C. Duez - Academia.edu (original) (raw)
Papers by C. Duez
…, 2001
A penicillin-resistant mutant, JH2-2r (MIC 75 microg ml(-1)), was isolated from Enterococcus faec... more A penicillin-resistant mutant, JH2-2r (MIC 75 microg ml(-1)), was isolated from Enterococcus faecalis JH2-2 (MIC 5 microg ml(-1)) by successive passages on plates containing increasing concentrations of benzylpenicillin. A comparison of the penicillin-binding protein (PBP) profiles in the two strains revealed a more intensely labelled PBP4 in JH2-2r. Because the sequences of the JH2-2 and JH2-2r pbp4 genes were strictly identical, even in their promoter regions, this intensive labelling could only be associated with an overproduction of the low-affinity PBP4. No psr gene analogous to that proposed to act as a regulator of PBP5 synthesis in Enterococcus hirae and Enterococcus faecium could be identified in the vicinity of pbp4 in E. faecalis JH2-2 and JH2-2r. However, a psr-like gene distant from pbp4 was identified. The cloning and sequencing of that psr-like gene from both E. faecalis strains indicated that they were identical. It is therefore postulated that the PBP4 overproduction in E. faecalis JH2-2r results from the modification of an as yet unidentified factor.
Biochemical Journal, 1976
The exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R39 is inhibited by fl-lactam ... more The exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R39 is inhibited by fl-lactam antibiotics according to the same general scheme of reaction as the exocellular DD-Carboxypeptidase-transpeptidase of Streptomyces R61. However, the values for the kinetic constants involved in the reaction are very different for the two enzymes, and provide an explanation for the observation that the R39 enzyme is more sensitive to .8-lactam antibiotics than the R61 enzyme. Further, particular fl-lactams influence the kinetic constants to different extents depending on the source of the enzyme, so that a physical basis for the spectrum of antibiotic activity against particular enzyme systems is provided.
Medecine Sciences M S, 1998
European Journal of Anaesthesiology
We investigate the dripping of liquids around solid surfaces in the regime of inertial flows, a s... more We investigate the dripping of liquids around solid surfaces in the regime of inertial flows, a situation commonly encountered with the so-called "teapot effect". We demonstrate that surface wettability is an unexpected key factor in controlling flow separation and dripping, the latter being completely suppressed in the limit of superhydrophobic substrates. This unforeseen coupling is rationalized in terms of a novel hydro-capillary adhesion framework, which couples inertial flows to surface wettability effects. This description of flow separation successfully captures the observed dependence on the various experimental parameters - wettability, flow velocity, solid surface edge curvature-. As a further illustration of this coupling, a real-time control of dripping is demonstrated using electro-wetting for contact angle actuation. Comment: 4 pages; movies at http://lpmcn.univ-lyon1.fr/~lbocquet
Revue Française d'Allergologie et d'Immunologie Clinique, 2008
Les allergènes sont capables d'induire une production d'IgE spécifiques et d'être reconnus par ce... more Les allergènes sont capables d'induire une production d'IgE spécifiques et d'être reconnus par ceux-ci afin d'activer les cellules exprimant leurs récepteurs, en particulier les mastocytes et basophiles qui expriment le FceRI, récepteur de haute affinité. Cependant, ils sont également capables de stimuler directement certaines cellules de la muqueuse respiratoire, notamment par une voie dépendante des protéases. Ainsi, de nombreux allergènes comme les acariens de la poussière de maison (Dermatophagoides pteronyssinus et Dermatophagoides farinae) présentent une activité protéasique impliquée dans l'activation des cellules épithéliales bronchiques, des cellules dendritiques, des lymphocytes T, des cellules B, des éosinophiles et des cellules musculaires lisses. L'ensemble de ces activations amplifient la polarisation Th2, le recrutement et l'activation de cellules de l'inflammation, ainsi que la contraction des cellules musculaires lisses. Des récepteurs comme les protease-activated receptor (PAR) ont été impliqués dans ces fonctions. Protease-activated receptor-2 (PAR-2) qui intervient dans l'activation dépendante des protéases de nombreux allergènes, est surexprimé dans les biopsies bronchiques des patients asthmatiques. Ces deux phénomènes pourraient participer au développement et à l'amplification de la réaction asthmatique allergique. # 2008 Elsevier Masson SAS. Tous droits réservés.
