The initiation of sporulation in Bacillus subtilis in controlled by five genes, spo0A, spo0B, spo0E, spo0F, and spo0H. The mechanism by which the products of these genes are able to control the transcription of key genes required for the initiation of sporulation as well as the synthesis of enzymes produced during the onset of stationary phase is unknown. One view of the role of the spo0 gene products in the control of the initiation of sporulation is focused around the function of the spo0A protein coded by the spo0A locus. The results are consistent with the idea that the activity of the spo0A protein is modulated by the products of the spo0B, spo0E and spo0F loci. The modified spo0A protein is thought to be a transcription factor or at least to influence transcription required for expression of certain key genes in the sporulation process. The research proposed in this application has three basic primary aims: 1) A detailed study of the subtilisin promoter as a paradigm for the action of spo0 products in transcription. 2) A study of the control of the expression of and the function of spo0 gene products by determination of the interrelationships of these products with themselves and with other components of the cell. 3) A detailed study of the function and structure of the spo0A protein will be undertaken through the use of site-directed mutagenesis techniques in order to gain a complete understanding of the role of this protein in the transcriptional activation of sporulation.