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See detailThe peptidoglycan crosslinking enzyme system in Streptomyces R61, K15 and rimosus. Immunological studies
Nguyen-Distèche, Martine ULg; Frère, Jean-Marie ULg; Dusart, Jean et al

in European Journal of Biochemistry (1977), 81(1), 29-32

The exocellular DD-carboxypeptidases from Streptomyces R61, K 15, the lysozyme-releasable DD-carboxypeptidases from Streptomyces R61, K15 and rimosus, and the membrane-bound DD-carboxypeptidase of ... [more ▼]

The exocellular DD-carboxypeptidases from Streptomyces R61, K 15, the lysozyme-releasable DD-carboxypeptidases from Streptomyces R61, K15 and rimosus, and the membrane-bound DD-carboxypeptidase of Streptomyces K15 are immunologically related to each other. [less ▲]

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See detailThe peptidoglycan crosslinking enzyme system in Streptomyces strains R61, K15 and rimosus : Kinetic Coefficients Involved in the Interactions of the Membrane-Bound Transpeptidase with Peptide Substrates and β-Lactam Antibiotics
Dusart, Jean; Leyh-Bouille, Mélina; Ghuysen, Jean-Marie ULg

in European Journal of Biochemistry (1977), 81(1), 33-44

The transpeptidation reaction performed by the membranes of Streptomyces strain R61 fits the general rate equation for an enzyme-catalysed bimolecular reaction. The same membranes (E) interact with beta ... [more ▼]

The transpeptidation reaction performed by the membranes of Streptomyces strain R61 fits the general rate equation for an enzyme-catalysed bimolecular reaction. The same membranes (E) interact with beta-lactams (I) to form inactive penicillin-enzyme-membrane complexes (EI) of rather high stability, which subsequently break down (E + I leads to EI leads to E + degradation products). The enzyme is regenerated and the antibiotic is released in the form of an inactive metabolite. With benzylpenicillin, the degradation product is benzylpenicilloic acid. The reaction is heat-labile. The first step of the reaction (E + I leads to EI) is characterized by a second-order rate constant (kformation in M-1 s-1) and the second step (EI leads to E + degradation products) by a first-order rate constant (kbreakdown in s-1). The effects in vitro of various beta-lactams on the membrane-bound transpeptidase, as expressed by the relevant kformation and kbreakdown values, parallel the effects in vivo of the same antibiotics as expressed by their ability to prevent the germination and growth of conidiospores. The kinetic parameters of the transpeptidase that was solubilized with N-cetyl-N,N,N-trimethylammonium bromide with respect to its interaction with both peptide substrates and beta-lactam antibiotics are quantitatively different from those of the membrane-bound enzyme. Moreover, the solubilized enzyme fragments benzylpenicillin with formation of phenylacetylglycine, a reaction which is similar to that catalysed by the exocellular R61 enzyme. The membranes of Streptomyces strains rimosus and K15 possess an active 'classic' penicillinase. They were not studied but the kinetic coefficients of the corresponding solubilized transpeptidases were determined and compared with those of the solubilized enzyme from strain R61. [less ▲]

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See detailThe peptidoglycan crosslinking enzyme system in Streptomyces strains R61, K15 and rimosus. Exocellular, lysozyme-releasable and membrane-bound enzymes.
Leyh-Bouille, Mélina; Dusart, Jean; Nguyen Van, Martine ULg et al

in European Journal of Biochemistry (1977), 81(1), 19-28

The DD-carboxypeptidase (I)-transpeptidase (II) system in Streptomyces strain K15 consists of: (1) a membrane-bound II capable of performing low I activity; and (2) a set of I: (a) membrane-bound, (b ... [more ▼]