Biochimica et biophysica acta, Jan 29, 1981
The Mr 37 000 D-alanyl-D-alanine peptidase excreted by Streptomyces R61 and the Mr 53 000 D-alany... more The Mr 37 000 D-alanyl-D-alanine peptidase excreted by Streptomyces R61 and the Mr 53 000 D-alanyl-D-alanine peptidase excreted by Actinomadura R39 are both characterized by a very uneven distribution of the basic (Arg + Lys) amino acid residues. Trypsin degradation of the heat-denatured enzymes generates (1) thirteen soluble peptides which contain from 2 to 28 residues in the case of the R61 enzyme and nineteen soluble peptides which contain 2 to 39 residues in the case of the R39 enzyme; and (2) three large segments or core peptides which, irrespective of the enzymes from which they originate, consist of 50-60, 70-80 and 110-120 residues. About 90% of the basic (Arg + Lys) amino acid residues are recovered in the soluble tryptic peptides. The core peptides represent 62% (Mr approximately 23 000) and 45% (Mr approximately 24 000) of the untreated R61 and R39 enzymes, respectively. One 28-residue soluble peptide isolated from the R61 enzyme represents the N-terminal portion of the p...
The Biochemical journal, 1981
The exocellular beta-lactamase of Streptomyces albus G has been purified to near protein homogene... more The exocellular beta-lactamase of Streptomyces albus G has been purified to near protein homogeneity. It consists of one single polypeptide chain of mol.wt. 30 000-31 000, has a rather low isoelectric point (at pH 6.0) and contains less lysine (2.1%) and more half-cystine residues than most beta-lactamases from other Gram-positive bacteria. Penicillins are much better substrates than delta 3-cephalosporins; the catalytic-centre activity of good penicillin substrates is 333-500 s-1. The exocellular, mol.wt. 17 000 DD-carboxypeptidase of S. albus G [previously purified to protein homogeneity; Duez, Frère, Geurts, Ghuysen, Dierickx & Delcambe (1978) Biochem. J. 175, 793-800] behaves as an exceedingly poor beta-lactamase, hydrolysing benzylpenicillin into benzylpenicilloate 5 x 10(-6)-fold less rapidly than does the exocellular beta-lactamase. To all appearances, the beta-lactamase has no bivalent cation requirement whereas, as shown elsewhere [Dideberg, Charlier, Dupont, Vermeire, Frèr...
The Biochemical journal, Jan 15, 1996
A gene of Pseudomonas alginovora, called aly, has been cloned in Escherichia coli using a battery... more A gene of Pseudomonas alginovora, called aly, has been cloned in Escherichia coli using a battery of PCR techniques and sequenced. It encodes a 210-amino-acid alginate lyase (EC 4.2.2.3), Aly, in the form of a 233-amino-acid precursor. P. alginovora Aly has been overproduced in E. coli with a His-tag sequence fused at the C-terminal end under conditions in which the formation of inclusion bodies is avoided. His-tagged P. alginovora Aly has the same enzymic properties as the wild-type enzyme and has the specificity of a mannuronate lyase. It can be purified in a one-step procedure by affinity chromatography on Ni(2+)-nitriloacetate resin. The yield is of 5 mg of enzyme per litre of culture. The amplification factor is 12.5 compared with the level of production by wild-type P. alginovora. The six alginate lyases of known primary structure fall into three distinct classes, one of which comprises the pair P. alginovora Aly and Klebsiella pneumoniae Aly.
The Biochemical journal, 1981
Heat denaturation and Pronase degradation of the complex previously formed between benzylpenicill... more Heat denaturation and Pronase degradation of the complex previously formed between benzylpenicillin and the exocellular DD-carboxypeptidase-transpeptidase of Actinomadura R39 yields a heptapeptide H-Leu-Pro-Ala-Ser-Asn-Gly-Val-OH, where the benzylpenicilloyl group is ester-linked to the serine residue. This linkage is very labile and its hydrolysis causes the release of benzylpenicilloate. In contrast, the native benzylpenicilloyl-enzyme complex is very stable (half-life 70 h at 37 degrees C) and its breakdown proceeds via fragmentation of the bound benzylpenicilloyl group [Fuad, Frère, Ghuysen, Duez & Iwatsubo (1976) Biochem. J. 155, 623-629].
