IDENTIFICATION OF A CONTROL REGION FOR EXPRESSION OF THE FORESPORE-SPECIFIC BACILLUS-SUBTILIS LOCUS SPOVA

The role of a 20 bp conserved region located 45-64 nucleotides 5' of t he spoVA transcription start point in Bacillus subtilis and Bacillus l icheniformis was investigated by deletion analysis and by mobility shi ft assay. Deletions 5' of this conserved sequence had little effect on expression of a spoVA-lacZ fusion, whereas deletions extending into t he sequence reduced expression of the spoVA-lacZ fusion by 85 %. The t iming of expression of spoVA was not affected by deletion of the seque nce. The region was shown by mobility shift assays to bind specificall y to a protein. Binding activity was detected in protein extracts prep ared from bacteria 1 h or more after they had started to sporulate, bu t not in extracts prepared from vegetative bacteria. Mutations in all known spoO loci were screened but none prevented appearance of the bin ding activity; nor did mutations in any of the stage II and III loci t ested. It is concluded that the 20 bp conserved region is the binding site of an activator that is subject to temporal regulation independen t of known spo loci.