# Cellular Protein Involved in Trafficking of HIV-1

> **NIH NIH R01** · STATE UNIVERSITY NEW YORK STONY BROOK · 2020 · $398,750

## Abstract

PROJECT ABSTRACT (provided by applicant): Tsg101, a component of ESCRT-I (endosomal
sorting complex required for transport-I), is required for budding of infectious HIV and several
other human pathogens. A proline-rich sequence, PTAP, in the viral-encoded structural precursor
polyprotein, Gag, recruits the cellular factor to virus assembly sites on the plasma membrane by
interacting with a PTAP-binding pocket in the Tsg101 N-terminal UEV [ubiquitin (Ub) E2 variant]
domain. The UEV domain also binds Ub, however, the role of Ub in budding and the relationship
of UEV Ub-binding to the PTAP-mediated recruitment of the ESCRT machinery is not clear.
Recently, using small molecules identified by high-throughput screening of a library for known
drugs capable of binding the UEV, we found agents that inhibit HIV-1 budding by disrupting Ub-
binding at the known pocket in the UEV without disturbing the PTAP-binding pocket. Our NMR
studies identified an additional Ub-binding site in the Tsg101 UEV domain and demonstrate that
the domain is capable of binding di-Ub moieties previously shown to participate in both endocytic
trafficking and budding. This application proposes to use the agents, mutagenesis and structural
analysis to define the mechanism by which the original and newly identified UEV Ub-binding sites
facilitate the budding process through achievement of 3 goals. The goal of AIM 1 is structure-
function analysis of the UEV-Ub complex employing site-directed mutagenesis and small
molecule probes. As we and others find that, while necessary, PT/SAP-mediated recruitment of
Tsg101 alone is not sufficient for budding, the goal of AIM 2 is to test the hypothesis that the
Tsg101 Ub- binding function is required in conjunction with the PTAP-binding function for efficient
recruitment of the protein to the plasma membrane. The goal of AIM 3 is to determine whether
the Tsg101 Ub-binding function is important for trafficking pathways where Tsg101 is not directly
engaged by a viral structural protein, i.e., pathways facilitated by the ESCRT adaptors Alix and
Nedd4. It is well-established that HIV utilizes alternative budding pathways when Gag interaction
with Tsg101 is disrupted: It is therefore important to understand if the required Tsg101-Ub binding
function is redundant. Collectively, the proposed studies will provide mechanistic understanding
of how Tsg101 facilitates HIV-1 Gag trafficking and virus budding and possibly also reveal new
targets for anti-viral drug development.

## Key facts

- **NIH application ID:** 9908088
- **Project number:** 8R01AI150489-11
- **Recipient organization:** STATE UNIVERSITY NEW YORK STONY BROOK
- **Principal Investigator:** Carol A. Carter
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $398,750
- **Award type:** 8
- **Project period:** 2007-06-15 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9908088

## Citation

> US National Institutes of Health, RePORTER application 9908088, Cellular Protein Involved in Trafficking of HIV-1 (8R01AI150489-11). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/9908088. Licensed CC0.

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