References of "Frère, Jean-Marie"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailKinetic properties of four plasmid-mediated AmpC beta-lactamases.
Bauvois, Cedric; Ibuka, Akiko Shimizu; Celso, Almeida et al

in Antimicrobial agents and chemotherapy (2005), 49(10), 4240-6

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 ... [more ▼]

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. [less ▲]

Detailed reference viewed: 14 (0 ULg)
Full Text
Peer Reviewed
See detailInactivation of bacterial DD-peptidase by beta-sultams.
Llinas, Antonio; Ahmed, Naveed; Cordaro, Massimiliano et al

in Biochemistry (2005), 44(21), 7738-46

N-Acyl-beta-sultams are time-dependent, irreversible active site-directed inhibitors of Streptomyces R61 DD-peptidase. The rate of inactivation is first order with respect to beta-sultam concentration ... [more ▼]

N-Acyl-beta-sultams are time-dependent, irreversible active site-directed inhibitors of Streptomyces R61 DD-peptidase. The rate of inactivation is first order with respect to beta-sultam concentration, and the second-order rate constants show a dependence on pH similar to that for the hydrolysis of a substrate. Inactivation is due to the formation of a stable 1:1 enzyme-inhibitor complex as a result of the active site serine being sulfonylated by the beta-sultam as shown by ESI-MS analysis and by X-ray crystallography. A striking feature of the sulfonyl enzyme is that the inhibitor is not bound to the oxyanion hole but interacts extensively with the "roof" of the active site where the Arg 285 is located. [less ▲]

Detailed reference viewed: 10 (1 ULg)
Full Text
Peer Reviewed
See detailIs it necessary to change the classification of ß-lactamases?
Frère, Jean-Marie ULg; Galleni, Moreno ULg; Bush, Karen et al

in Journal of Antimicrobial Chemotherapy (2005), 55(6), 1051-1053

Detailed reference viewed: 9 (0 ULg)
Full Text
Peer Reviewed
See detailSpecificity inversion of Ochrobactrum anthropi D-aminopeptidase to a D,D-carboxypeptidase with new penicillin binding activity by directed mutagenesis
Delmarcelle, Michaël ULg; Boursoit, Marie-Caroline; Filée, Patrice ULg et al

in Protein Science : A Publication of the Protein Society (2005), 14

Detailed reference viewed: 15 (5 ULg)
Full Text
Peer Reviewed
See detailCrystal structure of BRL 42715, C6-(N1-methyl-1,2,3-triazolylmethylene)penem, in complex with Enterobacter cloacae 908R beta-lactamase: evidence for a stereoselective mechanism from docking studies.
Michaux, Catherine; Charlier, Paulette ULg; Frère, Jean-Marie ULg et al

in Journal of the American Chemical Society (2005), 127(10), 3262-3

BRL 42715, C6-(N1-methyl-1,2,3-triazolylmethylene)penem, is an active-site-directed inactivator of bacterial beta-lactamases. The crystal structure of Enterobacter cloacae 908R class C beta-lactamase in ... [more ▼]

BRL 42715, C6-(N1-methyl-1,2,3-triazolylmethylene)penem, is an active-site-directed inactivator of bacterial beta-lactamases. The crystal structure of Enterobacter cloacae 908R class C beta-lactamase in complex with BRL 42715, docking, and energy minimization studies explain stereoselectivity of the binding of C6-(heterocyclic methylene)penems against class C beta-lactamase. [less ▲]

Detailed reference viewed: 15 (0 ULg)
Full Text
Peer Reviewed
See detailCrystal structure of the Actinomadura R39 DD-peptidase reveals new domains in penicillin-binding proteins.
Sauvage, Eric ULg; Herman, Raphaël ULg; Petrella, Stephanie et al

in Journal of Biological Chemistry (2005), 280(35), 31249-56

Actinomadura sp. R39 produces an exocellular DD-peptidase/penicillin-binding protein (PBP) whose primary structure is similar to that of Escherichia coli PBP4. It is characterized by a high beta-lactam ... [more ▼]

