101
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García-Saez I, Hopkins J, Papamicael C, Franceschini N, Amicosante G, Rossolini GM, Galleni M, Frère JM, Dideberg O. The 1.5-A structure of Chryseobacterium meningosepticum zinc beta-lactamase in complex with the inhibitor, D-captopril. J Biol Chem 2003; 278:23868-73. [PMID: 12684522 DOI: 10.1074/jbc.m301062200] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The crystal structure of the class-B beta-lactamase, BlaB, from the pathogenic bacterium, Chryseobacterium meningosepticum, in complex with the inhibitor, d-captopril, has been solved at 1.5-A resolution. The enzyme has the typical alphabeta/betaalpha metallo-beta-lactamase fold and the characteristic two metal binding sites of members of the subclass B1, in which two Zn2+ ions were identified. d-Captopril, a diastereoisomer of the commercial drug, captopril, acts as an inhibitor by displacing the catalytic hydroxyl ion required for antibiotic hydrolysis and intercalating its sulfhydryl group between the two Zn2+ ions. Interestingly, d-captopril is located on one side of the active site cleft. The x-ray structure of the complex of the closely related enzyme, IMP-1, with a mercaptocarboxylate inhibitor, which also contains a sulfhydryl group bound to the two Zn2+ ions, shows the ligand to be located on the opposite side of the active site cleft. A molecule generated by fusion of these two inhibitors would cover the entire cleft, suggesting an interesting approach to the design of highly specific inhibitors.
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Affiliation(s)
- Isabel García-Saez
- Laboratoire de Cristallographie Macromoléculaire, Institut de Biologie Structurale Jean-Pierre Ebel (CNRS-Commissariat à l'Energie Atomique, Saclay, France
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102
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Heinz U, Bauer R, Wommer S, Meyer-Klaucke W, Papamichaels C, Bateson J, Adolph HW. Coordination geometries of metal ions in d- or l-captopril-inhibited metallo-beta-lactamases. J Biol Chem 2003; 278:20659-66. [PMID: 12668674 DOI: 10.1074/jbc.m212581200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
d- and l-captopril are competitive inhibitors of metallo-beta-lactamases. For the enzymes from Bacillus cereus (BcII) and Aeromonas hydrophila (CphA), we found that the mononuclear enzymes are the favored targets for inhibition. By combining results from extended x-ray absorption fine structure, perturbed angular correlation of gamma-rays spectroscopy, and a study of metal ion binding, we derived that for Cd(II)1-BcII, the thiolate sulfur of d-captopril binds to the metal ion located at the site defined by three histidine ligand residues. This is also the case for the inhibited Co(II)1 and Co(II)2 enzymes as observed by UV-visible spectroscopy. Although the single metal ion in Cd(II)1-BcII is distributed between both available binding sites in both the uninhibited and the inhibited enzyme, Cd(II)1-CphA shows only one defined ligand geometry with the thiolate sulfur coordinating to the metal ion in the site composed of 1 Cys, 1 His, and 1 Asp. CphA shows a strong preference for d-captopril, which is also reflected in a very rigid structure of the complex as determined by perturbed angular correlation spectroscopy. For BcII and CphA, which are representatives of the metallo-beta-lactamase subclasses B1 and B2, we find two different inhibitor binding modes.
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Affiliation(s)
- Uwe Heinz
- Department of Biochemistry, University of the Saarland, D-66041 Saarbruecken, Germany
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103
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Goto M, Yasuzawa H, Higashi T, Yamaguchi Y, Kawanami A, Mifune S, Mori H, Nakayama H, Harada K, Arakawa Y. Dependence of hydrolysis of beta-lactams with a zinc(II)-beta-lactamase produced from Serratia marcescens (IMP-1) on pH and concentration of zinc(II) ion: dissociation of Zn(II) from IMP-1 in acidic medium. Biol Pharm Bull 2003; 26:589-94. [PMID: 12736495 DOI: 10.1248/bpb.26.589] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The pH dependence for the hydrolysis of beta-lactam antibiotics by a metallo-beta-lactamase (IMP-1) produced from Serratia marcescens was investigated varying the concentration of Zn(II). The activity of IMP-1 for imipenem was decreased at pH less than pH 5.3 without external addition of Zn(II) ions but was recovered with addition of Zn(II). Varying the concentration of external Zn(II), the molar activity of the enzyme, k(obs), that was defined by the velocity of hydrolysis of imipenem/concentration of IMP-1 was expressed by k(obs)=v(init)/[E](T)=k(max)[Zn]/(K(d)+[Zn]) in which K(d) stands for the dissociation constant between Zn(II) and IMP-1. The dissociation constants, K(d), vary with pH; K(d)=840 x 10(-6) M at pH 4.3 and K(d)=0.19 x 10(-6) M at pH 6.0. The plot of -log K(d) against pH showed a straight line having a slope of 4.0 below pH 5.0, showing the existence of four functional groups which may be protonated upon dissociation of Zn(II) ion(s). The k(cat), K(m), and k(cat)/K(m) of hydrolysis of imipenem and cephalothin in the presence of sufficient concentration of Zn(NO(3))(2) for saturation of IMP-1 with Zn(II) showed similar dependency to each other on pH between pH 6.0 and 9.0.
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Affiliation(s)
- Masafumi Goto
- Laboratory of Pharmaceutical Physical Chemistry, Faculty of Pharmaceutical Sciences, Kumamoto University, Honmachi, Japan.
