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The interaction between HIV-1 Gag and APOBEC3G
Shan Cen1, Fei Guo, Meijuan Niu
1Lady Davis Institute for Medical Research and McGill AIDS Centre, Jewish General Hospital, Department of Medicine, McGill University, Montreal, Quebec H3T 1E2, Canada.
The Journal of Biological Chemistry
|May 26, 2004
Summary
APOBEC3G inhibits HIV-1 by deaminating viral DNA. This study reveals how HIV-1 Gag protein facilitates APOBEC3G incorporation into viral particles, a process blocked by the viral Vif protein.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- APOBEC3G is a cellular deaminase that inhibits HIV-1 infectivity.
- HIV-1 Vif protein antagonizes APOBEC3G by preventing its virion incorporation.
- The mechanism of APOBEC3G packaging into HIV-1 remains incompletely understood.
Purpose of the Study:
- To investigate the mechanism of APOBEC3G incorporation into HIV-1 viral particles.
- To identify the viral and cellular factors involved in this packaging process.
Main Methods:
- Expression of HIV-1 Gag and Vif proteins in cellular systems.
- Analysis of APOBEC3G association with membranes and viral-like particles (VLPs).
- Immunoprecipitation assays and RNase treatment to assess protein interactions and RNA's role.
Main Results:
- Cytoplasmic APOBEC3G binds to cell membranes in the presence of HIV-1 Gag, independent of Vif.
- HIV-1 Gag is sufficient for APOBEC3G packaging into VLPs, requiring the Gag nucleocapsid.
- A specific region (amino acids 104-156) of APOBEC3G is essential for VLP incorporation.
- APOBEC3G incorporation is independent of viral genomic RNA, refuting an RNA bridge mechanism.
Conclusions:
- HIV-1 Gag mediates APOBEC3G incorporation into viral particles through a Vif-sensitive, membrane-associated mechanism.
- The Gag-nucleocapsid interaction and a specific APOBEC3G region are crucial for packaging.
- The interaction between Gag and APOBEC3G does not rely on viral RNA.