THE BACILLUS-SUBTILIS-SINR PROTEIN IS A REPRESSOR OF THE KEY SPORULATION GENE-SPO0A

Sine is a pleiotropic DNA binding protein that is essential for the la te-growth processes of competence and motility in Bacillus subtilis an d is also a repressor of others, e,g,, sporulation and subtilisin synt hesis. In this report, we show that SinR, in addition to being an inhi bitor of sporulation stage II gene expression, is a repressor of the k ey early sporulation gene spoOA. The sporulation-specific rise in spoO A expression at time zero is absent in a Sine-overproducing strain and is much higher than normal in strains with a disrupted sinR gene. Thi s effect is direct, since SinR binds specifically to spo0A in vitro, i n a region overlapping the -10 region bf the sporulation-specific P, p romoter that is recognized by E-sigma(H) polymerase, Methyl interferen ce and site-directed mutagenesis studies have identified guanine resid ues that are important for Sine recognition of this DNA sequence, Fina lly, we present evidence that SinR controls sporulation through severa l independent genes, i,e,, spo0A, spoIIA, and possibly spoIIG and spoI IE.