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104
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Abstract
It is shown here that phase diagrams of ligand-binding biological macromolecules provide a powerful tool for the analysis of reaction mechanisms. The present study provides simple rules for the construction and interpretation of such phase diagrams. We give examples for the derivation of reaction schemes for macromolecules that can bind two different kinds of ligands. By sampling one dimension of a phase diagram it is possible to reconstruct the second dimension, including the correct stoichiometry, positive and negative linkage between the ligands and equilibrium binding constants for the complete series of reactions. The discussion is generalised to temperature and pressure-dependent phase diagrams. To exemplify the new diagram method we analyse the pH-dependent binding of trans-beta-indole acrylic acid to apo-Trp repressor, the pH-dependent thermal denaturation of alpha-chymotrypsinogen A, calcium binding and denaturation of annexin I, high affinity zinc binding to a metallo-beta-lactamase and high-pressure and temperature denaturation of RNase A and staphylococcal nuclease.
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Affiliation(s)
- Jörg Rösgen
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Schlossplatz 4/7, 48149 Münster, Germany.
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105
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Bertrand M, Weber G, Schoefs B. Metal determination and quantification in biological material using particle-induced X-ray emission. Trends Analyt Chem 2003. [DOI: 10.1016/s0165-9936(03)00405-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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106
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Moali C, Anne C, Lamotte-Brasseur J, Groslambert S, Devreese B, Van Beeumen J, Galleni M, Frère JM. Analysis of the importance of the metallo-beta-lactamase active site loop in substrate binding and catalysis. CHEMISTRY & BIOLOGY 2003; 10:319-29. [PMID: 12725860 DOI: 10.1016/s1074-5521(03)00070-x] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The role of the mobile loop comprising residues 60-66 in metallo-beta-lactamases has been studied by site-directed mutagenesis, determination of kinetic parameters for six substrates and two inhibitors, pre-steady-state characterization of the interaction with chromogenic nitrocefin, and molecular modeling. The W64A mutation was performed in IMP-1 and BcII (after replacement of the BcII 60-66 peptide by that of IMP-1) and always resulted in increased K(i) and K(m) and decreased k(cat)/K(m) values, an effect reinforced by complete deletion of the loop. k(cat) values were, by contrast, much more diversely affected, indicating that the loop does not systematically favor the best relative positioning of substrate and enzyme catalytic groups. The hydrophobic nature of the ligand is also crucial to strong interactions with the loop, since imipenem was almost insensitive to loop modifications.
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Affiliation(s)
- Catherine Moali
- Centre d'Ingénierie des Protéines, Université de Liège, Sart-Tilman, B-4000 Liege, Belgium
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107
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Olsen L, Antony J, Ryde U, Adolph HW, Hemmingsen L. Lactam Hydrolysis Catalyzed by Mononuclear Metallo-β-lactamases: A Density Functional Study. J Phys Chem B 2003. [DOI: 10.1021/jp0275950] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lars Olsen
- Department of Mathematics and Physics, The Royal Veterinary and Agricultural University, 1871 Frederiksberg C, Denmark
| | - Jens Antony
- Department of Mathematics and Computer Science, Free University of Berlin, Arnimallee 2-6, D-14195, Germany
| | - Ulf Ryde
- Department of Theoretical Chemistry, University of Lund, Chemical Center, P.O.B. 124, S-221 00 Lund, Sweden
| | - Hans-Werner Adolph
- Center for Bioinformatics, University of the Saarland and Max-Planck-Institut for Informatics, D-66041 Saarbrücken, Germany
| | - Lars Hemmingsen
- Department of Physics, The Quantum Protein Centre, The Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
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108
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Murphy TA, Simm AM, Toleman MA, Jones RN, Walsh TR. Biochemical characterization of the acquired metallo-beta-lactamase SPM-1 from Pseudomonas aeruginosa. Antimicrob Agents Chemother 2003; 47:582-7. [PMID: 12543663 PMCID: PMC151762 DOI: 10.1128/aac.47.2.582-587.2003] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SPM-1 is a new metallo-beta-lactamase recently identified in Pseudomonas aeruginosa strain 48-1997A, isolated in Sao Paulo, Brazil. Kinetic analysis demonstrated that SPM-1 has a broad hydrolytic profile across a wide range of beta-lactam antibiotics. Considerable variation was observed within the penicillin, cephalosporin, and carbapenem subfamilies; however, on the whole, SPM-1 appears to preferentially hydrolyze cephalosporins. The highest k(cat/)K(m) ratios (in micromolar per second) overall were observed for this subgroup. The hydrolytic profile of SPM-1 bears the most similarity to that of the metallo-beta-lactamase IMP-1, yet for the most part, SPM-1 has k(cat)/K(m) values higher than those of IMP-1. Zinc chelator studies established that progressive inhibition of SPM-1 by EDTA, dipicolinic acid, and 1-10-o-phenanthroline demonstrated a biexponential pattern in which none of the chelators completely inhibited SPM-1. A homology model of SPM-1 was developed on the basis of the IMP-1 crystal structure, which showed the protein folding and active-site structure characteristic of metallo-beta-lactamases and which provides an explanation for the kinetic profiles observed.
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Affiliation(s)
- Tanya A Murphy
- Department of Pathology and Microbiology, University of Bristol, Bristol BS8 1TD, United Kingdom.
