PhD Transfer Seminar – Agatha Tymczak (Kanelis Lab)

Characterizing the roles of intrinsically disordered regions in the regulatory SUR2 subunit of ATP-sensitive potassium channels

Abstract

ATP-sensitive potassium (K_ATP) channels play key roles in different cell types, such as pancreatic cell insulin release or cardiac cell action potential. K_ATP channels are made up of 4 pore-forming inward rectifying K⁺ channels (Kir6), and 4 regulatory sulfonylurea receptor (SUR) proteins that surround the pore. SUR proteins are members of the ATP binding cassette (ABC) family of proteins. Proper functioning of the human K_ATP channel is essential, as mutations in either the Kir6 or SUR genes cause severe diseases, such as congenital hyperinsulinism, neonatal diabetes mellitus, or various cardiovascular disorders. Although cryo-EM structures of K_ATP channels have been determined, many disease-causing mutations are in disordered regions for which structural data is not available. Thus, I am studying the structural and functional consequences of several previously uncharacterized disease-causing mutations in the cardiac-specific K_ATP channel, using techniques such as ¹⁵N-¹H NMR spectroscopy, fluorescence spectrometry, and in-cell studies. One of these disordered segments is located within the first nucleotide binding domain (NBD1) of the SUR protein and another disordered segment is located N-terminal to NBD1. Data from NMR and fluorescence spectroscopy suggest that these disordered regions interact with each other. Specifically, mutations in or deletion of the R-loop affects residues of the L1 linker, and vice versa. Current studies are being conducted to probe the effect of mutations on the ATP binding activity of NBD1 and future studies will probe how the mutations affect interaction of NBD1 with other regions of the K_ATP channel.

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https://utoronto.zoom.us/j/82823388665

Host: Voula Kanelis (voula.kanelis@utoronto.ca)