# Reverse-Topology Mechanism of ESCRTs DuringHIV-1 Viral Release

> **NIH NIH F31** · UNIVERSITY OF CALIFORNIA BERKELEY · 2020 · $41,560

## Abstract

Project Summary
 The human immunodeficiency virus type 1 (HIV-1) is a retrovirus that completes its viral life cycle when the
newly assembled virion is released from the infected cell. The HIV-1 structural protein, Gag, recruits the host
cell’s endosomal sorting complex required for transport (ESCRT) proteins towards the neck of budding virions
to sever the nascent viral particle from the plasma membrane. In addition to viral-like particle (VLP) release,
ESCRTs are utilized in membrane scission of other topologically equivalent cellular processes such as
vesicular trafficking, cell division, exosome biogenesis, and plasma membrane repair. Recent advances in
molecular biology and virology highlight the importance and timing of recruitment of ESCRTs in achieving
proper viral particle release. However, a description of the biophysical mechanism of ESCRT-mediated
scission during HIV release remains a major goal in the field.
 Newly developed methods in our laboratory have now made possible the encapsulation of functional
human ESCRT and Gag proteins inside giant unilamellar vesicles (GUVs), thereby recapitulating the correct
topology for ESCRT function in vitro. We have integrated a high-speed confocal microscope with optical
trapping capabilities which allows the visualization and investigation, with piconewton resolution, of the force
generated during scission of a single membrane neck. Control of the reaction is modulated by UV photolysis of
a caged-nucleotide for this ATP-dependent process. Together, these innovations have given us a unique ability
to interrogate HIV-1 release by ESCRTs under a biophysical lens.
 This proposed research represents a focused and innovative approach to investigate the ATP-dependent
membrane scission mechanism of human ESCRT proteins in the setting of HIV-1 release; directly building and
expanding on our previous success with the yeast ESCRT system. Specifically, in aim 1, I will identify the
scission mechanism of human ESCRTs. Subsequently, aim 2 will provide a biophysical explanation of the
interplay between Gag binding and membrane scission by the ESCRT machinery. The overarching hypothesis
for this proposal is that ESCRTs apply mechanical force to membrane necks which destabilizes them and
leads to their scission. Ultimately, successful completion of this work allows for a detailed biophysical
understanding of HIV-1 release by ESCRTs that may lead to the design of novel antivirals.

## Key facts

- **NIH application ID:** 10012755
- **Project number:** 5F31AI150312-02
- **Recipient organization:** UNIVERSITY OF CALIFORNIA BERKELEY
- **Principal Investigator:** Abraham King Cada
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $41,560
- **Award type:** 5
- **Project period:** 2019-07-01 → 2022-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10012755

## Citation

> US National Institutes of Health, RePORTER application 10012755, Reverse-Topology Mechanism of ESCRTs DuringHIV-1 Viral Release (5F31AI150312-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10012755. Licensed CC0.

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