References of "Joris, Bernard"
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See detailDiversity of the Mechanisms of Resistance to Beta-Lactam Antibiotics
Frère, Jean-Marie ULg; Joris, Bernard ULg; Granier, B. et al

in Research in Microbiology (1991), 142(6, Jul-Aug), 705-10

The sensitivity of a bacterium to beta-lactam antibiotics depends upon the interplay between 3 independent factors: the sensitivity of the essential penicillin-binding enzyme(s), the quantity and ... [more ▼]

The sensitivity of a bacterium to beta-lactam antibiotics depends upon the interplay between 3 independent factors: the sensitivity of the essential penicillin-binding enzyme(s), the quantity and properties of the beta-lactamase(s) and the diffusion barrier that the outer-membrane of Gram-negative bacteria can represent. Those three factors can be modified by mutations or by the horizontal transfer of genes or portions of genes. [less ▲]

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See detailRole of the Conserved Amino Acids of the 'Sdn' Loop (Ser130, Asp131 and Asn132) in a Class a Beta-Lactamase Studied by Site-Directed Mutagenesis
Jacob, Françoise; Joris, Bernard ULg; Lepage, Sophie et al

in Biochemical Journal (1990), 271(2), 399-406

Ser130, Asp131 and Asn132 ('SDN') are highly conserved residues in class A beta-lactamases forming one wall of the active-site cavity. All three residues of the SDN loop in Streptomyces albus G beta ... [more ▼]

Ser130, Asp131 and Asn132 ('SDN') are highly conserved residues in class A beta-lactamases forming one wall of the active-site cavity. All three residues of the SDN loop in Streptomyces albus G beta-lactamase were modified by site-directed mutagenesis. The mutant proteins were expressed in Streptomyces lividans, purified from culture supernatants and their kinetic parameters were determined for several substrates. Ser130 was substituted by Asn, Ala and Gly. The first modification yielded an almost totally inactive protein, whereas the smaller-side-chain mutants (A and G) retained some activity, but were less stable than the wild-type enzyme. Ser130 might thus be involved in maintaining the structure of the active-site cavity. Mutations of Asp131 into Glu and Gly proved to be highly detrimental to enzyme stability, reflecting significant structural perturbations. Mutation of Asn132 into Ala resulted in a dramatically decreased enzymic activity (more than 100-fold) especially toward cephalosporin substrates, kcat. being the most affected parameter, which would indicate a role of Asn132 in transition-state stabilization rather than in ground-state binding. Comparison of the N132A and the previously described N132S mutant enzymes underline the importance of an H-bond-forming residue at position 132 for the catalytic process. [less ▲]

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See detailEngineering a Novel β-Lactamase by a Single Point Mutation
Jacob, F.; Joris, Bernard ULg; Dideberg, O. et al

in Protein Engineering (1990), 4(1), 79-86

beta-Lactamases are widespread and efficient bacterial enzymes which play a major role in bacterial resistance to penicillins and cephalosporins. In order to elucidate the role of the residues lying in a ... [more ▼]

beta-Lactamases are widespread and efficient bacterial enzymes which play a major role in bacterial resistance to penicillins and cephalosporins. In order to elucidate the role of the residues lying in a conserved loop of the enzymatic cavity of the active-site serine Streptomyces albus G beta-lactamase, modified proteins were produced by oligo-directed mutagenesis. Mutation of Asn116, which lies on one side of the active site cavity pointing to the substrate-binding site, into a serine residue resulted in spectacular modifications of the specificity profile of the enzyme. That replacement yielded an enzyme with a nearly unchanged activity towards good penicillin substrates. In sharp contrast its efficiency in hydrolysing cephalosporins was drastically reduced, the best substrates suffering the largest decrease in the second-order rate constant for serine acylation. In fact that single mutation generated a truly new enzyme behaving exclusively as a penicillinase, a situation which is never encountered to the same degree in any of the numerous naturally occurring variants of class A beta-lactamases. [less ▲]

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See detailExpression in Escherichia Coli of the Carboxy Terminal Domain of the Blar Sensory-Transducer Protein of Bacillus Licheniformis as a Water-Soluble Mr 26,000 Penicillin-Binding Protein
Joris, Bernard ULg; Ledent, P.; Kobayashi, T. et al

in FEMS Microbiology Letters (1990), 58(1), 107-113

A cloning vector has been constructed which allows production and export by Escherichia coli of the Met346-Arg601 carboxy terminal domain of the 601 amino acid BLAR sensory-transducer involved in beta ... [more ▼]

