Browsing by Author "Frieg, Benedikt"

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    Functional and structural characterization of interactions between opposite subunits in HCN pacemaker channels
    (N/A, 2021-08-05) Kondapuram, Mahesh; Frieg, Benedikt; Yüksel, Sezin; Schwabe, Tina; Sattler, Christian; Lelle, Marco; Schweinitz, Andrea; Schmauder, Ralf; Benndorf, Klaus; Gohlke, Holger; Kusch, Jana
    Hyperpolarization-activated and cyclic nucleotide (HCN) modulated channels are tetrameric cation channels. In each of the four subunits, the intracellular cyclic nucleotide-binding domain (CNBD) is coupled to the transmembrane domain via a helical structure, the C-linker. High-resolution channel structures suggest that the C-linker enables functionally relevant interactions with the opposite subunit, which might be critical for coupling the conformational changes in the CNBD to the channel pore. We combined mutagenesis, patch-clamp technique, confocal patch-clamp fluorometry, and molecular dynamics simulations to show that residue K464 of the C-linker is essential for stabilizing the closed state of the mHCN2 channel by forming interactions with the opposite subunit. MD simulations revealed that both cAMP and K464E induce a rotation of the intracellular domain relative to the channel pore, weakening the autoinhibitory effect of the unoccupied CL-CNBD region. The adopted poses are in excellent agreement with structural results.