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See detailThe Bacillus licheniformis BlaP beta-lactamase as a model protein scaffold to study the insertion of protein fragments.
Vandevenne, Marylène ULg; Filée, Patrice ULg; Scarafone, Natacha ULg et al

in Protein Science : A Publication of the Protein Society (2007), 16(10), 2260-71

Using genetic engineering technologies, the chitin-binding domain (ChBD) of the human macrophage chitotriosidase has been inserted into the host protein BlaP, a class A beta-lactamase produced by Bacillus ... [more ▼]

Using genetic engineering technologies, the chitin-binding domain (ChBD) of the human macrophage chitotriosidase has been inserted into the host protein BlaP, a class A beta-lactamase produced by Bacillus licheniformis. The product of this construction behaved as a soluble chimeric protein that conserves both the capacity to bind chitin and to hydrolyze beta-lactam moiety. Here we describe the biochemical and biophysical properties of this protein (BlaPChBD). This work contributes to a better understanding of the reciprocal structural and functional effects of the insertion on the host protein scaffold and the heterologous structured protein fragments. The use of BlaP as a protein carrier represents an efficient approach to the functional study of heterologous protein fragments. [less ▲]

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See detailThe expression of Clostridium perfringens consensus beta2 toxin is associated with bovine enterotoxaemia syndrome
Lebrun, Maud; Filée, Patrice ULg; Mousset, Bénédicte ULg et al

in Veterinary Microbiology (2007), 120(1-2), 151-157

Clostridium perfringens has been implicated in a broad array of enteric infections including the fatal haemorrhagic enteritis/enterotoxaemia syndrome in cattle. The beta2 toxin (CPB2), encoded by cpb2, is ... [more ▼]

Clostridium perfringens has been implicated in a broad array of enteric infections including the fatal haemorrhagic enteritis/enterotoxaemia syndrome in cattle. The beta2 toxin (CPB2), encoded by cpb2, is suspected to be implicated in this syndrome. However, among C. perfringens isolates from cattle suspected of clostridial disease, an atypical allele was recently found to predominate at the cpb2 locus and atypical corresponding CPB2 proteins were shown to be poorly expressed, thus arguing against a biologically significant role of the beta2 toxin in clostridial diseases in cattle. This study compared genotype and phenotype of the beta2 toxin between C. perfringens isolates from a group of healthy calves (n = 14, 87 isolates) and from a group of enterotoxaemic calves (n = 8,41 isolates). PCR results revealed the exclusive presence of the typical "consensus" cpb2 in the enterotoxaernic group. Western blot analysis demonstrated that the typical variant of CPB2 was often expressed in isolates from enterotoxaemic calves (43.9%) and infrequently in isolates from healthy cattle (6.9%). These data suggest that the typical variant of the CPB2 toxin may play a role in the pathogenesis of cattle enterotoxaemia. (c) 2006 Elsevier B.V. All rights reserved. [less ▲]

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See detailA novel extended-spectrum TEM-type beta-lactamase, TEM-138, from Salmonella enterica serovar Infantis.
chouchani, chedli; Berlemont, Renaud ULg; masmoudi, A. et al

in Antimicrobial Agents and Chemotherapy (2006), 50(9), 3183-5

A novel natural TEM beta-lactamase with extended-spectrum activity, TEM-138, was identified in a ceftazidime-resistant clinical isolate of Salmonella enterica serovar Infantis. Compared to TEM-1, TEM-138 ... [more ▼]

A novel natural TEM beta-lactamase with extended-spectrum activity, TEM-138, was identified in a ceftazidime-resistant clinical isolate of Salmonella enterica serovar Infantis. Compared to TEM-1, TEM-138 contains the following mutations: E104K, N175I, and G238S. The bla(TEM-138) gene was located on a 50-kb transferable plasmid. Expression studies with Escherichia coli revealed efficient ceftazidimase and cefotaximase activities for TEM-138. [less ▲]

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

in Biomacromolecules (2006), 7(8), 2291-2296

Poly[2-(tert-butylamino)ethyl methacrylate] (PTBAEMA) belongs to a novel class of water-insoluble biocides. Dispersion of a poly(ethylene-co-butylene)-b-poly[2-(tert-butylamino)ethyl methacrylate] diblock ... [more ▼]

