This family contains several bacterial MecA proteins. The development of competence in Bacillus subtilis is regulated by growth conditions and several regulatory genes. In complex media competence development is poor, and there is little or no expression of late competence genes. Mec mutations permit competence development and late competence gene expression in complex media, bypassing the requirements for many of the competence regulatory genes. The mecA gene product acts negatively in the development of competence. Null mutations in mecA allow expression of a late competence gene comG, under conditions where it is not normally expressed, including in complex media and in cells mutant for several competence regulatory genes. Overexpression of MecA inhibits comG transcription.