DNA damage-induced block of sporulation in Streptomyces venezuelae involves downregulation of ssgB

Abstract

DNA damage often causes an arrest of the cell cycle that provides time for genome integrity to be restored. In bacteria, the classical SOS DNA damage response leads to an inhibition of cell division resulting in temporarily filamentous growth. This raises the question as to whether such a response mechanism might similarly function in naturally filamentous bacteria such as Streptomyces. Streptomyces exhibit two functionally distinct forms of cell division: cross-wall formation in vegetative hyphae and sporulation septation in aerial hyphae. Here, we show that the genotoxic agent mitomycin C confers a block in sporulation septation in Streptomyces venezuelae in a mechanism that involves, at least in part, the downregulation of ssgB. Notably, this DNA damage response does not appear to block cross-wall formation and may be independent of canonical SOS and developmental regulators. We also show that the mitomycin C-induced block in sporulation can be partially bypassed by the constitutive expression of ssgB, though this appears to be largely limited to mitomycin C treatment and the resultant spore-like cells have reduced viability.

Genome-wide identification of the LexA-mediated DNA damage response inStreptomyces venezuelae

“…We note that our global transcriptional profiling analysis further showed that several genes required for sporulation were significantly downregulated following the treatment with MMC, including the classical Streptomyces developmental regulatory genes whiI, whiH and whiB , genes involved in cell division (ssgB) and chromosome segregation (smeA-sffA) and several genes within the whiE locus, which encodes the biosynthesis machinery for the production of the polyketide pigment associated with mature spores (16–19). These findings are in agreement with other recent studies, reporting that subinhibitory concentrations of MMC inhibit sporulation in S. venezuelae (9, 20).…”

Genome-Wide Identification of the LexA-Mediated DNA Damage Response in Streptomyces venezuelae

“…We note that our global transcriptional profiling analysis further showed that several genes required for sporulation were significantly downregulated following the treatment with MMC, including the classical Streptomyces developmental regulatory genes whiI , whiH , and whiB , genes involved in cell division ( ssgB ) and chromosome segregation ( smeA-sffA ) and several genes within the whiE locus, which encodes the biosynthesis machinery for the production of the polyketide pigment associated with mature spores ( 16 – 19 ). These findings are in agreement with those of other recent studies, reporting that subinhibitory concentrations of MMC inhibit sporulation in S. venezuelae ( 9 , 20 ).…”