References of "Galleni, Moreno"
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See detailFirst detection of CTX-M-28 in a Tunisian hospital from a cefotaxime-resistant Klebsiella pneumoniae strain.
Ben Achour, N.; Mercuri, Paola ULg; Power, P. et al

in Pathologie-biologie (2009), 57(5), 343-8

A cefotaxime-resistant Klebsiella pneumoniae ML4313 was obtained from a patient from intensive care unit of Military hospital in Tunisia. This strain was resistant to beta-lactams, aminoglycosides ... [more ▼]

A cefotaxime-resistant Klebsiella pneumoniae ML4313 was obtained from a patient from intensive care unit of Military hospital in Tunisia. This strain was resistant to beta-lactams, aminoglycosides, quinolones and phenicols, and tetracyclines. It was identified as producer of extended-spectrum beta-lactamases (ESBL) by double-disk synergy test between amoxicillin-clavulanate and cefotaxime, ceftriaxone, ceftazidime and aztreonam. The ESBL was identified as CTX-M-28 by sequencing of PCR products and by isoelectric focusing. The ESBL resistance was transferred by a 50kb plasmid. CTX-M-28 is closely related to CTX-M-15. This is the first description of this enzyme in Tunisia. [less ▲]

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See detailCharacterization of a novel extended-spectrum TEM-type beta-lactamase, TEM-164, in a clinical strain of Klebsiella pneumoniae in Tunisia.
Ben Achour, Nahed; Mercuri, Paola ULg; Ben Moussa, Mohamed et al

in Microbial drug resistance (Larchmont, N.Y.) (2009), 15(3), 195-9

Klebsiella pneumoniae ML1708 exhibited a multiresistance phenotype, including resistance to all beta-lactams tested, chloramphenicol, ciprofloxacin, nalidixic acid, tetracycline, and streptomycin. The ... [more ▼]

Klebsiella pneumoniae ML1708 exhibited a multiresistance phenotype, including resistance to all beta-lactams tested, chloramphenicol, ciprofloxacin, nalidixic acid, tetracycline, and streptomycin. The double-disk synergy test was positive. ML1708 harbored a 50 kb conjugative plasmid that encoded a beta-lactamase of pI 5.5. The corresponding bla gene was identified by polymerase chain reaction and sequencing as a bla(TEM) gene. The deduced protein sequence revealed a new variant of TEM-1 beta-lactamase designated TEM-164. TEM-164 contains the unusual following mutations: L40V and I279T. These modifications may result in a change of the pI to 5.5 and hydrolyze cefotaxime and ceftazidime. [less ▲]

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See detailInsights into bacterial cellulose biosynthesis by functional metagenomics on Antarctic soil samples.
Berlemont, Renaud ULg; Delsaute, Maud ULg; Pipers, Delphine ULg et al

in ISME Journal (The) (2009), 3(9), 1070-1081

In this study, the mining of an Antarctic soil sample by functional metagenomics allowed the isolation of a cold-adapted protein (RBcel1) that hydrolyzes only carboxymethyl cellulose. The new enzyme is ... [more ▼]

In this study, the mining of an Antarctic soil sample by functional metagenomics allowed the isolation of a cold-adapted protein (RBcel1) that hydrolyzes only carboxymethyl cellulose. The new enzyme is related to family 5 of the glycosyl hydrolase (GH5) protein from Pseudomonas stutzeri (Pst_2494) and does not possess a carbohydrate-binding domain. The protein was produced and purified to homogeneity. RBcel1 displayed an endoglucanase activity, producing cellobiose and cellotriose, using carboxymethyl cellulose as a substrate. Moreover, the study of pH and the thermal dependence of the hydrolytic activity shows that RBcel1 was active from pH 6 to pH 9 and remained significantly active when temperature decreased (18% of activity at 10 degrees C). It is interesting that RBcel1 was able to synthetize non-reticulated cellulose using cellobiose as a substrate. Moreover, by a combination of bioinformatics and enzyme analysis, the physiological relevance of the RBcel1 protein and its mesophilic homologous Pst_2494 protein from P. stutzeri, A1501, was established as the key enzymes involved in the production of cellulose by bacteria. In addition, RBcel1 and Pst_2494 are the two primary enzymes belonging to the GH5 family involved in this process.The ISME Journal advance online publication, 21 May 2009; doi:10.1038/ismej.2009.48. [less ▲]

