Regulation of stage II of sporulation in Bacillus subtilis

A mutation, spo-87, in the spo0J locus of Bacillus subtilis allows appreciable transcription of spoIIA, spoIID and spoIIG and later operons, even though most of the cells are morphologically blocked at stage 0 and the incidence of heat-resistant spores is about 1 per 10(4) cells. This mutation therefore appears to disengage the genetic control of sporulation from the morphological changes to which it should be connected. spoIIA and spoIIG are transcribed independently of one another. However, the products of both operons are needed for the activation of spoIID which occurs later. This indicates a convergence of parallel pathways of operon expression. We have also shown that nonsense mutations in spoIIAC (which codes for a sigma factor of RNA polymerase) prevent transcription of spoIID; by contrast, missense mutations in the same gene allow transcription of spoIID.