TY - JOUR TI - The isolated voltage sensing domain of the Shaker potassium channel forms a voltage-gated cation channel AU - Zhao, Juan AU - Blunck, Rikard A2 - Swartz, Kenton J VL - 5 PY - 2016 DA - 2016/10/06 SP - e18130 C1 - eLife 2016;5:e18130 DO - 10.7554/eLife.18130 UR - https://doi.org/10.7554/eLife.18130 AB - Domains in macromolecular complexes are often considered structurally and functionally conserved while energetically coupled to each other. In the modular voltage-gated ion channels the central ion-conducting pore is surrounded by four voltage sensing domains (VSDs). Here, the energetic coupling is mediated by interactions between the S4-S5 linker, covalently linking the domains, and the proximal C-terminus. In order to characterize the intrinsic gating of the voltage sensing domain in the absence of the pore domain, the Shaker Kv channel was truncated after the fourth transmembrane helix S4 (Shaker-iVSD). Shaker-iVSD showed significantly altered gating kinetics and formed a cation-selective ion channel with a strong preference for protons. Ion conduction in Shaker-iVSD developed despite identical primary sequence, indicating an allosteric influence of the pore domain. Shaker-iVSD also displays pronounced 'relaxation'. Closing of the pore correlates with entry into relaxation suggesting that the two processes are energetically related. KW - voltage sensor KW - potassium channel KW - gating KW - voltage-clamp fluorometry KW - mode-shift JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -