A SPORE COAT PROTEIN, COTS, OF BACILLUS-SUBTILIS IS SYNTHESIZED UNDERTHE REGULATION OF SIGMA(K) AND GERE DURING DEVELOPMENT AND IS LOCATEDIN THE INNER COAT LAYER OF SPORES

The spore coat of Bacillus subtilis has a unique morphology and consis ts of polypeptides of different sizes, whose synthesis and assembly ar e precisely regulated by a cascade of transcription factors and regula tory proteins. We examined the factors that regulate cotS gene express ion and CotS assembly into the coat layer of B. subtilis by Northern b lot and Western blot analysis. Transcription of cotS mRNA was not dete cted in sporulating cells of sigma(K) and gerE mutants by Northern blo t analysis. By Western blot analysis using anti-CotS antibody, CotS wa s first detected in protein samples solubilized from wild-type cells a t 5 h after the start of sporulation. CotS was not detected in the veg etative cells and spores of a gerE mutant or in the spores of mutants deficient in sigma(E), sigma(F), sigma(G), or sigma(K). CotS was detec ted in the sporangium but not in the spores of a cotE mutant. The sequ ence of the promoter region of cotS was similar to the consensus seque nces for binding of sigma(K) and GerE. These results demonstrate that sigma(K) and GerE are required for cotS expression and that CotE is es sential for the assembly of CotS in the coat. Immunoelectron microscop ic observation using anti-CotS antibody revealed that CotS is located within the spore coat, in particular in the inner coats of dormant spo res.