保守GTP酶EF-G在蛋白质合成中的功能研究

Function Study on Conserved GTPase EF-G in Protein Synthesis

延伸因子G(elongation factor G,EF-G)是一种保守的GTP水解酶,它是蛋白质翻译过程中一个重要的调控因子。同源模拟发现EF-G与核糖体保护蛋白Tet(O)具有相似的空间结构且都包含5个结构域,序列比对发现E.coliEF-G与Campylobacter jejuniTet(O)结构域Ⅳ保守的两个环状区不同。通过分子克隆构建EF-G嵌合体,表达纯化后的蛋白突变体通过核糖体依赖的GTP水解酶(GTPase)活性检测、多聚尿嘧啶(polyU)为mRNA合成苯丙氨酸多肽链、多聚核糖体的解聚检测及相关的体内实验,检测EF-G在肽链合成中的作用,结果发现EF-G嵌合体能够影响肽链生成过程中tRNA-mRNA复合物的移位,但不影响核糖体的再循环过程。

Elogation Factor G （EF-G）, a regulatory factor in protein synthesis, is one of the conserved GTPase. Homology-modelling indicates that the structure of ribosome protection protein C. jejuni Tet（O） has a similarity to EF-G and both contain five domains. The two conserved loops of domain IV in both proteins are different via sequence alignment, so the authors cloned the mutant gene of EF-G, then expressed and purified proteins. Through GTP hydrolysis, Poly（U）-dependent poly（Phe） Synthesis, Polysome breakdown assay and in vivo experiments, it was concluded that EF-G mutants could affect the translocation of mRNA-tRNA complex, but had no influence on ribosome recycling.