title: A protein ballet around the viral genome orchestrated by HIV-1 reverse transcriptase leads to an architectural switch: from nucleocapsid-condensed RNA to Vpr-bridged DNA.
abstract: HIV-1 reverse transcription is achieved in the newly infected cell before viral DNA (vDNA) nuclear import. Reverse transcriptase (RT) has previously been shown to function as a molecular motor, dismantling the nucleocapsid complex that binds the viral genome as soon as plus-strand DNA synthesis initiates. We first propose a detailed model of this dismantling in close relationship with the sequential conversion from RNA to double-stranded (ds) DNA, focusing on the nucleocapsid protein (NCp7). The HIV-1 DNA-containing pre-integration complex (PIC) resulting from completion of reverse transcription is translocated through the nuclear pore. The PIC nucleoprotein architecture is poorly understood but contains at least two HIV-1 proteins initially from the virion core, namely integrase (IN) and the viral protein r (Vpr). We next present a set of electron micrographs supporting that Vpr behaves as a DNA architectural protein, initiating multiple DNA bridges over more than 500 base pairs (bp). These complexes are shown to interact with NCp7 bound to single-stranded nucleic acid regions that are thought to maintain IN binding during dsDNA synthesis, concurrently with nucleocapsid complex dismantling. This unexpected binding of Vpr conveniently leads to a compacted but filamentous folding of the vDNA that should favor its nuclear import. Finally, nucleocapsid-like aggregates engaged in dsDNA synthesis appear to efficiently bind to F-actin filaments, a property that may be involved in targeting complexes to the nuclear envelope. More generally, this article highlights unique possibilities offered by in vitro reconstitution approaches combined with macromolecular imaging to gain insights into the mechanisms that alter the nucleoprotein architecture of the HIV-1 genome, ultimately enabling its insertion into the nuclear chromatin.
authors.affiliation: AIDS Research Group, IDIBAPS, E-08036 Barcelona, Spain.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Lyonnais
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Gorelick
authors.forename: Fatima
authors.initials: F
authors.lastname: Heniche-Boukhalfa
authors.forename: Serge
authors.initials: S
authors.lastname: Bouaziz
authors.forename: Vincent
authors.initials: V
authors.lastname: Parissi
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Mouscadet
authors.forename: Tobias
authors.initials: T
authors.lastname: Restle
authors.forename: Jose Maria
authors.initials: JM
authors.lastname: Gatell
authors.forename: Eric
authors.initials: E
authors.lastname: Le Cam
authors.forename: Gilles
authors.initials: G
authors.lastname: Mirambeau
mesh_terms: D042003:DNA Packaging; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016679:Genome, Viral; D019427:HIV Integrase / Q000235:genetics / Q000378:metabolism; D054303:HIV Reverse Transcriptase / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000737:chemistry / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D048348:Reverse Transcription; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism*; D054325:vpr Gene Products, Human Immunodeficiency Virus
chemical_list: D004279:DNA, Viral; C071884:NCP7 protein, Human immunodeficiency virus 1; D012367:RNA, Viral; D054301:gag Gene Products, Human Immunodeficiency Virus; D054325:vpr Gene Products, Human Immunodeficiency Virus; C514912:vpr protein, Human immunodeficiency virus 1; D019427:HIV Integrase; C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase