Cargando…

Mechanisms of PI(4,5)P2 Enrichment in HIV-1 Viral Membranes

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. Her...

Descripción completa

Detalles Bibliográficos
Autores principales: Wen, Yi, Feigenson, Gerald W., Vogt, Volker M., Dick, Robert A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8262684/
https://www.ncbi.nlm.nih.gov/pubmed/32739462
http://dx.doi.org/10.1016/j.jmb.2020.07.018
_version_ 1783719231565594624
author Wen, Yi
Feigenson, Gerald W.
Vogt, Volker M.
Dick, Robert A.
author_facet Wen, Yi
Feigenson, Gerald W.
Vogt, Volker M.
Dick, Robert A.
author_sort Wen, Yi
collection PubMed
description 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.
format Online
Article
Text
id pubmed-8262684
institution National Center for Biotechnology Information
language English
publishDate 2020
record_format MEDLINE/PubMed
spelling pubmed-82626842021-07-07 Mechanisms of PI(4,5)P2 Enrichment in HIV-1 Viral Membranes Wen, Yi Feigenson, Gerald W. Vogt, Volker M. Dick, Robert A. J Mol Biol Article 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. 2020-07-31 2020-09-04 /pmc/articles/PMC8262684/ /pubmed/32739462 http://dx.doi.org/10.1016/j.jmb.2020.07.018 Text en https://creativecommons.org/licenses/by/4.0/This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) ).
spellingShingle Article
Wen, Yi
Feigenson, Gerald W.
Vogt, Volker M.
Dick, Robert A.
Mechanisms of PI(4,5)P2 Enrichment in HIV-1 Viral Membranes
title Mechanisms of PI(4,5)P2 Enrichment in HIV-1 Viral Membranes
title_full Mechanisms of PI(4,5)P2 Enrichment in HIV-1 Viral Membranes
title_fullStr Mechanisms of PI(4,5)P2 Enrichment in HIV-1 Viral Membranes
title_full_unstemmed Mechanisms of PI(4,5)P2 Enrichment in HIV-1 Viral Membranes
title_short Mechanisms of PI(4,5)P2 Enrichment in HIV-1 Viral Membranes
title_sort mechanisms of pi(4,5)p2 enrichment in hiv-1 viral membranes
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8262684/
https://www.ncbi.nlm.nih.gov/pubmed/32739462
http://dx.doi.org/10.1016/j.jmb.2020.07.018
work_keys_str_mv AT wenyi mechanismsofpi45p2enrichmentinhiv1viralmembranes
AT feigensongeraldw mechanismsofpi45p2enrichmentinhiv1viralmembranes
AT vogtvolkerm mechanismsofpi45p2enrichmentinhiv1viralmembranes
AT dickroberta mechanismsofpi45p2enrichmentinhiv1viralmembranes