed that extracts 2, 6, 3 and 5 of the 16 plants investigated presented interesting in vitro beta-lactamase inhibition (over 90%), respectively, of the beta-lactamases TEM-1, OXA-10, IMP-1 and P99. These extracts were from Mammea africana (all beta-lactamases), Garcinia lucida, G. kola (OXA-10, IMP-1 and P99), Bridelia micrantha (OXA-10, P99), Ochna afzelii (OXA-10, P99), Prunus africana (IMP-1) and Adenia lobata (TEM-1). After elimination of tannins (according to the European Pharmacopoeia) the extracts from B. micrantha, G. lucida and M. africana were tested further for their anti-beta-lactamase activity. The extracts from B. micrantha and G. lucida exhibited potent inhibitory activity, respectively, of beta-lactamase OXA-10 (IC(50) = 0.02 mg/mL) and P99 (IC(50) = 0.01 mg/mL). The anti-beta-lactamase activity of M. africana extract was weak. The isolation and the structural elucidation of the active constituents of G. lucida and B. micrantha will provide useful leads in the development of beta-lactamase inhibitors.
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Affiliation(s)
- Joseph Gangoué-Piéboji
- Centre for Research on Medicinal Plants and Traditional Medicine, Institute of Medical Research and Medicinal Plant Studies, P.O. Box 8404, Yaoundé, Cameroon.
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23
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Kim JY, Jung HI, An YJ, Lee JH, Kim SJ, Jeong SH, Lee KJ, Suh PG, Lee HS, Lee SH, Cha SS. Structural basis for the extended substrate spectrum of CMY-10, a plasmid-encoded class C beta-lactamase. Mol Microbiol 2006; 60:907-16. [PMID: 16677302 DOI: 10.1111/j.1365-2958.2006.05146.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The emergence and dissemination of extended-spectrum (ES) beta-lactamases induce therapeutic failure and a lack of eradication of clinical isolates even by third-generation beta-lactam antibiotics like ceftazidime. CMY-10 is a plasmid-encoded class C beta-lactamase with a wide spectrum of substrates. Unlike the well-studied class C ES beta-lactamase from Enterobacter cloacae GC1, the Omega-loop does not affect the active site conformation and the catalytic activity of CMY-10. Instead, a three-amino-acid deletion in the R2-loop appears to be responsible for the ES activity of CMY-10. According to the crystal structure solved at 1.55 A resolution, the deletion significantly widens the R2 active site, which accommodates the R2 side-chains of beta-lactam antibiotics. This observation led us to demonstrate the hydrolysing activity of CMY-10 towards imipenem with a long R2 substituent. The forced mutational analyses of P99 beta-lactamase reveal that the introduction of deletion mutations into the R2-loop is able to extend the substrate spectrum of class C non-ES beta-lactamases, which is compatible with the isolation of natural class C ES enzymes harbouring deletion mutations in the R2-loop. Consequently, the opening of the R2 active site by the deletion of some residues in the R2-loop can be considered as an operative molecular strategy of class C beta-lactamases to extend their substrate spectrum.
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Affiliation(s)
- Jae Young Kim
- School of Biological Sciences, Seoul National University, Seoul 151-742, Republic of Korea
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24
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Power P, Galleni M, Ayala JA, Gutkind G. Biochemical and molecular characterization of three new variants of AmpC beta-lactamases from Morganella morganii. Antimicrob Agents Chemother 2006; 50:962-7. [PMID: 16495258 PMCID: PMC1426437 DOI: 10.1128/aac.50.3.962-967.2006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Morganella morganii produces an inducible, chromosomally encoded AmpC beta-lactamase. We describe in this study three new variants of AmpC within this species with apparent pIs of 6.6 (M19 from M. morganii strain PP19), 7.4 (M29 from M. morganii strain PP29), and 7.8 (M37 from M. morganii strain PP37). After gene sequencing, deduced amino acid sequences displayed one to six substitutions when compared to the available Morganella AmpC sequences. An AmpR-encoding gene was also found upstream of ampC, including the LysR regulators' helix-turn-helix DNA-binding domain and the putative T-N11-A-protected region in the ampR-ampC intercistronic sequence. All three AmpC variants were purified from in vitro-generated derepressed mutants and showed overall similar kinetic parameters. None of the observed amino acid changes, occurring at the surface of the protein, appear to have a major influence in their catalytic properties. Morganella AmpCs exhibit the highest catalytic efficiencies (k(cat)/K(m)) on classical penicillins, cefoxitin, narrow-spectrum cephalosporins, and cefotaxime. Cefotaxime was more effectively hydrolyzed than other oxyimino-cephalosporins, whereas cefepime was 3 log-fold less efficiently hydrolyzed than other cephalosporins such as cephalothin. Several differences with other AmpC beta-lactamases were found. Ampicillin was more efficiently hydrolyzed than benzylpenicillin. High k(cat)/K(m) values were observed for oxacillin and piperacillin, which are usually poor substrates for AmpC. A fairly efficient hydrolysis of imipenem was detected as well. Aztreonam, carbenicillin, and tazobactam were effective transient inactivators of these variants.
