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  • Activation of the archaeal ion channel MthK is exquisitely regulated by temperature.

Activation of the archaeal ion channel MthK is exquisitely regulated by temperature.

eLife (2020-12-05)
Yihao Jiang, Vinay Idikuda, Sandipan Chowdhury, Baron Chanda
摘要

Physiological response to thermal stimuli in mammals is mediated by a structurally diverse class of ion channels, many of which exhibit polymodal behavior. To probe the diversity of biophysical mechanisms of temperature-sensitivity, we characterized the temperature-dependent activation of MthK, a two transmembrane calcium-activated potassium channel from thermophilic archaebacteria. Our functional complementation studies show that these channels are more efficient at rescuing K+ transport at 37°C than at 24°C. Electrophysiological activity of the purified MthK is extremely sensitive (Q10 >100) to heating particularly at low-calcium concentrations whereas channels lacking the calcium-sensing RCK domain are practically insensitive. By analyzing single-channel activities at limiting calcium concentrations, we find that temperature alters the coupling between the cytoplasmic RCK domains and the pore domain. These findings reveal a hitherto unexplored mechanism of temperature-dependent regulation of ion channel gating and shed light on ancient origins of temperature-sensitivity.

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Sigma-Aldrich
胰蛋白酶 来源于牛胰腺, Type I, ~10,000 BAEE units/mg protein
Sigma-Aldrich
胰蛋白酶抑制剂 来源于鸡蛋白, Type II-O, Partially purified ovomucoid, containing ovoinhibitor