Repressor of comK, the master regulator of competence development (PubMed:11849533). Overexpression seems to be lethal (PubMed:11849533). Represses at least 20 genes that specify membrane-localized and secreted proteins, including some that encode products with antibiotic activity (PubMed:15743949). Binds to many AT-rich sites in the chromosome, many of which are known or thought to derive from horizontal gene transfer; helps keep mobile element ICEBs1 quiescent in the genome (PubMed:21085634). Binds to its own promoter and is thus probably autoregulatory (PubMed:21085634). Not uniformly distributed in the nucleoid, it forms several clusters (PubMed:21085634). Expression is constant during late log phase and for at least 2 hours in stationary phase (at protein level) (PubMed:11849533). Probably repressed by AbrB and SinR, as well as partially by ComK (PubMed:11849533). Probably negatively regulates its own expression (PubMed:11849533, PubMed:21085634). There are 1000-3000 proteins/chromosome in exponential phase grown in minimal medium (PubMed:21085634). The C-terminus (residues 95-191) binds DNA (PubMed:21085634). Increased expression of comK, increases transformation about 5-fold, decreases sporulation efficiency about 5-fold (PubMed:11849533). Increased excision of mobile element ICEBs1 (PubMed:21085634).