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Affiliation(s)
- Pablo Power
- Cátedra de Microbiología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 954, Buenos Aires 1113, Argentina
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25
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Bauvois C, Ibuka AS, Celso A, Alba J, Ishii Y, Frère JM, Galleni M. Kinetic properties of four plasmid-mediated AmpC beta-lactamases. Antimicrob Agents Chemother 2006; 49:4240-6. [PMID: 16189104 PMCID: PMC1251510 DOI: 10.1128/aac.49.10.4240-4246.2005] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The heterologous production in Escherichia coli, the purification, and the kinetic characterization of four plasmid-encoded class C beta-lactamases (ACT-1, MIR-1, CMY-2, and CMY-1) were performed. Except for their instability, these enzymes are very similar to the known chromosomally encoded AmpC beta-lactamases. Their kinetic parameters did not show major differences from those obtained for the corresponding chromosomal enzymes. However, the K(m) values of CMY-2 for cefuroxime, cefotaxime, and oxacillin were significantly decreased compared to those of the chromosomal AmpC enzymes. Finally, the susceptibility patterns of different E. coli hosts producing a plasmid- or a chromosome-encoded class C enzyme toward beta-lactam antibiotics are mainly due to the overproduction of the beta-lactamase in the periplasmic space of the bacteria rather than to a specific catalytic profile of the plasmid-encoded beta-lactamases.
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Affiliation(s)
- Cédric Bauvois
- Centre d'Ingénierie des Protéines, B6 Sart Tilman, Université de Liège, Belgium
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26
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Alba J, Bauvois C, Ishii Y, Galleni M, Masuda K, Ishiguro M, Ito M, Frere JM, Yamaguchi K. A detailed kinetic study of Mox-1, a plasmid-encoded class C beta-lactamase. FEMS Microbiol Lett 2003; 225:183-8. [PMID: 12951239 DOI: 10.1016/s0378-1097(03)00448-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Surveys of beta-lactamases in different parts of the world show an important increase in class C beta-lactamases, thus the study of these enzymes is becoming an important issue. We created an overproduction system for Mox-1, a plasmid class C beta-lactamase, by cloning the gene encoding this enzyme, and placing it under the control of a T7 promoter, using vector pET 28a. The enzyme, purified by ion exchange chromatography, was used to obtain the molecular mass (38246), the N-terminal sequence (GEASPVDPLRPVV), and pI (8.9), and to perform a detailed kinetic study. Cephalotin was used as reporter substrate in the case of poor substrates. The kinetic study showed that benzylpenicillin, cephalotin, cefcapene and moxalactam were good substrates for Mox-1 (k(cat)/K(m) values >2.5 x 10(6) M(-1) s(-1)). On the other hand, ceftazidime and cefepime were poor substrates for this enzyme (K(m) values >200 microM). Clavulanic acid had no inhibitory effect on Mox-1 (K(m)=30.2 mM), however aztreonam behaved as an inhibitor of Mox-1 (K(i)=2.85 microM).
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Affiliation(s)
- Jimena Alba
- Department of Microbiology, Toho University School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo 1438-540, Japan
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27
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Goldberg SD, Iannuccilli W, Nguyen T, Ju J, Cornish VW. Identification of residues critical for catalysis in a class C beta-lactamase by combinatorial scanning mutagenesis. Protein Sci 2003; 12:1633-45. [PMID: 12876313 PMCID: PMC2323950 DOI: 10.1110/ps.0302903] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Despite their clinical importance, the mechanism of action of the class C beta-lactamases is poorly understood. In contrast to the class A and class D beta-lactamases, which contain a glutamate residue and a carbamylated lysine in their respective active sites that are thought to serve as general base catalysts for beta-lactam hydrolysis, the mechanism of activation of the serine and water nucleophiles in the class C enzymes is unclear. To probe for residues involved in catalysis, the class C beta-lactamase from Enterobacter cloacae P99 was studied by combinatorial scanning mutagenesis at 122 positions in and around the active site. Over 1000 P99 variants were screened for activity in a high-throughput in vivo antibiotic resistance assay and sequenced by 96-capillary electrophoresis to identify residues that are important for catalysis. P99 mutants showing reduced capability to convey antibiotic resistance were purified and characterized in vitro. The screen identified an active-site hydrogen-bonding network that is key to catalysis. A second cluster of residues was identified that likely plays a structural role in the enzyme. Otherwise, residues not directly contacting the substrate showed tolerance to substitution. The study lends support to the notion that the class C beta-lactamases do not have a single residue that acts as the catalytic general base. Rather, catalysis is affected by a hydrogen-bonding network in the active site, suggesting a possible charge relay system.
