title: The bovine immunodeficiency virus Rev protein: identification of a novel nuclear import pathway and nuclear export signal among retroviral Rev/Rev-like proteins.
abstract: The Rev protein is essential for the replication of lentiviruses. Rev is a shuttling protein that transports unspliced and partially spliced lentiviral RNAs from the nucleus to the cytoplasm via the nucleopore. To transport these RNAs, the human immunodeficiency virus type 1 (HIV-1) Rev uses the karyopherin β family importin β and CRM1 proteins that interact with the Rev nuclear localization signal (NLS) and nuclear exportation signal (NES), respectively. Recently, we reported the presence of new types of bipartite NLS and nucleolar localization signal (NoLS) in the bovine immunodeficiency virus (BIV) Rev protein. Here we report the characterization of the nuclear import and export pathways of BIV Rev. By using an in vitro nuclear import assay, we showed that BIV Rev is transported into the nucleus by a cytosolic and energy-dependent importin α/β classical pathway. Results from glutathione S-transferase (GST) pulldown assays that showed the binding of BIV Rev with importins α3 and α5 were in agreement with those from the nuclear import assay. We also identified a leptomycin B-sensitive NES in BIV Rev, which indicates that the protein is exported via CRM1 like HIV-1 Rev. Mutagenesis experiments showed that the BIV Rev NES maps between amino acids 109 to 121 of the protein. Remarkably, the BIV Rev NES was found to be of the cyclic AMP (cAMP)-dependent protein kinase inhibitor (PKI) type instead of the HIV-1 Rev type. In summary, our data showed that the nuclear import mechanism of BIV Rev is novel among Rev proteins characterized so far in lentiviruses.
authors.affiliation: Department of Biological Sciences, University of Québec at Montréal, Québec, Canada.
authors.forename: Andrea
authors.initials: A
authors.lastname: Gomez Corredor
authors.forename: Denis
authors.initials: D
authors.lastname: Archambault
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D000255:Adenosine Triphosphate / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D015694:Gene Products, rev / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D016087:Immunodeficiency Virus, Bovine / Q000378:metabolism*; D028884:Karyopherins / Q000037:antagonists & inhibitors; D049790:Nuclear Export Signals; D022022:Nuclear Pore / Q000378:metabolism; D011485:Protein Binding; D020033:Protein Isoforms / Q000378:metabolism; D021381:Protein Transport; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors; D015398:Signal Transduction; D028901:alpha Karyopherins / Q000378:metabolism; D028961:beta Karyopherins / Q000378:metabolism; D020931:ran GTP-Binding Protein / Q000378:metabolism; D000097606:Exportin 1 Protein
chemical_list: D000255:Adenosine Triphosphate; D005231:Fatty Acids, Unsaturated; D015694:Gene Products, rev; D028884:Karyopherins; D049790:Nuclear Export Signals; D020033:Protein Isoforms; D018160:Receptors, Cytoplasmic and Nuclear; D028901:alpha Karyopherins; D028961:beta Karyopherins; D020931:ran GTP-Binding Protein; D000097606:Exportin 1 Protein; C038753:leptomycin B