title: HIV-1 splicing at the major splice donor site is restricted by RNA structure.
abstract: The 5' leader region of the HIV-1 RNA contains the major 5' splice site (ss) that is used in the production of all spliced viral RNAs. This splice-donor (SD) region can fold a stem-loop structure. We demonstrate that whereas stabilization of this SD hairpin reduces splicing efficiency, destabilization increases splicing. Both stabilization and destabilization reduce viral fitness. These results demonstrate that the stability of the SD hairpin can modulate the level of splicing, most likely by controlling the accessibility of the 5'ss for the splicing machinery. The natural stability of the SD hairpin restricts splicing and this stability seems to be fine-tuned to reach the optimal balance between unspliced and spliced RNAs for efficient virus replication. The 5'ss region of different HIV-1 isolates and the related SIVmac239 can fold a similar structure. This evolutionary conservation supports the importance of this structure in viral replication.
authors.affiliation: Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, The Netherlands. Electronic address: n.muller@amc.uva.nl.
authors.forename: Nancy
authors.initials: N
authors.lastname: Mueller
authors.affiliation: Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, The Netherlands. Electronic address: n.vanbel@amc.uva.nl.
authors.forename: Nikki
authors.initials: N
authors.lastname: van Bel
authors.affiliation: Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, The Netherlands. Electronic address: b.berkhout@amc.uva.nl.
authors.forename: Ben
authors.initials: B
authors.lastname: Berkhout
authors.affiliation: Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, The Netherlands. Electronic address: a.t.das@amc.uva.nl.
authors.forename: Atze T
authors.initials: AT
authors.lastname: Das
mesh_terms: D001483:Base Sequence; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D057809:HEK293 Cells; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D055029:Inverted Repeat Sequences; D009690:Nucleic Acid Conformation; D022821:RNA Splice Sites; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D022821:RNA Splice Sites; D012367:RNA, Viral
keywords: HIV-1; RNA structure; Splicing