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109
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Wommer S, Rival S, Heinz U, Galleni M, Frere JM, Franceschini N, Amicosante G, Rasmussen B, Bauer R, Adolph HW. Substrate-activated zinc binding of metallo-beta -lactamases: physiological importance of mononuclear enzymes. J Biol Chem 2002; 277:24142-7. [PMID: 11967267 DOI: 10.1074/jbc.m202467200] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have investigated the influence of substrate binding on the zinc ion affinity of representatives from the three metallo-beta-lactamase subclasses, B1 (BcII from Bacillus cereus and BlaB from Chryseobacterium meningosepticum), B2 (CphA from Aeromonas hydrophila), and B3 (L1 from Stenotrophomonas maltophilia). By competition experiments with metal-free apoenzymes and chromophoric zinc chelators or EDTA, we determined the dissociation constants in the absence and presence of substrates. For the formation of the monozinc enzymes we determined constants of 1.8, 5.1, 0.007, and 2.6 nm in the absence and 13.6, 1.8, 1.2, and 5.7 pm in the presence of substrates for BcII, BlaB, CphA, and L1, respectively. A second zinc ion binds in the absence (presence) of substrates with considerably higher dissociation constants, namely 1.8 (0.8), 0.007 (0.025), 50 (1.9), and 0.006 (0.12) microm for BcII, BlaB, CphA, and L1, respectively. We have concluded that the apo form might be the prevailing state of most of the metallo-beta-lactamases under physiological conditions in the absence of substrates. Substrate availability induces a spontaneous self-activation due to a drastic decrease of the dissociation constants, resulting in the formation of active mononuclear enzymes already at picomolar free zinc ion concentrations. In the presence of substrates, the binuclear state of the enzymes only exists at unphysiologic high zinc concentrations and might be of no biological relevance. From the competition experiments with EDTA it is further concluded that the reactivation rate does not depend on the pool of free zinc ions but proceeds via the EDTA-Zn(II)-enzyme ternary complexes.
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Affiliation(s)
- Sandra Wommer
- Department of Biochemistry, University of Saarland, D-66041 Saarbrücken, Germany
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110
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Siemann S, Brewer D, Clarke AJ, Dmitrienko GI, Lajoie G, Viswanatha T. IMP-1 metallo-beta-lactamase: effect of chelators and assessment of metal requirement by electrospray mass spectrometry. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1571:190-200. [PMID: 12090933 DOI: 10.1016/s0304-4165(02)00258-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Metallo-beta-lactamases have attracted considerable attention due to their role in microbial resistance to beta-lactam antibiotics. IMP-1, the binuclear Zn-dependent beta-lactamase produced by Pseudomonas aeruginosa and other microorganisms, is of particular interest in view of its increasing prevalence. An examination of the susceptibility of IMP-1 to inactivation by six different divalent metal ion chelators has revealed that all except Zincon cause inhibition by forming a complex with the holoenzyme. Exposure of the enzyme to dipicolinic acid (DPA), the most potent inhibitor, results in the production of the mononuclear Zn form of the protein as determined by electrospray ionization mass spectrometry (ESI-MS) under nondenaturing conditions. This mononuclear Zn species was found to be catalytically competent. Studies with the chromophoric chelator 4-(2-pyridylazo)resorcinol (PAR) show that the two zinc centers in IMP-1 differ in their accessibility, a feature that could be overcome in the presence of guanidine hydrochloride (GdnHCl, 1.5 M).
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Affiliation(s)
- Stefan Siemann
- Department of Chemistry, University of Waterloo, 200 University Ave. W, Waterloo, ON, Canada N2L 3G1
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111
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Majiduddin FK, Materon IC, Palzkill TG. Molecular analysis of beta-lactamase structure and function. Int J Med Microbiol 2002; 292:127-37. [PMID: 12195735 DOI: 10.1078/1438-4221-00198] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The extensive and sometimes irresponsible use of beta-lactam antibiotics in clinical and agricultural settings has contributed to the emergence and widespread dissemination of antibiotic-resistant bacteria. Bacteria have evolved three strategies to escape the activity of beta-lactam antibiotics: 1) alteration of the target site (e.g. penicillin-binding protein (PBPs), 2) reduction of drug permeation across the bacterial membrane (e.g. efflux pumps) and 3) production of beta-lactamase enzymes. The beta-lactamase enzymes inactivate beta-lactam antibiotics by hydrolyzing the peptide bond of the characteristic four-membered beta-lactam ring rendering the antibiotic ineffective. The inactivation of the antibiotic provides resistance to the bacterium. Currently, there are over 300 beta-lactamase enzymes described for which numerous kinetic, structural, computational and mutagenesis studies have been performed. In this review, we discuss the recent work performed on the four different classes (A, B, C, and D) of beta-lactamases. These investigative advances further expand our knowledge about these complex enzymes, and hopefully, will provide us with additional tools to develop new inhibitors and antibiotics based on structural and rational designs.
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Affiliation(s)
- Fahd K Majiduddin
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
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112
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Ku WY, Liu YW, Hsu YC, Liao CC, Liang PH, Yuan HS, Chak KF. The zinc ion in the HNH motif of the endonuclease domain of colicin E7 is not required for DNA binding but is essential for DNA hydrolysis. Nucleic Acids Res 2002; 30:1670-8. [PMID: 11917029 PMCID: PMC101835 DOI: 10.1093/nar/30.7.1670] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The HNH motif was originally identified in the subfamily of HNH homing endonucleases, which initiate the process of the insertion of mobile genetic elements into specific sites. Several bacteria toxins, including colicin E7 (ColE7), also contain the 30 amino acid HNH motif in their nuclease domains. In this work, we found that the nuclease domain of ColE7 (nuclease-ColE7) purified from Escherichia coli contains a one-to-one stoichiometry of zinc ion and that this zinc-containing enzyme hydrolyzes DNA without externally added divalent metal ions. The apo-enzyme, in which the indigenous zinc ion was removed from nuclease-ColE7, had no DNase activity. Several divalent metal ions, including Ni2+, Mg2+, Co2+, Mn2+, Ca2+, Sr2+, Cu2+ and Zn2+, re-activated the DNase activity of the apo-enzyme to various degrees, however higher concentrations of zinc ion inhibited this DNase activity. Two charged residues located at positions close to the zinc-binding site were mutated to alanine. The single-site mutants, R538A and E542A, showed reduced DNase activity, whereas the double-point mutant, R538A + E542A, had no observable DNase activity. A gel retardation assay further demonstrated that the nuclease-ColE7 hydrolyzed DNA in the presence of zinc ions, but only bound to DNA in the absence of zinc ions. These results demonstrate that the zinc ion in the HNH motif of nuclease-ColE7 is not required for DNA binding, but is essential for DNA hydrolysis, suggesting that the zinc ion not only stabilizes the folding of the enzyme, but is also likely to be involved in DNA hydrolysis.
