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Osmoregulation in Streptomyces coelicolor : modulation of SigB activity by OsaC
Author(s) -
Martínez Lorena Fernández,
Bishop Amy,
Parkes Lindsay,
Del Sol Ricardo,
Salerno Paola,
Sevcikova Beatrica,
Mazurakova Vladislava,
Kormanec January,
Dyson Paul
Publication year - 2009
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2009.06599.x
Subject(s) - biology , streptomyces coelicolor , sigma factor , phosphatase , gene , genetics , microbiology and biotechnology , pas domain , regulator , response regulator , biochemistry , gene expression , mutant , transcription factor , phosphorylation , promoter
Summary 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 σ 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 ΔPho , 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 σ B anti‐sigma factor. Indeed, co‐purification experiments indicate association of OsaC and σ B . These results support a model for post‐osmotic stress modulation of σ B activity by OsaC.