• Orbit mini

    Simultaneous recording from four lipid bilayers

2020 - Activation of the archaeal ion channel MthK is exquisitely regulated by temperature

Icon Orbit Mini  Orbit mini publication in eLife (2020)

Jiang Y., Idikuda V., Chowdhury S., Chanda B.

eLife (2020) doi: 10.7554/eLife.59055

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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