苏云金芽胞杆菌G03 spoIVF操纵子敲除对芽胞和晶体形成的影响

spoIVF是一个普遍存在于芽胞杆菌中的操纵子。在枯草芽胞杆菌中,它编码的两个蛋白是芽胞形成所必需的。采用基因重组技术敲除了苏云金芽胞杆菌G03菌株中的spoIVF操纵子,构建了spoIVF缺失株G03(spoIVF-)。研究表明:该突变株丧失了形成芽胞和晶体的能力。lacZ基因与cry1Aa基因的启动子融合表达分析发现:突变株中的cry1Aa基因的活性严重降低。利用载体pSTK携带spoIVF操纵子在突变株中的表达,使突变株部分恢复了产胞和形成杀虫晶体蛋白的能力。这说明spoIVF操纵子是所必需的,同时该操纵子还影响σ^E因子控制的cry1Aa基因表达。

Deletion of spoIVF operon affects the sporulation and the production of crystal in Bacillus thuringiensis G03

The spoIVF operon exists in Bacillus universally. Two proteins encoded by the spoIVF operon are essential for the sporulation of Bacillus subtilis. In this study, a spoIVF operon disruption mutant G03 (spoIVF-), in which the spoIVF operon was deleted, was constructed by homologous recombination. The result showed that the mutant strain lost the ability of sporulation. At the same time, the expression of Insecticidal Crystal Protein (ICP) was severely reduced in G03 (spoIVF-) mutant strain and resulted in no crystals. The lacZ gene was fused with the promoter of the cry1Aa gene and expressed in mutant strain G03 (spoIVF-) and G03 wild strain. The activity of beta-galactosidase much lower in mutant G03 (spoIVF-) strain than in the wild-type strain. This further suggested that the activity of sigmaE and sigmaK factors was affected in mutant G03 (spoIVF-) strain. The ability of sporulation and production of Insecticide Crystal Protein was complemented by the expression of spoIVF operon through the vector of pSTK in the mutant strain. In all, The spoIVF operon is essential for the sporulation and the expression of cry gene controlled by sigmaE and sigmaK factors.