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Affiliation(s)
- Wen-Yen Ku
- Graduate Institute of Life Science, National Defense Medical Center, Taipei, Taiwan 11472, Republic of China
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113
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Denny BJ, Lambert PA, West PWJ. The flavonoid galangin inhibits the L1 metallo-beta-lactamase from Stenotrophomonas maltophilia. FEMS Microbiol Lett 2002; 208:21-4. [PMID: 11934488 DOI: 10.1111/j.1574-6968.2002.tb11054.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The flavonoid galangin inhibits the partially purified metallo-beta-lactamase from Stenotrophomonas maltophilia. The effect was not reversed by the addition of ZnCl(2) suggesting that the inhibitory effect is not related to metal chelation. The flavonoid quercetin also has some inhibitory effect against the enzyme. Using the crystal structure of the enzyme, a molecular modelling study predicts a possible orientation of galangin at the active site of the enzyme.
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Affiliation(s)
- Brian J Denny
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Kuwait University, Kuwait, Kuwait.
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114
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Materon IC, Palzkill T. Identification of residues critical for metallo-beta-lactamase function by codon randomization and selection. Protein Sci 2001; 10:2556-65. [PMID: 11714924 PMCID: PMC2374027 DOI: 10.1110/ps.40884] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
IMP-1 beta-lactamase is a zinc metallo-enzyme encoded by the transferable bla(IMP-1) gene, which confers resistance to virtually all beta-lactam antibiotics including carbapenems. To understand how IMP-1 recognizes and hydrolyzes beta-lactam antibiotics it is important to determine which amino acid residues are critical for catalysis and which residues control substrate specificity. We randomized 27 individual codons in the bla(IMP-1) gene to create libraries that contain all possible amino acid substitutions at residue positions in and near the active site of IMP-1. Mutants from the random libraries were selected for the ability to confer ampicillin resistance to Escherichia coli. Of the positions randomized, >50% do not tolerate amino acid substitutions, suggesting they are essential for IMP-1 function. The remaining positions tolerate amino acid substitutions and may influence the substrate specificity of the enzyme. Interestingly, kinetic studies for one of the functional mutants, Asn233Ala, indicate that an alanine substitution at this position significantly increases catalytic efficiency as compared with the wild-type enzyme.
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Affiliation(s)
- I C Materon
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA
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115
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de Seny D, Heinz U, Wommer S, Kiefer M, Meyer-Klaucke W, Galleni M, Frere JM, Bauer R, Adolph HW. Metal ion binding and coordination geometry for wild type and mutants of metallo-beta -lactamase from Bacillus cereus 569/H/9 (BcII): a combined thermodynamic, kinetic, and spectroscopic approach. J Biol Chem 2001; 276:45065-78. [PMID: 11551939 DOI: 10.1074/jbc.m106447200] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
One high affinity (nm) and one low affinity (microM) macroscopic dissociation constant for the binding of metal ions were found for the wild-type metallo-beta-lactamase from Bacillus cereus as well as six single-site mutants in which all ligands in the two metal binding sites were altered. Surprisingly, the mutations did not cause a specific alteration of the affinity of metal ions for the sole modified binding site as determined by extended x-ray absorption fine structure (EXAFS) and perturbed angular correlation of gamma-rays spectroscopy, respectively. Also UV-visible absorption spectra for the mono-cobalt enzymes clearly contain contributions from both metal sites. The observations of the very similar microscopic dissociation constants of both binding sites in contrast to the significantly differing macroscopic dissociation constants inevitably led to the conclusion that binding to the two metal sites exhibits negative cooperativity. The slow association rates for forming the binuclear enzyme determined by stopped-flow fluorescence measurements suggested that fast metal exchange between the two sites for the mononuclear enzyme hinders the binding of a second metal ion. EXAFS spectroscopy of the mono- and di-zinc wild type enzymes and two di-zinc mutants provide a definition of the metal ion environments, which is compared with the available x-ray crystallographic data.
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Affiliation(s)
- D de Seny
- Centre d'Ingéniérie des Protéines, Institut de Chimie B6, Université de Liège, Sart-Tilman, B-4000 Liège, Belgium
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116
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Mollard C, Moali C, Papamicael C, Damblon C, Vessilier S, Amicosante G, Schofield CJ, Galleni M, Frere JM, Roberts GC. Thiomandelic acid, a broad spectrum inhibitor of zinc beta-lactamases: kinetic and spectroscopic studies. J Biol Chem 2001; 276:45015-23. [PMID: 11564740 DOI: 10.1074/jbc.m107054200] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Resistance to beta-lactam antibiotics mediated by metallo-beta-lactamases is an increasingly worrying clinical problem. Candidate inhibitors include mercaptocarboxylic acids, and we report studies of a simple such compound, thiomandelic acid. A series of 35 analogues were synthesized and examined as metallo-beta-lactamase inhibitors. The K(i) values (Bacillus cereus enzyme) are 0.09 microm for R-thiomandelic acid and 1.28 microm for the S-isomer. Structure-activity relationships show that the thiol is essential for activity and the carboxylate increases potency; the affinity is greatest when these groups are close together. Thioesters of thiomandelic acid are substrates for the enzyme, liberating thiomandelic acid, suggesting a starting point for the design of "pro-drugs." Importantly, thiomandelic acid is a broad spectrum inhibitor of metallo-beta-lactamases, with a submicromolar K(i) value for all nine enzymes tested, except the Aeromonas hydrophila enzyme; such a wide spectrum of activity is unprecedented. The binding of thiomandelic acid to the B. cereus enzyme was studied by NMR; the results are consistent with the idea that the inhibitor thiol binds to both zinc ions, while its carboxylate binds to Arg(91). Amide chemical shift perturbations for residues 30-40 (the beta(3)-beta(4) loop) suggest that this small inhibitor induces a movement of this loop of the kind seen for other larger inhibitors.
