THE REGULATION OF COMPETENCE TRANSCRIPTION FACTOR SYNTHESIS CONSTITUTES A CRITICAL CONTROL POINT IN THE REGULATION OF COMPETENCE IN BACILLUS-SUBTILIS

comK, which encodes the competence transcription factor, is itself tra nscriptionally activated at the transition from exponential growth to stationary phase in Bacillus subtilis. MecA, a negative regulator of c ompetence, also inhibits comK transcription when overexpressed, and a mecA null mutation results in comK overexpression. Although null mutat ions in mecA, as well as in another gene, mecB, are known to bypass th e requirements for nearly all of the competence regulatory genes, the comK requirement is not suppressed by mecA inactivation. Various compe tence regulatory genes (comA, srfA, degU, abrB, sin, and spoOA) are sh own to be required for the expression of comK. srfA transcription is s hown to occur equally in cells destined for competence and those desti ned not to become competent. In contrast, comK transcription is restri cted to the presumptive competent cells. These and other results are c ombined to describe a regulatory pathway for competence.