The DD-carboxypeptidase (I)-transpeptidase (II) system in Streptomyces strain K15 consists of: (1) a membrane-bound II capable of performing low I activity; and (2) a set of I: (a) membrane-bound, (b) lysozyme-releasable, and (c) exocellular, having low II activities in aq. media and at low acceptor concns. The I are related to each other and may belong to the same pathway leading to enzyme excretion. A similar system occurs in Streptomyces strain R61 except that the membrane-bound I activity is low when compared with the membrane-bound II activity. In S. rimosus, the system consists almost exclusively of the membrane-bound II and the levels of membrane-bound, lysozyme-releasable, and exocellular I are very low. [on SciFinder(R)] [less ▲]

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See detailA peptidoglycan fragment triggers beta-lactam resistance in Bacillus licheniformis.
Amoroso, Ana Maria ULg; Boudet, Julien; Berzigotti, Stephanie et al

in PLoS Pathogens (2012), 8(3), 1002571

To resist to beta-lactam antibiotics Eubacteria either constitutively synthesize a beta-lactamase or a low affinity penicillin-binding protein target, or induce its synthesis in response to the presence ... [more ▼]

To resist to beta-lactam antibiotics Eubacteria either constitutively synthesize a beta-lactamase or a low affinity penicillin-binding protein target, or induce its synthesis in response to the presence of antibiotic outside the cell. In Bacillus licheniformis and Staphylococcus aureus, a membrane-bound penicillin receptor (BlaR/MecR) detects the presence of beta-lactam and launches a cytoplasmic signal leading to the inactivation of BlaI/MecI repressor, and the synthesis of a beta-lactamase or a low affinity target. We identified a dipeptide, resulting from the peptidoglycan turnover and present in bacterial cytoplasm, which is able to directly bind to the BlaI/MecI repressor and to destabilize the BlaI/MecI-DNA complex. We propose a general model, in which the acylation of BlaR/MecR receptor and the cellular stress induced by the antibiotic, are both necessary to generate a cell wall-derived coactivator responsible for the expression of an inducible beta-lactam-resistance factor. The new model proposed confirms and emphasizes the role of peptidoglycan degradation fragments in bacterial cell regulation. [less ▲]

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See detailPeptidoglycan Glycosyltransferase Inhibition: New Perspectives for An Old Target.
Terrak, Mohammed ULg

in Anti-Infective Agents in Medicinal Chemistry (2008)

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See detailPeptidoglycan glycosyltransferase substrate mimics as templates for the design of new antibacterial drugs.
Derouaux, Adeline ULg; Sauvage, Eric ULg; Terrak, Mohammed ULg

in Frontiers in immunology (2013), 4

Peptidoglycan (PG) is an essential net-like macromolecule that surrounds bacteria, gives them their shape, and protects them against their own high osmotic pressure. PG synthesis inhibition leads to ... [more ▼]

Peptidoglycan (PG) is an essential net-like macromolecule that surrounds bacteria, gives them their shape, and protects them against their own high osmotic pressure. PG synthesis inhibition leads to bacterial cell lysis, making it an important target for many antibiotics. The final two reactions in PG synthesis are performed by penicillin-binding proteins (PBPs). Their glycosyltransferase (GT) activity uses the lipid II precursor to synthesize glycan chains and their transpeptidase (TP) activity catalyzes the cross-linking of two glycan chains via the peptide side chains. Inhibition of either of these two reactions leads to bacterial cell death. beta-lactam antibiotics target the transpeptidation reaction while antibiotic therapy based on inhibition of the GTs remains to be developed. Ongoing research is trying to fill this gap by studying the interactions of GTs with inhibitors and substrate mimics and utilizing the latter as templates for the design of new antibiotics. In this review we present an updated overview on the GTs and describe the structure-activity relationship of recently developed synthetic ligands. [less ▲]

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See detailThe peptidoglycan in walls of Butyribacterium rettgeri
Guinand, Micheline; Ghuysen, Jean-Marie ULg; Schleifer, Karl H. et al

in Biochemistry (1969), 8(1), 200-207

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See detailPeptidomic comparison and characterization of the major components of the venom of the giant ant Dinoponera quadriceps collected in four different areas of Brazil.
Cologna, Camila Takeno; Cardoso, Jaqueline Dos Santos; Jourdan, Emmanuel et al

in Journal of Proteomics (2013), 94

Despite the noxious effects inflicted by Dinoponera ant's envenomation, the information about the biological properties and composition of their venom is still very limited. Ants from the genus Dinoponera ... [more ▼]

