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Updated: Jul 14, 2026

Dual DNA Rulers to Study the Mechanism of Ribosome Translocation with Single-Nucleotide Resolution
Published on: July 8, 2019
The highly conserved LepA is a ribosomal elongation factor that back-translocates the ribosome
Yan Qin1, Norbert Polacek, Oliver Vesper
1Max-Planck-Institut für molekulare Genetik, D-14195 Berlin, Germany.
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).
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