SCO3129, a TetR family regulator, is responsible for osmotic stress in Streptomyces coelicolor

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.

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The Anti-Anti-Sigma Factor BldG Is Involved in Activation of the Stress Response Sigma Factor σH in Streptomyces coelicolor A3(2)

Journal of Bacteriology ◽

10.1128/jb.00828-10 ◽

2010 ◽

Vol 192 (21) ◽

pp. 5674-5681 ◽

Cited By ~ 19

Author(s):

Beatrica Sevcikova ◽

Bronislava Rezuchova ◽

Dagmar Homerova ◽

Jan Kormanec

Keyword(s):

Stress Response ◽

Osmotic Stress ◽

Sigma Factor ◽

Streptomyces Coelicolor ◽

Direct Interaction ◽

Morphological Differentiation ◽

Osmotic Stress Response ◽

Its Gene ◽

Two Hybrid

ABSTRACT The alternative stress response sigma factor σH has a role in regulation of the osmotic stress response and in morphological differentiation in Streptomyces coelicolor A3(2). Its gene, sigH, is located in an operon with the gene that encodes its anti-sigma factor UshX (PrsH). However, no gene with similarity to an anti-anti-sigma factor which may have a role in σH activation by a “partner-switching” mechanism is located in the operon. By using a combination of several approaches, including pull-down and bacterial two-hybrid assays and visualization of the complex by native polyacrylamide electrophoresis, we demonstrated a direct interaction between UshX and the pleiotropic sporulation-specific anti-anti-sigma factor BldG. Osmotic induction of transcription of the sigHp2 promoter that is specifically recognized by RNA polymerase containing σH was absent in an S. coelicolor bldG mutant, indicating a role of BldG in σH activation by a partner-switching-like mechanism.

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Cross-Recognition of Promoters by the Nine SigB Homologues Present in Streptomyces coelicolor A3(2)

International Journal of Molecular Sciences ◽

10.3390/ijms22157849 ◽

2021 ◽

Vol 22 (15) ◽

pp. 7849

Author(s):

Beatrica Sevcikova ◽

Bronislava Rezuchova ◽

Vladimira Mazurakova ◽

Dagmar Homerova ◽

Renata Novakova ◽

...

Keyword(s):

Stress Response ◽

Osmotic Stress ◽

Streptomyces Coelicolor ◽

Dominant Role ◽

Morphological Differentiation ◽

Sigma Factors ◽

Stress Conditions ◽

Phenotypic Analysis ◽

Specific Sequence ◽

Osmotic Stress Response

In contrast to Bacillus subtilis, Streptomyces coelicolor A3(2) contains nine homologues of stress response sigma factor SigB with a major role in differentiation and osmotic stress response. The aim of this study was to further characterize these SigB homologues. We previously established a two-plasmid system to identify promoters recognized by sigma factors and used it to identify promoters recognized by the three SigB homologues, SigF, SigG, and SigH from S. coelicolor A3(2). Here, we used this system to identify 14 promoters recognized by SigB. The promoters were verified in vivo in S. coelicolor A3(2) under osmotic stress conditions in sigB and sigH operon mutants, indicating some cross-recognition of these promoters by these two SigB homologues. This two-plasmid system was used to examine the recognition of all identified SigB-, SigF-, SigG-, and SigH-dependent promoters with all nine SigB homologues. The results confirmed this cross-recognition. Almost all 24 investigated promoters were recognized by two or more SigB homologues and data suggested some distinguishing groups of promoters recognized by these sigma factors. However, analysis of the promoters did not reveal any specific sequence characteristics for these recognition groups. All promoters showed high similarity in the -35 and -10 regions. Immunoblot analysis revealed the presence of SigB under osmotic stress conditions and SigH during morphological differentiation. Together with the phenotypic analysis of sigB and sigH operon mutants in S. coelicolor A3(2), the results suggest a dominant role for SigB in the osmotic stress response and a dual role for SigH in the osmotic stress response and morphological differentiation. These data suggest a complex regulation of the osmotic stress response in relation to morphological differentiation in S. coelicolor A3(2).

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Specialized osmotic stress response systems involve multiple SigB-like sigma factors in Streptomyces coelicolor

Molecular Microbiology ◽

10.1046/j.1365-2958.2003.03302.x ◽

2003 ◽

Vol 47 (3) ◽

pp. 699-714 ◽

Cited By ~ 58

Author(s):

Patrick H. Viollier ◽

Gabriella H. Kelemen ◽

Glenn E. Dale ◽

Kien T. Nguyen ◽

Mark J. Buttner ◽

...

Keyword(s):

Stress Response ◽

Osmotic Stress ◽

Streptomyces Coelicolor ◽

Sigma Factors ◽

Osmotic Stress Response ◽

Response Systems

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GlnR-Mediated Regulation ofectABCDTranscription Expands the Role of the GlnR Regulon to Osmotic Stress Management

Journal of Bacteriology ◽

10.1128/jb.00185-15 ◽

2015 ◽

Vol 197 (19) ◽

pp. 3041-3047 ◽

Cited By ~ 13

Author(s):

ZhiHui Shao ◽

WanXin Deng ◽

ShiYuan Li ◽

JuanMei He ◽

ShuangXi Ren ◽

...

Keyword(s):

Osmotic Stress ◽

Nitrogen Metabolism ◽

High Salinity ◽

Streptomyces Coelicolor ◽

Compatible Solutes ◽

Negative Regulator ◽

Global Regulator ◽

Content Type ◽

Bacterial Physiology

ABSTRACTEctoine and hydroxyectoine are excellent compatible solutes for bacteria to deal with environmental osmotic stress and temperature damages. The biosynthesis cluster of ectoine and hydroxyectoine is widespread among microorganisms, and its expression is activated by high salinity and temperature changes. So far, little is known about the mechanism of the regulation of the transcription ofectgenes and only two MarR family regulators (EctR1 in methylobacteria and the EctR1-related regulator CosR inVibrio cholerae) have been found to negatively regulate the expression ofectgenes. Here, we characterize GlnR, the global regulator for nitrogen metabolism in actinomycetes, as a negative regulator for the transcription of ectoine/hydroxyectoine biosynthetic genes (ectoperon) inStreptomyces coelicolor. The physiological role of this transcriptional repression by GlnR is proposed to protect the intracellular glutamate pool, which acts as a key nitrogen donor for both the nitrogen metabolism and the ectoine/hydroxyectoine biosynthesis.IMPORTANCEHigh salinity is deleterious, and cells must evolve sophisticated mechanisms to cope with this osmotic stress. Although production of ectoine and hydroxyectoine is one of the most frequently adopted strategies, the in-depth mechanism of regulation of their biosynthesis is less understood. So far, only two MarR family negative regulators, EctR1 and CosR, have been identified in methylobacteria andVibrio, respectively. Here, our work demonstrates that GlnR, the global regulator for nitrogen metabolism, is a negative transcriptional regulator forectgenes inStreptomyces coelicolor. Moreover, a close relationship is found between nitrogen metabolism and osmotic resistance, and GlnR-mediated regulation ofecttranscription is proposed to protect the intracellular glutamate pool. Meanwhile, the work reveals the multiple roles of GlnR in bacterial physiology.

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