The Stoichiometry of Trimeric SIV Glycoprotein Interaction with CD4 Differs from That of Anti-envelope Antibody Fab Fragments

Mikyung Kim, Bing Chen, Rebecca E. Hussey, Yasmin Chishti, David Montefiori, James A. Hoxie, Olwyn Byron, Gordon Campbell, Stephen C. Harrison, Ellis L. Reinherz

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

Human and simian immunodeficiency viruses infect host lymphoid cells by binding CD4 molecules via their gp160 envelope glycoproteins. Biochemical studies on recombinant SIVmac32H (pJ5) envelope ectodomain gp140 precursor protein show that the envelope is a trimer. Using size exclusion chromatography, quantitative amino acid analysis, analytical ultracentrifugation, and CD4-based competition assay, we demonstrate that the stoichiometry of CD4 receptor-oligomeric envelope interaction is 1:1. By contrast, Fab fragments of both neutralizing and non-neutralizing monoclonal antibodies bind at a 3:1 ratio. Thus, despite displaying equivalent CD4 binding sites on each of the three gp140 protomers within an uncleaved trimer, only one site binds the soluble 4-domain human CD4 extracellular segment. The anti-cooperativity and the faster koff of gp140 trimer:CD4 versus gp120 monomer:CD4 interaction suggest that CD4-induced conformational change is impeded in the intact envelope. The implications of these findings for immunity against human immunodeficiency virus and simian immunodeficiency virus are discussed.

Original languageEnglish (US)
Pages (from-to)42667-42676
Number of pages10
JournalJournal of Biological Chemistry
Volume276
Issue number46
DOIs
StatePublished - Nov 16 2001

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Kim, M., Chen, B., Hussey, R. E., Chishti, Y., Montefiori, D., Hoxie, J. A., Byron, O., Campbell, G., Harrison, S. C., & Reinherz, E. L. (2001). The Stoichiometry of Trimeric SIV Glycoprotein Interaction with CD4 Differs from That of Anti-envelope Antibody Fab Fragments. Journal of Biological Chemistry, 276(46), 42667-42676. https://doi.org/10.1074/jbc.M104166200