Structure-Based Identification and Characterization of Inhibitors of the Epilepsy-Associated KNa1.1 (KCNT1) Potassium Channel
Bethan A. Cole,
Rachel M. Johnson,
Hattapark Dejakaisaya,
Nadia Pilati,
Colin W.G. Fishwick,
Stephen P. Muench,
Jonathan D. Lippiat
Affiliations
Bethan A. Cole
School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
Rachel M. Johnson
School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
Hattapark Dejakaisaya
School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
Nadia Pilati
Autifony Srl, Istituto di Ricerca Pediatrica Citta’ della Speranza, Corso Stati Uniti, 4f, 35127 Padova, Italy
Colin W.G. Fishwick
Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; School of Chemistry, University of Leeds, Leeds LS2 9JT, UK
Stephen P. Muench
School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
Jonathan D. Lippiat
School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK; Corresponding author
Summary: Drug-resistant epileptic encephalopathies of infancy have been associated with KCNT1 gain-of-function mutations, which increase the activity of KNa1.1 sodium-activated potassium channels. Pharmacological inhibition of hyperactive KNa1.1 channels by quinidine has been proposed as a stratified treatment, but mostly this has not been successful, being linked to the low potency and lack of specificity of the drug. Here we describe the use of a previously determined cryo-electron microscopy-derived KNa1.1 structure and mutational analysis to identify how quinidine binds to the channel pore and, using computational methods, screened for compounds predicated to bind to this site. We describe six compounds that inhibited KNa1.1 channels with low- and sub-micromolar potencies, likely also through binding in the intracellular pore vestibule. In hERG inhibition and cytotoxicity assays, two compounds were ineffective. These may provide starting points for the development of new pharmacophores and could become tool compounds to study this channel further.
