Conférence du Dre Catherine Paradis-Bleau, postdoctoral fellow,
Department of Microbiology and Molecular Genetics Harvard Medical School.Cette conférence sera prononcée en anglais
Résumé
To fortify their cytoplasmic membrane and protect it from osmotic lysis, bacterial cells typically surround themselves with a crosslinked polysaccharide meshwork called peptidoglycan (PG). The major cellular PG synthases are thought to be the penicillinbinding proteins (PBPs); the targets of penicillin and related antibiotics. Although PBPs have been well characterized in vitro, surprisingly little is known about how these enzymes build the PG in vivo. Using Escherichia coli as a model organism, we developed a genetic screen to directly identify factors essential for the in vivo activity of the PBPs. We identified two outer membrane lipoproteins of previously unknown function as critical PG assembly factors. These proteins have been named LpoA and LpoB for lipoprotein modulators of PBP function from the outer membrane. We demonstrated that LpoA and LpoB form specific trans-envelope complexes with their cognate PBP and are essential for PBP function in vivo. Furthermore, we confirmed that the lipoproteins directly activate their cognate PBP in vitro. These results indicate that essential PBP accessory proteins play a central role in PG biogenesis, and like the PBPs they work with, these factors are attractive targets for antibiotic development.
Conférence présentée par le Département de microbiologie et immunologie de l'Université de Montréal.
Crédit photo : site Web du Département de microbiologie et immunologie
