KCNQ1 (Q1 or Kv7.1 or KvLQT1) is a membrane bound voltage gated potassium channel that is modulated by another membrane protein KCNE1 (E1). Q1 is an integral protein involved in the cardiac repolarization phase of a heartbeat following the action potential. E1 is an accessory protein that complexes with Q1 to form a 4:2 Q1:E1 molar ratio. The KCNQ1/KCNE1 interaction slows the activation kinetics of Q1 which is required for proper channel and heart function. Mutations within KCNQ1 have been previously linked to diseases such as Long-QT syndrome (LQTS), atrial fibrillation, sudden infant death syndrome, and cardiac arrhythmias. Human KCNQ1 is 676 residues with six alpha helices that transverse the membrane. The first four helices form the voltage sensing domain, Q1-VSD (S1-S4), which is linked to the pore domain (S5-S6) by the S4-S5 linker and the cytosolic N (100 residue) and C-terminal (300 residues) domains. KCNE1 contains a single alpha helix that transverses the membrane with 26 residues and N terminus with 45 residues and a C terminus with 56 residues. In this study we will report the purification and Solid State Nuclear Magnetic Resonance, SS-NMR, characterization of full length (100-370) Q1 channel containing all 6 transmembrane segments. We will also report preliminary KCNQ1/KCNE1 interactions using electron paramagnetic resonance (EPR) spectroscopy line shape analysis and site directed spin labeling (SDSL), specifically labeling the E1 protein. KCNE1 is labeled at different sites and incorporated into 3:1 PC:PG vesicles. Any changes that occur after the Q1 is added is due to the interactions between the E1 labeled site and the Q1 interaction.
Author: Colleen K. Jaycox
Faculty Advisors: Gunjan Dixit, Rebecca B. Stowe, Gary A. Lorigan, Department of Chemistry and Biochemistry
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