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Affiliation(s)
- Shalom D Goldberg
- Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027, USA
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28
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Baker K, Bleczinski C, Lin H, Salazar-Jimenez G, Sengupta D, Krane S, Cornish VW. Chemical complementation: a reaction-independent genetic assay for enzyme catalysis. Proc Natl Acad Sci U S A 2002; 99:16537-42. [PMID: 12482929 PMCID: PMC139179 DOI: 10.1073/pnas.262420099] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A high-throughput assay for enzyme activity has been developed that is reaction independent. In this assay, a small-molecule yeast three-hybrid system is used to link enzyme catalysis to transcription of a reporter gene in vivo. Here we demonstrate the feasibility of this approach by using a well-studied enzyme-catalyzed reaction, cephalosporin hydrolysis by the Enterobacter cloacae P99 cephalosporinase (beta-lactam hydrolase, EC ). We show that the three-hybrid system can be used to read out cephalosporinase activity in vivo as a change in the level of transcription of a lacZ reporter gene and that the wild-type cephalosporinase can be isolated from a pool of inactive mutants by using a lacZ screen. The assay has been designed so that it can be applied to different chemical reactions without changing the components of the three-hybrid system. A reaction-independent high-throughput assay for protein function should be a powerful tool for protein engineering and enzymology, drug discovery, and proteomics.
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Affiliation(s)
- Kathleen Baker
- Departments of Chemistry and Pharmacology, Columbia University, New York, NY 10027, USA
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Lakaye B, Dubus A, Joris B, Frère JM. Method for estimation of low outer membrane permeability to beta-lactam antibiotics. Antimicrob Agents Chemother 2002; 46:2901-7. [PMID: 12183245 PMCID: PMC127435 DOI: 10.1128/aac.46.9.2901-2907.2002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The outer membrane of gram-negative bacteria plays a major role in beta-lactam resistance as it slows down antibiotic entry into the periplasm and therefore acts in synergy with beta-lactamases and efflux systems. Up to now, the quantitative estimation of low outer membrane permeability by the method of Zimmermann and Rosselet was difficult because of the secreted and cell surface-associated beta-lactamases. The method presented here uses the acylation of a highly sensitive periplasmic penicillin-binding protein (PBP) (BlaR-CTD) to assess the rate of beta-lactam penetration into the periplasm. The method is dedicated to measurement of low permeability and is only valid when the diffusion rate through the outer membrane is rate limiting. Cytoplasmic membrane associated PBPs do not interfere since they are acylated after the very sensitive BlaR-CTD. This method was used to measure the permeability of beta-lactamase-deficient strains of Enterobacter cloacae and Enterobacter aerogenes to benzylpenicillin, ampicillin, carbenicillin, cefotaxime, aztreonam, and cephacetrile. Except for that of cephacetrile, the permeability coefficients were equal to or below 10(-7) cm/s. For cephacetrile, carbenicillin, and benzylpenicillin, the outer membrane of E. cloacae was 20 to 60 times less permeable than that of Escherichia coli, whereas for cefotaxime, aztreonam, and ampicillin it was, respectively, 400, 1,000, and 700 times less permeable. The permeability coefficient for aztreonam is the lowest ever measured (P = 3.2 x 10(-9) cm/s). Using these values, the MICs for a beta-lactamase-overproducing strain of E. cloacae were successfully predicted, demonstrating the validity of the method.
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Affiliation(s)
- Bernard Lakaye
- Laboratoire d'Enzymologie and Centre d'Ingénierie des Protéines, Université de Liège, Institut de Chimie, B-4000 Liège, Belgium
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30
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Alba J, Ishii Y, Galleni M, Frère JM, Ito M, Yamaguchi K. Cefcapene inactivates chromosome-encoded class C beta-lactamases. J Infect Chemother 2002; 8:207-10. [PMID: 12373482 DOI: 10.1007/s10156-002-0177-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The stability of cefcapene and cefpodoxime, oral antibacterial cephalosporins, toward different classes of beta-lactamases was evaluated. For the class A beta-lactamases, TEM-1, SHV-1, and NMC-A, only the steady-state kinetic parameter ( k(cat)/ Km) values were calculated (3100 - 1.1 x 10(7) M(-1) x s(-1)), because these enzymes have very high Km values for cefpodoxime and cefotaxime. As for class B beta-lactamases L1, IMP-1, and CcrA, in general, similar k(cat)/ Km values were obtained. However, regarding class C beta-lactamases from Enterobacter cloacae, Escherichia coli, Pseudomonas aeruginosa, and Citrobacter freundii, we found major differences in stability between the two compounds. Cefpodoxime acted as a good substrate for the class C beta-lactamases, except for the enzyme from E. cloacae; its k(cat) and Km values were successfully calculated ( k(cat)/ Km, 1.8 x 10(5) - 1.2 x 10(7) M(-1) x s(-1)). On the other hand, cefcapene acted as a poor substrate or an inactivator for class C beta-lactamases; its k(2)/ K value was successfully calculated (8.7 x 10(5) - 7.0 x 10(6) M(-1) x s(-1)). In addition, k(3) values were determined for beta-lactamases from P. aeruginosa (2.3 x 10(-2) x s(-1)) and C. freundii (2.1 x 10(-1) x s(-1)). Even though these values could be calculated, transient inactivation as an enzyme reactivation reaction for all these enzymes was observed. These findings suggest the potential of cephem compounds as inhibitors of class C beta-lactamases.