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See detailCritical role of tryptophan 154 for the activity and stability of class D beta-lactamases.
Baurin, Stephane; Vercheval, Lionel ULg; Bouillenne, Fabrice ULg et al

in Biochemistry (2009), 48(47), 11252-63

The catalytic efficiency of the class D beta-lactamase OXA-10 depends critically on an unusual carboxylated lysine as the general base residue for both the enzyme acylation and deacylation steps of ... [more ▼]

The catalytic efficiency of the class D beta-lactamase OXA-10 depends critically on an unusual carboxylated lysine as the general base residue for both the enzyme acylation and deacylation steps of catalysis. Evidence is presented that the interaction between the indole group of Trp154 and the carboxylated lysine is essential for the stability of the posttranslationally modified Lys70. Substitution of Trp154 by Gly, Ala, or Phe yielded noncarboxylated enzymes which displayed poor catalytic efficiencies and reduced stability when compared to the wild-type OXA-10. The W154H mutant was partially carboxylated. In addition, the maximum values of k(cat) and k(cat)/K(M) were shifted toward pH 7, indicating that the carboxylation state of Lys70 is dependent on the protonation level of the histidine. A comparison of the three-dimensional structures of the different proteins also indicated that the Trp154 mutations did not modify the overall structures of OXA-10 but induced an increased flexibility of the Omega-loop in the active site. Finally, the deacylation-impaired W154A mutant was used to determine the structure of the acyl-enzyme complex with benzylpenicillin. These results indicate a role of the Lys70 carboxylation during the deacylation step and emphasize the importance of Trp154 for the ideal positioning of active site residues leading to an optimum activity. [less ▲]

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See detailThe structure of the di-zinc subclass B2 metallo-beta-lactamase CphA reveals that the second inhibitory zinc ion binds in the "histidine" site.
Bebrone, Carine ULg; Delbrück, Heinrich; Kupper, Michaël et al

in Antimicrobial Agents and Chemotherapy (2009)

Bacteria can defend themselves against beta-lactam antibiotics through the expression of class B beta-lactamases, which cleave the beta-lactam amide bond and render the molecule harmless. There are three ... [more ▼]

Bacteria can defend themselves against beta-lactam antibiotics through the expression of class B beta-lactamases, which cleave the beta-lactam amide bond and render the molecule harmless. There are three subclasses of class B beta-lactamases (B1, B2 and B3), all of which require Zn(2+) for activity and can bind either one or two zinc ions. Whereas the B1 and B3 metallo-beta-lactamases are most active as di-zinc enzymes, subclass B2 enzymes such as Aeromonas hydrophila CphA are inhibited by the binding of a second zinc ion. We crystallized A. hydrophila CphA in order to determine the binding site of the inhibitory zinc ion. X-ray data from zinc-saturated crystals allowed us to solve the crystal structures of the di-zinc forms of the wild-type enzyme and N220G mutant. The first zinc ion binds in the "cysteine" site, as previously determined for the mono-zinc form of the enzyme. The second zinc ion occupies a slightly modified "histidine" site, where the conserved His118 and His196 residues act as metal ligands. This atypical coordination sphere probably explains the rather high dissociation constant for the second zinc ion compared to those observed in enzymes of subclasses B1 and B3. Inhibition by the second zinc ion results from immobilization of the catalytically-important His118 and His196 residues, as well as the folding of the Gly232-Asn233 loop into a position that covers the active site. [less ▲]

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See detailThe in-vitro antimicrobial activity of some medicinal plants against beta-lactam-resistant bacteria
Gangoue Pieboji, Joseph ULg; Eze, N.; Ngongang Djintchui, A. et al

in J Infect Dev Ctries (2009), 3(9), 671-80

BACKGROUND: In effort to identify novel bacterial agents, this study was initiated to evaluate the antimicrobial properties of 17 crude extracts from 12 medicinal plants against beta-lactam-resistant ... [more ▼]