Actinomadura sp. R39 produces an exocellular DD-peptidase/penicillin-binding protein (PBP) whose primary structure is similar to that of Escherichia coli PBP4. It is characterized by a high beta-lactam-binding activity (second order rate constant for the acylation of the active site serine by benzylpenicillin: k2/K = 300 mm(-1) s(-1)). The crystal structure of the DD-peptidase from Actinomadura R39 was solved at a resolution of 1.8 angstroms by single anomalous dispersion at the cobalt resonance wavelength. The structure is composed of three domains: a penicillin-binding domain similar to the penicillin-binding domain of E. coli PBP5 and two domains of unknown function. In most multimodular PBPs, additional domains are generally located at the C or N termini of the penicillin-binding domain. In R39, the other two domains are inserted in the penicillin-binding domain, between the SXXK and SXN motifs, in a manner similar to "Matryoshka dolls." One of these domains is composed of a five-stranded beta-sheet with two helices on one side, and the other domain is a double three-stranded beta-sheet inserted in the previous domain. Additionally, the 2.4-angstroms structure of the acyl-enzyme complex of R39 with nitrocefin reveals the absence of active site conformational change upon binding the beta-lactams. [less ▲]

Detailed reference viewed: 67 (20 ULg)
See detailOn the way of understanding the adaptation to extreme pH of family 11 xylanases: Structural comparison and mutational analysis
De Lemos Esteves, Frédéric ULg; Ruelle, Virginie; Gouders, Thierry et al

Poster (2004, December)

Detailed reference viewed: 13 (2 ULg)
Full Text
Peer Reviewed
See detailGuanidinium chloride denaturation of the dimeric Bacillus licheniformis Blal repressor highlights an independent domain unfolding pathway
Vreuls, Christelle ULg; Filée, Patrice ULg; Van Melckebeke, H. et al

in Biochemical Journal (2004), 384(Pt 1), 179-190

The Bacillus licheniformis 74911 BlaI repressor is a prokaryotic regulator that, in the absence of a P-lactam antibiotic, prevents the transcription of the blaP gene, which encodes the BlaP beta-lactamase ... [more ▼]

The Bacillus licheniformis 74911 BlaI repressor is a prokaryotic regulator that, in the absence of a P-lactam antibiotic, prevents the transcription of the blaP gene, which encodes the BlaP beta-lactamase. The BlaI repressor is composed of two structural domains. The 82-residue NTD (N-terminal domain) is a DNA-binding domain, and the CTD (C-terminal domain) containing the next 46 residues is a dimerization domain. Recent studies have shown the existence of the monomeric, dimeric and tetrameric forms of BlaI in solution. In the present study, we analyse the equilibrium unfolding of BlaI in the presence of GdmCl (guanidinium chloride) using different techniques: intrinsic and ANS (8-anilinonaphthalene-1-sulphonic acid) fluorescence, far- and near-UV CD spectroscopy, cross-linking, analytical ultracentrifugation, size exclusion chromatography and NMR spectroscopy. In addition, the intact NTD and CTD were purified after proteolysis of BlaI by papain, and their unfolding by GdmCl was also studied. GdmCl-induced equilibrium unfolding was shown to be fully reversible for BlaI and for the two isolated fragments. The results demonstrate that the NTD and CTD of BlaI fold/unfold independently in a four-step process, with no significant cooperative interactions between them. During the first step, the unfolding of the Blal CTD occurs, followed in the second step by the formation of an 'ANS-bound' intermediate state. Crosslinking and analytical ultracentrifugation experiments suggest that the dissociation of the dimer into two partially unfolded monomers takes place in the third step. Finally, the unfolding of the Blal NTD occurs at a GdmCI concentration of approx. 4 M. In summary, it is shown that the Blal CTD is structured, more flexible and less stable than the NTD upon GdmCI denaturation. These results contribute to the characterization of the Blal dimerization domain (i.e. CTD) involved in the induction process. [less ▲]

