Oxidation modulates LINGO2-induced inactivation of large conductance, Ca2+-activated potassium channels

Srikanth Dudem, Pei Xin Boon, Nicholas Mullins, Heather McClafferty, Michael J Shipston, Richard D A Wilkinson, Ian Lobb, Gerard P Sergeant, Keith D Thornbury, Irina G Tikhonova, Mark A Hollywood

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)
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Abstract

Ca 2+ and voltage-activated K + (BK) channels are ubiquitous ion channels that can be modulated by accessory proteins, including β, γ, and LINGO1 BK subunits. In this study, we utilized a combination of site-directed mutagenesis, patch clamp electrophysiology, and molecular modeling to investigate if the biophysical properties of BK currents were affected by co-expression of LINGO2 and to examine how they are regulated by oxidation. We demonstrate that LINGO2 is a regulator of BK channels, since its co-expression with BK channels yields rapid inactivating currents, the activation of which is shifted ∼-30 mV compared to that of BKα currents. Furthermore, we show oxidation of BK:LINGO2 currents (by exposure to epifluorescence illumination) abolished inactivation. This illumination effect depended on the presence of Green Fluorescent Protein (GFP), suggesting that it released free radicals which oxidized cysteine or methionine residues. In addition, the oxidation effects were resistant to treatment with the cysteine-specific reducing agent DTT, suggesting that methionine rather than cysteine residues may be involved. Our data with synthetic LINGO2 tail peptides further demonstrate that the rate of inactivation was slowed when residues M603 or M605 were oxidized, and practically abolished when both were oxidized. Taken together, these data demonstrate that both methionine residues in the LINGO2 tail mediate the effect of oxidation on BK:LINGO2 channels. Our molecular modeling suggests that methionine oxidation reduces the lipophilicity of the tail, thus preventing it from occluding the pore of the BK channel.

Original languageEnglish
Article number102975
JournalThe Journal of Biological Chemistry
Volume299
Issue number3
DOIs
Publication statusPublished - 08 Mar 2023

Bibliographical note

Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.

Keywords

  • LINGO subunits
  • Potassium channel
  • biophysics
  • electrophysiology
  • leucine rich repeat containing proteins
  • oxidation‐reduction

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