BACKGROUND: In effort to identify novel bacterial agents, this study was initiated to evaluate the antimicrobial properties of 17 crude extracts from 12 medicinal plants against beta-lactam-resistant bacteria. METHODOLOGY: The antimicrobial activities of plant extracts were evaluated against clinically proved beta-lactam-resistant bacteria (Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae, Serratia marcescens, Acinetobacter baumannii, Staphylococcus aureus and Enterococcus sp.) and reference strains of bacteria (Escherichia coli ATCC 35218, Enterobacter aerogenes ATCC 29751, E. aerogenes ATCC 13048, Pseudomonas aeruginosa ATCC 27853 and Enterococcus hirae ATCC 9790) by using disc-diffusion and agar-dilution assays. RESULTS: The crude plant extracts demonstrated broad spectrum activity against all bacteria tested with inhibition zones in the range of 8-30 mm. The minimal inhibitory concentration (MIC) values of different plant extracts against the tested bacteria were found to range from <or= 0.3 to >or= 10 mg ml(-1). The most active plant extracts were from Dortenia picta and Bridelia micrantha (MIC: 1.25-10 mg ml(-1)) on beta-lactam-resistant Gram-negative bacilli and the extracts from B. micrantha, Mallotus oppositifolius, Garcinia lucida, Garcinia. kola, Campylospermum densiflorum (leaves) and C. zenkeri (root) on beta-lactam-resistant Gram-positive cocci (MIC: <or= 0.3-5 mg ml(-1)). CONCLUSION: Of the 17 plant extracts studied, seven showed good antimicrobial activity against the tested bacteria. The stem bark of B. micrantha and the leaves of D. picta were most active towards beta-lactamase producing Gram-negative bacilli. This study shows that medicinal plants could be sources of compounds which can be used to fight against beta-lactam resistant bacteria. [less ▲]

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See detailPolyolefin matrixes with permanent antibacterial activity: preparation, antibacterial activity, and action mode of the active species
Lenoir, Sandrine; Pagnoulle, Christophe; Galleni, Moreno ULg et al

Poster (2008, May 22)

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See detailCefotaxime and ceftriaxon resistant Klebsiella pneumoniae associated with SHV-11 hyperproduction
Ben Achour, Nahed; Mercuri, Paola ULg; Belhadj, Chrifa et al

in Annals of Microbiology (2008), 5(4), 727-730

Klebsiella pneumoniae ML0306 was isolated from a patient in the intensive care unit of the Military hospital of Tunis in Tunisia. The strain was resistant to β-lactams, aminoglycosides, quinolones ... [more ▼]

Klebsiella pneumoniae ML0306 was isolated from a patient in the intensive care unit of the Military hospital of Tunis in Tunisia. The strain was resistant to β-lactams, aminoglycosides, quinolones, phenicols and tetracyclines. Crude extract from the isolate showed a broad-substrate profile by hydrolyzing benzylpenicillin, ampicillin, cloxacilline, cephalothin, cefotaxime and ceftriaxone but not ceftazidime, cefoxitin, cefpirome, imipinem and aztreonam. The isolate was identified as a producer of pI 7.6 β-lactamase. Sequencing of the β-lactamase gene showed that it coded for a penicillinase SHV-11. This is the first description of this enzyme in Tunisia. The gene encoding this enzyme was located on the chromosome and a 50 kb conjugative plasmid. The overproduction of SHV-11 was involved in the wading of the hydrolytic spectrum of the strain. [less ▲]

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See detailRapid and easy development of versatile tools to study protein/ligand interactions
Vandevenne, Marylène ULg; Gaspard, Gilles ULg; Yilmaz, Nursel et al

in Protein engineering, design & selection (2008)

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See detailStructure of the plasmid-mediated class C beta-lactamase ACT-1.
Shimizu-Ibuka, Akiko; Bauvois, Cedric; Sakai, Hiroshi et al

in Acta crystallographica. Section F, Structural biology and crystallization communications (2008), 64(Pt 5), 334-7

The crystallographic structure of ACT-1, which is the first plasmid-mediated AmpC-type beta-lactamase to have been completely analyzed in terms of nucleotide sequence and which has a high degree of ... [more ▼]

The crystallographic structure of ACT-1, which is the first plasmid-mediated AmpC-type beta-lactamase to have been completely analyzed in terms of nucleotide sequence and which has a high degree of sequence similarity to the chromosomal AmpC enzymes of Enterobacter cloacae and the plasmid-encoded MIR-1, has been solved at 2.4 A resolution. The overall structure of ACT-1 is similar to those of other class C beta-lactamases, such as the AmpC enzymes from E. cloacae P99 and Escherichia coli. [less ▲]