Detailed reference viewed: 57 (7 ULg)
Full Text
Peer Reviewed
See detailProbing the specificity of the subclass B3 FEZ-1 metallo-beta-lactamase by site-directed mutagenesis
Mercuri, P. S.; Garcia-Saez, I.; De Vriendt, K. et al

in Journal of Biological Chemistry (2004), 279(32), 33630-33638

The subclass B3 FEZ-1 beta-lactamase produced by Fluoribacter (Legionella) gormanii is a Zn(II)-containing enzyme that hydrolyzes the beta-lactam bond in penicillins, cephalosporins, and carbapenems. FEZ ... [more ▼]

The subclass B3 FEZ-1 beta-lactamase produced by Fluoribacter (Legionella) gormanii is a Zn(II)-containing enzyme that hydrolyzes the beta-lactam bond in penicillins, cephalosporins, and carbapenems. FEZ-1 has been extensively studied using kinetic, computational modeling and x-ray crystallography. In an effort to probe residues potentially involved in substrate binding and zinc binding, five site-directed mutants of FEZ-1 (H121A, Y156A, S221A, N225A, and Y228A) were prepared and characterized using metal analyses and steady state kinetics. The activity of H121A is dependent on zinc ion concentration. The H121A monozinc form is less active than the dizinc form, which exhibits an activity similar to that of the wild type enzyme. Tyr156 is not essential for binding and hydrolysis of the substrate. Substitution of residues Ser221 and Asn225 modifies the substrate profile by selectively decreasing the activity against carbapenems. The Y228A mutant is inhibited by the product formed upon hydrolysis of cephalosporins. A covalent bond between the side chain of Cys200 and the hydrolyzed cephalosporins leads to the formation of an inactive and stable complex. [less ▲]

Detailed reference viewed: 9 (0 ULg)
Full Text
Peer Reviewed
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

Detailed reference viewed: 25 (2 ULg)
Peer Reviewed
See detailTwo-color-sum-frequency generation characterization of a protein monolayer adsorbed on a metallic substrate
Dreesen, Laurent ULg; Sartenaer, Yannick; Humbert, Christophe et al

Poster (2004, June)

Detailed reference viewed: 18 (1 ULg)
See detailTwo-color-sum-frequency generation characterization of a protein monolayer adsorbed on a metallic substrate
Dreesen, Laurent ULg; Sartenaer, Yannick; Humbert, Christophe et al

Poster (2004, May 25)

Detailed reference viewed: 9 (1 ULg)
Full Text
Peer Reviewed
See detailThe inhibition of metallo-beta-lactamase by thioxo-cephalosporin derivatives
Tsang, W. Y.; Dhanda, A.; Schofield, C. J. et al

in Bioorganic & Medicinal Chemistry Letters (2004), 14(7), 1737-1739

The 8-thioxocephalosporins are poor substrates for the B. cereus metallo beta-lactamase (k(cat)/K-m = 61.4 M-1 s(-1)) and act as weak competitive inhibitors (K-i similar to 700 muM). The hydrolysis ... [more ▼]

The 8-thioxocephalosporins are poor substrates for the B. cereus metallo beta-lactamase (k(cat)/K-m = 61.4 M-1 s(-1)) and act as weak competitive inhibitors (K-i similar to 700 muM). The hydrolysis product of thioxocephalosporin, a thioacid, also inhibits the enzyme competitively with a K-i = 96 muM, whereas the cyclic thioxo-piperazinedione, formed by intramolecular aminolysis of thioxo-cephalexin has a K-i of 29 muM. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 164 (0 ULg)
Full Text
Peer Reviewed
See detailEvidence of an intramolecular interaction between the two domains of the BlaR1 penicillin receptor during the signal transduction
Hanique, Sophie; Colombo, Maria-Luigi; Goormaghtigh, Erik et al

in Journal of Biological Chemistry (2004), 279(14), 14264-14272

The BlaR1 protein is a penicillin-sensory transducer involved in the induction of the Bacillus licheniformis beta-lactamase. The amino-terminal domain of the protein exhibits four transmembrane segments ... [more ▼]

