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Late assembly domain function can exhibit context dependence and involves ubiquitin residues implicated in
Bettina Strack1, Arianna Calistri, Heinrich G Göttlinger
1Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.
Journal of Virology
|May 7, 2002
Summary
Retroviral late assembly (L) domains, crucial for virus release, require cooperation between motifs for full function. The P(T/S)APP motif needs the nucleocapsid-p1 region for human immunodeficiency virus type 1 (HIV-1) Gag polyprotein activity.
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Retroviral Gag polyproteins mediate virus particle release from host cells.
- Late assembly (L) domains within Gag are essential for efficient virus budding.
- HIV-1 L domains contain a conserved P(T/S)APP motif, while other retroviruses utilize a PPXY motif.
Purpose of the Study:
- To investigate the functional autonomy of the P(T/S)APP motif in HIV-1 Gag-mediated virus release.
- To determine the role of the PPXY motif and cooperating regions in L domain activity.
- To elucidate the mechanism of Gag ubiquitination and its impact on virus budding.
Main Methods:
- Site-directed mutagenesis of conserved L domain motifs (P(T/S)APP and PPXY) in HIV-1 Gag constructs.
- Analysis of virus-like particle (VLP) production and Gag ubiquitination levels.
- Examination of ubiquitin mutants affecting endocytosis and VLP production.
Main Results:
- Disruption of the PPXY motif abolished L domain activity in a minimal Gag context.
- The P(T/S)APP motif alone was insufficient for L domain function, requiring cooperation with the nucleocapsid-p1 region.
- Ubiquitin residues critical for endocytosis were also implicated in virus budding.
Conclusions:
- The HIV-1 L domain functions through a cooperative mechanism involving the P(T/S)APP motif and the nucleocapsid-p1 region.
- Efficient virus budding relies on specific interactions between Gag, L domains, and ubiquitination machinery.
- Understanding these interactions provides insights into retroviral replication and potential therapeutic targets.