The Regulation of Exosporium-Related Genes in Bacillus thuringiensis.
The Regulation of Exosporium-Related Genes in Bacillus thuringiensis.
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苏云金芽孢杆菌外孢子相关基因的调控
DOI：
10.1038/srep19005
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发表时间：
2016-01-25
影响因子：
4.6
通讯作者：
Song F
中科院分区：
文献类型：
--
作者：
Peng Q;Kao G;Qu N;Zhang J;Li J;Song F
炭疽芽孢杆菌、蜡样芽孢杆菌和苏云金芽孢杆菌（Bt）是蜡样芽孢杆菌群中能形成芽孢的成员。蜡样芽孢杆菌群菌种的芽孢被芽孢外壁环绕，芽孢外壁由外部毛发状绒毛层和类晶基层组成。尽管对芽孢外壁相关蛋白的结构进行了广泛研究，但对蜡样芽孢杆菌群中芽孢外壁基因表达的转录和调控知之甚少。在此，我们研究了Bt中几个芽孢外壁相关基因的调控。在编码毛发状绒毛层蛋白（bclA和bclB）、基层蛋白（bxpA、bxpB、cotB和exsY）以及肌苷水解酶（iunH）的基因上游存在一个SigK共有序列。sigK的突变降低了所有这些基因的转录活性，表明这些基因的转录受SigK控制。此外，gerE的突变降低了bclB、bxpB、cotB和iunH的转录活性，但增加了bxpA的表达，并且GerE与bclB、bxpB、cotB、bxpA和iunH的启动子结合。这些结果表明，GerE直接调控这些基因的转录，增加bclB、bxpB、cotB和iunH的表达，降低bxpA的表达。这些发现从转录水平上为芽孢外壁的组装过程提供了见解。
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. Herein, we studied the regulation of several exosporium-related genes in Bt. 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.