Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis (Bt) are spore-forming members of the Bacillus cereus group. Spores of B. cereus group species are encircled by exosporium, which is composed of an external hair-like nap and a paracrystalline basal layer. Despite the extensive studies on the structure of the exosporium-related proteins, little is known about the transcription and regulation of exosporium gene expression in the B. cereus group. Recently, researchers at State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection of CAAS have published a research paper about the Regulation of Exosporium-Related Genes in Bacillus thuringiensis.

Nucleotide sequence and transcriptional activity of the bclB promoter

The study showed that A SigK consensus sequence is present upstream of genes encoding hair-like nap proteins (bclA and bclB), basal layer proteins (bxpA, bxpB, cotB, and exsY), and inosine hydrolase (iunH). Mutation of sigK decreased the transcriptional activities of all these genes, indicating that the transcription of these genes is controlled by SigK. Furthermore, mutation of gerE decreased the transcriptional activities of bclB, bxpB, cotB, and iunH but increased the expression of bxpA, and GerE binds to the promoters of bclB, bxpB, cotB, bxpA, and iunH. These results suggest that GerE directly regulates the transcription of these genes, increasing the expression of bclB, bxpB, cotB, and iunH and decreasing that of bxpA. These findings provide insight into the exosporium assembly process at the transcriptional level.

More details are available on the bellow links:
http://www.nature.com/articles/srep19005

By Qi Peng
qpeng@ippcaas.cn