title: Cellular distribution of Lysyl-tRNA synthetase and its interaction with Gag during human immunodeficiency virus type 1 assembly.
abstract: Lysyl-tRNA synthetase (LysRS) is packaged into human immunodeficiency virus type 1 (HIV-1) via its interaction with Gag, and this enzyme facilitates the selective packaging of tRNA(3)(Lys), the primer for initiating reverse transcription, into HIV-1. The Gag/LysRS interaction is detected at detergent-resistant membrane but not in membrane-free cell compartments that contain Gag and LysRS. LysRS is found (i). in the nucleus, (ii). in a cytoplasmic high-molecular-weight aminoacyl-tRNA synthetase complex (HMW aaRS complex), (iii). in mitochondria, and (iv). associated with plasma membrane. The cytoplasmic form of LysRS lacking the mitochondrial import signal was previously shown to be efficiently packaged into virions, and in this report we also show that LysRS compartments in nuclei, in the HMW aaRS complex, and at the membrane are also not required as a primary source for viral LysRS. Exogenous mutant LysRS species unable to either enter the nucleus or bind to the cell membrane are still incorporated into virions. Many HMW aaRS components are not packaged into the virion along with LysRS, and the interaction of LysRS with p38, a protein that binds tightly to LysRS in the HMW aaRS complex, is not required for the incorporation of LysRS into virions. These data indicate that newly synthesized LysRS may interact rapidly with Gag before the enzyme has the opportunity to move to the above-mentioned cellular compartments. In confirmation of this idea, we found that newly synthesized LysRS is associated with Gag after a 10-min pulse with [(35)S]cysteine/methionine. This observation is also supported by previous work indicating that the incorporation of LysRS into HIV-1 is very sensitive to the inhibition of new synthesis of LysRS.
authors.affiliation: Lady Davis Institute for Medical Research, Jewish General Hospital, Quebec, Canada H3T 1E2.
authors.forename: Rabih
authors.initials: R
authors.lastname: Halwani
authors.forename: Shan
authors.initials: S
authors.lastname: Cen
authors.forename: Hassan
authors.initials: H
authors.lastname: Javanbakht
authors.forename: Jenan
authors.initials: J
authors.lastname: Saadatmand
authors.forename: Sunghoon
authors.initials: S
authors.lastname: Kim
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Shiba
authors.forename: Lawrence
authors.initials: L
authors.lastname: Kleiman
mesh_terms: D002460:Cell Line; D015683:Gene Products, gag / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008250:Lysine-tRNA Ligase / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D013347:Subcellular Fractions / Q000378:metabolism; D014162:Transfection; D014771:Virion / Q000378:metabolism; D019065:Virus Assembly
chemical_list: D015683:Gene Products, gag; D008250:Lysine-tRNA Ligase