A Novel Small Protein of Bacillus subtilisInvolved in Spore Germination and Spore Coat Assembly

Two small genes named sscA(previously yhzE) and orf-62, located in the prsA-yhaKintergenic region of the Bacillus subtilisgenome, were transcribed by SigK and GerE in the mother cells during the later stages of sporulation. The SscA-FLAG fusion protein was produced from T5of sporulation and incorporated into mature spores. sscAmutant spores exhibited poor germination, and Tricine–SDS–PAGE analysis showed that the coat protein profile of the mutant differed from that of the wild type. Bands corresponding to proteins at 59, 36, 5, and 3 kDa were reduced in the sscAnull mutant. Western blot analysis of anti-CotB and anti-CotG antibodies showed reductions of the proteins at 59 kDa and 36 kDa in the sscAmutant spores. These proteins correspond to CotB and CotG. By immunoblot analysis of an anti-CotH antibody, we also observed that CotH was markedly reduced in the sscAmutant spores. It appears that SscA is a novel spore protein involved in the assembly of several components of the spore coat, including CotB, CotG, and CotH, and is associated with spore germination.