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A molecular determinant of human immunodeficiency virus particle assembly located in matrix antigen p17
Y Morikawa1, T Kishi, W H Zhang
1Kitasato Institute, Kitasato University, Tokyo, Japan.
Abstract:
We report single-point mutations that are located in the matrix protein domain of the gag gene of human immunodeficiency virus type 1 and that prevent Gag particle formation. We show that mutations of p17 that abolish human immunodeficiency virus particle assembly also prevent the dimerization of p17 protein, as measured directly by a protein-protein binding assay. In the three-dimensional structure of p17, mutations that abolish dimerization are located in a single alpha helix that forms part of a fingerlike projection from one side of the molecule. Peptides derived from this region of p17 also reduce the level of p17 dimer when they are added to p17-expressing cells and compete for p17 self-association when present in protein-protein binding assays. We propose that the dimerization of the Gag precursor that occurs by the interdigitation of alpha helices on adjacent matrix molecules is a key stage in virion assembly and that the prevention of such an interaction is the molecular basis of particle misassembly.
Insights
Single-point mutations in human immunodeficiency virus type 1 Gag protein prevent particle formation by disrupting p17 matrix protein dimerization. This molecular interaction is crucial for viral assembly.
Area of Science:
- Virology
- Molecular Biology
- Structural Biology
Background:
- Human immunodeficiency virus type 1 (HIV-1) assembly relies on the Gag polyprotein precursor.
- The matrix protein (p17) is a key component of Gag, essential for viral particle formation.
Purpose of the Study:
- To investigate the role of p17 matrix protein dimerization in HIV-1 Gag particle assembly.
- To identify specific mutations affecting p17 dimerization and their impact on virion formation.
Main Methods:
- Site-directed mutagenesis to introduce single-point mutations in the p17 matrix protein domain of the HIV-1 gag gene.
- Protein-protein binding assays to directly measure p17 dimerization.
- Analysis of three-dimensional structure of p17 to locate mutation sites.
- In vitro assays using peptides derived from the p17 dimerization region.
Main Results:
- Specific single-point mutations in the p17 matrix protein domain abolish HIV-1 particle assembly.
- These mutations also prevent p17 protein dimerization, as confirmed by binding assays.
- Structural analysis revealed that dimerization-disrupting mutations are located in an alpha helix within a fingerlike projection of p17.
- Derived peptides inhibit p17 dimer formation and self-association in cells and binding assays.
Conclusions:
- p17 matrix protein dimerization, mediated by alpha helix interdigitation, is a critical step in HIV-1 virion assembly.
- Disruption of this dimerization interface is the molecular basis for particle misassembly.
- Targeting p17 dimerization presents a potential strategy for inhibiting HIV-1 replication.