Biophysical elucidation of ion channel complex function

点击翻译按钮获取中文摘要

Overall program rationale and focus: ***Ion channels regulate essential aspects of biological function by enabling critical processes to occur that can be as diverse as electrical signaling in the brain or heart and cell volume control. The molecular events underlying voltage-dependent gating that lead to the conducting or open state of voltage-activated ion channels, and subsequently to their inactivation and closure are still poorly defined in many situations.***Our long-term objective is to understand better the biophysical mechanisms of normal gating in potassium (IKr, IKs) and sodium (INa) ion channels, and this will be achieved by research addressing four related shorter-term goals:******#1) The kinetic structure of IKr voltage gating: We hypothesize that ion channel voltage sensor domain internal charge interactions control delayed Kv11.1 ion channel activation/deactivation and voltage sensor domain-turret rapid inactivation. Innovative gating current analysis, methane thio-sulphonate exposure studies, and genetic incorporation of fluorescent probes will be used to precisely map inter-subunit movements.******#2 and #3) Real-time studies of the structural basis of INa inactivation and IKs inter-subunit interactions: We hypothesize that a) transient molecular conformations of Nav1.5 domains define stability of inactivation, b) specific and unique physical associations between KCNQ1 and KCNE1-5 in exterior clefts confer gating properties, and c) control subunit stoichiometry. Genetically-encoded photo-activated bridges, MS analysis and whole cell and single channel patch recording will be used to map these interactions.******#4) Molecular mechanisms of drug effects on IKr kinetics: We hypothesize that a) cation-Pi interactions via S6 amino acid residues of hERG are critical for pore block, and fluorinated UAA series at F656 and Y652 will be used to examine ring charge distribution and determinants of block.******Training: My laboratory and the research group of faculty create a rigorous and diverse learning environment through advanced technical experimentation, graduate courses, lab meetings, journal clubs, and presentation at scientific meetings. Trainees acquire necessary experimental, presentation and writing skills to achieve independent and professional career goals, and give rise to new leaders in this field of biophysics.******Significant impact: Our in-depth studies of IKr, IKs and INa gating will uncover molecular events underlying opening and closing of these biological gatekeepers, which in turn will improve our understanding of mechanisms that control cell electrical activity. This knowledge will be disseminated via publication in high-impact journals, invited conference, and additionally, this work is anticipated to lead to further NSERC-partnered opportunities, e.g. IRAP to more widely utilize information and generate further economic opportunities.**