Properties of the Bacillus subtilis spore coat.
About 70% of the protein in isolated Bacillus subtilis spore coats was solubilized by treatment with a combination of reducing and denaturing agents at alkaline pH. The residue, consisting primarily of protein, was insoluble in a variety of reagents. The soluble proteins were resolved into at least seven bands by sodium dodecyl sulfate gel electrophoresis. About one-half of the total was four proteins of 8,000 to 12,000 daltons. These were relatively tyrosine rich, and one was a glycoprotein. There was also a cluster of proteins of about 40,000 daltons and two or three in the 20,000- to 25,000-dalton range. The insoluble fraction had an amino acid composition and N-terminal pattern of amino acids very similar to those of the soluble coat proteins. A major difference was the presence of considerable dityrosine in performic acid-oxidized preparations of insoluble coats. Coat antigen including a 60,000-dalton protein not present in extracts of mature spores was detected in extracts of sporulating cells by immunoprecipitation. This large antigen turned over in a pulse-chase experiment. Antibodies to either the array of 8,000- to 12,000-dalton coat polypeptides or to the larger coat proteins reacted with this 60,000-dalton species, suggesting a common precursor for many of the mature coat polypeptides. Spore coats seem to be assembled by processing of proteins and by secondary modifications including perhaps dityrosine formation for cross-linking.
D000596:Amino Acids / Q000032:analysis; D000942:Antigens, Bacterial / Q000032:analysis; D001412:Bacillus subtilis / Q000032:analysis* / Q000276:immunology; D001426:Bacterial Proteins / Q000032:analysis*; D002473:Cell Wall / Q000032:analysis / Q000276:immunology; D008970:Molecular Weight; D010455:Peptides / Q000032:analysis; D012995:Solubility; D013171:Spores, Bacterial / Q000032:analysis; D014443:Tyrosine / Q000032:analysis
D000596:Amino Acids; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D010455:Peptides; D014443:Tyrosine