The BlaR1 protein is a penicillin-sensory transducer involved in the induction of the Bacillus licheniformis beta-lactamase. The amino-terminal domain of the protein exhibits four transmembrane segments (TM1-TM4) that form a four-alpha-helix bundle embedded in the plasma bilayer. The carboxyl-terminal domain of 250 amino acids (BlaR-CTD) fused at the carboxyl end of TM4 possesses the amino acid sequence signature of penicillin-binding proteins. This membrane topology suggests that BlaR-CTD and the BlaR-amino-terminal domain are responsible for signal reception and signal transduction, respectively. With the use of phage display experiments, we highlight herein an interaction between BlaR-CTD and the extracellular, 63-amino acid L2 loop connecting TM2 and TM3. This interaction does not occur in the presence of penicillin. This result suggests that binding of the antibiotic to BlaR1 might entail the release of the interaction between L2 and BlaR-CTD, causing a motion of the alpha-helix bundle and transfer of the information to the cytoplasm of the cell. In addition, fluorescence spectroscopy, CD, and Fourier transform IR spectroscopy experiments indicate that in contrast to the behavior of the corresponding Staphylococcus aureus protein, the beta-lactam antibiotic does not induce a drastic conformational change in B. licheniformis BlaR-CTD. [less ▲]

Detailed reference viewed: 19 (6 ULg)
Full Text
Peer Reviewed
See detailInteractions between penicillin-binding proteins (PBPs) and two novel classes of PBP inhibitors, arylalkylidene rhodanines and arylalkylidene iminothiazolidin-4-ones
Zervosen, Astrid ULg; Lu, Wei-Ping; Chen, Zhouliang et al

in Antimicrobial Agents and Chemotherapy (2004), 48(3), 961-969

Several non-beta-lactam compounds were active against various gram-positive and gram-negative bacterial strains. The MICs of arylalkylidene rhodanines and arylalkylidene iminothiazolidin-4-ones were lower ... [more ▼]

Several non-beta-lactam compounds were active against various gram-positive and gram-negative bacterial strains. The MICs of arylalkylidene rhodanines and arylalkylidene iminothiazolidin-4-ones were lower than those of ampicillin and cefotaxime for methicillin-resistant Staphylococcus aureus M1339 and vancomycin-resistant Enterococcus faecium EF12. Several compounds were found to inhibit the cell wall synthesis of S. aureus and the last two steps of peptidoglycan biosynthesis catalyzed by ether-treated cells of Escherichia coli or cell wall membrane preparations of Bacillus megaterium. The effects of the arylalkylidene rhodanines and arylalkylidene iminothiazolidin-4-one derivatives on E. coli PBP 3 and PBP 5, Streptococcus pneumoniae PBP 2xS (PBP 2x from a penicillin-sensitive strain) and PBP 2xR (PBP 2x from a penicillin-resistant strain), low-affinity PBP 2a of S. aureus, and the Actinomadura sp. strain R39 and Streptomyces sp. strain R61 DD-peptidases were studied. Some of the compounds exhibited inhibitory activities in the 10 to 100 muM concentration range. The inhibition of PBP 2xS by several of them appeared to be noncompetitive. The dissociation constant for the best inhibitor (K-i = 10 muM) was not influenced by the presence of the substrate. [less ▲]

Detailed reference viewed: 36 (0 ULg)
Full Text
Peer Reviewed
See detailAcidophilic adaptation of family 11 endo--1,4-xylanases: Modeling and mutational analysis
De Lemos Esteves, Frédéric ULg; Ruelle, Virginie; Lamotte-Brasseur, Josette ULg et al

in Protein Science : A Publication of the Protein Society (2004), 13(5), 12091218

Xyl1 from Streptomyces sp. S38 belongs to the low molecular mass family 11 of endo--1,4-xylanases. Its three-dimensional structure has been solved at 2.0 Å and its optimum temperature and pH for enzymatic ... [more ▼]

