title: The RNA polymerase-binding protein RbpA confers basal levels of rifampicin resistance on Streptomyces coelicolor.
abstract: RbpA is an RNA polymerase-binding protein that occurs in the actinomycete family of bacteria and is regulated by the disulphide stress-response sigma factor, sigma(R), in Streptomyces coelicolor. Here we demonstrate that rbpA null mutants exhibit a slow-growth phenotype and are particularly sensitive to the transcription inhibitor rifampicin. Strikingly, transcription mapping experiments revealed that rbpA expression is induced upon exposure of S. coelicolor to rifampicin and that this, in part, involves an increase in the activity of sigma(R). In contrast, the ribosomal RNA operon promoter rrnDp3, which is recognized by the vegetative sigma factor sigma(HrdB), was strongly inhibited by rifampicin. Reconstitution of RNAP from an rbpA null mutant with purified RbpA revealed that RbpA stimulates transcription from rrnDp3, even in the presence of rifampicin. The data presented suggest that RbpA confers basal levels of rifampicin resistance and is a novel regulator of rRNA synthesis in S. coelicolor.
authors.affiliation: Department of Biochemistry, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK.
authors.forename: Katy V
authors.initials: KV
authors.lastname: Newell
authors.forename: Derek P
authors.initials: DP
authors.lastname: Thomas
authors.forename: Dimitris
authors.initials: D
authors.lastname: Brekasis
authors.forename: Mark S B
authors.initials: MS
authors.lastname: Paget
mesh_terms: D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D024881:Drug Resistance, Bacterial; D015964:Gene Expression Regulation, Bacterial; D018869:Heat-Shock Response; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D012293:Rifampin / Q000494:pharmacology*; D012808:Sigma Factor / Q000378:metabolism; D048372:Streptomyces coelicolor / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D000904:Antibiotics, Antitubercular; D001426:Bacterial Proteins; D003470:Culture Media; D012808:Sigma Factor; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin