# Mechanisms that determine subcellular sites of HIV-1 assembly

> **NIH NIH R37** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2024 · $76,288

## Abstract

Virus particle assembly of HIV-1, the causative agent of AIDS, takes place at the plasma membrane (PM)
in most cell types including natural host T cells. This process is driven by a viral structural protein Gag. The
N-terminal matrix (MA) domain of Gag determines Gag localization to and hence virus assembly at the PM.
MA mediates membrane binding of Gag via N-terminal myristoyl moiety and a highly basic region (HBR)
that binds acidic lipids. Binding of HBR to a PM-specific acidic phospholipid PI(4,5)P2 is critical for PM
localization of Gag and efficient virus release. Notably, we and others showed that MA HBR also interacts
with tRNAs, which suppress binding of Gag to non-PI(4,5)P2 acidic lipids, suggesting tRNAs as a host
factor that regulates MA-membrane interactions. However, structural determinants for the tRNA-MA HBR
interaction and its reversal by the interaction with PI(4,5)P2, combination of which regulates PM-specific
Gag localization, remain to be examined. Binding of tRNAs to MA HBR is most likely to occur at translation
sites due to limited availability of tRNAs outside of the translation machinery. However, little is known about
subcellular sites of Gag translation, where Gag begins its movement to the PM. At the PM, Gag
multimerization and subsequent accumulation of acidic lipids are likely to promote recruitment of host
transmembrane proteins, but their effects on virus spread to uninfected cells remains to be determined in
the context of cell-free and cell-to-cell transmission.
Our long-term goal is to elucidate mechanisms that determine sites of HIV-1 assembly and to use the
knowledge for developing antiviral strategies. Our central hypothesis in this application is that MA HBR
interactions with tRNAs, which begin during translation, and with acidic lipids determine subcellular Gag
localization and the properties of progeny virions. To test this hypothesis, we plan to: 1) identify structural
determinants for interactions of MA HBR with tRNAs and acidic lipids; 2) identify tRNAs that suppress
PI(4,5)P2-independent membrane binding but allow PI(4,5)P2-mediated reversal; 3) understand the effects
of Gag translation sites on the fate of Gag; and 4) examine the effects of host transmembrane proteins
incorporated into virus particles on formation of virological synapse and virus-cell contact. The knowledge
gained from experiments outlined in this proposal will likely help us develop antiviral strategies that target
mechanisms regulating Gag localization to the PM, thereby inhibiting extracellular virus release and
spread.

## Key facts

- **NIH application ID:** 11061606
- **Project number:** 3R37AI071727-18S1
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** Akira Ono
- **Activity code:** R37 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $76,288
- **Award type:** 3
- **Project period:** 2022-07-18 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11061606

## Citation

> US National Institutes of Health, RePORTER application 11061606, Mechanisms that determine subcellular sites of HIV-1 assembly (3R37AI071727-18S1). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/11061606. Licensed CC0.

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