College of Life Science, State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha 410081, PR China.
College of Life Science, State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha 410081, PR China.
J Invertebr Pathol. 2019 May;163:82-85. doi: 10.1016/j.jip.2019.03.009. Epub 2019 Mar 27.
To evaluate the function of conserved cysteine residues in Cry1Ac protoxin, we constructed a series of Cry1Ac mutants in which single or multiple cysteine residues were replaced with serine. It was found that cysteine substitution had little effect on the protoxin expression and bipyramidal crystal formation. Bioassays using Plutella xylostella larvae showed that two mutants with fourteen cysteine residues in the C-terminal half and all sixteen residues replaced had similar toxicity as wildtype Cry1Ac protoxin. Our study suggests that the conserved cysteine resudues in the Cry1Ac protoxin are not essential for deposition into a bipyramidal crystal even though the C-terminal half was directly involved in crystal formation.
为了评估 Cry1Ac 原毒素中保守半胱氨酸残基的功能，我们构建了一系列 Cry1Ac 突变体，其中单个或多个半胱氨酸残基被替换为丝氨酸。结果发现，半胱氨酸取代对原毒素表达和双锥晶体形成几乎没有影响。使用小菜蛾幼虫进行的生物测定表明，两个在 C 端一半有 14 个半胱氨酸残基且所有 16 个残基都被替换的突变体与野生型 Cry1Ac 原毒素具有相似的毒性。我们的研究表明，Cry1Ac 原毒素中保守的半胱氨酸残基对于沉积到双锥晶体中并不是必需的，即使 C 端直接参与晶体形成。
