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【目的】明确SigmaK和GerE对苏云金芽胞杆菌(Bacillus thuringiensis,简称Bt)芽胞外壁(exosporium)基质结构基因exsB的转录调控。【方法】序列比较蜡样芽胞杆菌群exsB及启动区序列,利用启动子融合lacZ技术检测exsB启动子的转录活性;通过凝胶阻滞方法检测GerE与exsB启动子的结合。【结果】在蜡样芽胞杆菌群中,exsB及其启动区具有较高的相似性,exsB启动子在芽胞形成期的晚期大量转录;sigK和gerE的突变影响了exsB启动子的转录活性,凝胶阻滞结果显示GerE蛋白与exsB启动子可以结合。【结论】本研究证明exsB在芽胞形成晚期受到SigmaK转录调控,并直接受到GerE的正调控。
【Objective】 The objective of this study was to determine the transcriptional regulation of exsB gene in exosporium of Bacillus thuringiensis (Bt) by SigmaK and GerE. 【Method】 Sequences of exsB and promoter region of Bacillus cereus were compared. The transcriptional activity of exsB promoter was detected by promoter fusion lacZ technique. The binding of GerE promoter to exsB promoter was detected by gel blocking assay. 【Result】 In Bacillus cereus, there was a high similarity between exsB and its promoter region. The exsB promoter was highly transcribed in late stage of sporulation. The mutation of sigK and gerE affected the transcriptional activity of exsB promoter. Gum blocking results show that the GerE protein can bind to the exsB promoter. 【Conclusion】 This study demonstrates that exsB is regulated by SigmaK in the late stage of sporulation and is directly regulated by GerE.