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Affiliation(s)
- C Mollard
- Biological NMR Centre, Department of Biochemistry, University of Leicester, P.O. Box 138, University Rd., Leicester LE1 9HN, United Kingdom
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117
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Spencer J, Clarke AR, Walsh TR. Novel mechanism of hydrolysis of therapeutic beta-lactams by Stenotrophomonas maltophilia L1 metallo-beta-lactamase. J Biol Chem 2001; 276:33638-44. [PMID: 11443136 DOI: 10.1074/jbc.m105550200] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Stopped-flow tryptophan fluorescence under single turnover and pseudo-first-order conditions has been used to investigate the kinetic mechanism of beta-lactam hydrolysis by the Stenotrophomonas maltophilia L1 metallo-beta-lactamase. For the cephalosporin substrates nitrocefin and cefaclor and the carbapenem meropenem, a substantial quench of fluorescence is observed on association of substrate with enzyme. We have assigned this to a rearrangement event subsequent to formation of an initial collision complex. For the colorimetric compound nitrocefin, decay of this dark inter- mediate represents the overall rate-determining step for the reaction and is equivalent to decay of a previously observed state in which the beta-lactam amide bond has already been cleaved. For both cefaclor and meropenem, the rate-determining step for hydrolysis is loss of a second, less quenched state, in which, however, the beta-lactam amide bond remains intact. We suggest, therefore, that the mechanism of hydrolysis of nitrocefin by binuclear metallo-beta-lactamases may be atypical and that cleavage of the beta-lactam amide bond is the rate-determining step for breakdown of the majority of beta-lactam substrates by the L1 enzyme.
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Affiliation(s)
- J Spencer
- Department of Pathology and Microbiology, University of Bristol School of Medical Sciences, University Walk, Bristol BS8 1TD, United Kingdom.
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118
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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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119
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Zervosen A, Valladares MH, Devreese B, Prosperi-Meys C, Adolph HW, Mercuri PS, Vanhove M, Amicosante G, van Beeumen J, Frère JM, Galleni M. Inactivation of Aeromonas hydrophila metallo-beta-lactamase by cephamycins and moxalactam. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:3840-50. [PMID: 11432752 DOI: 10.1046/j.1432-1327.2001.02298.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Incubation of moxalactam and cefoxitin with the Aeromonas hydrophila metallo-beta-lactamase CphA leads to enzyme-catalyzed hydrolysis of both compounds and to irreversible inactivation of the enzyme by the reaction products. As shown by electrospray mass spectrometry, the inactivation of CphA by cefoxitin and moxalactam is accompanied by the formation of stable adducts with mass increases of 445 and 111 Da, respectively. The single thiol group of the inactivated enzyme is no longer titrable, and dithiothreitol treatment of the complexes partially restores the catalytic activity. The mechanism of inactivation by moxalactam was studied in detail. Hydrolysis of moxalactam is followed by elimination of the 3' leaving group (5-mercapto-1-methyltetrazole), which forms a disulfide bond with the cysteine residue of CphA located in the active site. Interestingly, this reaction is catalyzed by cacodylate.
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Affiliation(s)
- A Zervosen
- Centre for Protein Engineering, University of Liège, Belgium
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120
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Mercuri PS, Bouillenne F, Boschi L, Lamotte-Brasseur J, Amicosante G, Devreese B, van Beeumen J, Frère JM, Rossolini GM, Galleni M. Biochemical characterization of the FEZ-1 metallo-beta-lactamase of Legionella gormanii ATCC 33297T produced in Escherichia coli. Antimicrob Agents Chemother 2001; 45:1254-62. [PMID: 11257043 PMCID: PMC90452 DOI: 10.1128/aac.45.4.1254-1262.2001] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bla(FEZ-1) gene coding for the metallo-beta-lactamase of Legionella (Fluoribacter) gormanii ATCC 33297T was overexpressed via a T7 expression system in Escherichia coli BL21(DE3)(pLysS). The product was purified to homogeneity in two steps with a yield of 53%. The FEZ-1 metallo-beta-lactamase exhibited a broad-spectrum activity profile, with a preference for cephalosporins such as cephalothin, cefuroxime, and cefotaxime. Monobactams were not hydrolyzed. The beta-lactamase was inhibited by metal chelators. FEZ-1 is a monomeric enzyme with a molecular mass of 29,440 Da which possesses two zinc-binding sites. Its zinc content did not vary in the pH range of 5 to 9, but the presence of zinc ions modified the catalytic efficiency of the enzyme. A model of the FEZ-1 three-dimensional structure was built.
