Structure of mammalian eif3 in the context of the 43s preinitiation complex.

• Autores: Amedee des Georges, Vidya Dhote, Lauriane Kuhn, Christopher U. T. Hellen, Tatyana V. Pestova, Joachim Frank, Yaser Hashem
• Localización: Nature: International weekly journal of science, ISSN 0028-0836, Vol. 525, Nº 7570, 2015, págs. 491-495
• Idioma: inglés
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• Resumen

  • AB : During eukaryotic translation initiation, 43S complexes, comprising a 40S ribosomal subunit, initiator transfer RNA and initiation factors (eIF) 2, 3, 1 and 1A, attach to the 5'-terminal region of messenger RNA and scan along it to the initiation codon. Scanning on structured mRNAs also requires the DExH-box protein DHX29. Mammalian eIF3 contains 13 subunits and participates in nearly all steps of translation initiation. Eight subunits having PCI (proteasome, COP9 signalosome, eIF3) or MPN (Mpr1, Pad1, amino-terminal) domains constitute the structural core of eIF3, to which five peripheral subunits are flexibly linked. Here we present a cryo-electron microscopy structure of eIF3 in the context of the DHX29-bound 43S complex, showing the PCI/MPN core at ~6 A resolution. It reveals the organization of the individual subunits and their interactions with components of the 43S complex. We were able to build near-complete polyalanine-level models of the eIF3 PCI/MPN core and of two peripheral subunits. The implications for understanding mRNA ribosomal attachment and scanning are discussed. (C) 2015 Nature Publishing Group