Xyl1 from Streptomyces sp. S38 belongs to the low molecular mass family 11 of endo--1,4-xylanases. Its three-dimensional structure has been solved at 2.0 Å and its optimum temperature and pH for enzymatic activity are 60°C and 6.0, respectively. Aspergillus kawachii xylanase XynC belongs to the same family but is an acidophilic enzyme with an optimum pH of 2.0. Structural comparison of Xyl1 and XynC showed differences in residues surrounding the two glutamic acid side chains involved in the catalysis that could be responsible for the acidophilic adaptation of XynC. Mutations W20Y, N48D, A134E, and Y193W were introduced by site-directed mutagenesis and combined in multiple mutants. Trp 20 and Tyr 193 are involved in substrate binding. The Y193W mutation inactivated Xyl1 whereas W20Y decreased the optimum pH of Xyl1 to 5.0 and slightly increased its specific activity. The N48D mutation also decreased the optimum pH of Xyl1 by one unit. The A134E substitution did not induce any change, but when combined with N48D, a synergistic effect was observed with a 1.4 unit decrease in the optimum pH. Modeling showed that the orientations of residue 193 and of the fully conserved Arg 131 are different in acidophilic and alkaline xylanases whereas the introduced Tyr 20 probably modifies the pKa of the acid-base catalyst via residue Asn 48. Docking of a substrate analog in the catalytic site highlighted striking differences between Xyl1 and XynC in substrate binding. Hydrophobicity calculations showed a correlation between acidophilic adaptation and a decreased hydrophobicity around the two glutamic acid side chains involved in catalysis. [less ▲]

Detailed reference viewed: 31 (8 ULg)
Full Text
Peer Reviewed
See detailThe ybxI gene of Bacillus subtilis 168 encodes a class D beta-lactamase of low activity
Colombo, Maria-Luigi; Hanique, Sophie; Baurin, Stéphane L. et al

in Antimicrobial Agents and Chemotherapy (2004), 48(2), 484-490

The ybxI gene of Bacillus subtilis 168 encodes a preprotein of 267 amino acid residues, including a putative signal peptide of 23 residues. The YbxI primary structure exhibits high similarity scores with ... [more ▼]

The ybxI gene of Bacillus subtilis 168 encodes a preprotein of 267 amino acid residues, including a putative signal peptide of 23 residues. The YbxI primary structure exhibits high similarity scores with two members of the superfamily of the serine penicillin-recognizing enzymes: the class D beta-lactamases and the hydrophilic carboxy-terminal domains of the BlaR and MecR penicillin receptors. To determine the function and the activity of this putative penicillin-recognizing enzyme, we have subcloned the ybxI gene in the pET-26b expression vector. Transformation of Escherichia coli BL21(DE3) by the recombinant plasmid pCIP51 resulted in the export of the mature YbxI in the periplasm as a water-soluble protein. The recombinant protein was purified to 95% homogeneity. YbxI interacts with several beta-lactam antibiotics and can hydrolyze some of them. YbxI is not inactivated by clavulanic acid. The YbxI function and its enzymatic activity in B. subtilis remain unknown. The acyl-enzyme obtained after incubation of YbxI with a fluorescent derivative of ampicillin can be detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, confirming that YbxI can be acylated by beta-lactam antibiotics. YbxI does not hydrolyze some of the standard substrates of D-alanyl-D-alanine peptidases, the targets of penicillin. YbxI belongs to the penicillin-recognizing enzyme family but has an activity intermediate between those of a penicillin-binding protein and a beta-lactamase. [less ▲]

