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

Elizabeth R. Wright, Jordan B. Schooler, H. Jane Ding, Collin Kieffer, Christopher Fillmore, Wesley I. Sundquist, Grant J. Jensen

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish (US)
Pages (from-to)2218-2226
Number of pages9
JournalEMBO Journal
Volume26
Issue number8
DOIs
StatePublished - Apr 18 2007

Keywords

  • Electron cryotomography
  • Gag
  • Human immunodeficiency virus type 1 (HIV-1)
  • Spacer peptide 1 (SP1)

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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    Wright, E. R., Schooler, J. B., Ding, H. J., Kieffer, C., Fillmore, C., Sundquist, W. I., & Jensen, G. J. (2007). Electron cryotomography of immature HIV-1 virions reveals the structure of the CA and SP1 Gag shells. EMBO Journal, 26(8), 2218-2226. https://doi.org/10.1038/sj.emboj.7601664