GENETIC NETWORKS CONTROLLING THE INITIATION OF SPORULATION AND THE DEVELOPMENT OF GENETIC COMPETENCE IN BACILLUS-SUBTILIS

Interconnected regulatory networks control the initiation of sporulati on and the development of genetic competence in Bacillus subtilis. The se two developmental pathways have both common and distinct elements a nd employ similar regulatory strategies. Activation of the ComK transc ription factor serves to integrate many of the physiological signals t hat control competence development, including cell density signals. Th e cell density signals for competence are mediated by two different pe ptide pheromones, the ComX pheromone, a 9 or 10 amino acid peptide wit h a modified tryptophan residue, and the competence stimulating factor , CSF, which is at least in part a peptide. Activation of the SpoOA tr anscription factor by phosphorylation serves as a developmental checkp oint and to integrate several physiological signals that control entry into the sporulation pathway. The physiological signals are generated by conditions of nutrient deprivation, high cell density, the Krebs c ycle, DNA replication, DNA damage, and some aspect of the chromosome p artitioning machinery. Both the ComK and SpoOA transcription factors a re part of autogenous regulatory loops that control entry into compete nce or sporulation.