A sporulation‐specific, sigF‐dependent protein, SspA, affects septum positioning in Streptomyces coelicolor. Issue 2 (19th December 2013)

• Record Type: Journal Article
• Authors: Tzanis, Angelos; Dalton, Kate A.; Hesketh, Andrew; den, Chris D.; Buttner, Mark J.; Thibessard, Annabelle; Kelemen, Gabriella H.
• Is Part Of: Molecular microbiology. Volume 91:Issue 2(2014)
• Page Start: 363
• Page End: 380
• Publication Date: 2013-12-19
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.12466
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>The RNA polymerase sigma factor SigF controls late development during sporulation in the filamentous bacterium <italic>Streptomyces coelicolor</italic>. The only known SigF‐dependent gene identified so far, <italic>SCO5321</italic>, is found in the biosynthetic cluster encoding spore pigment synthesis. Here we identify the first direct target for SigF, the gene <italic>sspA</italic>, encoding a <underline>s</underline>porulation‐<underline>s</underline>pecific <underline>p</underline>rotein. Bioinformatic analysis suggests that SspA is a secreted lipoprotein with two PepSY signature domains. The <italic>sspA</italic> 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 <italic>sspA</italic> transcription are absent from the <italic>sigF</italic> null mutant. Moreover, <italic>in vitro</italic> transcription assay confirmed that RNA polymerase holoenzyme containing SigF is sufficient for initiation of transcription from a single <italic>sspA</italic> promoter. In addition, <italic>in vivo</italic> and <italic>in vitro</italic> experiments showed that <italic>sspA</italic> is a direct target of BldD, which functions to repress sporulation genes, including <italic>whiG</italic>, <italic>ftsZ</italic> and <italic>ssgB</italic>, during vegetative growth, co‐ordinating their expression during sporulation septation.</p> </abstract>