RESTRICTED TRANSCRIPTION FROM SIGMA-H OR PHOSPHORYLATED SPO0A DEPENDENT PROMOTERS IN THE TEMPERATURE-SENSITIVE SECA341 MUTANT OF BACILLUS-SUBTILIS

The temperature-sensitive secA341 mutation of Bacillus subtilis affect s sporulation and sporulation-associated events as well as protein sec retion and cell septation. With lacZ or bgaB fusion genes, we examined the expression of the early sporulation genes in the mutant strain. T ranscriptional expression of sigma(H) dependent kinA, spo0A (Ps), phrC , spoVG, and citG (p2) genes was blocked by the secA341 mutation at 37 degrees C. On the other hand, neither repression of the abrB gene nor induction of the spo0H (sigma(H)) gene was affected. Active RNA polym erase containing sigma(H) was, however, found to be produced in the mu tant cells. Expression of the phosphorylated Spo0A dependent spoIIG op eron was also blocked. Thus the secA341 mutation blocks some step(s) o r factor(s) required for sigma(H)-dependent transcription in vivo.