title: A sporulation-specific, sigF-dependent protein, SspA, affects septum positioning in Streptomyces coelicolor.
abstract: The RNA polymerase sigma factor SigF controls late development during sporulation in the filamentous bacterium Streptomyces coelicolor. The only known SigF-dependent gene identified so far, SCO5321, is found in the biosynthetic cluster encoding spore pigment synthesis. Here we identify the first direct target for SigF, the gene sspA, encoding a sporulation-specific protein. Bioinformatic analysis suggests that SspA is a secreted lipoprotein with two PepSY signature domains. The sspA deletion mutant exhibits irregular sporulation septation and altered spore shape, suggesting that SspA plays a role in septum formation and spore maturation. The fluorescent translational fusion protein SspA-mCherry localized first to septum sites, then subsequently around the surface of the spores. Both SspA protein and sspA transcription are absent from the sigF null mutant. Moreover, in vitro transcription assay confirmed that RNA polymerase holoenzyme containing SigF is sufficient for initiation of transcription from a single sspA promoter. In addition, in vivo and in vitro experiments showed that sspA is a direct target of BldD, which functions to repress sporulation genes, including whiG, ftsZ and ssgB, during vegetative growth, co-ordinating their expression during sporulation septation.
authors.affiliation: University of East Anglia, Norwich Research Park, Norwich, UK.
authors.forename: Angelos
authors.initials: A
authors.lastname: Tzanis
authors.forename: Kate A
authors.initials: KA
authors.lastname: Dalton
authors.forename: Andrew
authors.initials: A
authors.lastname: Hesketh
authors.forename: Chris D
authors.initials: CD
authors.lastname: den Hengst
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Buttner
authors.forename: Annabelle
authors.initials: A
authors.lastname: Thibessard
authors.forename: Gabriella H
authors.initials: GH
authors.lastname: Kelemen
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019295:Computational Biology; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D055785:Gene Knockdown Techniques; D005798:Genes, Bacterial; D008074:Lipoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000378:metabolism*; D013171:Spores, Bacterial / Q000235:genetics / Q000502:physiology; D048372:Streptomyces coelicolor / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; C064971:FliA protein, Bacteria; D008074:Lipoproteins; D012808:Sigma Factor; C082314:SspA protein, bacteria; D012321:DNA-Directed RNA Polymerases