The Biochemical journal, Jan 15, 1989
By using the promoter-probe plasmid pIJ424, genomic DNA fragments of Actinomadura R39 were shown ... more By using the promoter-probe plasmid pIJ424, genomic DNA fragments of Actinomadura R39 were shown to have promoter activity in Streptomyces lividans. The same 100-200-copy-number plasmid was used to clone in S. lividans TK24, the gene that encodes the Actinomadura R39 beta-lactamase. Gene cloning resulted in an amplified expression of the beta-lactamase when compared with the amounts of enzyme produced by the original strain (1 mg versus 0.008 mg.litre of culture-1).
The Biochemical journal, 1978
The exocellular DD-carboxypeptidase-endopeptidase of Streptomyces albus G was purified to protein... more The exocellular DD-carboxypeptidase-endopeptidase of Streptomyces albus G was purified to protein homogeneity and compared with the exocellular DD-carboxypeptidases-transpeptidases of Streptomyces R61 and Actinomadura R39. The S. albus G enzyme, as it is isolated, occurs in two forms. Enzyme I (30% of the total amount) and enzyme II (70% of the total amount) are identical in all respects, except that, by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate, enzyme I has an apparent mol. wt. (9000) that is half of that found by molecular-sieve filtration under non-denaturing conditions. Irrespective of the technique used, enzyme II has an apparent mol. wt. of about 18500.
"Protein Engineering, Design and Selection", 1988
In free solution, the caseins behave as non-compact and largely flexible molecules with a high pr... more In free solution, the caseins behave as non-compact and largely flexible molecules with a high proportion of residues accessible to solvent. Historically, they have been described as random coil-type proteins with only a nutritional function. Nevertheless, secondary structure prediction algorithms indicate that many parts of the (unphosphorylated, unglycosylated) polypeptide chains can form regular structures. In particular, a recurrent motif of the Ca2+-sensitive caseins in man, rat, mouse, guinea pig and ruminant species is an alpha-helix--loop--alpha-helix conformation in which the loop region typically contains a cluster of sites of phosphorylation. The biological function of the caseins is considered and it is suggested that the potential or actual conformations of the group of Ca2+-sensitive caseins are suited to the function of modulating the precipitation of calcium phosphate from solution. Either they can act as sites for nucleation or they can bind rapidly to calcium phosphate nuclei as they form spontaneously from supersaturated solution.
Journal of Biotechnology, 2005
The cloning and sequencing of the rbpa gene coding for a versatile peroxidase from a novel Bjerka... more The cloning and sequencing of the rbpa gene coding for a versatile peroxidase from a novel Bjerkandera strain is hereby reported. The 1777 bp isolated fragment contained a 1698 bp peroxidase-encoding gene, interrupted by 11 introns. The 367 amino acid-deduced sequence includes a 27 amino acid-signal peptide. The molecular model, built via homology modelling with crystal structures of four fungal peroxidases, highlighted the amino acid residues putatively involved in manganese binding and aromatic substrate oxidation. The potential heme pocket residues (R44, F47, H48, E79, N85, H177, F194 and D239) include both distal and proximal histidines (H48 and H177). RBP possesses potential calcium-binding residues (D49, G67, D69, S71, S178, D195, T197, I200 and D202) and eight cysteine residues (C3, C15, C16, C35, C121, C250, C286, C316). In addition, RBP includes residues involved in substrate oxidation: three acidic residues (E37, E41 and D183)-putatively involved in manganese binding and H83 and W172-potentially involved in oxidation of aromatic substrates. Characterisation of nucleotide and amino acid sequences include RBP in versatile peroxidase group sharing catalytic properties of both LiP and MnP. In addition, the RBP enzyme appears to be closely related with the ligninolytic peroxidases from the Trametes versicolor strain.
