COMK ENCODES THE COMPETENCE TRANSCRIPTION FACTOR, THE KEY REGULATORY PROTEIN FOR COMPETENCE DEVELOPMENT IN BACILLUS-SUBTILIS

comK is a positive autoregulatory gene occupying a central position in the com petence-signal-transduction network. All regulatory routes id entified in this network converge at the level of comK expression. The ComK protein is required for the transcriptional induction of comK an d the late competence genes, which specify morphogenetic and structura l proteins necessary for construction of the DNA-binding and uptake ap paratus. In this report we demonstrate that ComK specifically binds to DNA fragments containing promoter and upstream sequences of the genes it affects (comC, comE, comF, comG and comK). Using portions of the r egion upstream of comC we show that the ComK-binding sequences are ess ential for the expression of competence. Moreover, we demonstrate that the presence of ComK stimulates the expression of comF-lacZ and comG- lacZ translational fusions in vivo in Escherichia coil. These results indicate that the gene product of comK is identical to the previously inferred competence transcription factor (CTF).