Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Identification of a host protein essential for assembly of immature HIV-1 capsids


To form an immature HIV-1 capsid, 1,500 HIV-1 Gag (p55) polypeptides must assemble properly along the host cell plasma membrane. Insect cells and many higher eukaryotic cell types support efficient capsid assembly1, but yeast2 and murine cells3,4 do not, indicating that host machinery is required for immature HIV-1 capsid formation. Additionally, in a cell-free system that reconstitutes HIV-1 capsid formation, post-translational assembly events require ATP and a subcellular fraction5, suggesting a requirement for a cellular ATP-binding protein. Here we identify such a protein (HP68), described previously as an RNase L inhibitor6, and demonstrate that it associates post-translationally with HIV-1 Gag in a cell-free system and human T cells infected with HIV-1. Using a dominant negative mutant of HP68 in mammalian cells and depletion–reconstitution experiments in the cell-free system, we demonstrate that HP68 is essential for post-translational events in immature HIV-1 capsid assembly. Furthermore, in cells the HP68–Gag complex is associated with HIV-1 Vif, which is involved in virion morphogenesis and infectivity. These findings support a critical role for HP68 in post-translational events of HIV-1 assembly and reveal a previously unappreciated dimension of host–viral interaction.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Prices vary by article type



Prices may be subject to local taxes which are calculated during checkout

Figure 1: Anti-HuHP68 co-immunoprecipitates HIV-1 Gag in mammalian cells.
Figure 2: Co-localization of HP68 with HIV-1 Gag in mammalian cells.
Figure 3: Truncated HP68 blocks virion production.
Figure 4: HP68 depletion–reconstitution.
Figure 5: Anti-HuHP68 co-immunoprecipitates HIV-1 Vif but not Nef or RNase L.


  1. Boulanger, P. & Jones, I. Use of heterologous expression systems to study retroviral morphogenesis. Curr. Top. Microbiol. Immunol. 214, 237–260 (1996).

    CAS  PubMed  Google Scholar 

  2. Jacobs, E., Gheysen, D., Thines, D., Francotte, M. & de Wilde, M. The HIV-1 Gag precursor Pr55gag synthesized in yeast is myristoylated and targeted to the plasma membrane. Gene 79, 71–81 (1989).

    Article  CAS  Google Scholar 

  3. Mariani, R. et al. A block to human immunodeficiency virus type 1 assembly in murine cells. J. Virol. 74, 3859–3870 (2000).

    Article  CAS  Google Scholar 

  4. Mariani, R. et al. Mouse-human heterokaryons support efficient human immunodeficiency virus type 1 assembly. J. Virol. 75, 3141–3151 (2001).

    Article  CAS  Google Scholar 

  5. Lingappa, J. R., Hill, R. L., Wong, M. L. & Hegde, R. S. A multistep, ATP-dependent pathway for assembly of human immunodeficiency virus capsids in a cell-free system. J. Cell Biol. 136, 567–581 (1997).

    Article  CAS  Google Scholar 

  6. Bisbal, C., Martinand, C., Silhol, M., Lebleu, B. & Salehzada, T. Cloning and characterization of a RNAse L inhibitor. A new component of the interferon-regulated 2-5A pathway. J. Biol. Chem. 270, 13308–13317 (1995).

    Article  CAS  Google Scholar 

  7. Singh, A. R., Hill, R. L. & Lingappa, J. R. Effect of mutations in Gag on assembly of immature human immunodeficiency virus type 1 capsids in a cell-free system. Virology 279, 257–270 (2001).

    Article  CAS  Google Scholar 

  8. Hynes, G. et al. Analysis of chaperonin-containing TCP-1 subunits in the human keratinocyte two-dimensional protein database: further characterisation of antibodies to individual subunits. Electrophoresis 17, 1720–1727 (1996).

    Article  CAS  Google Scholar 

  9. Willison, K. et al. The T complex polypeptide 1 (TCP-1) is associated with the cytoplasmic aspect of Golgi membranes. Cell 57, 621–632 (1989).

    Article  CAS  Google Scholar 

  10. Lingappa, J. R. et al. A eukaryotic cytosolic chaperonin is associated with a high molecular weight intermediate in the assembly of hepatitis B virus capsid, a multimeric particle. J. Cell Biol. 125, 99–111 (1994).

    Article  CAS  Google Scholar 

  11. Traut, T. W. The functions and consensus motifs of nine types of peptide segments that form different types of nucleotide-binding sites. Eur. J. Biochem. 222, 9–19 (1994).

    Article  CAS  Google Scholar 

  12. Salehzada, T., Silhol, M., Lebleu, B. & Bisbal, C. Polyclonal antibodies against RNase L. Subcellular localization of this enzyme in mouse cells. J. Biol. Chem. 266, 5808–5813 (1991).

    CAS  PubMed  Google Scholar 

  13. Zhou, A., Hassel, B. A. & Silverman, R. H. Expression cloning of 2-5A-dependent RNAase: a uniquely regulated mediator of interferon action. Cell 72, 753–765 (1993).

    Article  CAS  Google Scholar 

  14. Player, M. R. & Torrence, P. F. The 2-5A system: modulation of viral and cellular processes through acceleration of RNA degradation. Pharmacol. Ther. 78, 55–113 (1998).

