title: Activity of the human immunodeficiency virus type 1 cell cycle-dependent internal ribosomal entry site is modulated by IRES trans-acting factors.
abstract: The 5' leader of the human immunodeficiency virus type 1 (HIV-1) genomic RNA harbors an internal ribosome entry site (IRES) that is functional during the G2/M phase of the cell cycle. Here we show that translation initiation mediated by the HIV-1 IRES requires the participation of trans-acting cellular factors other than the canonical translational machinery. We used 'standard' chemical and enzymatic probes and an 'RNA SHAPE' analysis to model the structure of the HIV-1 5' leader and we show, by means of a footprinting assay, that G2/M extracts provide protections to regions previously identified as crucial for HIV-1 IRES activity. We also assessed the impact of mutations on IRES function. Strikingly, mutations did not significantly affect IRES activity suggesting that the requirement for pre-formed stable secondary or tertiary structure within the HIV-1 IRES may not be as strict as has been described for other viral IRESes. Finally, we used a proteomic approach to identify cellular proteins within the G2/M extracts that interact with the HIV-1 5' leader. Together, data show that HIV-1 IRES-mediated translation initiation is modulated by cellular proteins.
authors.affiliation: Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Facultad de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile.
authors.forename: Maricarmen
authors.initials: M
authors.lastname: Vallejos
authors.forename: Jules
authors.initials: J
authors.lastname: Deforges
authors.forename: Terra-Dawn M
authors.initials: TD
authors.lastname: Plank
authors.forename: Alejandro
authors.initials: A
authors.lastname: Letelier
authors.forename: Pablo
authors.initials: P
authors.lastname: Ramdohr
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Abraham
authors.forename: Fernando
authors.initials: F
authors.lastname: Valiente-Echeverría
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Kieft
authors.forename: Bruno
authors.initials: B
authors.lastname: Sargueil
authors.forename: Marcelo
authors.initials: M
authors.lastname: López-Lastra
mesh_terms: D020121:5' Untranslated Regions; D001483:Base Sequence; D002453:Cell Cycle / Q000235:genetics; D003593:Cytoplasm / Q000378:metabolism; D015497:HIV-1 / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010442:Peptide Chain Initiation, Translational; D017354:Point Mutation; D012367:RNA, Viral / Q000737:chemistry* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D038621:Regulatory Sequences, Ribonucleic Acid
chemical_list: D020121:5' Untranslated Regions; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D038621:Regulatory Sequences, Ribonucleic Acid