Despite the noxious effects inflicted by Dinoponera ant's envenomation, the information about the biological properties and composition of their venom is still very limited. Ants from the genus Dinoponera are believed to be the world's largest living ants with a body length of 3cm. Their occurrence is restricted to tropical areas of South America. In this work, we study the venom of the giant Dinoponera quadriceps ant collected in 4 different regions of Brazil. By using a combination of complementary mass spectrometric approaches, we aim at: (i) characterizing the venom composition of these ants; (ii) establishing a comparative analysis of the venom from four geographically different regions in Brazil. This approach demonstrates that ant venom is a copious source of new compounds. Several peptides were identified and selected for "de novo sequencing". Since most of the new peptides showed similarities with antimicrobial peptides (AMPs), antimicrobial assays were performed with the purpose of evaluating their activity. In regard to the comparative study of the four regions, we observed not only major differences in the venom compositions, but also that the venoms collected in closest areas are more similar than the ones collected in distant regions. These observations seem to highlight an adaption of the ant venoms to the local environment. Concerning the biological assays, the peptides called Dq-3162 and Da-3177 showed a wide-ranging antimicrobial activity. The characterization of new AMPs with a broad spectrum of activity and different scaffolds may aid scientists to design new therapeutic agents and understand the mechanisms of those peptides to interact with microbial membranes. The results obtained betoken the biotechnological potential of ant's venom. BIOLOGICAL SIGNIFICANCE: For the first time this manuscript describes an extensive proteomics characterization of the D. quadriceps venom. In addition this study reports the variation in venom composition of primitive ants from 4 geographically different areas of Brazil. The results reveal the presence of ~335 compounds for each venom/area and inter-colony variations were observed. 16 new peptides were characterized and 2 of them were synthesized and biologically assayed. These findings highlight the considerable and still unexplored diversity of ant's venom which could be used as valuable research tools in different areas of knowledge. [less ▲]

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See detailPer un insegnamento modulare dell’italiano LS
Lucchini, Silvia ULg

in Blommaert, M.-R.; Cannova, D. (Eds.) La didattica dell’italiano lingua straniera oggi. Realtà e prospettive (2000)

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See detailPer un non cauto omaggio a Fogazzaro : Nel centenario della morte (1911-2011)
Curreri, Luciano ULg

in Fedele ed altri racconti. Racconti brevi. Idillii spezzati (2014)

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See detailPer un'archeologia del sapere in Islam: il metodo di lavoro di uno storico del XV secolo
Bauden, Frédéric ULg

in Annali della Facoltà di Lingue et Letterature Straniere (Università degli Studi di Sassari) (2009), 2005(1), 209-223

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See detailPer una pedagogia della divergenza
de Landsheere, Gilbert ULg

in Scuola e Città (1967), 3

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See detailPer uno studio della metrica da Baudelaire: Una panoramica e qualche appunto sul «Viaggio» di Caproni e Raboni
Benzoni, Pietro ULg

in Stilistica e metrica italiana (2010), IX(9), 385-423

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See detailLa percée de l'entrepreneuriat social: clarifications conceptuelles
Defourny, Jacques ULg; Nyssens, Marthe

in Juris Associations (2011), 436(avril), 18-23

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See detailPerceived logistics service quality driven store Loyalty
Hammedi, Wafa ULg; Van Riel, Allard ULg; Semeijn, Janjaap

Poster (2009, July)

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See detailPerceived safety climate and job resources : relationships with safety behaviour.
Chmiel, N.; Hansez, Isabelle ULg

Conference (2008, April 12)

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See detailPerceiving prosodic prominence in a second language
Rasier, Laurent ULg; Caspers, Johanneke; Van Heuven, Vincent

Conference (2010)

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