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Affiliation(s)
- P S Mercuri
- Centre d'Ingénierie des Protéines, Université de Liège, B-4000 Liège, Belgium
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121
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D'Amico S, Gerday C, Feller G. Structural similarities and evolutionary relationships in chloride-dependent alpha-amylases. Gene 2000; 253:95-105. [PMID: 10925206 DOI: 10.1016/s0378-1119(00)00229-8] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The alpha-amylase sequences contained in databanks were screened for the presence of amino acid residues Arg195, Asn298 and Arg/Lys337 forming the chloride-binding site of several specialized alpha-amylases allosterically activated by this anion. This search provides 38 alpha-amylases potentially binding a chloride ion. All belong to animals, including mammals, birds, insects, acari, nematodes, molluscs, crustaceans and are also found in three extremophilic Gram-negative bacteria. An evolutionary distance tree based on complete amino acid sequences was constructed, revealing four distinct clusters of species. On the basis of multiple sequence alignment and homology modeling, invariable structural elements were defined, corresponding to the active site, the substrate binding site, the accessory binding sites, the Ca(2+) and Cl(-) binding sites, a protease-like catalytic triad and disulfide bonds. The sequence variations within functional elements allowed engineering strategies to be proposed, aimed at identifying and modifying the specificity, activity and stability of chloride-dependent alpha-amylases.
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Affiliation(s)
- S D'Amico
- Laboratory of Biochemistry, Institute of Chemistry B6, University of Liège, B-4000, Liège, Belgium.
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122
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Chantalat L, Duée E, Galleni M, Frère JM, Dideberg O. Structural effects of the active site mutation cysteine to serine in Bacillus cereus zinc-beta-lactamase. Protein Sci 2000; 9:1402-6. [PMID: 10933508 PMCID: PMC2144673 DOI: 10.1110/ps.9.7.1402] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Beta-lactamases are involved in bacterial resistance. Members of the metallo-enzyme class are now found in many pathogenic bacteria and are becoming thus of major clinical importance. Despite the availability of Zn-beta-lactamase X-ray structures their mechanism of action is still unclear. One puzzling observation is the presence of one or two zincs in the active site. To aid in assessing the role of zinc content in beta-lactam hydrolysis, the replacement by Ser of the zinc-liganding residue Cys168 in the Zn-beta-lactamase from Bacillus cereus strain 569/H/9 was carried out: the mutant enzyme (C168S) is inactive in the mono-Zn form, but active in the di-Zn form. The structure of the mono-Zn form of the C168S mutant has been determined at 1.85 A resolution. Ser168 occupies the same position as Cys168 in the wild-type enzyme. The protein residues mostly affected by the mutation are Asp90-Arg91 and His210. A critical factor for the activity of the mono-Zn species is the distance between Asp90 and the Zn ion, which is controlled by Arg91: a slight movement of Asp90 impairs catalysis. The evolution of a large superfamily including Zn-beta-lactamases suggests that they may not all share the same mechanism.
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Affiliation(s)
- L Chantalat
- Laboratoire de Cristallographie Macromoléculaire, Institut de Biologie Structurale Jean-Pierre Ebel, CNRS/CEA, Grenoble, France
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123
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Hernandez Valladares M, Kiefer M, Heinz U, Soto RP, Meyer-Klaucke W, Nolting HF, Zeppezauer M, Galleni M, Frère JM, Rossolini GM, Amicosante G, Adolph HW. Kinetic and spectroscopic characterization of native and metal-substituted beta-lactamase from Aeromonas hydrophila AE036. FEBS Lett 2000; 467:221-5. [PMID: 10675542 DOI: 10.1016/s0014-5793(00)01102-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Two metal ion binding sites are conserved in metallo-beta-lactamase from Aeromonas hydrophila. The ligands of a first zinc ion bound with picomolar dissociation constant were identified by EXAFS spectroscopy as one Cys, two His and one additional N/O donor. Sulfur-to-metal charge transfer bands are observed for all mono- and di-metal species substituted with Cu(II) or Co(II) due to ligation of the single conserved cysteine residue. Binding of a second metal ion results in non-competitive inhibition which might be explained by an alternative kinetic mechanism. A possible partition of metal ions between the two binding sites is discussed.
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124
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Abstract
This past year has produced determinations of X-ray crystal structures for three metallo-beta-lactamases and the elucidation of the catalytic mechanisms for a monozinc and a dizinc enzyme. These advances shed light on how such a diverse group of enzymes are evolving to inactivate so efficiently a broad spectrum of beta-lactam antibiotics.
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Affiliation(s)
- Z Wang
- The Pennsylvania State University, Department of Chemistry, 152 Davey Laboratory, University Park, PA 16802, USA
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125
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Cricco JA, Orellano EG, Rasia RM, Ceccarelli EA, Vila AJ. Metallo-β-lactamases: does it take two to tango? Coord Chem Rev 1999. [DOI: 10.1016/s0010-8545(99)00113-7] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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126
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Yang KW, Crowder MW. Inhibition studies on the metallo-beta-lactamase L1 from Stenotrophomonas maltophilia. Arch Biochem Biophys 1999; 368:1-6. [PMID: 10415104 DOI: 10.1006/abbi.1999.1293] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In an effort to identify a competitive inhibitor that can be used in future spectroscopic and crystallographic studies and to better understand the interaction of a mercaptoacetic acid-thiolester-containing compound with metallo-beta-lactamase L1 from Stenotrophomonas maltophilia, inhibition studies using two thiol-containing compounds were conducted. N-(2'-Mercaptoethyl)-2-phenylacetamide is a competitive inhibitor of L1 with a K(i) of 50 +/- 3 microM, and this compound is not a time-dependent inactivator of L1. N-Benzylacetyl-d-alanylthioacetic acid is a competitive inhibitor of L1 with a K(i) of 1.6 +/- 0.3 microM. Matrix-assisted laser desorption ionization time-of-flight mass spectrometric studies revealed that 2 mol of mercaptoacetate covalently bind to L1 upon incubation of the enzyme with N-benzylacetyl-d-alanylthioacetic acid; however, this covalently modified enzyme has the same activity as wild-type L1. Last, inhibition studies were used to demonstrate that 4-morpholinoethanesulfonic acid does not inhibit L1, even at concentrations up to 300 mM. This work identifies two possible competitive inhibitors which can be used in future structural studies and further demonstrates inhibitory heterogeneity among the metallo-beta-lactamases.
