# Arf Functional Landscapes

> **NIH NIH R01** · RENSSELAER POLYTECHNIC INSTITUTE · 2021 · $349,538

## Abstract

Summary
Membrane organization in eukaryotic cells is controlled by ADP ribosylation factors (Arfs), small
GTPases that function as molecular switches to activate signaling cascades. Arfs regulate vesicular
transport of lipids and proteins between the ER and the Golgi (Class I-Arf1) and endosome-plasma
membrane trafficking (Class III-Arf6), implicating Arf function in cytokinesis, cell shape, organelle
transport, mitochondrial and lipid droplet function and pH-dependent regulation of cell size. Mutations
in Arfs or their partners have been linked to genetic neurological diseases causing severe malformation
of the cerebral cortex or mental retardation. Moreover, many pathogenic bacteria and viruses
commandeer Arfs as they invade cells, thereby promoting infection. Our overall goal is to understand
the nucleotide exchange transitions of Arf GTPases, the mechanisms of which cannot be deduced from
their static structures. We hypothesize that the Arf conformations specifically recognized by their
cognate exchange factors correspond to significantly disrupted excited states that are populated at very
low levels under standard conditions. Specifically, we aim to map the GDP/GTP switches of Arf1 and
Arf6 (Aims 1 and 2), and using mutational analysis, establish the underlying molecular mechanisms of
their functional specificity (Aim 3). Our approach combines experimental biophysical tools (multi-
dimensional NMR, SAXS and fluorescence) with pressure perturbation and coarse-grained molecular
dynamics simulations constrained by our data, to provide structural ensembles and pseudo-free energy
landscapes that will reveal functionally relevant excited states implicated in Arf function and specificity.
These excited state structures will provide novel target sites for inhibiting Arf signaling pathways,
offering new avenues for developing approaches to mitigate the invasive capacity of bacteria and
viruses. More generally, the pressure-based mapping approach proposed here represents a powerful
means to characterize elusive states of proteins implicated in their functions.

## Key facts

- **NIH application ID:** 10248460
- **Project number:** 5R01GM137766-02
- **Recipient organization:** RENSSELAER POLYTECHNIC INSTITUTE
- **Principal Investigator:** CATHERINE A ROYER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $349,538
- **Award type:** 5
- **Project period:** 2020-09-01 → 2025-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10248460

## Citation

> US National Institutes of Health, RePORTER application 10248460, Arf Functional Landscapes (5R01GM137766-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10248460. Licensed CC0.

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