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Affiliation(s)
- Jimena Alba
- Department of Microbiology, Yamanashi Medical University, Tamaho-cho, Yamanashi 490-3898, Japan
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31
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Beadle BM, Trehan I, Focia PJ, Shoichet BK. Structural milestones in the reaction pathway of an amide hydrolase: substrate, acyl, and product complexes of cephalothin with AmpC beta-lactamase. Structure 2002; 10:413-24. [PMID: 12005439 DOI: 10.1016/s0969-2126(02)00725-6] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Beta-lactamases hydrolyze beta-lactam antibiotics and are the leading cause of bacterial resistance to these drugs. Although beta-lactamases have been extensively studied, structures of the substrate-enzyme and product-enzyme complexes have proven elusive. Here, the structure of a mutant AmpC in complex with the beta-lactam cephalothin in its substrate and product forms was determined by X-ray crystallography to 1.53 A resolution. The acyl-enzyme intermediate between AmpC and cephalothin was determined to 2.06 A resolution. The ligand undergoes a dramatic conformational change as the reaction progresses, with the characteristic six-membered dihydrothiazine ring of cephalothin rotating by 109 degrees. These structures correspond to all three intermediates along the reaction path and provide insight into substrate recognition, catalysis, and product expulsion.
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Affiliation(s)
- Beth M Beadle
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University, Chicago, Illinois 60611, USA
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32
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Bebrone C, Moali C, Mahy F, Rival S, Docquier JD, Rossolini GM, Fastrez J, Pratt RF, Frère JM, Galleni M. CENTA as a chromogenic substrate for studying beta-lactamases. Antimicrob Agents Chemother 2001; 45:1868-71. [PMID: 11353639 PMCID: PMC90559 DOI: 10.1128/aac.45.6.1868-1871.2001] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CENTA, a chromogenic cephalosporin, is readily hydrolyzed by beta-lactamases of all classes except for the Aeromonas hydrophila metalloenzyme. Although it cannot practically be used for the detection of beta-lactamase-producing strains on agar plates, it should be quite useful for kinetic studies and the detection of the enzymes in crude extracts and chromatographic fractions.
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Affiliation(s)
- C Bebrone
- Centre for Protein Engineering, University of Liège, Institut de Chimie B6, Sart Tilman, 4000 Liège, Belgium
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33
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Vilar M, Galleni M, Solmajer T, Turk B, Frère JM, Matagne A. Kinetic study of two novel enantiomeric tricyclic beta-lactams which efficiently inactivate class C beta-lactamases. Antimicrob Agents Chemother 2001; 45:2215-23. [PMID: 11451677 PMCID: PMC90634 DOI: 10.1128/aac.45.8.2215-2223.2001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A detailed kinetic study of the interaction between two ethylidene derivatives of tricyclic carbapenems, Lek 156 and Lek 157, and representative beta-lactamases and D-alanyl-D-alanine peptidases (DD-peptidases) is presented. Both compounds are very efficient inactivators of the Enterobacter cloacae 908R beta-lactamase, which is usually resistant to inhibition. Preliminary experiments indicate that various extended-spectrum class C beta-lactamases (ACT-1, CMY-1, and MIR-1) are also inactivated. With the E. cloacae 908R enzyme, complete inactivation occurs with a second-order rate constant, k(2)/K', of 2 x 10(4) to 4 x 10(4) M(-1) s(-1), and reactivation is very slow, with a half-life of >1 h. Accordingly, Lek 157 significantly decreases the MIC of ampicillin for E. cloacae P99, a constitutive class C beta-lactamase overproducer. With the other serine beta-lactamases tested, the covalent adducts exhibit a wide range of stabilities, with half-lives ranging from long (>4 h with the TEM-1 class A enzyme), to medium (10 to 20 min with the OXA-10 class D enzyme), to short (0.2 to 0.4 s with the NmcA class A beta-lactamase). By contrast, both carbapenems behave as good substrates of the Bacillus cereus metallo-beta-lactamase (class B). The Streptomyces sp. strain R61 and K15 extracellular DD-peptidases exhibit low levels of sensitivity to both compounds.
