SigB, an RNA polymerase sigma factor required for osmoprotection and proper differentiation of <i>Streptomyces coelicolor</i>

Cho, You‐Hee; Lee, Eun Jin; Ahn, Bo Eun; Roe, Jung Hye

doi:10.1046/j.1365-2958.2001.02622.x

Cited by 70 publications

(65 citation statements)

References 35 publications

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“…sigBp 1 expression is silenced at the vegetative mycelium phase but persistently increases when morphological differentiation progresses, consistent with the requirement of SigB for development into aerial hyphae and spores (11,24). The sigN promoter is also positively regulated by the developmental programs (12).…”

supporting

confidence: 59%

“…Microarray analysis suggests the transcriptional control of more than 280 genes by SigB after osmotic induction and a hierarchically transcriptional and posttranscriptional control order from SigB to SigL and SigM. Consistent with hierarchical regulation, SigB positively controls the aerial hyphal development and SigL is required for the sporulation, while SigM is involved in the full formation of spores (11,24).…”

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confidence: 84%

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Reciprocal Regulation between SigK and Differentiation Programs inStreptomyces coelicolor

et al. 2009

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Here we reported that deletion of SigK (SCO6520), a sigma factor in Streptomyces coelicolor, caused an earlier switch from vegetative mycelia to aerial mycelia and higher expression of chpE and chpH than that in the wild type. Loss of SigK also resulted in accelerated and enhanced production of antibiotics, actinorhodin, and undecylprodigiosin and increased expression of actII-orf4 and redD. These results suggested that SigK had a negative role in morphological transition and secondary metabolism. Furthermore, the sigK promoter (sigKp) activity gradually increased and sigK expression was partially dependent on SigK, but this dependence decreased during the developmental course of substrate mycelia. Meanwhile, two potentially nonspecific cleavages occurred between SigK and green fluorescent protein, and the SigK fusion proteins expressed under the constitutive promoter ermEp* sharply decreased and disappeared when aerial mycelia emerged. If expressed under sigKp, 3FLAG-SigK showed similar dynamic patterns but did not decrease as sharply as SigK expressed under ermEp*. These data suggested that the climbing expression of sigK might reduce the prompt degradation of SigK during vegetative hypha development for the proper timing of morphogenesis and that SigK vanished to remove the block for the emergence of aerial mycelia. Thus, we proposed that SigK had inhibitory roles on developmental events and that these inhibitory effects may be released by SigK degradation.

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confidence: 59%

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confidence: 84%

Reciprocal Regulation between SigK and Differentiation Programs inStreptomyces coelicolor

et al. 2009

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“…Sigma factors equivalent to s B have also been found in high-GC Gram-positive bacteria, including Mycobacterium tuberculosis and Streptomyces species (Mittenhuber, 2002). In Streptomyces coelicolor, s B acts in a complex network of several paralogous sigma factors, where it plays a role in osmotic and oxidative stress responses, as well as cellular differentiation and the production of antibiotics (Cho et al, 2001;Lee et al, 2005;Viollier et al, 2003).…”

Section: De Been and Othersmentioning

confidence: 99%

“…In S. coelicolor, these processes are also controlled by a seemingly complex network of s B -like sigma factors (Cho et al, 2001;Lee et al, 2005;Viollier et al, 2003). Indeed, experimental support for a functional link between OsaAB and a s B -like sigma factor (in this case s B itself) was recently provided (Fernández Martínez et al, 2009).…”

Section: Connections Of Rsbk Homologues With Cher and Cheb Homologuesmentioning

confidence: 99%

Novel σ B regulation modules of Gram-positive bacteria involve the use of complex hybrid histidine kinases

et al. 2011

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A common bacterial strategy to cope with stressful conditions is the activation of alternative sigma factors that control specific regulons enabling targeted responses. In the human pathogen Bacillus cereus, activation of the major stress-responsive sigma factor s B is controlled by a signalling route that involves the multi-sensor hybrid histidine kinase RsbK. RsbK-type kinases are not restricted to the B. cereus group, but occur in a wide variety of other bacterial species, including members of the the low-GC Gram-positive genera Geobacillus and Paenibacillus as well as the high-GC actinobacteria. Genome context and protein sequence analyses of 118 RsbK homologues revealed extreme variability in N-terminal sensory as well as C-terminal regulatory domains and suggested that RsbK-type kinases are subject to complex fine-tuning systems, including sensitization and desensitization via methylation and demethylation within the helical domain preceding the H-box. The RsbK-mediated stress-responsive sigma factor activation mechanism that has evolved in B. cereus and the other species differs markedly from the extensively studied and highly conserved RsbRST-mediated s B activation route found in Bacillus subtilis and other low-GC Gram-positive bacteria. Implications for future research on sigma factor control mechanisms are presented and current knowledge gaps are briefly discussed.