A cloning vector has been constructed which allows production and export by Escherichia coli of the Met346-Arg601 carboxy terminal domain of the 601 amino acid BLAR sensory-transducer involved in beta-lactamase inducibility in Bacillus licheniformis. The polypeptide, referred to as BLAR-CTD, accumulates in the periplasm of E. coli in the form of a water-soluble, Mr 26,000 penicillin-binding protein. These data and homology searches suggest that BLAR has a membrane topology similar to that of other sensory-transducers involved in chemotaxis. [less ▲]

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See detailThe Life-Cycle Proteins Roda of Escherichia Coli and Spove of Bacillus Subtilis Have Very Similar Primary Structures
Joris, Bernard ULg; Dive, Georges ULg; Henriques, A. et al

in Molecular Microbiology (1990), 4(3), 513-517

Comparison of the predicted amino acid sequence of the cell-cycle RodA protein with the National Research Foundation protein sequence database shows that the 370-amino-acid RodA, a protein that is ... [more ▼]

Comparison of the predicted amino acid sequence of the cell-cycle RodA protein with the National Research Foundation protein sequence database shows that the 370-amino-acid RodA, a protein that is essential for wall elongation in Escherichia coli and maintenance of the rod shape of the cell, is highly analogous, in terms of primary structure, with the Bacillus subtilis SpoVE protein involved in stage V of sporulation. [less ▲]

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See detailIdentification of BlaR, the signal transducer for β-lactamase production in Bacillus licheniformis, as a penicillin-binding protein with strong homology to the OXA-2 β-lactamase (class D) of Salmonella typhimurium
Zhu, Ying-Fang; Curran, Ivan H. A.; Joris, Bernard ULg et al

in Journal of Bacteriology (1990), 172(2), 1137-1141

The blaR gene of Bacillus licheniformis encodes the signal transducer for induction of the class A beta-lactamase. The protein product, BlaR, has a hydrophilic carboxy region that binds beta-lactams and ... [more ▼]

The blaR gene of Bacillus licheniformis encodes the signal transducer for induction of the class A beta-lactamase. The protein product, BlaR, has a hydrophilic carboxy region that binds beta-lactams and shows high sequence homology to the class D beta-lactamases, particularly the OXA-2 beta-lactamase of Salmonella typhimurium. The BlaR-beta-lactam complex is stable and may provide the continuing stimulus needed for the prolonged production of the enzyme. [less ▲]

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See detailThe Diversity of the Catalytic Properties of Class a Beta-Lactamases
Matagne, André ULg; Misselyn-Bauduin, A. M.; Joris, Bernard ULg et al

in Biochemical Journal (1990), 265(1), 131-46

The catalytic properties of four class A beta-lactamases were studied with 24 different substrates. They exhibit a wide range of variation. Similarly, the amino acid sequences are also quite different ... [more ▼]

The catalytic properties of four class A beta-lactamases were studied with 24 different substrates. They exhibit a wide range of variation. Similarly, the amino acid sequences are also quite different. However, no relationships were found between the sequence similarities and the substrate profiles. Lags and bursts were observed with various compounds containing a large sterically hindered side chain. As a group, the enzymes could be distinguished from the class C beta-lactamases on the basis of the kappa cat. values for several substrates, particularly oxacillin, cloxacillin and carbenicillin. Surprisingly, that distinction was impossible with the kappa cat./Km values, which represent the rates of acylation of the active-site serine residue by the beta-lactam. For several cephalosporin substrates (e.g. cefuroxime and cefotaxime) class A enzymes consistently exhibited higher kappa cat. values than class C enzymes, thus belying the usual distinction between 'penicillinases' and 'cephalosporinases'. The problem of the repartition of class A beta-lactamases into sub-classes is discussed. [less ▲]

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See detailNucleotide sequences of the pbpX genes encoding the penicillin-binding proteins 2x from Streptococcus pneumoniae R6 and a cefotaxime-resistant mutant, C506
Laible, G.; Hakenbeck, R.; Sicard, M. A. et al

in Molecular Microbiology (1989), 3(10), 1337-1348

Development of penicillin resistance in Streptococcus pneumoniae is due to successive mutations in penicillin-binding proteins (PBPs) which reduce their affinity for beta-lactam antibiotics. PBP2x is one ... [more ▼]

