GTP-independent tRNA delivery to the ribosomal P-site by a novel eukaryotic translation factor

  • J Biol Chem. 2010 Aug 27;285(35):26779-26787. doi: 10.1074/jbc.M110.119693.
Sergey E Dmitriev  1 ,  Ilya M Terenin  1 ,  Dmitri E Andreev  1 ,  Pavel A Ivanov  2 ,  Jacov E Dunaevsky  1 ,  William C Merrick  3 ,  Ivan N Shatsky  4
Affiliations
  • 1. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia.
  • 2. Faculty of Biology, Moscow State University, Moscow 119992, Russia.
  • 3. Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106.
  • 4. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia. Electronic address: [email protected].
PMID: 20566627 DOI: 10.1074/jbc.M110.119693
Abstract

During translation, aminoacyl-tRNAs are delivered to the ribosome by specialized GTPases called translation factors. Here, we report the tRNA binding to the P-site of 40 S ribosomes by a novel GTP-independent factor eIF2D isolated from mammalian cells. The binding of tRNA(i)(Met) occurs after the AUG codon finds its position in the P-site of 40 S ribosomes, the situation that takes place during initiation complex formation on the hepatitis C virus internal ribosome entry site or on some Other specific RNAs (leaderless mRNA and A-rich mRNAs with relaxed scanning dependence). Its activity in tRNA binding with 40 S subunits does not require the presence of the aminoacyl moiety. Moreover, the factor possesses the unique ability to deliver non-Met (elongator) tRNAs into the P-site of the 40 S subunit. The corresponding gene is found in all eukaryotes and includes an SUI1 domain present also in translation initiation factor eIF1. The versatility of translation initiation strategies in eukaryotes is discussed.