1类释放因子的GGQ基序促进的肽释放调节RF3的GTP酶活性。

Release of peptide promoted by the GGQ motif of class 1 release factors regulates the GTPase activity of RF3.

作者信息

Zavialov Andrei V, Mora Liliana, Buckingham Richard H, Ehrenberg Måns

机构信息

Department of Cell and Molecular Biology, BMC, Uppsala University, Box 596, S-75124, Uppsala, Sweden.

出版信息

Mol Cell. 2002 Oct;10(4):789-98. doi: 10.1016/s1097-2765(02)00691-3.

DOI:10.1016/s1097-2765(02)00691-3

PMID:12419223

Abstract

E. coli mutants of RF1 and RF2, in which the universal GGQ motif is changed to GAQ, are slow in peptide release from ribosomes. Other kinetic properties are unchanged, suggesting that the GGQ motif is in contact with the peptidyl-transferase center. Deacylated tRNA terminates protein synthesis codon specifically, indicating that the CCA end of tRNA and the GGQ motif operate similarly. Addition of a mutant factor to a pretermination ribosomal complex stimulates exchange of RF3-bound GDP with free GDP, but binding of GTP to RF3 and GTP hydrolysis requires peptide chain release. Therefore, the sequence of steps during termination of translation is regulated by removal of the polypeptide, an event that might trigger a conformational change in the ribosome.

摘要

RF1和RF2的大肠杆菌突变体中，通用的GGQ基序被改变为GAQ，其从核糖体释放肽的速度较慢。其他动力学特性未改变，这表明GGQ基序与肽基转移酶中心接触。脱酰基tRNA特异性地终止蛋白质合成密码子，表明tRNA的CCA末端和GGQ基序的作用类似。向终止前核糖体复合物中添加突变因子会刺激RF3结合的GDP与游离GDP的交换，但GTP与RF3的结合以及GTP水解需要肽链释放。因此，翻译终止过程中的步骤顺序受多肽去除的调节，这一事件可能会触发核糖体的构象变化。