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Affiliation(s)
- K W Yang
- Department of Chemistry and Biochemistry, Miami University, 112 Hughes Hall, Oxford, Ohio, 45056, USA
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127
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Paul-Soto R, Bauer R, Frère JM, Galleni M, Meyer-Klaucke W, Nolting H, Rossolini GM, de Seny D, Hernandez-Valladares M, Zeppezauer M, Adolph HW. Mono- and binuclear Zn2+-beta-lactamase. Role of the conserved cysteine in the catalytic mechanism. J Biol Chem 1999; 274:13242-9. [PMID: 10224083 DOI: 10.1074/jbc.274.19.13242] [Citation(s) in RCA: 119] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
When expressed by pathogenic bacteria, Zn2+-beta-lactamases induce resistance to most beta-lactam antibiotics. A possible strategy to fight these bacteria would be a combined therapy with non-toxic inhibitors of Zn2+-beta-lactamases together with standard antibiotics. For this purpose, it is important to verify that the inhibitor is effective under all clinical conditions. We have investigated the correlation between the number of zinc ions bound to the Zn2+-beta-lactamase from Bacillus cereus and hydrolysis of benzylpenicillin and nitrocefin for the wild type and a mutant where cysteine 168 is replaced by alanine. It is shown that both the mono-Zn2+ (mononuclear) and di-Zn2+ (binuclear) Zn2+-beta-lactamases are catalytically active but with different kinetic properties. The mono-Zn2+-beta-lactamase requires the conserved cysteine residue for hydrolysis of the beta-lactam ring in contrast to the binuclear enzyme where the cysteine residue is not essential. Substrate affinity is not significantly affected by the mutation for the mononuclear enzyme but is decreased for the binuclear enzyme. These results were derived from kinetic studies on two wild types and the mutant enzyme with benzylpenicillin and nitrocefin as substrates. Thus, targeting drug design to modify this residue might represent an efficient strategy, the more so if it also interferes with the formation of the binuclear enzyme.
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Affiliation(s)
- R Paul-Soto
- Fachrichtung 12.4 Biochemie, Universitaet des Saarlandes, D-66041 Saarbruecken, Germany
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128
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Laraki N, Franceschini N, Rossolini GM, Santucci P, Meunier C, de Pauw E, Amicosante G, Frère JM, Galleni M. Biochemical characterization of the Pseudomonas aeruginosa 101/1477 metallo-beta-lactamase IMP-1 produced by Escherichia coli. Antimicrob Agents Chemother 1999; 43:902-6. [PMID: 10103197 PMCID: PMC89223 DOI: 10.1128/aac.43.4.902] [Citation(s) in RCA: 174] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/1998] [Accepted: 01/05/1999] [Indexed: 01/25/2023] Open
Abstract
The blaIMP gene coding for the IMP-1 metallo-beta-lactamase produced by a Pseudomonas aeruginosa clinical isolate (isolate 101/1477) was overexpressed via a T7 expression system in Escherichia coli BL21 (DE3), and its product was purified to homogeneity with a final yield of 35 mg/liter of culture. The structural and functional properties of the enzyme purified from E. coli were identical to those of the enzyme produced by P. aeruginosa. The IMP-1 metallo-beta-lactamase exhibits a broad-spectrum activity profile that includes activity against penicillins, cephalosporins, cephamycins, oxacephamycins, and carbapenems. Only monobactams escape its action. The enzyme activity was inhibited by metal chelators, of which 1,10-o-phenanthroline and dipicolinic acid were the most efficient. Two zinc-binding sites were found. The zinc content of the P. aeruginosa 101/1477 metallo-beta-lactamase was not pH dependent.
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Affiliation(s)
- N Laraki
- Laboratoire d'Enzymologie, Institut de Chimie, Université de Liège, Belgium
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129
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130
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Prosperi-Meys C, Llabres G, de Seny D, Soto RP, Valladares MH, Laraki N, Frere JM, Galleni M. Interaction between class B beta-lactamases and suicide substrates of active-site serine beta-lactamases. FEBS Lett 1999; 443:109-11. [PMID: 9989585 DOI: 10.1016/s0014-5793(98)01689-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The most widely used inactivators of active-site serine beta-lactamases behave as substrates of four class B metallo-beta-lactamases, but the efficiency of the catalytic process can vary by several orders of magnitude. A comparison of the kinetic parameters for the alpha and beta isomers of 6-iodopenicillanic acid shows that there is no general preference for the alpha isomer and that the efficient hydrolysis of imipenem by these enzymes must rest on other factors.
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Affiliation(s)
- C Prosperi-Meys
- Centre d'Ingénierie des Protéines (B6), Université de Liège, Belgium.
