A Caltech Library Service

Electron cryotomography of immature HIV-1 virions reveals the structure of the CA and SP1 Gag shells

Wright, Elizabeth R. and Schooler, Jordan B. and Ding, H. Jane and Kieffer, Collin and Fillmore, Christopher and Sundquist, Wesley I. and Jensen, Grant J. (2007) Electron cryotomography of immature HIV-1 virions reveals the structure of the CA and SP1 Gag shells. EMBO Journal, 26 (8). pp. 2218-2226. ISSN 0261-4189. PMCID PMC1852790. doi:10.1038/sj.emboj.7601664.

[img] Video (QuickTime) - Supplemental Material
See Usage Policy.


Use this Persistent URL to link to this item:


The major structural elements of retroviruses are contained in a single polyprotein, Gag, which in human immunodeficiency virus type 1 (HIV-1) comprises the MA, CA, spacer peptide 1 (SP1), NC, SP2, and p6 polypeptides. In the immature HIV-1 virion, the domains of Gag are arranged radially with the N-terminal MA domain at the membrane and C-terminal NC-SP2-p6 region nearest to the center. Here, we report the three-dimensional structures of individual immature HIV-1 virions, as obtained by electron cryotomography. The concentric shells of the Gag polyprotein are clearly visible, and radial projections of the different Gag layers reveal patches of hexagonal order within the CA and SP1 shells. Averaging well-ordered unit cells leads to a model in which each CA hexamer is stabilized by a bundle of six SP1 helices. This model suggests why the SP1 spacer is essential for assembly of the Gag lattice and how cleavage between SP1 and CA acts as a structural switch controlling maturation.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle
Kieffer, Collin0000-0001-9051-3819
Jensen, Grant J.0000-0003-1556-4864
Additional Information:© 2007 European Molecular Biology Organization. Received: 3 January 2007; accepted: 5 March 2007; published online: 29 March 2007. This work was supported in part by NIH Grant PO1 GM66521 (to WIS and GJJ), NIH Grant A145405 (to WIS), NIH Grant F32 GM075543 (to ERW), the Beckman Institute at Caltech, and gifts to Caltech from the Ralph M Parsons Foundation, the Agouron Institute, and the Gordon and Betty Moore Foundation. Supplementary data are available at The EMBO Journal Online (
Funding AgencyGrant Number
NIHPO1 GM66521
NIH Postdoctoral FellowshipF32 GM075543
Caltech Beckman InstituteUNSPECIFIED
Ralph M. Parsons FoundationUNSPECIFIED
Agouron InstituteUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:electron cryotomography, Gag, human immunodeficiency virus type 1 (HIV-1), spacer peptide 1 (SP1)
Issue or Number:8
PubMed Central ID:PMC1852790
Record Number:CaltechAUTHORS:20110803-142323319
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:24664
Deposited By: George Porter
Deposited On:03 Aug 2011 21:45
Last Modified:09 Nov 2021 16:25

Repository Staff Only: item control page