苏云金芽胞杆菌Cry7Ba1晶体蛋白溶解性的改良

Improvement of Solubility of Cry7Ba1 Crystal Protein from Bacillus thuringiensis

研究了苏云金芽胞杆菌(Bacillus thuringiensis,Bt)Cry7Bal的C-端半胱氨酸(Cys)在溶解性改良过程中的作用。本实验通过定点突变将Cry7Bal的C-端834和854位的Cys突变成丝氨酸(Ser),SDS-PAGE和镜检结果表明两个突变体在蛋白表达和晶体形成方面与Cry7Bal没有显著差别;溶解性实验结果表明C854S可以在pH 11.5时很好地溶解,C834S可以在pH9.5时很好地溶解。本研究通过对Cry7Bal的C-端单个半胱氨酸的突变,提高了Cry7Bal的溶解性。这为恢复Cry7Bal晶体蛋白的杀虫活性提供了可能性,也为这一类由于不能溶解而发挥不出活性的Cry蛋白的应用提供了新的思路。

Cry7Ba1 crystal protein from Bacillus thuringiensis has no insecticidal activity due to it is not dissolved in insect gut of pH 9.5.In this study,the 834 and 854 cysteine of Cry7Ba1’s C-terminal were substituted by serine to improve Cry7Ba1 solubility.The expression and formation of the crystal showed no differences between the two mutants and Cry7Ba1,however,solubility experiment results indicated that the C834S and C854S could be dissolved in alkaline condition at pH 9.5 and at pH 11.5,respectively. The solubility of Cry7Ba1 could be improved through site-directed mutagensis the cysteine of Cry7Bal’s C-terminal and the possibility for resumption of insecticidal activity of the crystal proteins (like Cry7Ba1) was provided for the Cry protein application.