…, 2001
A penicillin-resistant mutant, JH2-2r (MIC 75 microg ml(-1)), was isolated from Enterococcus faec... more A penicillin-resistant mutant, JH2-2r (MIC 75 microg ml(-1)), was isolated from Enterococcus faecalis JH2-2 (MIC 5 microg ml(-1)) by successive passages on plates containing increasing concentrations of benzylpenicillin. A comparison of the penicillin-binding protein (PBP) profiles in the two strains revealed a more intensely labelled PBP4 in JH2-2r. Because the sequences of the JH2-2 and JH2-2r pbp4 genes were strictly identical, even in their promoter regions, this intensive labelling could only be associated with an overproduction of the low-affinity PBP4. No psr gene analogous to that proposed to act as a regulator of PBP5 synthesis in Enterococcus hirae and Enterococcus faecium could be identified in the vicinity of pbp4 in E. faecalis JH2-2 and JH2-2r. However, a psr-like gene distant from pbp4 was identified. The cloning and sequencing of that psr-like gene from both E. faecalis strains indicated that they were identical. It is therefore postulated that the PBP4 overproduction in E. faecalis JH2-2r results from the modification of an as yet unidentified factor.
Biochemical Journal, 1976
The exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R39 is inhibited by fl-lactam ... more The exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R39 is inhibited by fl-lactam antibiotics according to the same general scheme of reaction as the exocellular DD-Carboxypeptidase-transpeptidase of Streptomyces R61. However, the values for the kinetic constants involved in the reaction are very different for the two enzymes, and provide an explanation for the observation that the R39 enzyme is more sensitive to .8-lactam antibiotics than the R61 enzyme. Further, particular fl-lactams influence the kinetic constants to different extents depending on the source of the enzyme, so that a physical basis for the spectrum of antibiotic activity against particular enzyme systems is provided.
Medecine Sciences M S, 1998
European Journal of Anaesthesiology
We investigate the dripping of liquids around solid surfaces in the regime of inertial flows, a s... more We investigate the dripping of liquids around solid surfaces in the regime of inertial flows, a situation commonly encountered with the so-called "teapot effect". We demonstrate that surface wettability is an unexpected key factor in controlling flow separation and dripping, the latter being completely suppressed in the limit of superhydrophobic substrates. This unforeseen coupling is rationalized in terms of a novel hydro-capillary adhesion framework, which couples inertial flows to surface wettability effects. This description of flow separation successfully captures the observed dependence on the various experimental parameters - wettability, flow velocity, solid surface edge curvature-. As a further illustration of this coupling, a real-time control of dripping is demonstrated using electro-wetting for contact angle actuation. Comment: 4 pages; movies at http://lpmcn.univ-lyon1.fr/~lbocquet
Revue Française d'Allergologie et d'Immunologie Clinique, 2008
Les allergènes sont capables d'induire une production d'IgE spécifiques et d'être reconnus par ce... more Les allergènes sont capables d'induire une production d'IgE spécifiques et d'être reconnus par ceux-ci afin d'activer les cellules exprimant leurs récepteurs, en particulier les mastocytes et basophiles qui expriment le FceRI, récepteur de haute affinité. Cependant, ils sont également capables de stimuler directement certaines cellules de la muqueuse respiratoire, notamment par une voie dépendante des protéases. Ainsi, de nombreux allergènes comme les acariens de la poussière de maison (Dermatophagoides pteronyssinus et Dermatophagoides farinae) présentent une activité protéasique impliquée dans l'activation des cellules épithéliales bronchiques, des cellules dendritiques, des lymphocytes T, des cellules B, des éosinophiles et des cellules musculaires lisses. L'ensemble de ces activations amplifient la polarisation Th2, le recrutement et l'activation de cellules de l'inflammation, ainsi que la contraction des cellules musculaires lisses. Des récepteurs comme les protease-activated receptor (PAR) ont été impliqués dans ces fonctions. Protease-activated receptor-2 (PAR-2) qui intervient dans l'activation dépendante des protéases de nombreux allergènes, est surexprimé dans les biopsies bronchiques des patients asthmatiques. Ces deux phénomènes pourraient participer au développement et à l'amplification de la réaction asthmatique allergique. # 2008 Elsevier Masson SAS. Tous droits réservés.