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Affiliation(s)
- M Vilar
- Laboratoire d'Enzymologie, Centre for Protein Engineering, University of Liège, Institut de Chimie, Belgium
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34
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López-Hernández S, Alarcón T, López-Brea M. Biochemical characterization of chromosomal cephalosporinases from isolates belonging to the Acinetobacter baumannii complex. Clin Microbiol Infect 2001; 7:218-26. [PMID: 11422246 DOI: 10.1046/j.1469-0691.2001.00222.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- S López-Hernández
- Department of Microbiology, Hospital Universitario de la Princesa, Diego de León, 62, 28006 Madrid, Spain.
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35
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Abstract
The introduction of a large array of beta-lactam antibiotics has spawned the emergence of an even larger variety of beta-lactamases designed to confer resistance to these agents. beta-lactamases are produced by both gram-positive and gram-negative bacteria, but their clinical importance is far greater among the gram-negatives. The virtual explosion in our knowledge about the variety of these enzymes can often create confusion and frustration among those not well versed in the field. In this paper, we attempt to focus the discussion of beta-lactamases on those enzymes that are of the greatest clinical importance, the Ambler Class A and C enzymes. We also discuss the growing importance of the Ambler Class B metallo beta-lactamases, which hydrolyze carbapenems and are increasing in prevalence in areas of significant carbapenem usage. Copyright 2000 Harcourt Publishers Ltd.
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Affiliation(s)
- Louis B. Rice
- Medical Service, Department of Veterans Affairs Medical Center, Departments of Medicine, Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
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36
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Mazzariol A, Cornaglia G, Nikaido H. Contributions of the AmpC beta-lactamase and the AcrAB multidrug efflux system in intrinsic resistance of Escherichia coli K-12 to beta-lactams. Antimicrob Agents Chemother 2000; 44:1387-90. [PMID: 10770787 PMCID: PMC89880 DOI: 10.1128/aac.44.5.1387-1390.2000] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The roles of the AmpC chromosomal beta-lactamase and the AcrAB efflux system in levels of intrinsic resistance and susceptibility of Escherichia coli to beta-lactams were studied with a set of isogenic strains. MICs of ureidopenicillins, carbenicillin, oxacillin, and cloxacillin were drastically reduced by the inactivation of AcrAB, whereas those of the earlier cephalosporins were affected mostly by the loss of AmpC beta-lactamase.
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Affiliation(s)
- A Mazzariol
- Institute of Microbiology, University of Verona, Verona, Italy
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37
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Buynak JD, Doppalapudi VR, Adam G. The synthesis and evaluation of 3-substituted-7-(alkylidene)cephalosporin sulfones as beta-lactamase inhibitors. Bioorg Med Chem Lett 2000; 10:853-7. [PMID: 10853646 DOI: 10.1016/s0960-894x(00)00098-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A series of 3-substituted-7-(alkylidene)cephaloporin sulfones were prepared and evaluated as inhibitors of representative class A and class C serine beta-lactamase. Appropriate substituents resulted in a 1000-fold improvement in the inhibition of the class A enzymes and a simultaneous 20-fold improvement in the inhibition of class C. These new compounds have achieved the goal of creating broad scale inhibitors in the cephalosporin series.
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Affiliation(s)
- J D Buynak
- Department of Chemistry, Southern Methodist University, Dallas, TX 75275-0314, USA.
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38
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Tavío Pérez MM, Amicosante G, Franceschini N, Vila J, Ruiz J, Oratore A, Martín-Sánchez AM, Jiménez de Anta MT. Decreased production of AmpC-type beta-lactamases associated with the development of resistance to quinolones in Citrobacter freundii strains. Microb Drug Resist 2000; 5:235-40. [PMID: 10647079 DOI: 10.1089/mdr.1999.5.235] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The effect of fluoroquinolones in Citrobacter freundii strains that results in a decreased expression of cephalosporin-hydrolysing beta-lactamases was studied. Resistance to broad-spectrum cephalosporins and penicillins in two C. freundii clinical isolates was associated with moderate production of chromosomal AmpC-type-beta-lactamase in addition to changes in the outer membrane proteins profile with respect to wild-type C. freundii strains. Ten quinolone-resistant mutants were derived from the two clinical isolates using increasing fluoroquinolone concentrations. The level of susceptibility to cephalosporins and meropenem of these 10 mutants was increased and was associated with a 3.6-32% diminution in the hydrolyzing activity of their periplasmic extracts containing beta-lactamases on cephaloridine as compared with those from their parent strains. Susceptibility to cephalosporins and meropenem, as well as the expression of chromosomal AmpC-type-beta-lactamase in C. freundii strains, was influenced by the exposure to quinolones.
