THE ROLE OF SIGMA-F IN PRESPORE-SPECIFIC TRANSCRIPTION IN BACILLUS-SUBTILIS

Sporulation in Bacillus subtilis is a simple developmental system in which a single cell undergoes differentiation to two 'sister' cells, namely the prespore and the sporangium. Prespore-specific gene expression is largely dependent on the synthesis of a transcription factor, sigma-G. Transcription of spoIIIG, the gene encoding sigma-G, is under precise temporal and spatial control, requiring the products of at least eight genes that are expressed in the pre-divisional cell. Here we show that the product of one of these genes, another sigma factor, sigma-F, is by itself sufficient to direct transcription of spoIIIG in non-sporulating cells. The results indicate that the cell-specificity of prespore gene expression is determined by a mechanism that exerts temporal and spatial control over the activity of sigma-F.