The highly conserved LepA is a ribosomal elongation factor that back-translocates the ribosome.

Qin, Yan; Polacek, Norbert; Vesper, Oliver; Staub, Eike; Einfeldt, Edda; Wilson, Daniel N; Nierhaus, Knud H · Cell · 2006

basic_science · Level V

Where this comes from

Abstract

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).

Medical subject headings