Development of penicillin resistance in Streptococcus pneumoniae is due to successive mutations in penicillin-binding proteins (PBPs) which reduce their affinity for beta-lactam antibiotics. PBP2x is one of the high-Mr PBPs which appears to be altered both in resistant clinical isolates, and in cefotaxime-resistant laboratory mutants. In this study, we have sequenced a 2564 base-pair chromosomal fragment from the penicillin-sensitive S. pneumoniae strain R6, which contains the PBP2x gene. Within this fragment, a 2250 base-pair open reading frame was found which coded for a protein having an Mr of 82.35kD, a value which is in good agreement with the Mr of 80-85 kD measured by SDS-gel electrophoresis of the PBP2x protein itself. The N-terminal region resembled an unprocessed signal peptide and was followed by a hydrophobic sequence that may be responsible for membrane attachment of PBP2x. The corresponding nucleotide sequence of the PBP2x gene from C504, a cefotaxime-resistant laboratory mutant obtained after five selection steps, contained three nucleotide substitutions, causing three amino acid alterations within the beta-lactam binding domain of the PBP2x protein. Alterations affecting similar regions of Escherichia coli PBP3 and Neisseria gonorrhoeae PBP2 from beta-lactam-resistant strains are known. The penicillin-binding domain of PBP2x shows highest homology with these two PBPs and S. pneumoniae PBP2b. In contrast, the N-terminal extension of PBP2x has the highest homology with E. coli PBP2 and methicillin-resistant Staphylococcus aureus PBP2'. No significant homology was detected with PBP1a or PBP1b of Escherichia coli, or with the low-Mr PBPs. [less ▲]

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See detailQuantitative Relationship between Sensitivity to Beta-Lactam Antibiotics and Beta-Lactamase Production in Gram-Negative Bacteria--II. Non-Steady-State Treatment and Progress Curves
Frère, Jean-Marie ULg; Joris, Bernard ULg; Crine, Michel ULg et al

in Biochemical Pharmacology (1989), 38(9), 1427-33

A non-steady-state model is discussed for the study of the interplay between beta-lactamase activity and outer membrane permeability with slowly hydrolysed beta-lactams. The analysis shows: (1) that the ... [more ▼]

A non-steady-state model is discussed for the study of the interplay between beta-lactamase activity and outer membrane permeability with slowly hydrolysed beta-lactams. The analysis shows: (1) that the simple, steady-state model presented in the accompanying paper remains valid as long as kcat (i.e. k3 with chromosome-encoded class C beta-lactamases) is larger than 10(-3)/sec (generation time = 20 min or more); (2) that among the beta-lactam antibiotics studied here, the complete, non-steady-state model needs only be used in the case of aztreonam; (3) that the term "trapping" should be replaced by "formation of a covalent acyl-enzyme" and that such a phenomenon only contributes significantly to the resistance when penetration and hydrolysis are very slow and the periplasmic beta-lactamase concentration is very high. Aztreonam seems to be the only compound which fulfils the first two conditions. [less ▲]

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See detailThe Streptomyces K15 DD-peptidase/penicillin-binding protein. Active site and sequence of the N-terminal region.
Leyh-Bouille, Mélina; Vanbeeumen, Jozef; Renier-Pirlot, Suzanne et al

in Biochemical Journal (1989), 260(2), 601-604

The N-terminal region of the Streptomyces K15 DD-peptidase/penicillin-binding protein shows high homology with that of other penicillin-interactive proteins or domains. The active-site serine residue of ... [more ▼]

The N-terminal region of the Streptomyces K15 DD-peptidase/penicillin-binding protein shows high homology with that of other penicillin-interactive proteins or domains. The active-site serine residue of the conserved tetrad Ser-Xaa-Xaa-Lys occurs at position 35. There is no indication for the presence of a signal peptide or an N-terminal hydrophobic sequence, suggesting that the Streptomyces K15 enzyme is probably anchored to the membrane by a C-terminal peptide segment. [less ▲]

