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Publication Abstract from PubMed

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.

Calcium-gated potassium channel blockade via membrane-facing fenestrations.,Fan C, Flood E, Sukomon N, Agarwal S, Allen TW, Nimigean CM Nat Chem Biol. 2023 Aug 31. doi: 10.1038/s41589-023-01406-2. PMID:37653172^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.