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Affiliation(s)
- M M Tavío Pérez
- Department of Clinical Sciences, School of Medicine, University of Las Palmas de G.C., Spain
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39
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Rhazi N, Galleni M, Page MI, Frère JM. Peptidase activity of beta-lactamases. Biochem J 1999; 341 ( Pt 2):409-13. [PMID: 10393100 PMCID: PMC1220374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Although beta-lactamases have generally been considered as being devoid of peptidase activity, a low but significant hydrolysis of various N-acylated dipeptides was observed with representatives of each class of beta-lactamases. The kcat/Km values were below 0.1 M(-1). s(-1), but the enzyme rate enhancement factors were in the range 5000-20000 for the best substrates. Not unexpectedly, the best 'peptidase' was the class C beta-lactamase of Enterobacter cloacae P99, but, more surprisingly, the activity was always higher with the phenylacetyl- and benzoyl-d-Ala-d-Ala dipeptides than with the diacetyl- and alpha-acetyl-l-Lys-d-Ala-d-Ala tripeptides, which are the preferred substrates of the low-molecular-mass, soluble dd-peptidases. A comparison between the beta-lactamases and dd-peptidases showed that it might be as difficult for a dd-peptidase to open the beta-lactam ring as it is for the beta-lactamases to hydrolyse the peptides, an observation which can be explained by geometric and stereoelectronic considerations.
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Affiliation(s)
- N Rhazi
- Centre d'Ingénierie des Protéines and Laboratoire d'Enzymologie, Université de Liège, Institut de Chimie B6, Sart Tilman, B-4000 Liège, Belgium
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40
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Lakaye B, Dubus A, Lepage S, Groslambert S, Frère JM. When drug inactivation renders the target irrelevant to antibiotic resistance: a case story with beta-lactams. Mol Microbiol 1999; 31:89-101. [PMID: 9987113 DOI: 10.1046/j.1365-2958.1999.01150.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
By challenging the efficiency of some of our most useful antimicrobial weapons, bacterial antibiotic resistance is becoming an increasingly worrying clinical problem. A good antibiotic is expected to exhibit a high affinity for its target and to reach it rapidly, while escaping chemical modification by inactivating enzymes and elimination by efflux mechanisms. A study of the behaviour of a beta-lactamase-overproducing mutant of Enterobacter cloacae in the presence of several penicillins and cephalosporins showed that the minimum inhibitory concentration (MIC) values for several compounds were practically independent of the sensitivity of the target penicillin binding protein (PBP), even for poor beta-lactamase substrates. This apparent paradox was explained by analysing the equation that relates the antibiotic concentration in the periplasm to that in the external medium. Indeed, under conditions that are encountered frequently in clinical isolates, the factor characterizing the PBP sensitivity became negligible. The conclusions can be extended to all antibiotics that are sensitive to enzymatic inactivation and efflux mechanisms and must overcome permeability barriers. It would be a grave mistake to neglect these considerations in the design of future antibacterial chemotherapeutic agents.
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Affiliation(s)
- B Lakaye
- Centre d'Ingénierie des Protéines, Université de Liège, Belgium
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41
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Pierrard A, Ledent P, Docquier J, Feller G, Gerday C, Frère J. Inducible class C β-lactamases produced by psychrophilic bacteria. FEMS Microbiol Lett 1998. [DOI: 10.1111/j.1574-6968.1998.tb12962.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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42
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Filali FR, Zaid A, Zekhnini Z, Frere JM. [Thermophilic bacteria resistant to antibiotics in traditional public baths]. Comp Immunol Microbiol Infect Dis 1997; 20:335-44. [PMID: 9481518 DOI: 10.1016/s0147-9571(97)00013-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Three thermophilic bacteria strains, designated strain BS1, BS2 and BS3, resistant to beta-lactam antibiotics, and leaving at an optimal temperature for growth of about 50 degrees C, were isolated from traditional baths in Meknes-city in Morocco. Physiological and biochemical studies showed that these organisms belong to Gram positive Bacilli. They could not be identified with the Bergey's Manuel of Systematic Bacteriology (1986). The dosage of beta-lactamase during the exponential growth phase has revealed that the strain BS3 produces a maximal amount of this enzyme. Studies aimed at determining the optimal conditions for incubation and growth have been performed in order to optimize the excretion of beta-lactamase by BS3 cells and thus facilitate the purification and and characterization of this enzyme.
