title: Structural variability of the initiation complex of HIV-1 reverse transcription.
abstract: HIV-1 reverse transcription is initiated from a tRNA(3)(Lys) molecule annealed to the viral RNA at the primer binding site (PBS), but the structure of the initiation complex of reverse transcription remains controversial. Here, we performed in situ structural probing, as well as in vitro structural and functional studies, of the initiation complexes formed by highly divergent isolates (MAL and NL4.3/HXB2). Our results show that the structure of the initiation complex is not conserved. In MAL, and according to sequence analysis in 14% of HIV-1 isolates, formation of the initiation complex is accompanied by complex rearrangements of the viral RNA, and extensive interactions with tRNA(3)(Lys) are required for efficient initiation of reverse transcription. In NL4.3, HXB2, and most isolates, tRNA(3)(Lys) annealing minimally affects the viral RNA structure and no interaction outside the PBS is required for optimal initiation of reverse transcription. We suggest that in MAL, extensive interactions with tRNA(3)(Lys) are required to drive the structural rearrangements generating the structural elements ultimately recognized by reverse transcriptase. In NL4.3 and HXB2, these elements are already present in the viral RNA prior to tRNA(3)(Lys) annealing, thus explaining that extensive interactions with the primer are not required. Interestingly, such interactions are required in HXB2 mutants designed to use a non-cognate tRNA as primer (tRNA(His)). In the latter case, the extended interactions are required to counteract a negative contribution associate with the alternate primer.
authors.affiliation: Unité Propre de Recherche 9002 du CNRS conventionnée à l'Université Louis Pasteur, IBMC, 15 rue René Descartes, 67084 Strasbourg cedex, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Goldschmidt
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Paillart
authors.forename: Mickaël
authors.initials: M
authors.lastname: Rigourd
authors.forename: Bernard
authors.initials: B
authors.lastname: Ehresmann
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Aubertin
authors.forename: Chantal
authors.initials: C
authors.lastname: Ehresmann
authors.forename: Roland
authors.initials: R
authors.lastname: Marquet
mesh_terms: D001483:Base Sequence; D015658:HIV Infections / Q000235:genetics / Q000821:virology; D015497:HIV-1 / Q000737:chemistry / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D012357:RNA, Transfer, Lys / Q000737:chemistry / Q000235:genetics; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics; D048348:Reverse Transcription; D016415:Sequence Alignment; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics; D014779:Virus Replication / Q000235:genetics
chemical_list: D012357:RNA, Transfer, Lys; D012367:RNA, Viral; D014157:Transcription Factors