title: Osmoregulation in Streptomyces coelicolor: modulation of SigB activity by OsaC.
abstract: As free-living non-motile saprophytes, Streptomyces need to adapt to a wide range of environmental conditions and this is reflected by an enormous diversity of regulatory proteins encoded by, for example, the genome of the model streptomycete Streptomyces coelicolor. In this organism, we have identified a new osmoregulation gene, osaC, encoding a member of a novel family of regulatory proteins. Members of the family have a predicted domain composition consisting of an N-terminal kinase domain related to anti-sigma factors, sensory Pas and Gaf domains, and a C-terminal phosphatase domain. osaC is linked to the response regulator gene osaB; expression analysis of the latter revealed that it is induced after osmotic stress in a sigma(B)-dependent manner. OsaC is required to return osaB and sigB expression back to constitutive levels after osmotic stress. From analysis of the activities of OsaC(DeltaPho), lacking the C-terminal phosphatase domain, and OsaC(N92A), with a substitution of a critical asparagine residue in the kinase domain, we infer that this N-terminal domain functions as a sigma(B) anti-sigma factor. Indeed, co-purification experiments indicate association of OsaC and sigma(B). These results support a model for post-osmotic stress modulation of sigma(B) activity by OsaC.
authors.affiliation: Institute of Life Science, School of Medicine, Swansea University, Singleton Park, Swansea SA28PP, UK.
authors.forename: Lorena
authors.initials: L
authors.lastname: Fernández Martínez
authors.forename: Amy
authors.initials: A
authors.lastname: Bishop
authors.forename: Lindsay
authors.initials: L
authors.lastname: Parkes
authors.forename: Ricardo
authors.initials: R
authors.lastname: Del Sol
authors.forename: Paola
authors.initials: P
authors.lastname: Salerno
authors.forename: Beatrica
authors.initials: B
authors.lastname: Sevcikova
authors.forename: Vladislava
authors.initials: V
authors.lastname: Mazurakova
authors.forename: January
authors.initials: J
authors.lastname: Kormanec
authors.forename: Paul
authors.initials: P
authors.lastname: Dyson
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009997:Osmotic Pressure; D011401:Promoter Regions, Genetic; D054730:Protein Interaction Domains and Motifs; D012329:RNA, Bacterial / Q000378:metabolism; D016415:Sequence Alignment; D012808:Sigma Factor / Q000378:metabolism*; D048372:Streptomyces coelicolor / Q000235:genetics / Q000378:metabolism*; D014882:Water-Electrolyte Balance
chemical_list: D001426:Bacterial Proteins; D012329:RNA, Bacterial; C079011:SigB protein, Bacteria; D012808:Sigma Factor