Gene structure and precursor processing of a novel Bacillus subtilis spore coat protein.

The gene for an unusual 8kD Bacillus subtilis spore coat polypeptide has been cloned and sequenced. It contains high percentages of proline, glycine and tyrosine, lacks thirteen amino acids, and is present as the carboxyl two-thirds of an open reading frame encoding a 12kD polypeptide. Two presumptive precursors which could be converted to the 8kD antigen by incubation with trypsin were found in extracts of cells or spores of a strain containing multiple copies of this gene. Large amounts of these coat antigens were also present in extracts of a germination-defective mutant which is altered in spore coat structure. There was little 8kD coat protein in the mutant, however, implying that processing is dependent on proper coat assembly. This gene was mapped to the metA region of the B. subtilis chromosome, a unique location as is true for other spore coat genes. Transcription and translation occurred late in sporulation (stage V) and the upstream region contained sequences similar to those found in other spore coat genes.