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131
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Ullah JH, Walsh TR, Taylor IA, Emery DC, Verma CS, Gamblin SJ, Spencer J. The crystal structure of the L1 metallo-beta-lactamase from Stenotrophomonas maltophilia at 1.7 A resolution. J Mol Biol 1998; 284:125-36. [PMID: 9811546 DOI: 10.1006/jmbi.1998.2148] [Citation(s) in RCA: 278] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The structure of the L1 metallo-beta-lactamase from the opportunistic pathogen Stenotrophomonas maltophilia has been determined at 1.7 A resolution by the multiwavelength anomalous dispersion (MAD) approach exploiting both the intrinsic binuclear zinc centre and incorporated selenomethionine residues. L1 is unique amongst all known beta-lactamases in that it exists as a tetramer. The protein exhibits the alphabeta/betaalpha fold found only in the metallo-beta-lactamases and displays several unique features not previously observed in these enzymes. These include a disulphide bridge and two substantially elongated loops connected to the active site of the enzyme. Two closely spaced zinc ions are bound at the active site with tetrahedral (Zn1) and trigonal bipyramidal (Zn2) co-ordination, respectively; these are bridged by a water molecule which we propose acts as the nucleophile in the hydrolytic reaction. Ligation of the second zinc ion involves both residues and geometry which have not been previously observed in the metallo-beta-lactamases. Simulated binding of the substrates ampicillin, ceftazidime and imipenem suggests that the substrate is able to bind to the enzyme in a variety of different conformations whose common features are direct interactions of the beta-lactam carbonyl oxygen and nitrogen with the zinc ions and of the beta-lactam carboxylate with Ser187. We describe a catalytic mechanism whose principal features are a nucleophilic attack of the bridging water on the beta-lactam carbonyl carbon, electrostatic stabilisation of a negatively charged tetrahedral transition state and protonation of the beta-lactam nitrogen by a second water molecule co-ordinated by Zn2. Further, we propose that direct metal:substrate interactions provide a substantial contribution to substrate binding and that this may explain the lack of specificity which is a feature of this class of enzyme.
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Affiliation(s)
- J H Ullah
- Division of Protein Structure, National Institute of Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK
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132
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Paul-Soto R, Hernandez-Valladares M, Galleni M, Bauer R, Zeppezauer M, Frère JM, Adolph HW. Mono- and binuclear Zn-beta-lactamase from Bacteroides fragilis: catalytic and structural roles of the zinc ions. FEBS Lett 1998; 438:137-40. [PMID: 9821975 DOI: 10.1016/s0014-5793(98)01289-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The Bacteroides fragilis Zn-beta-lactamase is active with a mono- and a binuclear zinc site. The apoenzyme produced by removal of both Zn ions does not recover full activity upon readdition of Zn2+ in contrast to an active mono-Zn form prepared at pH 6.0. Differences in k(cat) values observed are substrate-dependent implying distinct mechanisms for the mono- and binuclear species. The substrate profile of a Zn,Cd hybrid obtained by selective exchange of one zinc ion is different from that of the Zn2 enzyme with a remarkable 15-fold increased activity with cefoxitin as substrate.
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Affiliation(s)
- R Paul-Soto
- Fachrichtung 12.4 Biochemie, Universität des Saarlandes, Saarbrücken, Germany
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133
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Wang Z, Benkovic SJ. Purification, characterization, and kinetic studies of a soluble Bacteroides fragilis metallo-beta-lactamase that provides multiple antibiotic resistance. J Biol Chem 1998; 273:22402-8. [PMID: 9712862 DOI: 10.1074/jbc.273.35.22402] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Resistance to multiple beta-lactam antibiotics traced to the expression of Zn(II) requiring metallo-beta-lactamases has emerged in clinical isolates of several bacterial strains including Bacteroides fragilis, a pathogen commonly found in suppurative/surgical infections. A soluble B. fragilis metallo-beta-lactamase has been purified to homogeneity from the cell growth medium after expression as a secretory protein in Escherichia coli. The enzyme requires two tightly bound Zn(II) ions for full activity, and the Zn(II) ions can be removed by EDTA from the enzyme. The apoenzyme is reactivated by stoichiometric amounts of Zn(II) and Co(II) ions. The Co(II)-substituted enzyme exhibits a UV-visible spectrum characterized by strong Co(II) d-d transitions at 510, 548, 615, and 635 nm and an EPR spectrum with g values of 5. 52, 4.25, and 2.01: features that serve as useful spectroscopic handles for the mechanistic studies of the enzyme. Although steady-state and transient-state kinetic studies of the soluble Zn(II) enzyme with nitrocefin as substrate found no ionizable groups with pKa values between 5.25 and 10.0 involved in catalysis, a kinetically significant proton transfer step in turnover was implicated by studies in deuterium oxide. These studies also detected the accumulation of an enzyme-bound intermediate and provide the basis for a minimal kinetic scheme describing metallo-beta-lactamase-catalyzed nitrocefin hydrolysis.
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Affiliation(s)
- Z Wang
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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134
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Crowder MW, Walsh TR, Banovic L, Pettit M, Spencer J. Overexpression, purification, and characterization of the cloned metallo-beta-lactamase L1 from Stenotrophomonas maltophilia. Antimicrob Agents Chemother 1998; 42:921-6. [PMID: 9559809 PMCID: PMC105568 DOI: 10.1128/aac.42.4.921] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The metallo-beta-lactamase L1 from Stenotrophomonas maltophilia was cloned, overexpressed, and characterized by spectrometric and biochemical techniques. Results of metal analyses were consistent with the cloned enzyme having 2 mol of tightly bound Zn(II) per monomer. Gel filtration chromatography demonstrated that the cloned enzyme exists as a tightly held tetramer with a molecular mass of ca. 115 kDa, and matrix-assisted laser desorption ionization and time-of-flight mass spectrometry indicated a monomeric molecular mass of 28.8 kDa. Steady-state kinetic studies with a number of diverse penicillin and cephalosporin antibiotics demonstrated that L1 effectively hydrolyzes all tested compounds, with k(cat)/Km values ranging between 0.002 and 5.5 microM(-1) s(-1). These characteristics of the recombinant enzyme are contrasted to those previously reported for metallo-beta-lactamases isolated directly from S. maltophilia.
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Affiliation(s)
- M W Crowder
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, USA.
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