Download MendeleyCalcium-gated potassium channel blockade via membrane-facing fenestrations.
Fan, C., Flood, E., Sukomon, N., Agarwal, S., Allen, T.W., Nimigean, C.M.(2023) Nat Chem Biol
- PubMed: 37653172
- DOI: https://doi.org/10.1038/s41589-023-01406-2
- Primary Citation of Related Structures:
5BKI, 5BKJ, 5BKK, 8DJB, 8FZ7 - PubMed Abstract:
Quaternary ammonium blockers were previously shown to bind in the pore to block both open and closed conformations of large-conductance calcium-activated potassium (BK and MthK) channels. Because blocker entry was assumed through the intracellular entryway (bundle crossing), closed-pore access suggested that the gate was not at the bundle crossing. Structures of closed MthK, a Methanobacterium thermoautotrophicum homolog of BK channels, revealed a tightly constricted intracellular gate, leading us to investigate the membrane-facing fenestrations as alternative pathways for blocker access directly from the membrane. Atomistic free energy simulations showed that intracellular blockers indeed access the pore through the fenestrations, and a mutant channel with narrower fenestrations displayed no closed-state TPeA block at concentrations that blocked the wild-type channel. Apo BK channels display similar fenestrations, suggesting that blockers may use them as access paths into closed channels. Thus, membrane fenestrations represent a non-canonical pathway for selective targeting of specific channel conformations, opening novel ways to selectively drug BK channels.
Organizational Affiliation:
Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA.