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Affiliation(s)
- F R Filali
- Département de Biologie, Faculté des Sciences, Université My Ismaïl, Zitoune, Meknès, Maroc
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43
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Feller G, Zekhnini Z, Lamotte-Brasseur J, Gerday C. Enzymes from cold-adapted microorganisms. The class C beta-lactamase from the antarctic psychrophile Psychrobacter immobilis A5. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 244:186-91. [PMID: 9063463 DOI: 10.1111/j.1432-1033.1997.00186.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A heat-labile beta-lactamase has been purified from culture supernatants of Psychrobacter immobilis A5 grown at 4 degrees C and the corresponding chromosomal ampC gene has been cloned and sequenced. All structural and kinetic properties clearly relate this enzyme to class C beta-lactamases. The kinetic parameters of P. immobilis beta-lactamase for the hydrolysis of some beta-lactam antibiotics are in the same range as the values recorded for the highly specialized cephalosporinases from pathogenic mesophilic bacteria. By contrast, the enzyme displays a low apparent optimum temperature of activity and a reduced thermal stability. Structural factors responsible for the latter property were analysed from the three-dimensional structure built by homology modelling. The deletion of proline residues in loops, the low number of arginine-mediated H-bonds and aromatic-aromatic interactions, the lower global hydrophobicity and the improved solvent interactions through additional surface acidic residues appear to be the main determinants of the enzyme flexibility.
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Affiliation(s)
- G Feller
- Laboratoire de Biochimie, Institut de Chimie B6, Université de Liège, Belgium
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44
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45
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Knox JR, Moews PC, Frere JM. Molecular evolution of bacterial beta-lactam resistance. CHEMISTRY & BIOLOGY 1996; 3:937-47. [PMID: 8939710 DOI: 10.1016/s1074-5521(96)90182-9] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Two groups of penicillin-destroying enzymes, the class A and class C beta-lactamases, may have evolved from bacterial transpeptidases that transfer X-D-Ala-D-Ala peptides to the growing peptidoglycan during cell wall synthesis. Both the transpeptidases and the beta-lactamases are acylated by beta-lactam antibiotics such as penicillin, which mimic the peptide, but breakdown and removal of the antibiotic is much faster in the beta-lactamases, which lack the ability to process D-Ala-D-Ala peptides. Stereochemical factors driving this evolution in specificity are examined. RESULTS We have compared the crystal structures of two classes of beta-lactamases and a beta-lactam-sensitive D-alanyl-D-alanine carboxy-peptidase/transpeptidase (DD-peptidase). The class C beta-lactamase is more similar to the DD-peptidase than to another beta-lactamase of class A. CONCLUSIONS The two classes of beta-lactamases appear to have developed from an ancestral protein along separate evolutionary paths. Structural differentiation of the beta-lactamases from the DD-peptidases appears to follow differences in substrate shapes. The structure of the class A beta-lactamase has been further optimized to exclude D-alanyl peptides and process penicillin substrates with near catalytic perfection.
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Affiliation(s)
- J R Knox
- Department of Molecular and Cell Biology, The University of Connecticut, Storrs, CT 06269-3125, USA.
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46
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Dubus A, Ledent P, Lamotte-Brasseur J, Frère JM. The roles of residues Tyr150, Glu272, and His314 in class C beta-lactamases. Proteins 1996; 25:473-85. [PMID: 8865342 DOI: 10.1002/prot.7] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Serine beta-lactamases contribute widely to the beta-lactam resistance phenomena. Unfortunately, the intimate details of their catalytic mechanism remain elusive and subject to some controversy even though many "natural" and "artificial" mutants of these different enzymes have been isolated. This paper is essentially focused on class C beta-lactamases, which contain a Tyr (Tyr150) as the first residue of the second conserved element, in contrast to their class A counterparts, in which a Ser is found in the corresponding position. We have modified this Tyr residue by site-directed mutagenesis. On the basis of the three-dimensional structure of the Enterobacter cloacae P99 enzyme, it seemed that residues Glu272 and His314 might also be important. They were similarly substituted. The modified enzymes were isolated and their catalytic properties determined. Our results indicated that His314 was not required for catalysis and that Glu272 did not play an important role in acylation but was involved to a small extent in the deacylation process. Conversely, Tyr150 was confirmed to be central for catalysis, at least with the best substrates. On the basis of a comparison of data obtained for several class C enzyme mutants and in agreement with recent structural data, we propose that the phenolate anion of Tyr150, in conjunction with the alkyl ammonium of Lys315, acts as the general base responsible for the activation of the active-site Ser64 during the acylation step and for the subsequent activation of a water molecule in the deacylation process. The evolution of the important superfamily of penicillin-recognizing enzymes is further discussed in the light of this proposed mechanism.
