# Structural and Functional Studies of Potassium Channels by Solid State NMR

> **NIH NIH R01** · COLUMBIA UNIV NEW YORK MORNINGSIDE · 2022 · $361,194

## Abstract

Abstract
Potassium channels control numerous signaling processes for humans and pathogens. Essentially all
characterized K+ channels inactivate spontaneously after opening, due to a transmembrane allosteric
process that acts to control mean open time. Inactivation modulates function for many important channels
and drug targets: for example, neurons use K+ channel inactivation to modulate their firing frequency, and
inactivation in the channels of the human heart has strong effects on heart timing. Our recent work provided
evidence that the molecular basis of C type inactivation in KcsA is transmembrane allosteric coupling, where
opening of the intracellular activation gate causes the extracellular selectivity filter to lose its affinity for K+. We
showed that this transmembrane allosteric coupling is strong in the wild type channel in bilayers and absent in
several inactivation-less mutants. In the upcoming period we plan to delineate the mechanism for this
transmembrane allosteric control of channel activity. In our first aim, we will systematically identify residues that
participate in the mechanism, i.e. residues that “sense” and “couple” both binding phenomena and mediate the
allosteric response. We will implement an NMR chemical shift based strategy to identify likely candidates. To
confirm the key role of candidate sites, we will manipulate the strength of the coupling through mutation at
these sites. The functional hallmark of allostery, modulation of ligands’ affinities through binding of another,
distal ligand, will be probed by NMR to quantitatively assess the impact of mutation on coupling. In our second
aim, we will determine the structure of the Activated state and contrast key interactions involving the allosteric
participants in the Activated state vs the Deactivated (Resting) and Inactivated states, to test hypotheses about
the molecular basis for allostery. The Activated state is the only state that transmits ions, and is the key
metastable intermediate of allosteric response. The structure of the wild type activated channel in bilayers has
been elusive. In contrast to other kinds of studies, our SSNMR studies are done on hydrated, wild type
channels in bilayers; the pH and ion concentrations are freely varied. In the previous grant period, we identified
conditions for preparing the Activated state. In our third aim we will characterize dynamic exchange processes
in the Activated state in order to obtain insights into spontaneous Inactivation. We will use recently developed
rotating frame solid state NMR pulse sequences that allow measurement at numerous sites, minimizing
unwanted coherent evolution of the spins. We will contrast the conformational dynamics of the Activated state
in hydrated bilayers to other states of the system (Deactivated, Inactivated). By comparing the exchange
timescales and amplitudes to those expected from MD-based models of activation coupled inactivation we will
test a variety of mechanisms for alloster...

## Key facts

- **NIH application ID:** 10460945
- **Project number:** 5R01GM088724-12
- **Recipient organization:** COLUMBIA UNIV NEW YORK MORNINGSIDE
- **Principal Investigator:** ANN E MCDERMOTT
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $361,194
- **Award type:** 5
- **Project period:** 2009-09-30 → 2023-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10460945

## Citation

> US National Institutes of Health, RePORTER application 10460945, Structural and Functional Studies of Potassium Channels by Solid State NMR (5R01GM088724-12). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10460945. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*