Mechanisms of PI(4,5)P2 Enrichment in HIV-1 Viral Membranes
| Autor: | Robert A. Dick, Gerald W. Feigenson, Yi Wen, Volker M. Vogt |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Phosphatidylinositol 4
5-Diphosphate giant unilamellar vesicle viruses matrix protein HIV Infections gag Gene Products Human Immunodeficiency Virus Article 03 medical and health sciences chemistry.chemical_compound 0302 clinical medicine Structural Biology Humans Phosphatidylinositol Molecular Biology Unilamellar Liposomes 030304 developmental biology Myristoylation large unilamellar vesicle 0303 health sciences Liposome Viral matrix protein human immunodeficiency virus myristoylation Virus Assembly Vesicle Cell Membrane Viral membrane Pleckstrin homology domain Membrane chemistry Host-Pathogen Interactions HIV-1 Biophysics lipids (amino acids peptides and proteins) 030217 neurology & neurosurgery Protein Binding |
| Zdroj: | Journal of molecular biology |
| ISSN: | 0022-2836 |
| Popis: | Phosphatidylinositol 4,5-bisphosphate (PIP2) is critical for HIV-1 virus assembly. The viral membrane is enriched in PIP2, suggesting that the virus assembles at PIP2-rich microdomains. We showed previously that in model membranes PIP2 can form nanoscopic clusters bridged by multivalent cations. Here, using purified proteins we quantitated the binding of HIV-1 Gag-related proteins to giant unilamellar vesicles containing either clustered or free PIP2. Myristoylated MA strongly preferred binding to clustered PIP2. By contrast, unmyristoylated HIV-1 MA, RSV MA, and a PH domain all preferred to interact with free PIP2. We also found that HIV-1 Gag multimerization promotes PIP2 clustering. Truncated Gag proteins comprising the MA, CA, and SP domains (MACASP) or the MA and CA domains (MACA) induced self-quenching of acyl chain-labeled fluorescent PIP2 in liposomes, implying clustering. However, HIV-1 MA itself did not induce PIP2 clustering. A CA inter-hexamer dimer interface mutation led to a loss of induced PIP2 clustering in MACA, indicating the importance of protein multimerization. Cryo-electron tomography of liposomes with bound MACA showed an amorphous protein layer on the membrane surface. Thus, it appears that while protein-protein interactions are required for PIP2 clustering, formation of a regular lattice is not. Protein-induced PIP2 clustering and multivalent cation-induced PIP2 clustering are additive. Taken together, these results provide the first evidence that HIV-1 Gag can selectively target pre-existing PIP2-enriched domains of the plasma membrane for viral assembly, and that Gag multimerization can further enrich PIP2 at assembly sites. These effects could explain the observed PIP2 enrichment in HIV-1. |
| Databáze: | OpenAIRE |
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