The sigma-like product of sporulation gene spoIIAC of Bacillus subtilis is toxic to Escherichia coli.

The amino-acid sequence deduced from the nucleotide sequence of the spoIIAC gene of Bacillus subtilis has been shown to be homologous to that of the sigma subunit of the Escherichia coli RNA polymerase (Errington et al. 1985). I now describe results that indicate that this gene can be cloned in E. coli only under conditions in which it is not expressed.