title: Redefining the role of psr in beta-lactam resistance and cell autolysis of Enterococcus hirae.
abstract: The contribution of penicillin-binding protein 5 (PBP5) and the PBP5 synthesis repressor (Psr) to the beta-lactam resistance, growth, and cell autolysis of wild-type strain ATCC 9790 and resistant strain R40 of Enterococcus hirae was investigated by disruption or substitution of the corresponding pbp5 and psr genes by Campbell-type recombination. The resulting modifications were confirmed by hybridization and PCR. The low susceptibility of E. hirae to beta-lactams was confirmed to be largely dependent on the presence of PBP5. However, against all expectations, inactivation of psr in ATCC 9790 or complementation of R40 cells with psr did not modify the susceptibility to benzylpenicillin or the growth and cell autolysis rates. These results indicated that the psr gene does not seem to be involved in the regulation of PBP5 synthesis and consequently in beta-lactam resistance or in the regulation of cell autolysis in E. hirae.
authors.affiliation: Department of Molecular Biology and Microbiology, School of Medicine, Tufts University, Boston, Massachusetts 02111, USA.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Sapunaric
authors.forename: Christine
authors.initials: C
authors.lastname: Franssen
authors.forename: Patrick
authors.initials: P
authors.lastname: Stefanic
authors.forename: Ana
authors.initials: A
authors.lastname: Amoroso
authors.forename: Olivier
authors.initials: O
authors.lastname: Dardenne
authors.forename: Jacques
authors.initials: J
authors.lastname: Coyette
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001433:Bacteriolysis; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D016983:Enterococcus / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D006602:Hexosyltransferases / Q000235:genetics / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D002267:Muramoylpentapeptide Carboxypeptidase / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D018440:beta-Lactam Resistance
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; C080374:Psr protein, Enterococcus hirae; D012097:Repressor Proteins; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase