Regulation of σB by an anti- and an anti-anti-sigma factor in Streptomyces coelicolor in response to osmotic stress

Eun Jin Lee, You Hee Cho, Hyo Sub Kim, Bo Eun Ahn, Jung Hye Roe

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35 Citations (Scopus)

Abstract

σB, a homolog of stress-responsive σB of Bacillus subtilis, controls both osmoprotection and differentiation in Streptomyces coelicolor A3 (2). Its gene is preceded by rsbA and rsbB genes encoding homologs of an anti-sigma factor, RsbW, and its antagonist, RsbV, of B. subtilis, respectively. Purified RsbA bound to σB and prevented σB-directed transcription from the sigBp1 promoter in vitro. An rsbA-null mutant exhibited contrasting behavior to the sigB mutant, with elevated sigBp1 transcription, no actinorhodin production, and precocious aerial mycelial formation, reflecting enhanced activity of σB in vivo. Despite sequence similarity to RsbV, RsbB lacks the conserved phosphorylatable serine residue and its gene disruption produced no distinct phenotype. RsbV (SCO7325) from a putative six-gene operon (rsbV-rsbR-rsbS-rsbT- rsbU1-rsbU) was strongly induced by osmotic stress in a σB- dependent manner. It antagonized the inhibitory action of RsbA on σB-directed transcription and was phosphorylated by RsbA in vitro. These results support the hypothesis that the rapid induction of σB target genes by osmotic stress results from modulation of σB activity by the kinase-anti-sigma factor RsbA and its phosphorylatable antagonist RsbV, which function by a partner-switching mechanism. Amplified induction could result from a rapid increase in the synthesis of both σB and its inhibitor antagonist.

Original languageEnglish
Pages (from-to)8490-8498
Number of pages9
JournalJournal of Bacteriology
Volume186
Issue number24
DOIs
Publication statusPublished - 2004 Dec

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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