Dataset Information

Molecular mechanism of exchange coupling in CLC chloride/proton antiporters

ABSTRACT: The ubiquitous CLC membrane transporters are the only transporter family known to exchange anions for cations. Despite extensive study, there is no model to completely explain the 2:1 Cl‒/H+ stoichiometric exchange mechanism. Here, we provide such a model. Using CLC-ec1, a bacterial homolog that has served as a paradigm for the family, we determined cryo-EM structures at pH 7, pH 4.5, and pH 3. Molecular dynamics simulations of the pH-3 structure reveal critical steps in the transport mechanism, including release of Cl- ions to the extracellular side, opening of the inner gate, and water wires that facilitate H+ transport. Water wires are observed frequently in both the canonical H+-transport pathway and in the Cl- pathway, where they had not been previously reported. We propose that tight coupling of Cl‒/H+ transport is maintained (uncoupled H+ transport is avoided) because H+ transfer from the water wires to the catalytic glutamate is favored only when Cl‒ is also present in the pathway . Mutations that weaken Cl‒ binding without changing the pathway structure exhibit functional properties consistent with this model.

INSTRUMENT(S):

ORGANISM(S): Escherichia Coli

SUBMITTER: Jasmína Portašiková

LAB HEAD: Petr Man

PROVIDER: PXD058693 | Pride | 2025-07-21

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	240320-CLCwt_MSMS_13007-SumPeak.csv	Csv
	240320-CLCwt_MSMS_13007-SumPeak.mgf	Mgf
	240320-CLCwt_MSMS_13009-SumPeak.csv	Csv
	240320-CLCwt_MSMS_13009-SumPeak.mgf	Mgf
	240320-CLCwt_MSMS_13010-SumPeak.csv	Csv

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Publications

Molecular mechanism of exchange coupling in CLC chloride/proton antiporters.

Aydin Deniz D Chien Chih-Ta CT Kreiter Jürgen J Nava Amy R AR Portasikova Jasmina M JM Fojtik Lukas L Sobecks Briana L BL Mosquera Catalina C Man Petr P Dror Ron O RO Chiu Wah W Maduke Merritt M

Nature communications 20260108 1

The ubiquitous CLC membrane transporters are unique in their ability to exchange anions for cations. Despite extensive study, there is no mechanistic model that fully explains their 2:1 Cl<sup>‒</sup>/H<sup>+</sup> stoichiometric exchange mechanism. Here, we provide such a model. Using differential hydrogen-deuterium exchange mass spectrometry, cryo-EM structure determination, and molecular dynamics simulations, we uncovered conformational dynamics in CLC-ec1, a bacterial CLC homolog that has se ...[more]

PMID: 41507156

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