Suppressor mutations for crs mutants of Bacillus subtilis.

Mutants of Bacillus subtilis which carried suppressor mutations for catabolite-resistance gene crsA47 were isolated from methylmethanesulfonate-treated cultures of GLU-47 (crsA47). The suppressor mutation, sca19, suppressed resistance of crsA47 mutant to glucose and other inhibitors of sporulation. Moreover, the suppressor mutation could restore the rate of growth and the level of IMP dehydrogenase and alkaline phosphatase of crsA47 mutant to the wild-type level. The scal19 mutation was also able to suppress catabolite resistance of other crs mutants. The map position of the sca19 mutation indicated that this mutation was an intergenic suppressor for the crs mutants. It was also found that an erythromycin-resistance mutation, eryl, could suppress the catabolite resistance of some of the crs mutants. Our results were discussed in relation to the importance of a proper state of metabolic activities and membrane functions during the initiation of sporulation.