Biochimica et biophysica acta, Jan 29, 1981
The Mr 37 000 D-alanyl-D-alanine peptidase excreted by Streptomyces R61 and the Mr 53 000 D-alany... more The Mr 37 000 D-alanyl-D-alanine peptidase excreted by Streptomyces R61 and the Mr 53 000 D-alanyl-D-alanine peptidase excreted by Actinomadura R39 are both characterized by a very uneven distribution of the basic (Arg + Lys) amino acid residues. Trypsin degradation of the heat-denatured enzymes generates (1) thirteen soluble peptides which contain from 2 to 28 residues in the case of the R61 enzyme and nineteen soluble peptides which contain 2 to 39 residues in the case of the R39 enzyme; and (2) three large segments or core peptides which, irrespective of the enzymes from which they originate, consist of 50-60, 70-80 and 110-120 residues. About 90% of the basic (Arg + Lys) amino acid residues are recovered in the soluble tryptic peptides. The core peptides represent 62% (Mr approximately 23 000) and 45% (Mr approximately 24 000) of the untreated R61 and R39 enzymes, respectively. One 28-residue soluble peptide isolated from the R61 enzyme represents the N-terminal portion of the p...
The Biochemical journal, 1981
The exocellular beta-lactamase of Streptomyces albus G has been purified to near protein homogene... more The exocellular beta-lactamase of Streptomyces albus G has been purified to near protein homogeneity. It consists of one single polypeptide chain of mol.wt. 30 000-31 000, has a rather low isoelectric point (at pH 6.0) and contains less lysine (2.1%) and more half-cystine residues than most beta-lactamases from other Gram-positive bacteria. Penicillins are much better substrates than delta 3-cephalosporins; the catalytic-centre activity of good penicillin substrates is 333-500 s-1. The exocellular, mol.wt. 17 000 DD-carboxypeptidase of S. albus G [previously purified to protein homogeneity; Duez, Frère, Geurts, Ghuysen, Dierickx & Delcambe (1978) Biochem. J. 175, 793-800] behaves as an exceedingly poor beta-lactamase, hydrolysing benzylpenicillin into benzylpenicilloate 5 x 10(-6)-fold less rapidly than does the exocellular beta-lactamase. To all appearances, the beta-lactamase has no bivalent cation requirement whereas, as shown elsewhere [Dideberg, Charlier, Dupont, Vermeire, Frèr...
The Biochemical journal, Jan 15, 1996
A gene of Pseudomonas alginovora, called aly, has been cloned in Escherichia coli using a battery... more A gene of Pseudomonas alginovora, called aly, has been cloned in Escherichia coli using a battery of PCR techniques and sequenced. It encodes a 210-amino-acid alginate lyase (EC 4.2.2.3), Aly, in the form of a 233-amino-acid precursor. P. alginovora Aly has been overproduced in E. coli with a His-tag sequence fused at the C-terminal end under conditions in which the formation of inclusion bodies is avoided. His-tagged P. alginovora Aly has the same enzymic properties as the wild-type enzyme and has the specificity of a mannuronate lyase. It can be purified in a one-step procedure by affinity chromatography on Ni(2+)-nitriloacetate resin. The yield is of 5 mg of enzyme per litre of culture. The amplification factor is 12.5 compared with the level of production by wild-type P. alginovora. The six alginate lyases of known primary structure fall into three distinct classes, one of which comprises the pair P. alginovora Aly and Klebsiella pneumoniae Aly.
The Biochemical journal, 1981
Heat denaturation and Pronase degradation of the complex previously formed between benzylpenicill... more Heat denaturation and Pronase degradation of the complex previously formed between benzylpenicillin and the exocellular DD-carboxypeptidase-transpeptidase of Actinomadura R39 yields a heptapeptide H-Leu-Pro-Ala-Ser-Asn-Gly-Val-OH, where the benzylpenicilloyl group is ester-linked to the serine residue. This linkage is very labile and its hydrolysis causes the release of benzylpenicilloate. In contrast, the native benzylpenicilloyl-enzyme complex is very stable (half-life 70 h at 37 degrees C) and its breakdown proceeds via fragmentation of the bound benzylpenicilloyl group [Fuad, Frère, Ghuysen, Duez & Iwatsubo (1976) Biochem. J. 155, 623-629].
