Qin Yan, Polacek Norbert, Vesper Oliver, Staub Eike, Einfeldt Edda, Wilson Daniel N, Nierhaus Knud H
Max-Planck-Institut für molekulare Genetik, D-14195 Berlin, Germany.
Cell. 2006 Nov 17;127(4):721-33. doi: 10.1016/j.cell.2006.09.037.
The ribosomal elongation cycle describes a series of reactions prolonging the nascent polypeptide chain by one amino acid and driven by two universal elongation factors termed EF-Tu and EF-G in bacteria. Here we demonstrate that the extremely conserved LepA protein, present in all bacteria and mitochondria, is a third elongation factor required for accurate and efficient protein synthesis. LepA has the unique function of back-translocating posttranslocational ribosomes, and the results suggest that it recognizes ribosomes after a defective translocation reaction and induces a back-translocation, thus giving EF-G a second chance to translocate the tRNAs correctly. We suggest renaming LepA as elongation factor 4 (EF4).
核糖体延伸循环描述了一系列反应，这些反应通过添加一个氨基酸来延长新生多肽链，并由细菌中称为EF-Tu和EF-G的两种通用延伸因子驱动。在这里，我们证明了存在于所有细菌和线粒体中的高度保守的LepA蛋白是准确高效蛋白质合成所需的第三种延伸因子。LepA具有使转位后核糖体反向转位的独特功能，结果表明它在转位反应有缺陷后识别核糖体并诱导反向转位，从而使EF-G有第二次机会正确转位tRNA。我们建议将LepA重新命名为延伸因子4（EF4）。
