Role of Ion Distribution and Energy Barriers for Concerted Motion of Subunits in Selectivity Filter Gating of a K+ Channel

• DOI: 10.1016/j.jmb.2022.167522
• Publication Date: 2022-03-04T09:17:47Z
• Authors: Oliver Rauh; Jennifer Opper; Maximilian Sturm; Nils Drexler; Deborah D. Scheub; Ulf-P. Hansen; Gerhard Thiel; Indra Schroeder
• Keywords: KcsA potassium channel; Helix (gastropod)

Most potassium channels have two main gate locations, hosting an inner at the cytosolic entrance and a filter in selectivity filter; function of these gates is many coupled. To obtain exclusive insights into molecular mechanisms that determine opening closing gate, we use combination single-channel recordings gating analysis minimal viral channel KcvNTS. This has no its fast negative voltages can therefore be entirely assigned to gate. We find mutations S42 pore helix severely slow down this effect which not correlated with hydrogen bond formation by amino acid position. Hence, different from KcsA, contains critical E71 equivalent position forming salt bridge, coupling between surrounding structures for must KcvNTS rely on modes interaction. Quantitative concatemers carrying numbers S42T reveals each subunit contributes same amount ∼ 0.4 kcal/mol energy barrier closure indicating concerted action subunits. Since neither influence unitary current nor voltage dependency data stress high cooperativity mediated through conformational changes rather than ion occupation filter.