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Human immunodeficiency virus type 1 Gag assembly through assembly intermediates
Yuko Morikawa1, Toshiyuki Goto, Fumitaka Momose
1Kitasato Institute of Life Sciences, Kitasato University, Shirokane 5-9-1, Minato-ku, Tokyo 108-8641, Japan. morikawa@lisci.kitasato-u.ac.jp
The Journal of Biological Chemistry
|May 21, 2004
Summary
Human immunodeficiency virus Gag protein assembly into virus-like particles is temperature-dependent. The 60S multimer is a key intermediate, with conformational changes at 37°C driving capsid formation.
Area of Science:
- Virology
- Structural Biology
- Biochemistry
Background:
- Human immunodeficiency virus (HIV) Gag protein self-assembly is crucial for viral particle formation.
- Previous studies suggest assembly intermediates form during Gag protein self-assembly.
Purpose of the Study:
- To elucidate the nature of Gag assembly intermediates.
- To understand the mechanism of Gag protein assembly into virus-like particles.
Main Methods:
- Expression of Gag protein in Escherichia coli at different temperatures (30°C and 37°C).
- In vitro assembly reactions using purified Gag protein.
- Electron microscopy and sedimentation analysis (60S).
- Cross-linking of 60S multimers and ATP depletion experiments.
Main Results:
- Expression at 37°C yielded high-order Gag multimers (virus-like particles) via a 60S intermediate.
- Expression at 30°C produced only 60S multimers and incomplete structures.
- In vitro assembly at 37°C formed higher-order multimers, but this was blocked if 60S multimers were cross-linked.
- Chaperonin GroEL-GroES and ATP depletion did not affect assembly, implicating conformational changes.
Conclusions:
- The 60S multimer is a key intermediate in Gag protein assembly.
- Temperature-induced conformational changes at 37°C are essential for capsid formation.
- Gag assembly mechanism involves conformational changes rather than chaperonin-assisted refolding.