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See detailDynamic combinatorial mass spectrometry leads to metallo-beta-lactamase inhibitors.
Lienard, Benoit M. R.; Huting, Rebekka; Lassaux, Patricia ULg et al

in Journal of medicinal chemistry (2008), 51(3), 684-8

The use of protein ESI mass spectrometry under non-denaturing conditions to analyze a dynamic combinatorial library of thiols/disulfides with the BcII metallo-beta-lactamase enabled the rapid ... [more ▼]

The use of protein ESI mass spectrometry under non-denaturing conditions to analyze a dynamic combinatorial library of thiols/disulfides with the BcII metallo-beta-lactamase enabled the rapid identification of an inhibitor with a K(i) of < 1 microM. The study exemplifies the utility of protein-MS for screening dynamic mixtures of potential enzyme-inhibitors. [less ▲]

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See detailIsolation of novel hydrolytic genes from an Antarctic metagenomic library
Pipers, D.; Berlemont, R.; Power, P. et al

Poster (2008)

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See detailCharacterization of the cattle serum antibody responses against TEM beta-lactamase and the nonimmunogenic Escherichia coli heat-stable enterotoxin (STaI)
Zervosen, Astrid ULg; Saegerman, Claude ULg; Antoniotti, Ingrid et al

in FEMS Immunology & Medical Microbiology (2008), 54(3), 319-329

In order to test the use of a subunit recombinant vaccine for its capacity to induce antibodies against the nonimmunogenic heat-stable enterotoxin STa from Escherichia coli and the TEM-1 beta-lactamase ... [more ▼]

In order to test the use of a subunit recombinant vaccine for its capacity to induce antibodies against the nonimmunogenic heat-stable enterotoxin STa from Escherichia coli and the TEM-1 beta-lactamase, cattle were immunized with a hybrid protein created by insertion of the STa sequence at position 197 of the TEM-1 beta-lactamase. Specific anti-STa IgG and IgG1 antibodies were detected at low levels, while no IgG2 antibodies were detected. In contrast, high levels of the different anti-TEM IgG subtypes were detected in cattle sera. In addition, beta-lactamase activity was inhibited by the sera. The presence of antibodies against STa and TEM-1 beta-lactamase was assessed in sera from 366 cattle taken from the field. No significant level of IgGs against the toxin or the TEM-1 was detected. A comparison of the antibody level between the immunized and the nonimmunized animals clearly demonstrated that STa was not able to induce a significant level of antibodies in the vaccinated animals. In contrast, a strong antibody response against TEM-1 beta-lactamase was demonstrated. [less ▲]

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See detailActivation mechanism of recombinant Der p 3 allergen zymogen - Contribution of cysteine protease Der p 1 and effect of propeptide glycosylation
Dumez, Marie-Eve ULg; Teller, Nathalie; Mercier, Frédéric ULg et al

in Journal of Biological Chemistry (2008), 283(45), 30606-30617

The trypsin-like protease Der p 3, a major allergen of the house dust mite Dermatophagoides pteronyssinus, is synthesized as a zymogen, termed proDer p 3. No recombinant source of Der p 3 has been ... [more ▼]

The trypsin-like protease Der p 3, a major allergen of the house dust mite Dermatophagoides pteronyssinus, is synthesized as a zymogen, termed proDer p 3. No recombinant source of Der p 3 has been described yet, and the zymogen maturation mechanism remains to be elucidated. The Der p 3 zymogen was produced in Pichia pastoris. We demonstrated that the recombinant zymogen is glycosylated at the level of its propeptide. We showed that the activation mechanism of proDer p 3 is intermolecular and is mediated by the house dust mite cysteine protease Der p 1. The primary structure of the proDer p 3 propeptide is associated with a unique zymogen activation mechanism, which is different from those described for the trypsin-like family and relies on the house dust mite papain-like protease Der p 1. This is the first report of a recombinant source of Der p 3, with the same enzymatic activity as the natural enzyme and trypsin. Glycosylation of the propeptide was found to decrease the rate of maturation. Finally, we showed that recombinant Der p 3 is inhibited by the free modified prosequence TP1R. [less ▲]

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See detailCreating hybrid proteins by insertion of exogenous peptides into permissive sites of a class A beta-lactamase
Ruth, Nadia ULg; Quinting, Brigitte; Mainil, Jacques ULg et al

in FEBS Journal (2008), 275

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See detailAstrobiologie
Javaux, Emmanuelle ULg; Claeys, Philippe; Dehant, Véronique et al

Learning material (2008)

powerpoint sur MyULg, notes partielles imprimées

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