    Article  CAS  Google Scholar 

  15. Martinand, C. et al. RNase L inhibitor is induced during human immunodeficiency virus type 1 infection and down regulates the 2-5A/RNase L pathway in human T cells. J. Virol. 73, 290–296 (1999).

    CAS  PubMed  PubMed Central  Google Scholar 

  16. Kimpton, J. & Emerman, M. Detection of replication-competent and pseudotyped human immunodeficiency virus with a sensitive cell line on the basis of activation of an integrated β-galactosidase gene. J. Virol. 66, 2232–2239 (1992).

    CAS  PubMed  PubMed Central  Google Scholar 

  17. Smith, A. J., Srinivasakumar, N., Hammarskjold, M. L. & Rekosh, D. Requirements for incorporation of Pr160gag-pol from human immunodeficiency virus type 1 into virus-like particles. J. Virol. 67, 2266–2275 (1993).

    CAS  PubMed  PubMed Central  Google Scholar 

  18. Gheysen, D. et al. Assembly and release of HIV-1 precursor Pr55gag virus-like particles from recombinant baculovirus-infected insect cells. Cell 59, 103–112 (1989).

    Article  CAS  Google Scholar 

  19. Hockley, D. J., Nermut, M. V., Grief, C., Jowett, J. B. & Jones, I. M. Comparative morphology of Gag protein structures produced by mutants of the gag gene of human immunodeficiency virus type 1. J. Gen. Virol. 75, 2985–2997 (1994).

    Article  CAS  Google Scholar 

  20. Jowett, J. B., Hockley, D. J., Nermut, M. V. & Jones, I. M. Distinct signals in human immunodeficiency virus type 1 Pr55 necessary for RNA binding and particle formation. J. Gen. Virol. 73, 3079–3086 (1992).

    Article  CAS  Google Scholar 

  21. Royer, M. et al. Functional domains of HIV-1 gag-polyprotein expressed in baculovirus-infected cells. Virology 184, 417–422 (1991).

    Article  CAS  Google Scholar 

  22. Bukovsky, A. A., Dorfman, T., Weimann, A. & Gottlinger, H. G. Nef association with human immunodeficiency virus type 1 virions and cleavage by the viral protease. J. Virol. 71, 1013–1018 (1997).

    CAS  PubMed  PubMed Central  Google Scholar 

  23. Pandori, M. W. et al. Producer-cell modification of human immunodeficiency virus type 1: Nef is a virion protein. J. Virol. 70, 4283–4290 (1996).

    CAS  PubMed  PubMed Central  Google Scholar 

  24. Welker, R., Harris, M., Cardel, B. & Krausslich, H. G. Virion incorporation of human immunodeficiency virus type 1 Nef is mediated by a bipartite membrane-targeting signal: analysis of its role in enhancement of viral infectivity. J. Virol. 72, 8833–8840 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  25. Cohen, E. A., Subbramanian, R. A. & Gottlinger, H. G. Role of auxiliary proteins in retroviral morphogenesis. Curr. Top. Microbiol. Immunol. 214, 219–235 (1996).

    CAS  PubMed  Google Scholar 

  26. Madani, N. & Kabat, D. An endogenous inhibitor of human immunodeficiency virus in human lymphocytes is overcome by the viral Vif protein. J. Virol. 72, 10251–10255 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  27. Simon, J. H. & Malim, M. H. The human immunodeficiency virus type 1 Vif protein modulates the postpenetration stability of viral nucleoprotein complexes. J. Virol. 70, 5297–5305 (1996).

    CAS  PubMed  PubMed Central  Google Scholar 

  28. Simon, J. H. et al. The regulation of primate immunodeficiency virus infectivity by Vif is cell species restricted: a role for Vif in determining virus host range and cross-species transmission. EMBO J. 17, 1259–1267 (1998).

    Article  CAS  Google Scholar 

  29. Kozak, M. Interpreting cDNA sequences: some insights from studies on translation. Mamm. Genome 7, 563–574 (1996).

    Article  CAS  Google Scholar 

  30. Folks, T. M. et al. Tumor necrosis factor α induces expression of human immunodeficiency virus in a chronically infected T-cell clone. Proc. Natl Acad. Sci. USA 86, 2365–2368 (1989).

    Article  ADS  CAS  Google Scholar 

Download references


Vif monoclonal antibody (TG001; Transgene) and Nef monoclonal antibody (EH1; gift of J. Hoxie) were provided by the AIDS Research and Reference Reagent Program, Division of AIDS, NIAID, National Institutes of Health. We thank J. Kucinski and F. Calayag for technical assistance; M. Hayden, T. Liegler, R. Grant and the Gladstone Institute, San Francisco, for assistance with HIV-infected cells; V. Kewalramani, D. Littman, M. Goldsmith and W. Hansen for advice or, reagents; L. Caldwell and the Electron Microscopy Laboratory at the Fred Hutchinson Cancer Research Center in Seattle; and V. Lingappa, J. Lingappa, J. Dooher, J. Overbaugh, J. M. McCune, M. Linial and R. Hegde for discussions. This work was supported by grants to J.R.L. from the National Institutes of Health AIDS Division, Pediatric AIDS Foundation, and the University of California Universitywide AIDS Research Program.

Author information

Authors and Affiliations


Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Zimmerman, C., Klein, K., Kiser, P. et al. Identification of a host protein essential for assembly of immature HIV-1 capsids. Nature 415, 88–92 (2002).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing