Organization of immature human immunodeficiency virus type 1.
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.
Wilk
T
T
The Structural Biology Programme, European Molecular Biology Laboratory, D69012 Heidelberg, Federal Republic of Germany.
Gross
I
I
Gowen
B E
BE
Rutten
T
T
de Haas
F
F
Welker
R
R
Kräusslich
H G
HG
Boulanger
P
P
Fuller
S D
SD
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
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