# Structural dynamics in cyclic nucleotide-modulated channels

> **NIH NIH R01** · WEILL MEDICAL COLL OF CORNELL UNIV · 2020 · $332,644

## Abstract

Cyclic nucleotide-modulated channels play major roles in pacemaking activity in heart and brain as well as in
olfactory and visual signal transduction in the nervous system. Defects in the functioning of these channels lead
to diseases such as epilepsy, cardiac arrhythmia, and color blindness. The overall objective of this grant is to
understand how binding of cyclic nucleotides gates (opens/closes) the channels at the molecular level and how
lipids modulate the open-closed equilibrium. We will accomplish this by combining state-of-the-art techniques
like single-particle cryo electron microscopy (croEM) with high-speed atomic force microscopy (HS-AFM) and
functional assays like single-channel electrophysiology and stopped flow fluorescence assays. Our first aim is
to determine using single-particle cryoEM high-resolution structures of these channels, in different
conformations (no ligand bound, cAMP-bound, cGMP-bound) and with different lipids (by varying the lipid
composition in nanodiscs) and assigning these structures to specific ion channel functional states determined
using single-channel electrophysiology. Using lipid bilayer single-channel recordings of the channels in
various lipid environments, we will assign functional states (open, closed, etc) to the structures and
conformations obtained. This aim will not only yield the first ever atomic-resolution structure of a cyclic nucleotide-
modulated channel but also structures of other conformations that will allow us to initiate the building of a
structural gating model. Our second aim is to determine the various channel conformations in close-to-native
conditions (channels reconstituted in lipid bilayers and in physiological buffer at ambient temperature and
pressure) using AFM imaging (including HS-AFM). We will determine the conformational landscape at steady
states (i.e. in the presence or absence of ligand) as well as the conformational changes that these channels
undergo in real time upon ligand binding and how the equilibrium changes with different lipids. We will directly
compare these conformations with those obtained by cryoEM in Aim 1. Using stopped-flow fluorescence
macroscopic assays of the channels in liposomes, we will investigate how the activation/inactivation kinetics
compares with the real time conformational dynamics measured by HS-AFM. The final goal is to formulate
structural gating models for cyclic nucleotide-modulated channels using the conformations determined in aims 1
and 2 with assigned functional states.

## Key facts

- **NIH application ID:** 9928058
- **Project number:** 5R01GM124451-04
- **Recipient organization:** WEILL MEDICAL COLL OF CORNELL UNIV
- **Principal Investigator:** Crina M Nimigean
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $332,644
- **Award type:** 5
- **Project period:** 2017-09-01 → 2021-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9928058

## Citation

> US National Institutes of Health, RePORTER application 9928058, Structural dynamics in cyclic nucleotide-modulated channels (5R01GM124451-04). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9928058. Licensed CC0.

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