The human KCNQ1 voltage-gated potassium channel is modulated by interactions with an accessory subunit, KCNE1, a process that is essential for healthy cardiac and auditory function. Mutations in KCNQ1 and KCNE1 result in congenital long QT syndrome (LQTS) and some forms of deafness. KCNE1 acts both to slow down voltages-stimulated channel activation and also dramatically enhances the conductance of the open state. Other KCNE family members exert radically different changes in KCNQ1 channel function. In the upcoming phase of this project the aims are:
Aim 1. Use NMR to determine the 3-D structure of KCNE1 under conditions in which it is solubilized in actual lipid bilayers.
This aim will test whether the structure of KCNE1 we recently determined in classical micelles represents the bona fide structure of the protein in lipid bilayers, or whether elements of the determined structure that were crucial in formulating our working model for KCNE1 function were, in fact, artifacts of working in micelles.
Aim 2. Using mutagenesis of both KCNE1 and KCNQ1, biochemical measurements, and electrophysiological recordings of KCNQ1 channel properties, critically evaluate and refine the current working model for how KCNE1 slows down KCNQ1 channel opening and enhances open state conductance.
Aim 3. Determine the 3-D structure of KCNE3 in bilayers and formulate a working model for how KCNE3 rapidly activates Q1 channel function.
Aim 4. Carry out structure-function and biochemical testing/refinement of the new model for how KCNE3 rapidly activates KCNQ1 channel function.
Aim 5. Determine the structure of KCNE4 in bilayers and formulate a working model for how KCNE4 inhibits KCNQ1 channel function.

Public Health Relevance

Studies are being undertaken of the structures and interactions of the human KCNE1, KCNE3, and KCNE4 proteins with the KCNQ1 potassium channel in order to determine how these KCNE family proteins modulate the function of this channel, as can occur in an aberrant manner that causes certain forms of deafness and heart disease.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC007416-09
Application #
8658419
Study Section
Biochemistry and Biophysics of Membranes Study Section (BBM)
Program Officer
Freeman, Nancy
Project Start
2005-04-01
Project End
2015-03-31
Budget Start
2014-04-01
Budget End
2015-03-31
Support Year
9
Fiscal Year
2014
Total Cost
$346,588
Indirect Cost
$122,860
Name
Vanderbilt University Medical Center
Department
Biochemistry
Type
Schools of Medicine
DUNS #
004413456
City
Nashville
State
TN
Country
United States
Zip Code
37212
Kroncke, Brett M; Van Horn, Wade D; Smith, Jarrod et al. (2016) Structural basis for KCNE3 modulation of potassium recycling in epithelia. Sci Adv 2:e1501228
Kroncke, Brett M; Vanoye, Carlos G; Meiler, Jens et al. (2015) Personalized biochemistry and biophysics. Biochemistry 54:2551-9
Schlebach, Jonathan P; Sanders, Charles R (2015) Influence of Pathogenic Mutations on the Energetics of Translocon-Mediated Bilayer Integration of Transmembrane Helices. J Membr Biol 248:371-81
Schlebach, Jonathan P; Sanders, Charles R (2015) The safety dance: biophysics of membrane protein folding and misfolding in a cellular context. Q Rev Biophys 48:1-34
Zhang, Rongfu; Sahu, Indra D; Gibson, Kaylee R et al. (2015) Development of electron spin echo envelope modulation spectroscopy to probe the secondary structure of recombinant membrane proteins in a lipid bilayer. Protein Sci 24:1707-13
Sahu, Indra D; Craig, Andrew F; Dunagan, Megan M et al. (2015) Probing Structural Dynamics and Topology of the KCNE1 Membrane Protein in Lipid Bilayers via Site-Directed Spin Labeling and Electron Paramagnetic Resonance Spectroscopy. Biochemistry 54:6402-12
Song, Yuanli; Kenworthy, Anne K; Sanders, Charles R (2014) Cholesterol as a co-solvent and a ligand for membrane proteins. Protein Sci 23:1-22
Sahu, Indra D; Kroncke, Brett M; Zhang, Rongfu et al. (2014) Structural investigation of the transmembrane domain of KCNE1 in proteoliposomes. Biochemistry 53:6392-401
Peng, Dungeng; Kim, Ji-Hun; Kroncke, Brett M et al. (2014) Purification and structural study of the voltage-sensor domain of the human KCNQ1 potassium ion channel. Biochemistry 53:2032-42
Mittendorf, Kathleen F; Kroncke, Brett M; Meiler, Jens et al. (2014) The homology model of PMP22 suggests mutations resulting in peripheral neuropathy disrupt transmembrane helix packing. Biochemistry 53:6139-41

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