Hyperpolarization-activated cyclic nucleotide-modulated (HCN) ion channels were first discovered in photoreceptors where they shape the light response. They exhibit several properties that make them specialized for retinal signaling: 1) they are activated by membrane hyperpolarization instead of depolarization, 2) they are regulated by the direct binding of cyclic nucleotides to an intracellular domain, and 3) they are expressed in the distal dendrites of neurons. Recently an accessory subunit of HCN channels in photoreceptors and other neurons was discovered, called TRIP8b, that has a profound effect on each of these important channel properties. Our long term goal is to understand the molecular mechanisms for these properties. In previous funding periods we have made great progress toward achieving this goal. We have solved the X-ray crystal structure of the cyclic nucleotide-binding domain of HCN2 and the structure of TRIP8b bound to HCN2. We have also invented three ground-breaking new fluorescence methods that allow us to record molecular rearrangements in intact channels simultaneous with electrophysiological recording. In this funding period, we propose to combine these methods with double electron-electron resonance (DEER), a powerful magnetic resonance-based method, and molecular dynamics simulations, to measure and model the structure and dynamics of the HCN channel and its interaction with TRIP8b. These experiments will lead to the first dynamic picture for how HCN channels regulate the excitability of photoreceptors and other neurons.

Public Health Relevance

Hyperpolarization-activated cyclic nucleotide-modulated (HCN) ion channels control the electrical signals in our retina in response to light. Our long term goal is to understand the molecular mechanisms for the specialized gating properties of HCN channels to better understand our visual signaling and better design therapies for treatment of diseases.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
2R01EY010329-21
Application #
8694326
Study Section
Biochemistry and Biophysics of Membranes Study Section (BBM)
Program Officer
Greenwell, Thomas
Project Start
Project End
Budget Start
Budget End
Support Year
21
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Washington
Department
Physiology
Type
Schools of Medicine
DUNS #
City
Seattle
State
WA
Country
United States
Zip Code
98195
Edwards, Thomas H; Stoll, Stefan (2016) A Bayesian approach to quantifying uncertainty from experimental noise in DEER spectroscopy. J Magn Reson 270:87-97
Hayes, Ellen C; Porter, Thomas R; Barrows, Charles J et al. (2016) Electronic Structure of a Cu(II)-Alkoxide Complex Modeling Intermediates in Copper-Catalyzed Alcohol Oxidations. J Am Chem Soc 138:4132-45
Aman, Teresa K; Gordon, Sharona E; Zagotta, William N (2016) Regulation of CNGA1 Channel Gating by Interactions with the Membrane. J Biol Chem 291:9939-47
Zagotta, William N; Gordon, Moshe T; Senning, Eric N et al. (2016) Measuring distances between TRPV1 and the plasma membrane using a noncanonical amino acid and transition metal ion FRET. J Gen Physiol 147:201-16
Gordon, Sharona E; Senning, Eric N; Aman, Teresa K et al. (2016) Transition metal ion FRET to measure short-range distances at the intracellular surface of the plasma membrane. J Gen Physiol 147:189-200
Tait, Claudia E; Stoll, Stefan (2016) Coherent pump pulses in Double Electron Electron Resonance spectroscopy. Phys Chem Chem Phys 18:18470-85
DeBerg, Hannah A; Brzovic, Peter S; Flynn, Galen E et al. (2016) Structure and Energetics of Allosteric Regulation of HCN2 Ion Channels by Cyclic Nucleotides. J Biol Chem 291:371-81
DeBerg, Hannah A; Bankston, John R; Rosenbaum, Joel C et al. (2015) Structural mechanism for the regulation of HCN ion channels by the accessory protein TRIP8b. Structure 23:734-44
Puljung, Michael C; DeBerg, Hannah A; Zagotta, William N et al. (2014) Double electron-electron resonance reveals cAMP-induced conformational change in HCN channels. Proc Natl Acad Sci U S A 111:9816-21
Sun, Ji; Bankston, John R; Payandeh, Jian et al. (2014) Crystal structure of the plant dual-affinity nitrate transporter NRT1.1. Nature 507:73-7

Showing the most recent 10 out of 58 publications