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

> **NIH NIH R01** · COLUMBIA UNIV NEW YORK MORNINGSIDE · 2024 · $379,751

## Abstract

Potassium channels control membrane potential and signaling processes for humans and pathogens. Essentially all
characterized K+ channels inactivate after opening due to a transmembrane allosteric process that appears to be a
slow result of activation and involves residues near the selectivity filter in the pore domain (c-type inactivation). Since
the activated state is the only conductive species, and is metastable, inactivation controls mean open time and
thereby modulates function
for many important channels and drug targets. For example, neurons use K+ channel
inactivation kinetics to modulate their firing frequency, and inactivation kinetics in the channels of the human heart
have strong effects on heart timing. Our research provided evidence in the K+ channel KcsA that the molecular basis of
c-type inactivation is transmembrane allosteric coupling between the activation gate (H+ binding to the intracellular pH
sensor) and the inactivation gate (K+ release from the extracellular selectivity filter). In recent efforts, we have delineated
the mechanism for transmembrane allosteric control of channel activity by identifying residues that serve important roles
in the allosteric response using NMR chemical shifts and mutation. We showed that activation and opening directly lead to
K+ loss in the selectivity filter for wild type, but not for inactivation-reduced mutants, for which thermodynamic coupling
between opening and K+ affinity is reduced. Our studies use solid state NMR measurements on full-length wild-type
channels in hydrated proteoliposomes and offer atomistic access to structure, as well as the dynamics and
thermodynamics of ligand binding. Thus, studies in the last period offer support for the hypothesis that allosteric coupling
between activation and inactivation is the basis for inactivation and channel timing. The studies also give support for the
specific identities of the “hotspots”. (Aim 1) In the upcoming period, a definitive test will be based on mutants that are
accelerated in inactivation, in the sense that these mutants increase the “timing” function rather than abolish it. Many of
these faster-inactivating mutants are also of interest because of similarities or analogies to eukaryotic channels that are
fast-inactivating. (Aim 2) We plan to probe the conformational dynamics of the activated open state of the channel with
recently developed NMR methods, to identify spontaneous conversion to early intermediates of inactivation. Specific
methods developed in the last period allow us to carry out studies of the dynamics of key carbonyl and aromatic groups.
Recent breakthroughs in the sensitivity of solid state NMR methods will be harnessed so that controls can be performed
to test hypothesized relationships between dynamics and function, for example from molecular dynamics simulations.
(Aim 3) Finally, in Ktr, a related channel that has been identified as a drug target for many pathogenic bacteria, we plan to
clarify ligand-cha...

## Key facts

- **NIH application ID:** 10886731
- **Project number:** 5R01GM088724-14
- **Recipient organization:** COLUMBIA UNIV NEW YORK MORNINGSIDE
- **Principal Investigator:** ANN E MCDERMOTT
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $379,751
- **Award type:** 5
- **Project period:** 2009-09-30 → 2027-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10886731

## Citation

> US National Institutes of Health, RePORTER application 10886731, Structural and Functional Studies of Potassium Channels by Solid State NMR (5R01GM088724-14). Retrieved via AI Analytics 2026-06-02 from https://api.ai-analytics.org/grant/nih/10886731. Licensed CC0.

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