Poly[2-(tert-butylamino)ethyl methacrylate] (PTBAEMA) belongs to a novel class of water-insoluble biocides. Dispersion of a poly(ethylene-co-butylene)-b-poly[2-(tert-butylamino)ethyl methacrylate] diblock copolymer (PEB-b-PTBAEMA) within low-density polyethylene (LDPE) imparts antimicrobial properties to the polyolefin as assessed by the viable cell counting method against Escherichia coli (E. coli). This diblock copolymer has been synthesized by atom transfer radical polymerization (ATRP) with a poly(ethylene-co-butylene) (PEB) oligomer end-capped by an activated bromide as a macroinitiator for the polymerization of 2-(tert-butylamino)ethyl methacrylate (TBAEMA). Morphological changes of E. coli bacteria in contact with modified LDPE have been observed by transmission and scanning electron microscopy and indicate that the diblock copolymer is bactericide rather than bacteriostatic. Finally, the action mode of the PEB-b-PTBAEMA copolymer more likely relies on the displacement of the Ca2+ and/or Mg2+ ions of the outer membrane of the bacteria, which is disorganized and finally disrupted. [less ▲]

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See detailNew antibacterial cationic surfactants prepared by Atom Transfer Radical Polymerization
Lenoir, Sandrine ULg; Pagnoulle, Christophe; Detrembleur, Christophe ULg et al

in Journal of Polymer Science. Part A, Polymer Chemistry (2006), 44(3), 1214-1224

Efficient antibacterial surfactants have been prepared by the quaternization of the amino groups of poly(ethylene-co-butylene)-b-poly[2-(dimethylamino)ethylmethacrylate] (PEB-b-PDMAEMA) diblock copolymers ... [more ▼]

Efficient antibacterial surfactants have been prepared by the quaternization of the amino groups of poly(ethylene-co-butylene)-b-poly[2-(dimethylamino)ethylmethacrylate] (PEB-b-PDMAEMA) diblock copolymers by octyl bromide. The diblock copolymers have been synthesized by ATRP of 2-(dimethylamino)ethylmethacrylate (DMAEMA) initiated by an activated bromide-end-capped poly(ethylene-co-butylene). In the presence of CuBr, 1,4,7,10,10-hexamethyl-triethylenetetramine (HMTETA), and toluene at 50 °C, the initiation is slow in comparison with propagation. This situation has been improved by the substitution of CuCl for CuBr, all the other conditions being the same. Finally, the addition of an excess of CuCl2 (deactivator) to the CuCl/HMTETA catalyst is very beneficial in making the agreement between the theoretical and experimental number-average molecular weights excellent. The antibacterial activity of PEB-b-PDMAEMA quaternized by octyl bromide has been assessed against bacteria and is comparable to the activity of a commonly used disinfectant, that is, benzalkonium chloride. [less ▲]

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See detailMonitoring the zinc affinity of the metallo-beta-lactamase CphA by automated nanoESI-MS
De Vriendt, K.; Van Driessche, G.; Devreese, B. et al

in Journal of the American Society for Mass Spectrometry (2006), 17(2), 180-188

Metallo-beta-lactamases are zinc containing enzymes that are able to hydrolyze and inactivate beta-lactam antibiotics. The subclass B2 enzyme CphA of Aeromonas hydrophila is a unique metallo-p-lactamase ... [more ▼]

Metallo-beta-lactamases are zinc containing enzymes that are able to hydrolyze and inactivate beta-lactam antibiotics. The subclass B2 enzyme CphA of Aeromonas hydrophila is a unique metallo-p-lactamase because it degrades only carbapenems efficiently and is only active when it has one zinc ion bound. A zinc titration experiment was used to study the zinc affinity of the wild-type and of several mutant CphA enzymes. It shows that a second Zn2+ is also bound at high ion concentrations. All samples were analyzed using mass spectrometry in combination with an automated nanoESI source. The metal-free enzyme has a bimodal charge distribution indicative of two conformational states. A completely folded enzyme is detected when the apo-enzyme has bound the first zinc. Intensity ratios of the different enzyme forms were used to deduce the zinc affinities. CphA enzymes mutated in metal ligands show decreased zinc affinity compared to wild-type, especially D120 mutants. [less ▲]

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See detailCrystal structure of the Mycobacterium fortuitum class A beta-lactamase: structural basis for broad substrate specificity.
Sauvage, Eric ULg; Fonze, Eveline; Quinting, Birgit et al

in Antimicrobial Agents and Chemotherapy (2006), 50(7), 2516-21

beta-Lactamases are the main cause of bacterial resistance to penicillins and cephalosporins. Class A beta-lactamases, the largest group of beta-lactamases, have been found in many bacterial strains ... [more ▼]

beta-Lactamases are the main cause of bacterial resistance to penicillins and cephalosporins. Class A beta-lactamases, the largest group of beta-lactamases, have been found in many bacterial strains, including mycobacteria, for which no beta-lactamase structure has been previously reported. The crystal structure of the class A beta-lactamase from Mycobacterium fortuitum (MFO) has been solved at 2.13-A resolution. The enzyme is a chromosomally encoded broad-spectrum beta-lactamase with low specific activity on cefotaxime. Specific features of the active site of the class A beta-lactamase from M. fortuitum are consistent with its specificity profile. Arg278 and Ser237 favor cephalosporinase activity and could explain its broad substrate activity. The MFO active site presents similarities with the CTX-M type extended-spectrum beta-lactamases but lacks a specific feature of these enzymes, the VNYN motif (residues 103 to 106), which confers on CTX-M-type extended-spectrum beta-lactamases a more efficient cefotaximase activity. [less ▲]

