title: Analysis of the assembly function of the human immunodeficiency virus type 1 gag protein nucleocapsid domain.
abstract: Previous studies have shown that in addition to its function in specific RNA encapsidation, the human immunodeficiency virus type 1 (HIV-1) nucleocapsid (NC) is required for efficient virus particle assembly. However, the mechanism by which NC facilitates the assembly process is not clearly established. Formally, NC could act by constraining the Pr559gag polyprotein into an assembly-competent conformation or by masking residues which block the assembly process. Alternatively, the capacity of NC to bind RNA or make interprotein contacts might affect particle assembly. To examine its role in the assembly process, we replaced the NC domain in Pr55gag with polypeptide domains of known function, and the chimeric proteins were analyzed for their abilities to direct the release of virus-like particles. Our results indicate that NC does not mask inhibitory domains and does not act passively, by simply providing a stable folded monomeric structure. However, replacement of NC by polypeptides which form interprotein contacts permitted efficient virus particle assembly and release, even when RNA was not detected in the particles. These results suggest that formation of interprotein contacts by NC is essential to the normal HIV-1 assembly process.
authors.affiliation: Vollum Institute for Advanced Biomedical Research and Department of Molecular Microbiology and Immunology, Oregon Health Sciences University, Portland 97201-3098, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: H
authors.initials: H
authors.lastname: Qian
authors.forename: Z
authors.initials: Z
authors.lastname: Love
authors.forename: E
authors.initials: E
authors.lastname: Barklis
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D019556:COS Cells; D015683:Gene Products, gag / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D017909:Levivirus; D008969:Molecular Sequence Data; D016296:Mutagenesis; D019251:Nucleocapsid / Q000235:genetics / Q000378:metabolism; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D014771:Virion; D019065:Virus Assembly
chemical_list: D015683:Gene Products, gag; D011498:Protein Precursors; D011993:Recombinant Fusion Proteins; C059767:p55 gag precursor protein, Human immunodeficiency virus 1