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“…The ECF sigma factor BldN is required for aerial mycelium formation and is directly involved in transcription of the bldM gene, encoding a response regulator (5). S. coelicolor B is necessary for protection from osmotic stress, but it is also needed for normal differentiation, as a sigB mutant is bald and overproduces the polyketide antibiotic actinorhodin on rich medium (11). SigB also appears to control a cascade of other group 3 sigma factors ( L and M ) important for downstream events in sporulation (36).…”

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confidence: 99%

Secreted-Protein Response to σ^UActivity inStreptomyces coelicolor

et al. 2008

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The filamentous bacterium Streptomyces coelicolor forms an aerial mycelium as a prerequisite to sporulation, which occurs in the aerial hyphae. Uncontrolled activity of the extracytoplasmic function sigma factor U blocks the process of aerial mycelium formation in this organism. Using a green fluorescent protein transcriptional reporter, we have demonstrated that sigU transcription is autoregulated. We have defined a U -dependent promoter sequence and used this to identify 22 likely U regulon members in the S. coelicolor genome. Since many of these genes encode probable secreted proteins, we characterized the extracellular proteome of a mutant with high U activity caused by disruption of rsuA, the presumed cognate anti-sigma factor of U . This mutant secreted a much greater quantity and diversity of proteins than the wild-type strain. Peptide mass fingerprinting was used to identify 79 proteins from the rsuA mutant culture supernatant. The most abundant species, SCO2217, SCO0930, and SCO2207, corresponded to secreted proteins or lipoproteins of unknown functions whose genes are in the proposed U regulon. Several unique proteases were also detected in the extracellular proteome of the mutant, and the levels of the protease inhibitor SCO0762 were much reduced compared to those of the wild type. Consequently, extracellular protease activity was elevated about fourfold in the rsuA mutant. The functions of the proteins secreted as a result of U activity may be important for combating cell envelope stress and modulating morphological differentiation in S. coelicolor.The Streptomyces species of gram-positive soil bacteria exhibit a complex life cycle that culminates in the production of unigenomic spores by sporulation of multigenomic, filamentous hyphae (8,56). While vegetative growth is characterized by the extension and branching of hyphae over and into the substratum, sporulation requires the construction of a distinct aerial mycelium composed of aerial hyphae that project above the colony surface. A number of mutants of the model organism Streptomyces coelicolor that fail to form an aerial mycelium have been described; these so-called bald (bld) mutants often have defects in antibiotic production, which is another hallmark of this genus. Many of the corresponding bld genes have been identified, and most are predicted to encode regulatory proteins (reviewed in reference 9).A growing body of evidence suggests that pathways mediating environmental stress responses and morphological development are linked in S. coelicolor (9,19,31,35,36,62). The functions of alternative sigma factors appear to play an important role in connecting these processes. The S. coelicolor genome encodes 65 sigma factors (4

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SigB, an RNA polymerase sigma factor required for osmoprotection and proper differentiation of Streptomyces coelicolor

Abstract: SummaryA gene (sigB ) encoding an alternative sigma factor s B in Streptomyces coelicolor A3 (2)

Cited by 70 publications

References 35 publications

Reciprocal Regulation between SigK and Differentiation Programs inStreptomyces coelicolor

Reciprocal Regulation between SigK and Differentiation Programs inStreptomyces coelicolor

Novel σ B regulation modules of Gram-positive bacteria involve the use of complex hybrid histidine kinases

Secreted-Protein Response to σ^UActivity inStreptomyces coelicolor

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SigB, an RNA polymerase sigma factor required for osmoprotection and proper differentiation of Streptomyces coelicolor

Abstract: SummaryA gene (sigB ) encoding an alternative sigma factor s B in Streptomyces coelicolor A3 (2)

Cited by 70 publications

References 35 publications

Reciprocal Regulation between SigK and Differentiation Programs inStreptomyces coelicolor

Reciprocal Regulation between SigK and Differentiation Programs inStreptomyces coelicolor

Novel σ B regulation modules of Gram-positive bacteria involve the use of complex hybrid histidine kinases

Secreted-Protein Response to σUActivity inStreptomyces coelicolor

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Secreted-Protein Response to σ^UActivity inStreptomyces coelicolor