title: eIF5A promotes translation of polyproline motifs.
abstract: Translation factor eIF5A, containing the unique amino acid hypusine, was originally shown to stimulate Met-puromycin synthesis, a model assay for peptide bond formation. More recently, eIF5A was shown to promote translation elongation; however, its precise requirement in protein synthesis remains elusive. We use in vivo assays in yeast and in vitro reconstituted translation assays to reveal a specific requirement for eIF5A to promote peptide bond formation between consecutive Pro residues. Addition of eIF5A relieves ribosomal stalling during translation of three consecutive Pro residues in vitro, and loss of eIF5A function impairs translation of polyproline-containing proteins in vivo. Hydroxyl radical probing experiments localized eIF5A near the E site of the ribosome with its hypusine residue adjacent to the acceptor stem of the P site tRNA. Thus, eIF5A, like its bacterial ortholog EFP, is proposed to stimulate the peptidyl transferase activity of the ribosome and facilitate the reactivity of poor substrates like Pro.
authors.affiliation: Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Erik
authors.initials: E
authors.lastname: Gutierrez
authors.forename: Byung-Sik
authors.initials: BS
authors.lastname: Shin
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Woolstenhulme
authors.forename: Joo-Ran
authors.initials: JR
authors.lastname: Kim
authors.forename: Preeti
authors.initials: P
authors.lastname: Saini
authors.forename: Allen R
authors.initials: AR
authors.lastname: Buskirk
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Dever
mesh_terms: D020816:Amino Acid Motifs; D008954:Models, Biological; D008958:Models, Molecular; D010448:Peptide Initiation Factors / Q000502:physiology*; D010455:Peptides / Q000378:metabolism*; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins / Q000502:physiology*; D012270:Ribosomes / Q000378:metabolism / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis / Q000737:chemistry; D000097574:Eukaryotic Translation Initiation Factor 5A
chemical_list: D010448:Peptide Initiation Factors; D010455:Peptides; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D000097574:Eukaryotic Translation Initiation Factor 5A; C011083:polyproline