期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1977
卷号：74
期号：3
页码：1254-1258
DOI：10.1073/pnas.74.3.1254
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A mutant with an alteration in the major intracellular serine protease produced by postexponential Bacillus cereus was isolated by screening mutants defective in spore germination. The purified enzyme from the mutant is more labile to heat and alkaline pH than the protease from the wild type. Protease activity appears at the same time as in the wild type but only reaches 50% of the specific activity and decays more rapidly during sporulation. Coincident with the decay is a decrease in the rate of protein turnover. Generation of amino acids by turnover seems to be important for sporulation because the number of spores produced by the mutant is increased 4- to 10-fold by addition of casamino acids. As anticipated, the mutant produces spores that germinate poorly but, surprisingly, these spores are very deficient in coat protein. Coat antigen is present in cell extracts of mutant and wild type, however, both as large molecules not found on mature spores and as spore coat protein monomers. The large molecules rapidly disappear in a pulse chase experiment in the wild type with some increase in the coat monomers. In mutant extracts, however, this large coat antigen is slowly and improperly processed.
