CLONING AND CHARACTERIZATION OF SPOVR, A GENE FROM BACILLUS-SUBTILIS INVOLVED IN SPORE CORTEX FORMATION

Screening for sigma(E)-dependent promoters led to the isolation of a g ene from Bacillus subtilis, designated spoVR, which appears to be invo lved in spore cortex formation. Cultures of strains carrying mutations in spoVR had an increased proportion of phase-dark spores, which corr elated with an increased proportion of cortexless spores seen by elect ron microscopy. The numbers of heat- and chloroform-resistant phase-br ight spores produced by these mutants were decreased by about 3- to 10 -fold, and accumulation of dipicolinate was decreased by more than 3-f old. The spoVR gene was located on the B. subtilis chromosome immediat ely upstream from, and in the opposite orientation of, the phoAIV gene . Expression of spoVR was initiated at the second hour of sporulation from a sigma(E)-dependent promoter, and this expression did not requir e any of the other known mother-cell-specific transcriptional regulato rs. The spoVR gene was predicted to encode a product of 468 residues.