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See detailSequence and Comparative Analysis of Three Enterobacter Cloacae Ampc Beta-Lactamase Genes and Their Products
Galleni, Moreno ULg; Lindberg, F.; Normark, S. et al

in Biochemical Journal (1988), 250(3), 753-60

The sequences of three Enterobacter cloacae ampC beta-lactamase genes have been determined. The deduced amino acid sequences are very similar: out of a total of 361 residues, only eight positions were ... [more ▼]

The sequences of three Enterobacter cloacae ampC beta-lactamase genes have been determined. The deduced amino acid sequences are very similar: out of a total of 361 residues, only eight positions were found to be variable, and several mutations yielded residues with very similar properties. The kinetic properties of two of the enzymes were not significantly different. The three enzymes also exhibited a high degree of homology (greater than 70%) with the ampC beta-lactamases of Escherichia coli K12 and Citrobacter freundii, confirming the homogeneity of class-C beta-lactamases. [less ▲]

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See detailThe Active-Site-Serine Penicillin-Recognizing Enzymes as Members of the Streptomyces R61 Dd-Peptidase Family
Joris, Bernard ULg; Ghuysen, Jean-Marie ULg; Dive, Georges ULg et al

in Biochemical Journal (1988), 250(2), 313-324

Homology searches and amino acid alignments, using the Streptomyces R61 DD-peptidase/penicillin-binding protein as reference, have been applied to the beta-lactamases of classes A and C, the Oxa-2 beta ... [more ▼]

Homology searches and amino acid alignments, using the Streptomyces R61 DD-peptidase/penicillin-binding protein as reference, have been applied to the beta-lactamases of classes A and C, the Oxa-2 beta-lactamase (considered as the first known member of an additional class D), the low-Mr DD-peptidases/penicillin-binding proteins (protein no. 5 of Escherichia coli and Bacillus subtilis) and penicillin-binding domains of the high-Mr penicillin-binding proteins (PBP1A, PBP1B, PBP2 and PBP3 of E. coli). Though the evolutionary distance may vary considerably, all these penicillin-interactive proteins and domains appear to be members of a single superfamily of active-site-serine enzymes distinct from the classical trypsin or subtilisin families. The amino acid alignments reveal several conserved boxes that consist of strict identities or homologous amino acids. The significance of these boxes is highlighted by the known results of X-ray crystallography, chemical derivatization and site-directed-mutagenesis experiments. [less ▲]

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See detailStructure-Activity Relationships in the Beta-Lactam Family: An Impossible Dream
Frère, Jean-Marie ULg; Joris, Bernard ULg; Varetto, Louis ULg et al

in Biochemical Pharmacology (1988), 37(1), 125-32

The difficulty of establishing structure-activity relationships in the beta-lactam family of antibiotics stems from the fact that: (1) The targets in various bacteria exhibit widely different ... [more ▼]

The difficulty of establishing structure-activity relationships in the beta-lactam family of antibiotics stems from the fact that: (1) The targets in various bacteria exhibit widely different sensitivities. (2) Some bacteria produce beta-lactamases, enzymes capable of destroying the antibiotics. The rates of the reactions with the beta-lactamases and the target enzymes are not necessarily related. (3) In Gram-negative bacteria, the diffusion rate through the outer membrane varies independently from the two other factors. [less ▲]

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See detailPurification and Characterization of a β-lactam-Resistant Penicillin-Binding Protein from Enterococcus hirae (Streptococcus faecium)
Jacques, Philippe; El Kharroubi, Aboubaker; Joris, Bernard ULg et al

in Actor, Paul; Daneo-Moore, Lolita; Higgins, Michael L. (Eds.) et al Antibiotic Inhibition of Bacterial Cell Surface Assembly and Function (1988)

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See detailChromosome-encoded beta-lactamases of Citrobacter diversus. Interaction with beta-iodopenicillanate and labelling of the active site.
Amicosante, G; Oratore, A; Joris, Bernard ULg et al

in Biochemical Journal (1988), 254(3), 891-3

Both forms of the chromosome-encoded beta-lactamase of Citrobacter diversus react with beta-iodopenicillanate at a rate characteristic of class A beta-lactamases. The active site of form I was labelled ... [more ▼]

Both forms of the chromosome-encoded beta-lactamase of Citrobacter diversus react with beta-iodopenicillanate at a rate characteristic of class A beta-lactamases. The active site of form I was labelled with the same reagent. The sequence of the peptide obtained after trypsin hydrolysis is identical with that of a peptide obtained in a similar manner from the chromosome-encoded beta-lactamase of Klebsiella pneumoniae. [less ▲]

