title: The highly conserved LepA is a ribosomal elongation factor that back-translocates the ribosome.
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).
authors.affiliation: Max-Planck-Institut für molekulare Genetik, D-14195 Berlin, Germany.
authors.forename: Yan
authors.initials: Y
authors.lastname: Qin
authors.forename: Norbert
authors.initials: N
authors.lastname: Polacek
authors.forename: Oliver
authors.initials: O
authors.lastname: Vesper
authors.forename: Eike
authors.initials: E
authors.lastname: Staub
authors.forename: Edda
authors.initials: E
authors.lastname: Einfeldt
authors.forename: Daniel N
authors.initials: DN
authors.lastname: Wilson
authors.forename: Knud H
authors.initials: KH
authors.lastname: Nierhaus
mesh_terms: D000595:Amino Acid Sequence; D019295:Computational Biology; D017124:Conserved Sequence; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D020653:Peptide Elongation Factor G / Q000737:chemistry; D010445:Peptide Elongation Factors / Q000378:metabolism*; D010448:Peptide Initiation Factors; D010802:Phylogeny; D014176:Protein Biosynthesis / Q000235:genetics*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012270:Ribosomes / Q000378:metabolism*; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; C515651:LepA protein, E coli; D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors; D010448:Peptide Initiation Factors; D035602:Transcriptional Elongation Factors; D049452:Green Fluorescent Proteins; D020558:GTP Phosphohydrolases