BACILLUS-SUBTILIS SPORE COAT ASSEMBLY REQUIRES COTH GENE-EXPRESSION

Endospores of Bacillus subtilis are encased in a protein shell, known as the spore coat, composed of a lamella-like inner layer and an elect ron-dense outer layer, We report the identification and characterizati on of a gene, herein called cotH, located at 300 degrees on the B. sub tilis genetic map between two divergent cot genes, cotB and cotG. The cotH open reading frame extended for 1,086 bp and corresponded to a po lypeptide of 42.8 kDa. Spores of a cotH null mutant were normally heat , lysozyme, and chloroform resistant but were impaired in germination. The mutant spores were also pleiotropically deficient in several coat proteins, including the products of the previously cloned cotB, -C, a nd -G genes. On the basis of the analysis of a cotE cotH double mutant , we infer that CotH is probably localized in the inner coat and is in volved in the assembly of several proteins in the outer layer of the c oat.