title: Differential regulation of L1 and L2 beta-lactamase expression in Stenotrophomonas maltophilia.
abstract: It has been reported that Stenotrophomonas maltophilia L1 and L2 beta-lactamase expression is coordinated. We have isolated S. maltophilia mutants where (i) L1 is constitutively hyper-expressed and L2 is inducible; (ii) L2 is hyper-expressed and L1 is inducible; and (iii) L1 and L2 are constitutively hyper-expressed. The frequency of isolating type 1 and 2 mutants is c. 10(-7), indicating that promoter mutations are probably not involved and providing strong evidence that L1 and L2 expression is not, after all, coordinated. The frequency of isolating type 3 mutants is c. 10(-9), however, implying that there is a significant overlap between the regulatory mechanisms.
authors.affiliation: Bristol Centre for Antimicrobial Research and Evaluation, Department of Pathology and Microbiology, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK. matthewb.avison@bris.ac.uk
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Avison
authors.forename: Catherine S
authors.initials: CS
authors.lastname: Higgins
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Ford
authors.forename: Charlotte J
authors.initials: CJ
authors.lastname: von Heldreich
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Walsh
authors.forename: Peter M
authors.initials: PM
authors.lastname: Bennett
mesh_terms: D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D006801:Humans; D009154:Mutation; D020615:Stenotrophomonas maltophilia / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
chemical_list: C088032:beta-lactamase L1; C425104:beta-lactamase L2; D001618:beta-Lactamases