Sergiev Petr V, Lesnyak Dmitry V, Burakovsky Dmitry E, Kiparisov Sergey V, Leonov Andrei A, Bogdanov Alexey A, Brimacombe Richard, Dontsova Olga A
Department of Chemistry and A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119992, Russia.
J Biol Chem. 2005 Sep 9;280(36):31882-9. doi: 10.1074/jbc.M505670200. Epub 2005 Jul 12.
Translocation catalyzed by elongation factor G occurs after the peptidyltransferase reaction on the large ribosomal subunit. Deacylated tRNA in the P-site stimulates multiple turnover GTPase activity of EF-G. We suggest that the allosteric signal from the peptidyltransferase center that activates EF-G may involve the alteration in the conformation of elongation factor binding center of the ribosome. The latter consists of the moveable GTPase-associated center and the sarcin-ricin loop that keeps its position on the ribosome during translation elongation. The position of the GTPase-associated center was altered by mutagenesis. An insertion of additional base pair at positions C1030/G1124 was lethal and affected function of EF-G, but not that of EF-Tu. Structure probing revealed a putative allosteric signal pathway connecting the P-site with the binding site of the elongation factors. The results are consistent with the different structural requirements for EF-G and EF-Tu function, where the integrity of the path between the peptidyltransferase center and both GTPase-associated center and sarcin-ricin loop is important for EF-G binding.
延伸因子G催化的转位发生在大核糖体亚基上的肽基转移酶反应之后。P位点上的脱酰基tRNA刺激EF-G的多次周转GTP酶活性。我们认为，来自肽基转移酶中心激活EF-G的变构信号可能涉及核糖体延伸因子结合中心构象的改变。后者由可移动的GTP酶相关中心和在翻译延伸过程中保持其在核糖体上位置的肌动蛋白-蓖麻毒素环组成。通过诱变改变了GTP酶相关中心的位置。在C1030/G1124位置插入额外的碱基对是致命的，并影响EF-G的功能，但不影响EF-Tu的功能。结构探测揭示了一条将P位点与延伸因子结合位点连接起来的假定变构信号通路。结果与EF-G和EF-Tu功能的不同结构要求一致，其中肽基转移酶中心与GTP酶相关中心和肌动蛋白-蓖麻毒素环之间路径的完整性对于EF-G结合很重要。
