title: HCV and CSFV IRES domain II mediate eIF2 release during 80S ribosome assembly.
abstract: Internal ribosome entry site (IRES) RNAs from the hepatitis C virus (HCV) and classical swine fever virus (CSFV) coordinate cap-independent assembly of eukaryotic 48S initiation complexes, consisting of the 40S ribosomal subunit, eukaryotic initiation factor (eIF) 3 and the eIF2/GTP/Met-tRNA(i)(Met) ternary complex. Here, we report that these IRESes also play a functional role during 80S ribosome assembly downstream of 48S complex formation, in promoting eIF5-induced GTP hydrolysis and eIF2/GDP release from the initiation complex. We show that this function is encoded in their independently folded IRES domain II and that it depends both on its characteristic bent conformation and two conserved RNA motifs, an apical hairpin loop and a loop E. Our data suggest a general mode of subunit joining in HCV and HCV-like IRESes.
authors.affiliation: MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Locker
authors.forename: Laura E
authors.initials: LE
authors.lastname: Easton
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Lukavsky
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics*; D020029:Base Pairing; D001483:Base Sequence; D015152:Blotting, Northern; D006692:Classical Swine Fever Virus / Q000235:genetics*; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D016174:Hepacivirus / Q000235:genetics*; D015151:Immunoblotting; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010448:Peptide Initiation Factors / Q000378:metabolism; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins / Q000378:metabolism; D012270:Ribosomes / Q000235:genetics* / Q000502:physiology; D000097574:Eukaryotic Translation Initiation Factor 5A
chemical_list: D020121:5' Untranslated Regions; D015852:Eukaryotic Initiation Factor-2; D010448:Peptide Initiation Factors; D016601:RNA-Binding Proteins; D000097574:Eukaryotic Translation Initiation Factor 5A