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See detailPenicillin-recognizing enzymes
Frère, Jean-Marie ULg; Joris, Bernard ULg; Dideberg, Otto et al

in Biochemical Society Transactions (1988), 16(6), 934-938

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See detailBeta-Lactamases as the Main Resistance Factor to Penicillin-Related Antibiotics
Frère, Jean-Marie ULg; Joris, Bernard ULg

in Annales de Biologie Clinique (1988), 46(2), 151-6

The interplay between the three factors involved in the resistance of bacteria to beta-lactam antibiotics (sensitivity of target, synthesis of beta-lactamase, permeability barrier) is analysed and ... [more ▼]

The interplay between the three factors involved in the resistance of bacteria to beta-lactam antibiotics (sensitivity of target, synthesis of beta-lactamase, permeability barrier) is analysed and discussed on the basis of a simple kinetic model. The three factors do not act independently. In Gram-negative bacteria, the permeability barrier is only significant when the bacterial cell also produces a beta-lactamase. Special attention is devoted to cases where large periplasmic beta-lactamase concentrations prevail, a situation which has been observed in some clinical isolates. [less ▲]

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See detailBeta-Lactamase-induced resistance
Frère, Jean-Marie ULg; Joris, Bernard ULg

in Actor, Paul; Daneo-Moore, Lolita; Higgins, Michael, L. (Eds.) et al Antibiotic Inhibition of Bacterial Cell Surface Assembly and Function (1988)

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See detailNucleotide sequence of the gene encoding the Streptomyces albus G β-lactamase precursor
Dehottay, Philippe; Dusart, Jean; De Meester, Fabien et al

in European Journal of Biochemistry (1987), 166(2), 345-350

A 1400-base DNA fragment, which contains the gene encoding the extracellular active-site serine beta-lactamase of Streptomyces albus G previously cloned into Streptomyces lividans [Dehottay et al. (1986 ... [more ▼]

A 1400-base DNA fragment, which contains the gene encoding the extracellular active-site serine beta-lactamase of Streptomyces albus G previously cloned into Streptomyces lividans [Dehottay et al. (1986) Gene 42, 31-36], was sequenced. The gene codes for a 314-amino-acid precursor, the N-terminal region of which has the characteristics of a signal peptide. The beta-lactamase as excreted by the host strain S. lividans PD6 has a ragged N-terminus, indicating either the presence of a leader peptidase of poor specificity or the action of an aminopeptidase. The primary structure (as deduced from the nucleotide sequence) was confirmed by amino acid sequencing of a 16-residue stretch at the amino terminus of the protein, a 12-residue stretch containing the active-site serine [De Meester et al. (1987) Biochem. J. 244, 427-432] and a 23-residue stretch obtained by trypsin digestion of the protein. The beta-lactamase belongs to class A, has three half-cystine residues (one of which occurs on the amino side of the active-site serine) and is inactivated by thiol reagents. Putative ribosome binding site and terminator region were identified. [less ▲]

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See detailPrimary structure of the Streptomyces R61 extracellular DD-peptidase. 2. Amino acid sequence data
Joris, Bernard ULg; Jacques, Philippe; Frère, Jean-Marie ULg et al

in European Journal of Biochemistry (1987), 162(3), 519-524

In order to confirm the Streptomyces codon usage, the Streptomyces R61 DD-peptidase was fragmented by cyanogen bromide cleavage of the carboxymethylated protein, trypsin digestion of the carboxymethylated ... [more ▼]

In order to confirm the Streptomyces codon usage, the Streptomyces R61 DD-peptidase was fragmented by cyanogen bromide cleavage of the carboxymethylated protein, trypsin digestion of the carboxymethylated protein and trypsin digestion of the protein treated with beta-iodopenicillinate and endoxo-delta 4-tetrahydrophthalic acid. The isolated peptides, which altogether represented more than 50% of the polypeptide chain, were sequenced. The data thus obtained were in excellent agreement with the primary structure of the protein as deduced from the nucleotide sequence of the cloned gene. Though a weak acylating agent, beta-iodopenicillanate reacted selectively with the active site of the DD-peptidase and formed an adduct which mas much more stable than that formed with benzylpenicillin, thus facilitating the isolation and characterization of the active-site peptide. [less ▲]

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