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See detailAntimicrobial activity of polyestyrene particles coated by photo-crooslinked block copolymers containing a biocidal polymethacrylate block
Lenoir, Sandrine ULg; Pagnoulle, Christophe; Detrembleur, Christophe ULg et al

in e-Polymers (2005), 74

A commercially available poly(ethylene-co-butylene) copolymer, end-capped by a short polyisoprene block and a hydroxyl group (PI-b-PEB-OH), has been derivatized into a macroinitiator for atom transfer ... [more ▼]

A commercially available poly(ethylene-co-butylene) copolymer, end-capped by a short polyisoprene block and a hydroxyl group (PI-b-PEB-OH), has been derivatized into a macroinitiator for atom transfer radical polymerization (ATRP) by esterification of the hydroxyl end-group by an activated bromide-containing acyl bromide. Two types of triblock copolymers, Pl-b-PEB-b-poly(dimethylaminoethyl methacrylate) (PDMAEMA) and Pl-b-PEB-b-poly[2-(tert-butylamino)ethyl methacrylate] (PTBAEMA), have been synthesized and used to coat polystyrene particles. These coatings have been permanently immobilized by UV cross-linking of the isoprene units. They exhibit a biocidal activity against Gram-negative bacteria either intrinsically in case of the PTBAEMA block or upon quaternization of the PDMAEMA block by octyl bromide. The antimicrobial activity is directly related to the concentration of coated PS particles in the medium. [less ▲]

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See detailFrom dormant to germinating spores of Streptomyces coelicolor A3(2): new perspectives from the crp null mutant.
Piette, André ULg; Derouaux, Adeline ULg; Gerkens, Pascal et al

in Journal of Proteome Research (2005), 4(5), 1699-708

The complete understanding of the morphological differentiation of streptomycetes is an ambitious challenge as diverse sensors and pathways sensitive to various environmental stimuli control the process ... [more ▼]

The complete understanding of the morphological differentiation of streptomycetes is an ambitious challenge as diverse sensors and pathways sensitive to various environmental stimuli control the process. Germination occupies a particular position in the life cycle as the good achievement of the process depends on events occurring both during the preceding sporulation and during germination per se. The cyclic AMP receptor protein (crp) null mutant of Streptomyces coelicolor, affected in both sporulation and germination, was therefore presented as a privileged candidate to highlight new proteins involved in the shift from dormant to germinating spores. Our multidisciplinary approach-combining in vivo data, the analysis of spores morphological properties, and a proteome study-has shown that Crp is a central regulatory protein of the life cycle in S. coelicolor; and has identified spores proteins with statistically significant increased or decreased expression that should be listed as priority targets for further investigations on proteins that trigger both ends of the life cycle. [less ▲]

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See detailDramatic broadening of the substrate profile of the Aeromonas hydrophila CphA metallo-beta-lactamase by site-directed mutagenesis
Bebrone, Carine ULg; Anne, C.; De Vriendt, K. et al

in Journal of Biological Chemistry (2005), 280(31), 28195-28202

Among class B beta-lactamases, the subclass B2 CphA enzyme is characterized by a unique specificity profile. CphA efficiently hydrolyzes only carbapenems. In this work, we generated site-directed mutants ... [more ▼]

Among class B beta-lactamases, the subclass B2 CphA enzyme is characterized by a unique specificity profile. CphA efficiently hydrolyzes only carbapenems. In this work, we generated site-directed mutants that possess a strongly broadened activity spectrum when compared with the WT CphA. Strikingly, the N116H/N220G double mutant exhibits a substrate profile close to that observed for the broad spectrum subclass B1 enzymes. The double mutant is significantly activated by the binding of a second zinc ion under conditions where the WT enzyme is non-competitively inhibited by the same ion. [less ▲]

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See detailATRP of aminated methacrylates: a route to effective antimicrobial surfactants, coatings and additives
Lenoir, Sandrine; Pagnoulle, Christophe; Detrembleur, Christophe ULg et al

Conference (2005, June 01)

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See detailATRP of aminated methacrylates: a route to effective antimicrobial surfactants, coatings and additives
Lenoir, Sandrine; Pagnoulle, Christophe; Galleni, Moreno ULg et al

