eIF5A promotes translation of polyproline motifs.

摘要: 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 promote translation elongation; however, its precise requirement in protein synthesis remains elusive. We use in vivo assays yeast and in vitro reconstituted reveal specific formation between consecutive Pro residues. Addition of relieves ribosomal stalling during three residues in vitro, loss function impairs polyproline-containing proteins in vivo. Hydroxyl radical probing experiments localized near E site ribosome with hypusine residue adjacent acceptor stem P tRNA. Thus, like bacterial ortholog EFP, is proposed peptidyl transferase activity facilitate reactivity poor substrates Pro.