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Affiliation(s)
- A Dubus
- Centre d'Ingénierie des Protéines, Université de Liége, Belgium
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47
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Perilli M, Felici A, Oratore A, Cornaglia G, Bonfiglio G, Rossolini GM, Amicosante G. Characterization of the chromosomal cephalosporinases produced by Acinetobacter lwoffii and Acinetobacter baumannii clinical isolates. Antimicrob Agents Chemother 1996; 40:715-9. [PMID: 8851599 PMCID: PMC163186 DOI: 10.1128/aac.40.3.715] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The beta-lactamases produced by Acinetobacter lwoffii ULA-501, Acinetobacter baumannii ULA-187, and A. baumannii AC-14 strains were purified and characterized, and their kinetic interactions with several beta-lactam molecules, including substrates and inhibitors, were studied in detail. The three enzymes appeared to be cephalosporinases with different acylation efficiencies (kcat/Km ratio values), and their hydrolytic activities were inhibited by benzylpenicillin, piperacillin, and cefotaxime, which did not behave as substrates. Carbenicillin was a substrate for the beta-lactamase from A. lwoffii ULA-501, whereas it acted as a transient inactivator of the enzymes produced by the two A. baumannii strains. Clavulanic acid was unable to inactivate the three beta-lactamases, whereas sulbactam behaved as an inactivator only at a high concentration (1 mM) which is difficult to achieve during antibiotic therapy. Analysis of the interaction with 6-beta-iodopenicillanic acid also allowed us to better discriminate the three beta-lactamases analyzed in the present study, which can be included in the group 1 functional class (5).
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Affiliation(s)
- M Perilli
- Dipartimento di Scienze e Tecnologie Biomediche e di Biometria, Università degli Studi dell'Aquila, Italy
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48
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Abstract
The majority of the human microflora consists of anaerobic bacteria. Normally these bacteria have low pathogenicity, but under certain conditions, such as destruction of tissues and poor circulation or impaired host defense, they may cause serious infections. Bacteroides species are the most frequently isolated microorganisms from suppurative anaerobic infections and they have the broadest spectrum of resistance to the commonly used antimicrobial agents. Resistance to antimicrobial agents is an increasing problem, especially to beta-lactam compounds. Multiresistant clinical isolates, resistant to beta-lactam antibiotics as well as other antimicrobial agents used in the treatment and prophylaxis of anaerobic infections are now occurring. Resistance to beta-lactam antibiotics is usually mediated by beta-lactamase production. A few isolates of Bacteroides fragilis are producing metallo-beta-lactamases which are capable of hydrolyzing beta-lactamase stable compounds such as cefoxitin and imipenem. The enzyme activity in metallo-beta-lactamases is not affected by the clinically used beta-lactamase inhibitors clavulanic acid, sulbactam and tazobactam. Other resistance mechanisms are alterations in the penicillin-binding proteins (PBPs) or a decreased permeability through the outer membrane. Beta-lactam resistance and beta-lactamase production have also been detected in some species of clostridia, fusobacteria, Prevotella, Porphyromonas and in some other anaerobic bacteria.
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Affiliation(s)
- M Hedberg
- Department of Immunology, Microbiology, Pathology and Infectious Diseases, Huddinge University Hospital, Stockholm, Sweden
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Feller G, Sonnet P, Gerday C. The beta-lactamase secreted by the antarctic psychrophile Psychrobacter immobilis A8. Appl Environ Microbiol 1995; 61:4474-6. [PMID: 8534113 PMCID: PMC167757 DOI: 10.1128/aem.61.12.4474-4476.1995] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
A class C beta-lactamase has been purified from the culture supernatant of the antarctic psychrophile Psychrobacter immobilis A8. This psychrophilic beta-lactamase displays a low level of thermal stability and a low optimal temperature of activity. In contrast to other cold-adapted enzymes, its level of specific activity is not higher than that of mesophilic class C beta-lactamases.
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Affiliation(s)
- G Feller
- Laboratory of Biochemistry, Université de Liège, Liège-Sart Tilman, Belgium
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Lepage S, Galleni M, Lakaye B, Joris B, Thamm I, Frere JM. Kinetic properties of the Bacillus licheniformis penicillin-binding proteins. Biochem J 1995; 309 ( Pt 1):49-53. [PMID: 7619081 PMCID: PMC1135798 DOI: 10.1042/bj3090049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In the analysis of the interactions between beta-lactam antibiotics and their target enzymes, it is often difficult to estimate the kinetic properties of the molecules which react rapidly with their targets and in consequence behave as the most efficient antibiotics. The combined utilization of fluorescein-labelled penicillins and of a new competition method has allowed an accurate determination of the high second-order rate constants characterizing the acylation of Bacillus licheniformis penicillin-binding protein 1 (PBP1) by penicillins and cephalosporins. Strategies were devised for measuring high acylation rates while avoiding titration effects. The method was also suitable for measuring the PBP kinetic parameters in intact cells. These results also confirmed that PBP1 is probably the main target of most beta-lactam antibiotics. Cephalexin, however, reacted faster with PBP3.
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Affiliation(s)
- S Lepage
- Laboratoire d'Enzymologie, Université de Liège, Belgium
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