Conference (2005, May 19)

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See detailDNA vaccination for the priming of neutralizing antibodies against non-immunogenic STa enterotoxin from enterotoxigenic Escherichia coli
Ruth, Nadia ULg; Mainil, Jacques ULg; Roupie, Virginie et al

in Vaccine (2005), 23(27), 3618-3627

In order to test the use of DNA vaccination for its capacity to induce antibodies against the non-immunogenic heat-stable enterotoxin STa from Escherichia coli, BALB/c mice were immunized with plasmid DNA ... [more ▼]

In order to test the use of DNA vaccination for its capacity to induce antibodies against the non-immunogenic heat-stable enterotoxin STa from Escherichia coli, BALB/c mice were immunized with plasmid DNA encoding hybrid proteins made by the insertion of wild type STa or insertion of the Cys6Ala, Cys17Ala and Cys6Ala-Cys17Ala STa mutants at positions 195 or 216 of the TEM-1 beta-lactamase. No STa specific antibodies could be detected after three plasmid injections, but a subsequent boost with native STa peptide was capable of inducing low levels of neutralizing antibodies, as tested in the suckling mouse assay. Highest STa specific responses were found in mice primed with the double mutated STa inserted in position 195. This plasmid induced highest T-cell responses to the TEM-1 protein, indicating that priming of helper T-cell responses to the carrier protein was essential. Mixed IgG1/IgG2a isotypes also reflected this T helper 1 type priming. Moreover, insertion into loop A of the TEM-1 carrier may be more suitable than insertion into loop B, because of reduced competition between carrier and hapten B cell responses. [less ▲]

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See detailA metallo-beta-lactamase enzyme in action: Crystal structures of the monozinc carbapenemase CphA and its complex with biapenem
Garau, Gianpiero; Bebrone, Carine ULg; Anne, Christine et al

in Journal of Molecular Biology (2005), 345(4), 785-795

One strategy developed by bacteria to resist the action of beta-lactam antibiotics is the expression of metallo-beta-lactamases. CphA from Aeromonas hydrophila is a member of a clinically important ... [more ▼]

One strategy developed by bacteria to resist the action of beta-lactam antibiotics is the expression of metallo-beta-lactamases. CphA from Aeromonas hydrophila is a member of a clinically important subclass of metallo-beta-lactamases that have only one zinc ion in their active site and for which no structure is available. The crystal structures of wild-type CphA and its N220G mutant show the structural features of the active site of this enzyme, which is modeled specifically for carbapenem hydrolysis. The structure of CphA after reaction with a carbapenem substrate, biapenem, reveals that the enzyme traps a reaction intermediate in the active site. These three X-ray structures have allowed us to propose how the enzyme recognizes carbapenems and suggest a mechanistic pathway for hydrolysis of the beta-lactam. This will be relevant for the design of metallo-beta-lactamase inhibitors as well as of antibiotics that escape their hydrolytic activity. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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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

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See detailDescription of In116, the first blaCTX-M-2-containing complex class 1 integron found in Morganella morganii isolates from Buenos Aires, Argentina
Power, pablo; Galleni, Moreno ULg; Di Conza, José et al

in Journal of Antimicrobial Chemotherapy (2005), 55(4), 461-465

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See detailSynthesis of copolymer brushes endowed with adhesion to stainless steel surfaces and antibacterial properties by controlled nitroxide-mediated radical polymerization
Ignatova, Miléna; Voccia, Samuel; Gilbert, Bernard ULg et al

in Langmuir (2004), 20(24), 10718-10726

Novel copolymer brushes have been synthesized by a two-step "grafting from" method that consists of the electrografting of poly(2-phenyl-2-(2,2,6,6-tetramethyl-piperidin-1-yloxy)-ethylacrylate) onto ... [more ▼]

Novel copolymer brushes have been synthesized by a two-step "grafting from" method that consists of the electrografting of poly(2-phenyl-2-(2,2,6,6-tetramethyl-piperidin-1-yloxy)-ethylacrylate) onto stainless steel, followed by the nitroxide-mediated radical polymerization of 2-(dimethylamino ethyl)acrylate and styrene or n-butyl acrylate, initiated from the electrografted polyacrylate chains. The grafted copolymers were quaternized in order to endow them with antibacterial properties. Peeling tests have confirmed the strong adhesion of the grafted copolymer onto the stainless steel substrate. Quartz crystal microbalance experiments have proven that fibrinogen adhesion is lower on the hydrophilic quaternized films compared to the nonionic counterpart. Such quaternized copolymers exhibit significant antibacterial activity against the Gram-positive bacteria S. aureus and the Gram-negative bacteria E. coli. [less ▲]

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

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

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