No abstract

During sporulation, Bacillus subtilis undergoes successive morphological changes that can be arrested at various stages by mutations in many genes. One of these, spollGB, encodes a transcriptional factor, cr ~, which is necessary to proceed beyond stage II and to differentiate the cell in two compartments, the forespore and the mother cell. Mutations were introduced in an open reading [tame located immediately downstream of spollGB. They block sporulation at stage III and define a new gene, spolllG, encoding a 260-amino-acid polypeptide highly similar to bacterial ~r-factors. A promoter was identified in the spollGB-spolllG interval by transcriptional fusion to lacZ. It is turned on I hr after the start of ~r ~ synthesis and is specifically activated in the forespore. The tandemly arranged spollGB and spoHIG genes appear to encode homologous proteins that modulate transcription in a sequential fashion during sporulation.

Evidence is presented that the sporulationessential locus spolIG codes for both 29 subtilis strain with a mutation at the spolIG locus (spoIIG41).The appearance of P25 and P21 occurs in this mutant at a time when P31 and Ca29 would normally appear and suggests that they are homologous proteins. Transformation of the spoIlG41 strain with plasmid DNA carrying the structural gene for spolIG complements the Spo-phenotype and results in the synthesis of P31, a'29 p25, and P21 at the appropriate times during sporulation. In Escherichia coli, the cloned spolIG sequence encoded a protein that reacted with the anti-P31/Oa'29 monoclonal antibody and had the electrophoretic mobility of authentic P31.The spore-forming bacterium Bacillus subtilis synthesizes at least five forms of DNA-dependent RNA polymerase, which are distinguished by the promoter specificity determinant (o, factor) that each carries on a common core enzyme (1-5). One of the a-factors, cr29, is a protein (Mr, 29,000) that is detected only during endospore formation and was therefore predicted to be an important element of spore gene regulation (3, 6,

Sporulation of Bacillus subtilis involves sequential morphological and biochemical changes and is regulated by specific genes (spo genes) estimated to occupy more than 30 loci. A mutation in any one of these genes blocks the sporulation process at the corresponding developmental stage. Despite intensive genetic studies, the nature and function of the spo gene products remain unknown. Vegetative B. subtilis RNA polymerase core enzyme may interact with several sigma factors and discriminate among different classes of promoters. During sporulation, new polypeptides are associated with the core enzyme which may have a central role in modifying its promoter recognition specificity. As a first step to understanding their function in the switch from vegetative to sporulation mode, several early sporulation genes have been cloned and analysed. Here we report the cloning and nucleotide sequence of the spoIIG gene of B. subtilis. This gene encodes a polypeptide with a predicted relative molecular mass of 27,652 which contains a 65-amino acid region highly homologous to an internal part of the Escherichia coli sigma factor.