The Bacillus subtilis yaaH Gene Is Transcribed by SigE RNA Polymerase during Sporulation, and Its Product Is Involved in Germination of Spores

The expression of 21 novel genes located in the region fromdnaA toabrB of theBacillus subtilis chromosome was analyzed. One of the genes,yaaH , had a predicted promoter sequence conserved among SigE-dependent genes. Northern blot analysis revealed thatyaaH mRNA was first detected from 2 h after the cessation of logarithmic growth (T 2 ) of sporulation in wild-type cells and inspoIIIG (SigG− ) andspoIVCB (SigK− ) mutants but not inspoIIAC (SigF− ) andspoIIGAB (SigE− ) mutants. The transcription start point was determined by primer extension analysis; the −10 and −35 regions are very similar to the consensus sequences recognized by SigE-containing RNA polymerase. A YaaH-His tag fusion encoded by a plasmid with a predicted promoter for theyaaH gene was produced fromT 2 of sporulation in aB. subtilis transformant and extracted from mature spores, indicating that theyaaH gene product is a spore protein. Inactivation of theyaaH gene by insertion of an erythromycin resistance gene did not affect vegetative growth or spore resistance to heat, chloroform, and lysozyme. The germination ofyaaH mutant spores in a mixture ofl -asparagine,d -glucose,d -fructose, and potassium chloride was almost the same as that of wild-type spores, but the mutant spores were defective inl -alanine-stimulated germination. These results suggest thatyaaH is a novel gene encoding a spore protein produced in the mother cell compartment fromT 2 of sporulation and that it is required for thel -alanine-stimulated germination pathway.