title: Induction of a secretable beta-lactamase requires a long lag time in Xanthomonas campestris pv. campestris str. 17.
abstract: Xanthomonas campestris pv. campestris (Xcc) constitutively expresses penicillinase activity in the absence of an inducer. An ampR-bla module is required for the antibiotic resistance phenotype. In this study, we demonstrate that AmpR negatively autoregulates its own expression in a β-lactam-independent manner. In the absence of inducer, bla is expressed at a high basal level. Expression of bla is inducible by β-lactam, however, with a period. AmpR protein and the LysR-motif located upstream of bla promoter are essential for basal expression and induction of bla. Most β-lactamase activity is present in the culture medium, suggesting that Bla protein can be secreted by Xcc into the environment.
authors.affiliation: Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei 112, Taiwan.
authors.forename: Tsuey-Ching
authors.initials: TC
authors.lastname: Yang
authors.forename: Mei-Jung
authors.initials: MJ
authors.lastname: Tsai
authors.forename: Jeffrey J P
authors.initials: JJ
authors.lastname: Tsai
authors.forename: Rouh-Mei
authors.initials: RM
authors.lastname: Hu
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D002440:Cefoxitin / Q000494:pharmacology; D003470:Culture Media / Q000737:chemistry; D015964:Gene Expression Regulation, Bacterial; D013997:Time Factors; D014158:Transcription, Genetic; D016959:Xanthomonas campestris / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D047090:beta-Lactams; C071526:AmpR protein, Bacteria; D002440:Cefoxitin; D001618:beta-Lactamases