Identification of the promoter and the transcriptional start site of the spoVA operon of Bacillus subtilis and Bacillus licheniformis

Abstract

The region upstream of the coding sequence of the spoVA operon was studied by several techniques to identify the promoter and to determine the start point for transcription of spoVA. The results of plasmid integration analysis in Bacillus subtilis showed that no more than 119 bp upstream of the coding sequence is needed for expression. A comparison of the sequence of this upstream region with the corresponding sequence from Bacillus licheniformis showed four stretches that were perfectly conserved, interspersed with poorly conserved stretches; the second and third of these conserved stretches appeared to represent the '-35' and '-10' regions of a promoter recognized by RNA polymerase containing sigma G. Primer extension analysis in B. subtilis revealed a spoVA transcript which had apparently initiated 6 bp downstream of the putative '-10' heptanucleotide CATACTA, that is, 27 bp upstream of the coding sequence. This transcript was observed 4 h and 5 h after the initiation of sporulation, but not at earlier times.