Transcriptional regulation of exosporium basal layer structural gene exsB in Bacillus thuringiensis by SigmaK and GerE

OBJECTIVE: To identify the transcriptional regulation of exosporium basal layer structural gene exsB in Bacillus thuringiensis. METHODS: We analyzed exsB and its promoter sequence in Bacillus cereus group by sequence alignment. We performed beta-galactosidase assay of exsB-lacZ gene fusion to analyze transcriptional activation of exsB promoter; we used Electrophoretic mobility shift assays to detect binding of GerE and exsB promoter. RESULTS: exsB was the high similarity in Bacillus cereus group strains. Beta-galactosidase assay showed that exsB promoter had the strong transcriptional activation on the late sporulation phase. Deletion of gerE or sigK gene decreased the activation of exsB promoter. Electrophoretic mobility shift assays showed that GerE could bind with exsB promoter. CONCLUSION: The exsB gene is regulated by SigmaK and GerE on the late sporulation phase.