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Visualization of HIV-1 Gag Binding to Giant Unilamellar Vesicle (GUV) Membranes
Published on: July 28, 2016
Human immunodeficiency virus type 1 matrix protein assembles on membranes as a hexamer
Ayna Alfadhli1, Doug Huseby, Eliot Kapit
1Vollum Institute and Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University, Mail Code L220, 3181 SW Sam Jackson Park Road, Portland, OR 97201-3098, USA.
Journal of Virology
|November 17, 2006
Summary
Human immunodeficiency virus type 1 matrix (MA) proteins unexpectedly form hexamer rings on membranes, not trimers. This finding impacts models of HIV assembly and viral glycoprotein interactions.
Area of Science:
- Virology
- Structural Biology
- Biochemistry
Background:
- The matrix (MA) domain of human immunodeficiency virus type 1 (HIV-1) Gag precursor protein is crucial for viral assembly and membrane binding.
- Previous models proposed MA trimers align with capsid (CA) N-terminal domains (NTDs) in hexagonal lattices.
- The precise organization of MA on the viral membrane remains incompletely understood.
Purpose of the Study:
- To investigate the in vitro assembly of myristoylated HIV-1 matrix (MyrMA) and matrix-capsid (MyrMACA) proteins on membranes.
- To determine the oligomeric state and lattice formation of MA proteins upon membrane binding.
- To propose a revised model for MA domain organization during HIV-1 assembly.
Main Methods:
- In vitro binding assays using naturally myristoylated HIV-1 MyrMA and MyrMACA proteins.
- Formation of hexagonal cage lattices on phosphatidylserine-cholesterol membranes.
- Analysis of protein organization and oligomeric states (trimers vs. hexamers).
Main Results:
- Both MyrMA and MyrMACA proteins unexpectedly assembled into hexagonal cage lattices on membranes.
- Membrane-bound MyrMA proteins organized into hexamer rings, not the previously assumed trimer units.
- This hexameric organization differs from the trimeric state observed in solution and crystallization.
Conclusions:
- MA domains stack directly above NTD hexamers in immature HIV-1 particles.
- The formation of MA hexamers on the membrane has significant implications for HIV assembly.
- This study refines our understanding of MA-membrane interactions and their role in viral glycoprotein association.
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