References of "Galleni, Moreno"
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See detailUpdate of the standard numbering scheme for class B beta-lactamases
Garau, G.; Garcia-Saez, I.; Bebrone, Carine ULg et al

in Antimicrobial Agents and Chemotherapy (2004), 48(7), 2347-2349

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See detailSynthesis and evaluation of N1/C4-substituted beta-lactams as PPE and HLE inhibitors
Gérard, Stéphane; Galleni, Moreno ULg; Dive, Georges ULg et al

in Bioorganic & Medicinal Chemistry (2004), 12(1), 129-138

4-(Alkylamino)carbonyl-1-(alkoxy)carbonyl-2-azetidinones (9-11) have been prepared in five steps from 4-(benzyloxy)carbonyl-1-(t-butyidimethyl)silyl-2-azetidinone (1). The P-lactam reactivity of 9 has ... [more ▼]

4-(Alkylamino)carbonyl-1-(alkoxy)carbonyl-2-azetidinones (9-11) have been prepared in five steps from 4-(benzyloxy)carbonyl-1-(t-butyidimethyl)silyl-2-azetidinone (1). The P-lactam reactivity of 9 has been established by H-1 NMR experiment. Compound 11 was a good reversible inhibitor of PPE and HLE. Based on theoretical design, series of 2-azetidinones (12-17) and 4(alkoxy)carbonyl-2-azetidinones (18-21) bearing various carbonyl (ester, thiolester, amide) and thiocarbonyl (thioamide) functionalities at position N1 were similarly prepared. In the absence of C4-substituent, the compounds were inactive against elastases. On the other hand, 4-(benzyloxy)carbonyl-1-(ethylthioxy)carbonyl-2-azetidinone (19) and 4-(benzyloxy)carbonyl-1-(benzylamino)-thiocarbonyl-2-azetidinone (21) were both good reversible inhibitors, but acting most probably via different mechanisms (enzymic processing of the exocyclic ester function or beta-lactam ring opening). (C) 2003 Elsevier Ltd. All rights reserved. [less ▲]

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See detailRole of Cys221 and Asn116 in the zinc-binding sites of the Aeromonas hydrophila metallo-beta-lactamase.
Vanhove, Marc; Zakhem, M.; Devreese, B. et al

in Cellular and molecular life sciences : CMLS (2003), 60(11), 2501-9

The CphA metallo-beta-lactamase produced by Aeromonas hydrophila exhibits two zinc-binding sites. Maximum activity is obtained upon binding of one zinc ion, whereas binding of the second zinc ion results ... [more ▼]

The CphA metallo-beta-lactamase produced by Aeromonas hydrophila exhibits two zinc-binding sites. Maximum activity is obtained upon binding of one zinc ion, whereas binding of the second zinc ion results in a drastic decrease in the hydrolytic activity. In this study, we analyzed the role of Asn116 and Cys221, two residues of the active site. These residues were replaced by site-directed mutagenesis and the different mutants were characterized. The C221S and C221A mutants were seriously impaired in their ability to bind the first, catalytic zinc ion and were nearly completely inactive, indicating a major role for Cys221 in the binding of the catalytic metal ion. By contrast, the binding of the second zinc ion was only slightly affected, at least for the C221S mutant. Mutation of Asn116 did not lead to a drastic decrease in the hydrolytic activity, indicating that this residue does not play a key role in the catalytic mechanism. However, the substitution of Asn116 by a Cys or His residue resulted in an approximately fivefold increase in the affinity for the second, inhibitory zinc ion. Together, these data suggested that the first zinc ion is located in the binding site involving the Cys221 and that the second zinc ion binds in the binding site involving Asn116 and, presumably, His118 and His196. [less ▲]

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See detailActive-site mutants of class B beta-lactamases: substrate binding and mechanistic study
Prosperi-Meys, C.; De Seny, Dominique ULg; Llabres, Gabriel ULg et al

in Cellular & Molecular Life Sciences (2002), 59(12), 2136-2143

Increased resistance to beta-lactam antibiotics is mainly due to beta-lactamases. X-ray structures of zinc beta-lactamases unraveled the coordination of the metal ions, but their mode of action remains ... [more ▼]

