title: Organization of immature human immunodeficiency virus type 1.
abstract: Immature retrovirus particles contain radially arranged Gag polyproteins in which the N termini lie at the membrane and the C termini extend toward the particle's center. We related image features to the polyprotein domain structure by combining mutagenesis with cryoelectron microscopy and image analysis. The matrix (MA) domain appears as a thin layer tightly associated with the inner face of the viral membrane, separated from the capsid (CA) layer by a low-density region corresponding to its C terminus. Deletion of the entire p6 domain has no effect on the width or spacing of the density layers, suggesting that p6 is not ordered in immature human immunodeficiency virus type 1 (HIV-1). In vitro assembly of a recombinant Gag polyprotein containing only capsid (CA) and nucleocapsid (NC) domains results in the formation of nonenveloped spherical particles which display two layers with density matching that of the CA-NC portion of immature HIV-1 Gag particles. Authentic, immature HIV-1 displays additional surface features and an increased density between the lipid bilayers which reflect the presence of gp41. The other internal features match those of virus-like particles.
authors.affiliation: The Structural Biology Programme, European Molecular Biology Laboratory, D69012 Heidelberg, Federal Republic of Germany.
authors.forename: T
authors.initials: T
authors.lastname: Wilk
authors.forename: I
authors.initials: I
authors.lastname: Gross
authors.forename: B E
authors.initials: BE
authors.lastname: Gowen
authors.forename: T
authors.initials: T
authors.lastname: Rutten
authors.forename: F
authors.initials: F
authors.lastname: de Haas
authors.forename: R
authors.initials: R
authors.lastname: Welker
authors.forename: H G
authors.initials: HG
authors.lastname: Kräusslich
authors.forename: P
authors.initials: P
authors.lastname: Boulanger
authors.forename: S D
authors.initials: SD
authors.lastname: Fuller
mesh_terms: D002213:Capsid / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism; D020285:Cryoelectron Microscopy; D017353:Gene Deletion; D015683:Gene Products, gag / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015497:HIV-1 / Q000737:chemistry* / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008051:Lipid Bilayers; D019251:Nucleocapsid / Q000737:chemistry; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D014763:Viral Matrix Proteins / Q000737:chemistry / Q000235:genetics; D014771:Virion / Q000737:chemistry / Q000648:ultrastructure; D019065:Virus Assembly; D054301:gag Gene Products, Human Immunodeficiency Virus
chemical_list: D015683:Gene Products, gag; D008051:Lipid Bilayers; D011994:Recombinant Proteins; D014763:Viral Matrix Proteins; D054301:gag Gene Products, Human Immunodeficiency Virus; C083002:p6 gag protein, Human immunodeficiency virus 1