A Bacillus subtilis morphogene cluster that includes spoVE is homologous to the mra region of Escherichia coli

Abstract

It is known that there is a strong similarity in amino acid sequence between the products of the Escherichia coli morphogenes ftsW (mra region at 2 min) and rodA (mrd region at 14 min) and the Bacillus subtilis SpoVE protein which is required for spore cortex formation. We show here that the predicted amino acid sequences coded for by the genes flanking spoVE are homologous to the products of the E coli genes murD and murG, which flank ftsW, and are involved in peptidoglycan biosynthesis. During vegetative growth and early stationary phase spoVE is cotranscribed with murD and murG in the form of very long polycistronic messages originating upstream of murD. However, this transcriptional activity is shut-off soon (approximately 1 h) after the cells enter stationary phase, and spoVE is then transcribed at two times during sporulation from its own promoter(s). Insertional in vitro mutagenesis of the region revealed that although murD and murG are essential for normal vegetative growth, spoVE is only required for sporulation: spoVE null mutants display a sporulation stage V phenotype indistinguishable by light microscopy from the phenotype conferred by the spoVE85 and spoVE153 alleles that originally defined the locus.