Increased resistance to beta-lactam antibiotics is mainly due to beta-lactamases. X-ray structures of zinc beta-lactamases unraveled the coordination of the metal ions, but their mode of action remains unclear. Recently, enzymes in which one of the zinc ligands was mutated have been characterized and their catalytic activity against several beta-lactam antibiotics measured. A molecular modeling study of these enzymes was performed here to explain the catalytic activity of the mutants. Coordination around the zinc ions influences the way the tetrahedral intermediate is bound; any modification influences the first recognition of the substrate by the enzyme. For all the studied mutants, at least one of the interactions fails, inducing a loss of catalytic efficiency compared to the wild type. The present studies show that the enzyme cavity is a structure of high plasticity both structurally and mechanistically and that local modifications may propagate its effects far from the mutated amino acid. [less ▲]

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See detailMutational analysis of the two zinc-binding sites of the Bacillus cereus 569/H/9 metallo-beta-lactamase
De Seny, Dominique ULg; Prosperi, Christelle ULg; Bebrone, Carine ULg et al

in Biochemical Journal (2002), 363(Pt 3), 687-696

The metallo-beta-lactamase BcII from Bacillus cereus 569/H/9 possesses a binuclear zinc centre. The mono-zinc form of the enzyme displays an appreciably high activity. although full efficiency is observed ... [more ▼]

The metallo-beta-lactamase BcII from Bacillus cereus 569/H/9 possesses a binuclear zinc centre. The mono-zinc form of the enzyme displays an appreciably high activity. although full efficiency is observed for the di-zinc enzyme. In an attempt to assign the involvement of the different zinc ligands in the catalytic properties of BcII, individual substitutions of selected amino acids were generated. With the exception of His(116) --> Ser (H116S), C221A and C221S, the mono- and di-zinc forms of all the other mutants were poorly active. The activity of H116S decreases by a factor of 10 when compared with the wild type. The catalytic efficiency of C221A and C221S was zinc-dependent. The monozinc forms of these mutants exhibited a low activity, whereas the catalytic efficiency of their respective di-zinc forms was comparable with that of the wild type. Surprisingly, the zinc contents of the mutants and the wild-type Bell were similar. These data suggest that the affinity of the beta-lactamase for the metal was not affected by the substitution of the ligand. The pH-dependence of the H196S catalytic efficiency indicates that the zinc ions participate in the hydrolysis of the beta-lactam ring by acting as a Lewis acid. The zinc ions activate the catalytic water molecule, but also polarize the carbonyl bond of the beta-lactam ring and stabilize the development of a negative charge on the carbonyl oxygen of the tetrahedral reaction intermediate. Our studies also demonstrate that Asn(233) is not directly involved in the interaction with the substrates. [less ▲]

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See detailMetal 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
De Seny, Dominique ULg; Heinz, U.; Wommer, S. et al

in Journal of Biological Chemistry (2001), 276(48), 45065-78

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 ... [more ▼]

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. [less ▲]

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See detailKinetic Study of Two Novel Enantiomeric Tricyclic Beta-Lactams Which Efficiently Inactivate Class C Beta-Lactamases
Vilar, M.; Galleni, Moreno ULg; Solmajer, T. et al

in Antimicrobial Agents and Chemotherapy (2001), 45(8), 2215-23

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 ... [more ▼]

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. [less ▲]

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See detailInactivation of Aeromonas Hydrophila Metallo-Beta-Lactamase by Cephamycins and Moxalactam
Zervosen, Astrid ULg; Valladares, Maria Hernandez; Devreese, Bart et al

in European Journal of Biochemistry (2001), 268(13), 3840-50

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 ... [more ▼]

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. [less ▲]

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See detailCenta as a Chromogenic Substrate for Studying Beta-Lactamases
Bebrone, Carine ULg; Moali, C.; Mahy, F. et al

in Antimicrobial Agents and Chemotherapy (2001), 45(6), 1868-71

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 ... [more ▼]

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. [less ▲]

