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Topology of the C-terminal tail of HIV-1 gp41: Differential exposure of the Kennedy epitope on cell and viral membranes

Steckbeck, JD and Sun, C and Sturgeon, TJ and Montelaro, RC (2010) Topology of the C-terminal tail of HIV-1 gp41: Differential exposure of the Kennedy epitope on cell and viral membranes. PLoS ONE, 5 (12).

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The C-terminal tail (CTT) of the HIV-1 gp41 envelope (Env) protein is increasingly recognized as an important determinant of Env structure and functional properties, including fusogenicity and antigenicity. While the CTT has been commonly referred to as the "intracytoplasmic domain" based on the assumption of an exclusive localization inside the membrane lipid bilayer, early antigenicity studies and recent biochemical analyses have produced a credible case for surface exposure of specific CTT sequences, including the classical "Kennedy epitope" (KE) of gp41, leading to an alternative model of gp41 topology with multiple membrane-spanning domains. The current study was designed to test these conflicting models of CTT topology by characterizing the exposure of native CTT sequences and substituted VSV-G epitope tags in cell- and virionassociated Env to reference monoclonal antibodies (MAbs). Surface staining and FACS analysis of intact, Env-expressing cells demonstrated that the KE is accessible to binding by MAbs directed to both an inserted VSV-G epitope tag and the native KE sequence. Importantly, the VSV-G tag was only reactive when inserted into the KE; no reactivity was observed in cells expressing Env with the VSV-G tag inserted into the LLP2 domain. In contrast to cell-surface expressed Env, no binding of KE-directed MAbs was observed to Env on the surface of intact virions using either immune precipitation or surface plasmon resonance spectroscopy. These data indicate apparently distinct CTT topologies for virion- and cell-associated Env species and add to the case for a reconsideration of CTT topology that is more complex than currently envisioned. © 2010 Steckbeck et al.


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Item Type: Article
Status: Published
CreatorsEmailPitt UsernameORCID
Steckbeck, JD
Sun, Cchs79@pitt.eduCHS79
Sturgeon, TJsturgeon@pitt.eduSTURGEON
Montelaro, RCrmont@pitt.eduRMONT
ContributionContributors NameEmailPitt UsernameORCID
Centers: Other Centers, Institutes, Offices, or Units > Center for Vaccine Research
Date: 20 December 2010
Date Type: Publication
Journal or Publication Title: PLoS ONE
Volume: 5
Number: 12
DOI or Unique Handle: 10.1371/journal.pone.0015261
Refereed: Yes
MeSH Headings: Amino Acid Sequence; Cell Separation; Detergents--pharmacology; Epitopes--chemistry; Flow Cytometry; HIV Envelope Protein gp41--chemistry; HIV Envelope Protein gp41--metabolism; HIV-1--metabolism; Humans; Lipid Bilayers--chemistry; Membrane Glycoproteins--chemistry; Molecular Sequence Data; Protein Conformation; Protein Structure, Tertiary; Sequence Homology, Amino Acid; Surface Plasmon Resonance; Viral Envelope Proteins--chemistry
Other ID: NLM PMC2998427
PubMed Central ID: PMC2998427
PubMed ID: 21151874
Date Deposited: 22 Aug 2012 21:57
Last Modified: 16 Oct 2017 02:55


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