X-ray structures of the hexameric building block of the HIV capsid.
The mature capsids of HIV and other retroviruses organize and package the viral genome and its associated enzymes for delivery into host cells. The HIV capsid is a fullerene cone: a variably curved, closed shell composed of approximately 250 hexamers and exactly 12 pentamers of the viral CA protein. We devised methods for isolating soluble, assembly-competent CA hexamers and derived four crystallographically independent models that define the structure of this capsid assembly unit at atomic resolution. A ring of six CA N-terminal domains form an apparently rigid core, surrounded by an outer ring of C-terminal domains. Mobility of the outer ring appears to be an underlying mechanism for generating the variably curved lattice in authentic capsids. Hexamer-stabilizing interfaces are highly hydrated, and this property may be key to the formation of quasi-equivalent interactions within hexamers and pentamers. The structures also clarify the molecular basis for capsid assembly inhibition and should facilitate structure-based drug design strategies.
Pornillos
Owen
O
Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Ganser-Pornillos
Barbie K
BK
Kelly
Brian N
BN
Hua
Yuanzi
Y
Whitby
Frank G
FG
Stout
C David
CD
Sundquist
Wesley I
WI
Hill
Christopher P
CP
Yeager
Mark
M
D036022:Capsid Proteins / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D015497:HIV-1 / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011108:Polymers / Q000378:metabolism; D017434:Protein Structure, Tertiary
D036022:Capsid Proteins; D011108:Polymers