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See detailBeta-lactamases, an old but ever renascent problem
Matagne, André ULg; Galleni, Moreno ULg; Laraki, Nezha et al

in van Broekhoven, A (Ed.) Novel Frontiers in the Production of Compounds for Biomedical Use (2001)

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See detailBeta-lactamase inhibitors derived from single-domain antibody fragments elicited in the camelidae.
Conrath, K. E.; Lauwereys, M.; Galleni, Moreno ULg et al

in Antimicrobial Agents and Chemotherapy (2001), 45(10), 2807-12

Small, soluble single-domain fragments derived from the unique variable region of dromedary heavy-chain antibodies (VHHs) against enzymes are known to be potent inhibitors. The immunization of dromedaries ... [more ▼]

Small, soluble single-domain fragments derived from the unique variable region of dromedary heavy-chain antibodies (VHHs) against enzymes are known to be potent inhibitors. The immunization of dromedaries with the TEM-1 and BcII beta-lactamases has lead to the isolation of such single-domain antibody fragments specifically recognizing and inhibiting those beta-lactamases. Two VHHs were isolated that inhibit TEM-1 and one BcII inhibiting VHH was identified. All inhibitory VHHs were tight-binding inhibitors. The 50% inhibitory concentrations were determined for all inhibitors and they were all in the same range as the enzyme concentration used in the assay. Addition of the VHHs to the TEM-1 beta-lactamase, expressed on the surface of bacteria, leads to a higher ampicillin sensitivity of the bacteria. This innovative strategy could generate multiple potent inhibitors for all types of beta-lactamases. [less ▲]

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See detailThiomandelic acid, a broad spectrum inhibitor of zinc beta-lactamases: kinetic and spectroscopic studies.
Mollard, C.; Moali, C.; Papamicael, C. et al

in Journal of Biological Chemistry (2001), 276(48), 45015-23

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 ... [more ▼]

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. [less ▲]

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See detailPeptidase Activity of Beta-Lactamases
Rhazi, Noureddine ULg; Galleni, Moreno ULg; Page, Michael I. et al

in Biochemical Journal (1999), 341((Pt 2)), 409-13

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 ... [more ▼]

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. [less ▲]

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See detailThe Beta-Lactamase Cycle: A Tale of Selective Pressure and Bacterial Ingenuity
Matagne, André ULg; Dubus, Alain; Galleni, Moreno ULg et al

in Natural Product Reports (1999), 16(1), 1-19

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See detailMechanistic Diversity of Beta-Lactamases
Frère, Jean-Marie ULg; Dubus, Alain; Galleni, Moreno ULg et al

in Biochemical Society Transactions (1999), 27(2), 58-63

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See detailInteraction between Class B Beta-Lactamases and Suicide Substrates of Active-Site Serine Beta-Lactamases
Prosperi-Meys, C.; Llabres, Gabriel ULg; De Seny, Dominique ULg et al

in FEBS Letters (1999), 443(2), 109-11

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 ... [more ▼]

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. [less ▲]

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See detailMono- and binuclear Zn2+-beta-lactamase. Role of the conserved cysteine in the catalytic mechanism.
Paul-Soto, R.; Bauer, R.; Frère, Jean-Marie ULg et al

in The Journal of biological chemistry (1999), 274(19), 13242-9

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 ... [more ▼]

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. [less ▲]

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See detailH-1-N-15 HMQC for the identification of metal-bound histidines in Cd-113-substituted Bacillus cereus zinc beta-lactamase
Damblon, Christian ULg; Prosperi, Christelle ULg; Lian, L. Y. et al

in Journal of the American Chemical Society (1999), 121(49), 11575-11576

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See detailRésistance bactérienne aux beta-lactamines
Charlier, Paulette ULg; Coyette, Jacques ULg; Dehareng, Dominique ULg et al

in Medecine Sciences : M/S (1998), 14(5), 544-555

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See detailEtude des beta-lactamases de 7 souches hospitalières de Klebsiella pneumoniae
Evrard, Béatrice; MELIN, Pierrette ULg; Galleni, Moreno ULg et al

Poster (1995, October)

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