Helix alpha-3 inter-molecular salt bridges and conformational changes are essential for toxicity of Bacillus thuringiensis 3D-Cry toxin family

文献类型： 外文期刊

第一作者： Gomez, Isabel

作者： Gomez, Isabel;Sanchez, Jorge;Garcia-Gomez, Blanca-Ines;Soberon, Mario;Bravo, Alejandra;Czajkowsky, Daniel M.;Zhang, Jie

作者机构：

期刊名称：SCIENTIFIC REPORTS （ 影响因子：4.379； 五年影响因子：5.133 ）

ISSN： 2045-2322

年卷期： 2018 年 8 卷

页码：

收录情况： SCI

摘要： Bacillus thuringiensis insecticidal Cry toxins break down larval midgut-cells after forming pores. The 3D-structures of Cry4Ba and Cry5Ba revealed a trimeric-oligomer after cleavage of helices alpha-1 and alpha-2a, where helix alpha-3 is extended and made contacts with adjacent monomers. Molecular dynamic simulations of Cry1Ab-oligomer model based on Cry4Ba-coordinates showed that E101 forms a salt-bridge with R99 from neighbor monomer. An additional salt bridge was identified in the trimericCry5Ba, located at the extended helix alpha-3 in the region corresponding to the alpha-2b and alpha-3 loop. Both salt-bridges were analyzed by site directed mutagenesis. Single-point mutations in the Lepidopteraspecific Cry1Ab and Cry1Fa toxins were affected in toxicity, while reversed double-point mutant partially recovered the phenotype, consistent with a critical role of these salt-bridges. The single-point mutations in the salt-bridge at the extended helix alpha-3 of the nematicidal Cry5Ba were also non-toxic. The incorporation of this additional salt bridge into the nontoxic Cry1Ab-R99E mutant partially restored oligomerization and toxicity, supporting that the loop between alpha-2b and alpha-3 forms part of an extended helix alpha-3 upon oligomerization of Cry1 toxins. Overall, these results highlight the role in toxicity of saltbridge formation between helices alpha-3 of adjacent monomers supporting a conformational change in helix alpha-3.

分类号：

  • 相关文献
作者其他论文 更多>>

微信小程序