title: The ECF sigma factor SigT regulates actinorhodin production in response to nitrogen stress in Streptomyces coelicolor.
abstract: Sigma factors of the extracytoplasmic function (ECF) subfamily are important regulators of stress responses in bacteria. This work described the characterization of ECF sigma factor SigT in Streptomyces coelicolor. We found the absence of sigT almost abolished the production of the antibiotics actinorhodin (Act) under nitrogen stress. Under nitrogen-limited conditions, significantly reduced Act production and linked actII-ORF4 transcription with respect to wild type were observed in the sigT-null mutant. Using reporter (xylE) fusion to sigT promoter, we demonstrated that sigT was induced by nitrogen limitation in a SigT-dependent manner. Transcriptional analyses showed that SigT controlled the expression of relA, the ppGpp synthetase gene, and consequently affected the Act production upon nitrogen starvation. Co-transcription analysis revealed that sigT was co-transcribed with rstB (gene upstream of sigT) but not with rstA (gene downstream of sigT). Phenotypic and transcriptional results suggested RstA may modulate the activity of SigT positively.
authors: College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
authors: Wei-Hong
authors: WH
authors: Feng
authors: Xu-Ming
authors: XM
authors: Mao
authors: Zhen-Hua
authors: ZH
authors: Liu
authors: Yong-Quan
authors: YQ
authors: Li
mesh_terms: D000880:Anthraquinones / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D048372:Streptomyces coelicolor / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D000095622:Benzoisochromanequinones
chemical_list: D000880:Anthraquinones; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D009584:Nitrogen; D012808:Sigma Factor; C013390:actinorhodin; D000095622:Benzoisochromanequinones