Organization of HIV-1 capsid proteins on a lipid monolayer.
In an in vitro system that mimics the assembly of immature human immunodeficiency virus (HIV) particles, ordered arrays of HIV-1 capsid (CA) proteins encoded by the viral gag gene have been obtained by incubation of histidine-tagged capsid proteins (His-HIVCA) beneath lipid monolayers containing the nickel-chelating lipid, 1,2-di-O-hexadecyl-sn-glycero-3-(1'-2"-R-hydroxy-3'-N-(5-amino-1- carboxypentyl)iminodiacetic acid)propyl ether. The membrane-bound His-HIVCA proteins formed small crystalline arrays of primitive (p1) unit cells with dimensions of a = 74.2 A, b = 126.2 A, gamma = 89.3 degrees. The image-analyzed two-dimensional projection of His-HIVCA assemblies shows a cage-like lattice, consisting of hexamer and trimer units, surrounding protein-free cage holes. The hexamer-coordinated cage holes of 26.3-A diameter are spaced at 74. 2-A intervals: these distances, and the hexamer-trimer arrangement, are consistent with previous, lower resolution studies on immature HIV-1 virus particles produced in vivo. Additionally, HIV-1 matrix protein trimer unit structures align to the His-HIVCA trimer units such that residues previously shown to interact with the HIV-1 gp120/gp41 envelope protein complex are oriented toward the hexamer cage holes. Our results form a bridge between results from conventional methods for the analysis of HIV particle structure.
Barklis
E
E
Vollum Institute and Department of Microbiology, Oregon Health Sciences University, Portland, Oregon 97201-3098, USA. barklis@ohsu.edu
McDermott
J
J
Wilkens
S
S
Fuller
S
S
Thompson
D
D
D002213:Capsid / Q000737:chemistry* / Q000502:physiology; D018360:Crystallography, X-Ray; D015497:HIV-1 / Q000502:physiology; D006801:Humans; D008563:Membrane Lipids / Q000737:chemistry*; D008854:Microscopy, Electron; D009905:Optical Rotatory Dispersion; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D019065:Virus Assembly
D008563:Membrane Lipids