GENETIC RECOMBINATION IN BACILLUS SUBTILIS

Genetic competence is defined as the ability of bacterial cells to bind and internalize high molecular weight DNA, which may then be established as an autonomous replicon or recombine with a resident DNA molecule. Competence in Bacillus subtilis is one of several post-exponentially expressed systems, the best characterized of which is sporulation. The present study is directed towards unraveling the complex network of events that determine the onset of competence expression in response to a set of nutritional, growth stage and cell-type specific signals. This network is known to include at least one phosphorylation cascade and possibly several, and included a likely transmembrane signaling event. We will investigate the role of the two-component regulators, ComP and ComQ, in signaling the onset of transcription of srfA, a key intermediate in the regulatory pathway. We will investigate the role of comK in competence regulation and that of MecA, a probable negative regulator of several post-exponential expression systems. We will also attempt to clone and characterize ctf, which appears to encode a transcriptional activator of late competence genes. The interaction of this regulatory pathway with those governing other post-exponential expression systems will also be studied.