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Insights into CLC-0's Slow-Gating from Intracellular Proton Inhibition.
- Source :
-
International journal of molecular sciences [Int J Mol Sci] 2024 Jul 16; Vol. 25 (14). Date of Electronic Publication: 2024 Jul 16. - Publication Year :
- 2024
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Abstract
- The opening of the Torpedo CLC-0 chloride (Cl <superscript>-</superscript> ) channel is known to be regulated by two gating mechanisms: fast gating and slow (common) gating. The structural basis underlying the fast-gating mechanism is better understood than that of the slow-gating mechanism, which is still largely a mystery. Our previous study on the intracellular proton (H <superscript>+</superscript> <subscript>i</subscript> )-induced inhibition of the CLC-0 anionic current led to the conclusion that the inhibition results from the slow-gate closure (also called inactivation). The conclusion was made based on substantial evidence such as a large temperature dependence of the H <superscript>+</superscript> <subscript>i</subscript> inhibition similar to that of the channel inactivation, a resistance to the H <superscript>+</superscript> <subscript>i</subscript> inhibition in the inactivation-suppressed C212S mutant, and a similar voltage dependence between the current recovery from the H <superscript>+</superscript> <subscript>i</subscript> inhibition and the recovery from the channel inactivation. In this work, we further examine the mechanism of the H <superscript>+</superscript> <subscript>i</subscript> inhibition of wild-type CLC-0 and several mutants. We observe that an anion efflux through the pore of CLC-0 accelerates the recovery from the H <superscript>+</superscript> <subscript>i</subscript> -induced inhibition, a process corresponding to the slow-gate opening. Furthermore, various inactivation-suppressed mutants exhibit different current recovery kinetics, suggesting the existence of multiple inactivated states (namely, slow-gate closed states). We speculate that protonation of the pore of CLC-0 increases the binding affinity of permeant anions in the pore, thereby generating a pore blockage of ion flow as the first step of inactivation. Subsequent complex protein conformational changes further transition the CLC-0 channel to deeper inactivated states.
Details
- Language :
- English
- ISSN :
- 1422-0067
- Volume :
- 25
- Issue :
- 14
- Database :
- MEDLINE
- Journal :
- International journal of molecular sciences
- Publication Type :
- Academic Journal
- Accession number :
- 39063037
- Full Text :
- https://doi.org/10.3390/ijms25147796