Detailed reference viewed: 65 (3 ULg)
Full Text
Peer Reviewed
See detailMutational analysis of the catalytic centre of the Citrobacter freundii AmpD N-acetylmuramyl-L-alanine amidase
Genereux, Catherine ULg; Dehareng, Dominique ULg; Devreese, Bart et al

in Biochemical Journal (2004), 377(Pt 1), 111-120

Citrobacter freundii AmpD is an intracellular 1,6-anhydro-N-acetylmuramyl-L-alanine amidase involved in both peptidoglycan recycling and beta-lactamase induction. AmpD exhibits a strict specificity for 1 ... [more ▼]

Citrobacter freundii AmpD is an intracellular 1,6-anhydro-N-acetylmuramyl-L-alanine amidase involved in both peptidoglycan recycling and beta-lactamase induction. AmpD exhibits a strict specificity for 1,6-anhydromuropeptides and requires zinc for enzymic activity. The AmpD three-dimensional structure exhibits a fold similar to that of another Zn2+ N-acetylmuramyl-L-alanine amidase, the T7 lysozyme, and these two enzymes define a new family of Zn-amidases which can be related to the eukaryotic PGRP (peptidoglycan-recognition protein) domains. In an attempt to assign the different zinc ligands and to probe the catalytic mechanism of AmpD amidase, molecular modelling based on the NMR structure and site-directed mutagenesis were performed. Mutation of the two residues presumed to act as zinc ligands into alanine (H34A and D164A) yielded inactive proteins which had also lost their ability to bind zinc. By contrast, the active H154N mutant retained the capacity to bind the metal ion. Three other residues which could be involved in the AmpD catalytic mechanism have been mutated (Y63F, E116A, K162H and K162Q). The E116A mutant was inactive, but on the basis of the molecular modelling this residue is not directly involved in the catalytic mechanism, but rather in the binding of the zinc by contributing to the correct orientation of His-34. The K162H and K162Q mutants retained very low activity (0.7 and 0.2% of the wildtype activity respectively), whereas the Y63F mutant showed 16% of the wild-type activity. These three latter mutants exhibited a good affinity for Zn ions and the substituted residues are probably involved in the binding of the substrate. We also describe a new method for generating the N-acetylglucosaminyl-1,6-anhydro-N-acetylmuramyl-tripeptide AmpD substrate from purified peptidoglycan by the combined action of two hydrolytic enzymes. [less ▲]

Detailed reference viewed: 41 (10 ULg)
See detailNovel use of lipopeptide preparations
Deleu, Magali ULg; Brans, Alain; Brasseur, Robert ULg et al

Patent (2004)

Detailed reference viewed: 5 (0 ULg)
Full Text
Peer Reviewed
See detailElectronic and Molecular Properties of an Adsorbed Protein Monolayer Probed by Two-Color Sum-Frequency Generation Spectroscopy
Dreesen, Laurent ULg; Humbert, C.; Sartenaer, Y. et al

in Langmuir (2004), 20(17), 7201-7207

Two-color sum-frequency generation spectroscopy (2C-SFG) is used to probe the molecular and electronic properties of an adsorbed layer of the green fluorescent protein mutant 2 (GFPmut2) on a platinum ... [more ▼]

Two-color sum-frequency generation spectroscopy (2C-SFG) is used to probe the molecular and electronic properties of an adsorbed layer of the green fluorescent protein mutant 2 (GFPmut2) on a platinum (111) substrate. First, the spectroscopic measurements, performed under different polarization combinations, and atomic force microscopy (AFM) show that the GFPmut2 proteins form a fairly ordered monolayer on the platinum surface. Next, the nonlinear spectroscopic data provide evidence of particular coupling phenomena between the GFPmut2 vibrational and electronic properties. This is revealed by the occurrence of two doubly resonant sum-frequency generation processes for molecules having both their Raman and infrared transition moments in a direction perpendicular to the sample plane. Finally, our 2C-SFG analysis reveals two electronic transitions corresponding to the absorption and fluorescence energy levels which are related to two different GFPmut2 conformations: the B (anionic) and I forms, respectively. Their observation and wavelength positions attest the keeping of the GFPmut2 electronic properties upon adsorption on the metallic surface. [less ▲]

Detailed reference viewed: 19 (0 ULg)