# Dynamics and Evolution of HIV Gag and GagPol processing

> **NIH NIH R56** · UNIV OF MASSACHUSETTS MED SCH WORCESTER · 2024 · $752,745

## Abstract

SUMMARY
Maturation of the HIV-1 capsid requires activation of the viral protease (PR) and proteolytic processing of the
Gag and GagPol polyproteins. Previous studies support a model in which HIV-1 maturation depends on the
proper order and timing of proteolytic events in Gag by PR. According to this model, ordered Gag processing is
determined by the rate of proteolysis at the individual cleavage sites. The structural and dynamic features of
Gag, GagPol, and the immature virion that determine the kinetics and order of processing by PR, including the
autoprocessing of GagPol, have not been characterized. Furthermore, the evolutionary constraints that ensure
the maintenance of ordered and efficient Gag processing are unknown. Previous studies of Gag processing and
GagPol autoprocessing have been limited by a lack of experimental approaches capable of probing dynamic
events and the organization of GagPol within virions. Furthermore, molecular simulations have generally been
performed on reduced structures that do not capture the full complexity of Gag and GagPol complexes. Here,
we will use molecular dynamics (MD) simulation of full-length Gag and GagPol complexes to probe the dynamics
that occur prior to and during interaction with PR and provide atomic resolution detail of these interactions. These
simulations will suggest hypotheses regarding large-scale motions of Gag and GagPol domains that will be
tested through the application of single-molecule Förster resonance energy transfer (smFRET) imaging and cryo-
electron tomography (cryoET). These approaches enable visualization of the structure and dynamics of Gag and
GagPol that enable ordered processing by PR in the context of polyprotein monomers, dimers, hexamers, and
intact immature virions. Finally, through consideration of diverse HIV-1 strains and Gag variants that circumvent
inhibition of maturation by modulating the flexibility of the immature lattice, we will determine the evolutionary
constraints on Gag and GagPol that ensure sufficient dynamics are maintained. These data will inform
development of the next generation of maturation inhibitors.

## Key facts

- **NIH application ID:** 11118329
- **Project number:** 1R56AI179730-01A1
- **Recipient organization:** UNIV OF MASSACHUSETTS MED SCH WORCESTER
- **Principal Investigator:** James B Munro
- **Activity code:** R56 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $752,745
- **Award type:** 1
- **Project period:** 2024-08-06 → 2026-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11118329

## Citation

> US National Institutes of Health, RePORTER application 11118329, Dynamics and Evolution of HIV Gag and GagPol processing (1R56AI179730-01A1). Retrieved via AI Analytics 2026-06-12 from https://api.ai-analytics.org/grant/nih/11118329. Licensed CC0.

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