Oxidation promotes insertion of the CLIC1 chloride intracellular channel into the membrane
- 476 Downloads
Members of the chloride intracellular channel (CLIC) family exist primarily as soluble proteins but can also auto-insert into cellular membranes to form ion channels. While little is known about the process of CLIC membrane insertion, a unique feature of mammalian CLIC1 is its ability to undergo a dramatic structural metamorphosis between a monomeric glutathione-S-transferase homolog and an all-helical dimer upon oxidation in solution. Whether this oxidation-induced metamorphosis facilitates CLIC1 membrane insertion is unclear. In this work, we have sought to characterise the role of oxidation in the process of CLIC1 membrane insertion. We examined how redox conditions modify the ability of CLIC1 to associate with and insert into the membrane using fluorescence quenching studies and a sucrose-loaded vesicle sedimentation assay to measure membrane binding. Our results suggest that oxidation of monomeric CLIC1, in the presence of membranes, promotes insertion into the bilayer more effectively than the oxidised CLIC1 dimer.
KeywordsCLIC1 Fluorescence quenching Membrane protein Ion channel
Chloride intracellular channel
Putative transmembrane region encompassing Cys24 through Val46 in CLIC1
This work was supported by an Australian Research Council (ARC) grant and an ARC APD fellowship to LJB.
- Warton K, Tonini R, Fairlie WD et al (2002) Recombinant CLIC1 (NCC27) assembles in lipid bilayers via a pH-dependent two-state process to form chloride ion channels with identical characteristics to those observed in Chinese hamster ovary cells expressing CLIC1. J Biol Chem 277:26003–26011. doi: 10.1074/jbc.M203666200 CrossRefPubMedGoogle Scholar