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

Yihao Jiang, Vinay Idikuda, Sandipan Chowdhury, Baron Chanda

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish
JournaleLife
Volume9
DOIs
StatePublished - Dec 4 2020

Keywords

  • allosteric coupling
  • archaebacteria
  • calcium activation
  • ion channels
  • molecular biophysics
  • RCK domain
  • structural biology
  • thermo-sensing

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