Transformation of Bacillus subtilis competent cells: Identification and regulation of the rec E gene product

Summary

On the basis of genetic mapping and phenotypic properties the rec mutations recE4, rec45, recA1, and rec73 were found to belong to two loci, the recE locus (recE4 and recE45) and the recA locus (recA1 and recA73). In strains carrying the recE4, recA1, and recA73 mutations the 45 KD recombination protein (de Vos and Venema 1982) was absent. The recE45 strain, which appeared to be conditionally (cold-sensitive) recombination deficient, contained a 45 KD protein with an isoelectric point higher than the wild-type protein. Based on the observation that limited proteolysis of the mutant and wild-type 45 KD proteins yielded similar degradation products, we conclude that the recE gene specifies the 45 KD protein (redE protein), the primary structure of which is affected by the recE45 mutation. Since the recE45 protein is not inducible by treatments (ultraviolet light irradiation, competence development) that induce the wild-type recE protein, we assume that the recE protein affects its own synthesis. A possible model is discussed for the regulation of the recE protein which postulates a repressor role for the recA gene product.