PT  - JOURNAL ARTICLE
AU  - Arpa Hudait
AU  - James H. Hurley
AU  - Gregory A. Voth
TI  - Organization of Upstream ESCRT Machinery at the HIV-1 Budding Site
AID  - 10.1101/2022.09.13.507863
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.09.13.507863
4099  - http://biorxiv.org/content/early/2022/09/14/2022.09.13.507863.short
4100  - http://biorxiv.org/content/early/2022/09/14/2022.09.13.507863.full
AB  - In the late stages of the HIV-1 life cycle, membrane localization and self-assembly of the Gag polyproteins induce membrane deformation and budding. However, release of the immature virion requires direct interaction between Gag lattice and upstream ESCRT machinery at the budding site, followed by assembly of the downstream ESCRT-III factors, culminating in membrane scission. In this work, using “bottom-up” coarse-grained (CG) molecular dynamics (MD) simulations we investigated the interactions between Gag and different upstream ESCRT components to delineate the molecular organization of proteins at the membrane neck of the HIV-1 budding site. We developed CG models of upstream ESCRT proteins and HIV-1 structural protein Gag based on experimental structural data and extensive all-atom MD simulations. We find that ESCRT-I proteins bound to the immature Gag lattice can recruit multiple copies of ESCRT-II coating the membrane neck. ESCRT-I can effectively oligomerize to higher-order complexes both in absence of ESCRT-II and when multiple copies of ESCRT-II are localized at the bud neck. The ESCRT-I/II supercomplexes observed in our simulations exhibit predominantly extended conformations. Importantly, the ESCRT-I/II supercomplex modulates the membrane mechanical properties at the budding site by decreasing the overall Gaussian curvature of membrane neck. Our findings serve to elucidate a network of interactions between the upstream ESCRT machinery, immature Gag lattice, and membrane bud neck that regulate the protein assemblies and enable bud neck constriction.Competing Interest StatementThe authors have declared no competing interest.ESCRTendosomal sorting complexes required for transportAA MDAll-Atom Molecular DynamicsCG MDCoarse-Grained Molecular DynamicsRMSFroot mean square fluctuation