The flow of potassium across cell membranes is controlled by potassium channels (K channels). By regulating the flow of charged potassium ions, K channel proteins play a fundamental role in gating electrical impulses in excitable cells, and play a fundamental role in controling electrolyte balance in virtually all cells. In this project, research will focus on defining the structural basis for activation of a large subfamily of K channels that contain regulator of K-conductance (RCK) domains. RCK domains are modulatory ligand-binding domains that control gating of K channels in a wide range of prokaryotic and eukaryotic organisms by binding calcium ions and other ligands. Despite their fundamental importance, the key molecular interactions that lead to ligand-dependent opening of the channel have yet to be clearly defined. Mechanisms of activation in RCK-containing K channels will be investigated through a combination of electrophysiological and X-ray crystallographic analysis. The approach will involve atomic resolution determination of a series of structures representing different conformations of the RCK domain from the prototypical K channel MthK from the archaebacterium Methanobacterium thermoautotrophicum. Studying the MthK channel has unique advantages over other systems, and will yield high-resolution atomic structural data that can be directly linked to channel function, which will hopefully lead to a profound understanding of basic mechanisms of activation in this ubiquitous class of ion channels.
BROADER IMPACTS This research will use methodologies that straddle the interfaces of biology, chemistry, physics, and mathematics, and the goal is to continue to promote training of beginning investigators in approaches that combine these disciplines. The PI's laboratory has a strong record of training personnel at the undergraduate, post-baccalaureate, graduate, and post-doctoral levels in the fundamentals and theory of ion channel biology and membrane biophysics, as well as the practice of experimental techniques in the laboratory. Past trainees have continued in successful scientific careers in academia, industry, and government agencies. Notably, the majority of the PI's previous trainees have been women and/or minorities, and this project will continue to recruit and train young scientists from underrepresented groups from among outstanding undergraduate participants at Temple University's Undergraduate Research Program (URP), in addition to training of graduate students. The PI also participates in activities that promote science education in local secondary schools in the Philadelphia area, and will broaden these activities in the context of this research proposal.
This project is jointly supported by the Cellular Dynamics and Function Cluster in the Division of Molecular and Cellular Biosciences and the Chemistry of Life Processes program in the Chemistry Division.
