title: HIV-2 genomic RNA contains a novel type of IRES located downstream of its initiation codon.
abstract: Eukaryotic translation initiation begins with assembly of a 48S ribosomal complex at the 5' cap structure or at an internal ribosomal entry segment (IRES). In both cases, ribosomal positioning at the AUG codon requires a 5' untranslated region upstream from the initiation site. Here, we report that translation of the genomic RNA of human immunodeficiency virus type 2 takes place by attachment of the 48S ribosomal preinitiation complex to the coding region, with no need for an upstream 5' untranslated RNA sequence. This unusual mechanism is mediated by an RNA sequence that has features of an IRES with the unique ability to recruit ribosomes upstream from its core domain. A combination of translation assays and structural studies reveal that sequences located 50 nucleotides downstream of the AUG codon are crucial for IRES activity.
authors.affiliation: Inserm, U 412, Ecole Normale Supérieure de Lyon, LaboRétro, Unité de virologie humaine, IFR 128, 46 Allée d'Italie, 69364 Lyon 07, France.
authors.forename: Cécile H
authors.initials: CH
authors.lastname: Herbreteau
authors.forename: Laure
authors.initials: L
authors.lastname: Weill
authors.forename: Didier
authors.initials: D
authors.lastname: Décimo
authors.forename: Déborah
authors.initials: D
authors.lastname: Prévôt
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Darlix
authors.forename: Bruno
authors.initials: B
authors.lastname: Sargueil
authors.forename: Théophile
authors.initials: T
authors.lastname: Ohlmann
mesh_terms: D020029:Base Pairing; D001483:Base Sequence; D015498:HIV-2 / Q000235:genetics*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009841:Oligonucleotides; D014176:Protein Biosynthesis / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012270:Ribosomes / Q000235:genetics*; D013329:Structure-Activity Relationship; D014764:Viral Proteins / Q000378:metabolism
chemical_list: D009841:Oligonucleotides; D012367:RNA, Viral; D014764:Viral Proteins