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Multimeric CD4 binding exhibited by human and simian immunodeficiency virus envelope protein dimers
1Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892.
Journal of Virology
|September 1, 1992
Summary
Human and simian immunodeficiency virus envelope glycoproteins bind two CD4 molecules simultaneously as dimers, not monomers. This multimeric binding impacts viral entry and therapeutic strategies.
Area of Science:
- Virology
- Immunology
- Structural Biology
Background:
- Human and simian immunodeficiency virus (HIV and SIV) envelope (Env) glycoproteins mediate viral entry.
- Env glycoproteins form noncovalently associated oligomers critical for virus-cell interactions.
- High-affinity interaction with CD4 is essential for viral binding and membrane fusion.
Purpose of the Study:
- To investigate the stoichiometry of CD4 binding to Env protein oligomers.
- To determine if Env monomers or dimers exhibit differential CD4 binding capabilities.
- To explore the implications of multimeric CD4 binding on viral fusion and therapeutic interventions.
Main Methods:
- Biochemical assays to analyze Env glycoprotein oligomerization.
- Binding studies to quantify CD4 interactions with Env monomers and dimers.
- Structural analysis to elucidate the binding interface.
Main Results:
- Env protein dimers, in contrast to monomers, were shown to bind two CD4 molecules simultaneously.
- Evidence suggests multimeric CD4 binding enhances Env protein-CD4 avidity.
- Findings indicate potential implications for CD4-induced gp120 release and subunit cooperativity.
Conclusions:
- The dimeric form of HIV/SIV Env glycoproteins is the functional unit for high-affinity CD4 binding.
- Multivalent engagement of CD4 by Env dimers has significant consequences for viral fusion mechanisms.
- Understanding these interactions is crucial for developing effective antiviral therapies targeting viral entry.