The Biochemical journal, Jan 15, 1989
By using the promoter-probe plasmid pIJ424, genomic DNA fragments of Actinomadura R39 were shown ... more By using the promoter-probe plasmid pIJ424, genomic DNA fragments of Actinomadura R39 were shown to have promoter activity in Streptomyces lividans. The same 100-200-copy-number plasmid was used to clone in S. lividans TK24, the gene that encodes the Actinomadura R39 beta-lactamase. Gene cloning resulted in an amplified expression of the beta-lactamase when compared with the amounts of enzyme produced by the original strain (1 mg versus 0.008 mg.litre of culture-1).
The Biochemical journal, 1978
The exocellular DD-carboxypeptidase-endopeptidase of Streptomyces albus G was purified to protein... more The exocellular DD-carboxypeptidase-endopeptidase of Streptomyces albus G was purified to protein homogeneity and compared with the exocellular DD-carboxypeptidases-transpeptidases of Streptomyces R61 and Actinomadura R39. The S. albus G enzyme, as it is isolated, occurs in two forms. Enzyme I (30% of the total amount) and enzyme II (70% of the total amount) are identical in all respects, except that, by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate, enzyme I has an apparent mol. wt. (9000) that is half of that found by molecular-sieve filtration under non-denaturing conditions. Irrespective of the technique used, enzyme II has an apparent mol. wt. of about 18500.
"Protein Engineering, Design and Selection", 1988
In free solution, the caseins behave as non-compact and largely flexible molecules with a high pr... more In free solution, the caseins behave as non-compact and largely flexible molecules with a high proportion of residues accessible to solvent. Historically, they have been described as random coil-type proteins with only a nutritional function. Nevertheless, secondary structure prediction algorithms indicate that many parts of the (unphosphorylated, unglycosylated) polypeptide chains can form regular structures. In particular, a recurrent motif of the Ca2+-sensitive caseins in man, rat, mouse, guinea pig and ruminant species is an alpha-helix--loop--alpha-helix conformation in which the loop region typically contains a cluster of sites of phosphorylation. The biological function of the caseins is considered and it is suggested that the potential or actual conformations of the group of Ca2+-sensitive caseins are suited to the function of modulating the precipitation of calcium phosphate from solution. Either they can act as sites for nucleation or they can bind rapidly to calcium phosphate nuclei as they form spontaneously from supersaturated solution.
Journal of Biotechnology, 2005
The cloning and sequencing of the rbpa gene coding for a versatile peroxidase from a novel Bjerka... more The cloning and sequencing of the rbpa gene coding for a versatile peroxidase from a novel Bjerkandera strain is hereby reported. The 1777 bp isolated fragment contained a 1698 bp peroxidase-encoding gene, interrupted by 11 introns. The 367 amino acid-deduced sequence includes a 27 amino acid-signal peptide. The molecular model, built via homology modelling with crystal structures of four fungal peroxidases, highlighted the amino acid residues putatively involved in manganese binding and aromatic substrate oxidation. The potential heme pocket residues (R44, F47, H48, E79, N85, H177, F194 and D239) include both distal and proximal histidines (H48 and H177). RBP possesses potential calcium-binding residues (D49, G67, D69, S71, S178, D195, T197, I200 and D202) and eight cysteine residues (C3, C15, C16, C35, C121, C250, C286, C316). In addition, RBP includes residues involved in substrate oxidation: three acidic residues (E37, E41 and D183)-putatively involved in manganese binding and H83 and W172-potentially involved in oxidation of aromatic substrates. Characterisation of nucleotide and amino acid sequences include RBP in versatile peroxidase group sharing catalytic properties of both LiP and MnP. In addition, the RBP enzyme appears to be closely related with the ligninolytic peroxidases from the Trametes versicolor strain.