Regulation and Expression of a Key Proteolytic Enzyme in Bacterial Sporulation and Germination

摘要

Highlights of research findings in the past 3 1/2 years are: 1) The gene which we believe codes for the Bacillus megaterium spore protease has been cloned and its sequence is essentially complete; 2) We have generated deletion mutations of B. subtilis which lack genes for the three major small acid-soluble spore proteins (SASP). While all of these mutants grow and sporulate normally, mutations in two of these genes (sspA and sspB loci) results in spores which are more heat sensitive than wild type spores, and much more sensitive to ultraviolet (UV) irradiation. This UV sensitive spore phenotype is cured by restoration of multiple copies of either the sspA or B genes; 3) UV irradiation of the mutant spores generated thymine dimers, in contrast to the spore photoproduct formed on comparable irradiation of wild type spores; 4) Findings 2 and 3 strongly suggest that SASP play a major casual role in spore UV resistance.