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 late-growth processes of competence and motility in Bacillus subtilis and is also a repressor of others, e,g,, sporulation and subtilisin synthesis. In this report, we show that SinR, in addition to being an inhibitor of sporulation stage II gene expression, is a repressor of the key early sporulation gene spoOA. The sporulation-specific rise in spoOA expression at time zero is absent in a Sine-overproducing strain and is much higher than normal in strains with a disrupted sinR gene. This effect is direct, since SinR binds specifically to spo0A in vitro, in a region overlapping the -10 region bf the sporulation-specific P, promoter that is recognized by E-sigma(H) polymerase, Methyl interference and site-directed mutagenesis studies have identified guanine residues that are important for Sine recognition of this DNA sequence, Finally, we present evidence that SinR controls sporulation through several independent genes, i,e,, spo0A, spoIIA, and possibly spoIIG and spoIIE.