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Dynamics of HIV-1 assembly and release
Sergey Ivanchenko1, William J Godinez, Marko Lampe
1Physical Chemistry, Department of Chemistry and Biochemistry, Munich Center for Integrated Protein Science (CiPSM) and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany.
Plos Pathogens
|November 7, 2009
Summary
Human immunodeficiency virus type 1 (HIV-1) assembly at the cell membrane is rapid, taking 8-9 minutes to complete a single virion. This process involves Gag polyproteins and occurs at discrete sites, with release following about 25 minutes after assembly begins.
Area of Science:
- Virology
- Cell Biology
- Biophysics
Background:
- Human immunodeficiency virus (HIV) assembly and release occur at the plasma membrane, driven by the Gag polyprotein.
- Previous studies lacked dynamic and kinetic information on viral morphogenesis, relying on static imaging and biochemical methods.
Purpose of the Study:
- To investigate the dynamic and kinetic aspects of HIV-1 assembly and release at the plasma membrane of living cells.
- To determine the kinetics of Gag polyprotein recruitment and virion formation.
- To assess the influence of cellular machinery and viral factors on assembly kinetics.
Main Methods:
- Utilized wide-field and total internal reflection fluorescence microscopy for high time-resolution imaging of fluorescently labeled HIV-1.
- Employed a photoconvertible fluorescent protein fused to Gag to track molecule origins and assembly nucleation.
- Monitored Gag cluster formation, accumulation at assembly sites, and extracellular particle release.
Main Results:
- HIV-1 Gag assembled into discrete clusters representing single virions, with rare formation of multiple particles from one site.
- Assembly was nucleated by Gag molecules newly arrived at the plasma membrane or from the cytosol.
- Assembly kinetics were rapid, with 90% completion in 8-9 minutes, and virion release occurred ~1500-2200 seconds post-assembly onset.
- ESCRT machinery recruitment, Vpu absence, or proteolytic maturation did not significantly alter assembly kinetics.
Conclusions:
- HIV-1 assembly at the plasma membrane is a rapid, tightly regulated process driven by Gag polyproteins.
- The study provides crucial kinetic data on viral assembly, revealing the speed and dynamics of virion formation.
- Assembly site dynamics and kinetics are largely independent of key viral and cellular factors, suggesting a robust core mechanism.
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