The ClC-0 chloride channel is a 'broken' Cl−/H+ antiporter

Lísal, Jiří; Maduke, Merritt

doi:10.1038/nsmb.1466

Cited by 94 publications

(99 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1c and Supplementary Figs S7 and S8). From comparison with the mechanism proposed by Feng et al 13 for proton transport in ClC antiporters, it is possible that protonation of E232 in this conformation leads to opening of the common gate and H þ transport from the intracellular to the extracellular solution 2,30 . The H þ transport pathway of ClC-1 is unknown, as the intracellular glutamate residue proposed to form the intracellular H þ transport pathway in Cl À /H þ antiporters 36 is not conserved in ClC channels ( Supplementary Fig.…”

Section: Discussionmentioning

confidence: 99%

“…In the same experiments Picollo and Pusch 6 did not observe H þ transport by ClC-0 channels, which contained a mutation (C212S) that removes common gating 32 . It therefore seems possible that common gating of ClC channels is an evolutionary vestige of the conformational changes that catalyse coupled anion/H þ transport 30 .…”

mentioning

confidence: 99%

“…Remarkably, ClC-0 channels appear to behave as 'broken' antiporters, where common gating transitions are linked to H þ transport 30 . ClC-0 gating deviates from equilibrium in that closure of the common gate is typically preceded by closure of one of the protopore gates, and the common gate opens to a state where both protopore gates are open 31 .…”

mentioning

confidence: 99%

“…ClC-0 gating deviates from equilibrium in that closure of the common gate is typically preceded by closure of one of the protopore gates, and the common gate opens to a state where both protopore gates are open 31 . The energy source driving non-equilibrium gating appears to be transport of H þ by the common gating mechanism 30 . ClC-1 channels have also been shown to transport H þ 6 .…”

mentioning

confidence: 99%

See 3 more Smart Citations

Molecular determinants of common gating of a ClC chloride channel

Bennetts

Parker

2013

Nat Commun

View full text Add to dashboard Cite

Uniquely, the ClC family harbours dissipative channels and anion/H þ transporters that share unprecedented functional characteristics. ClC-1 channels are homodimers in which each monomer supports an identical pore carrying three anion-binding sites. Transient occupancy of the extracellular binding site by a conserved glutamate residue, E232, independently gates each pore. A common gate, the molecular basis of which is unknown, closes both pores simultaneously. Mutations affecting common gating underlie myotonia congenita in humans. Here we show that the common gate likely occludes the channel pore via interaction of E232 with a highly conserved tyrosine, Y578, at the central anion-binding site. We also identify structural linkages important for coordination of common gating between subunits and modulation by intracellular molecules. Our data reveal important molecular determinants of common gating of ClC channels and suggest that the molecular mechanism is an evolutionary vestige of coupled anion/H þ transport.

show abstract

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Molecular determinants of common gating of a ClC chloride channel

Bennetts

Parker

2013

Nat Commun

View full text Add to dashboard Cite

show abstract

“…The results, by providing a detailed microscopic view of the dynamics of water wire formation and confirming the involvement of specific protein residues, offer a mechanism for the coupled transport of H + and Cl − ions in CLC transporters. membrane transporters | membrane proteins | membrane exchangers | antiporters | coupling mechanism T he chloride channel (CLC) family (1, 2) includes both passive Cl − channels and secondary active H + -coupled Cl − transporters (3)(4)(5)(6)(7)(8). The latter, also known as H + /Cl − exchangers, drive uphill movement of H + by coupling the process to downhill movement of Cl − or vice versa, thereby exchanging the two types of ions across the membrane at fixed stoichiometry (9).…”

mentioning

confidence: 99%

Water access points and hydration pathways in CLC H ⁺ /Cl ⁻ transporters

Han

Cheng

Maduke

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

CLC transporters catalyze transmembrane exchange of chloride for protons. Although a putative pathway for Cl − has been established, the pathway of H + translocation remains obscure. Through a highly concerted computational and experimental approach, we characterize microscopic details essential to understanding H + -translocation. An extended (0.4 μs) equilibrium molecular dynamics simulation of membrane-embedded, dimeric ClC-ec1, a CLC from Escherichia coli, reveals transient but frequent hydration of the central hydrophobic region by water molecules from the intracellular bulk phase via the interface between the two subunits. We characterize a portal region lined by E202, E203, and A404 as the main gateway for hydration. Supporting this mechanism, sitespecific mutagenesis experiments show that ClC-ec1 ion transport rates decrease as the size of the portal residue at position 404 is increased. Beyond the portal, water wires form spontaneously and repeatedly to span the 15-Å hydrophobic region between the two known H + transport sites [E148 (Glu ex ) and E203 (Glu in )]. Our finding that the formation of these water wires requires the presence of Cl − explains the previously mystifying fact that Cl − occupancy correlates with the ability to transport protons. To further validate the idea that these water wires are central to the H + transport mechanism, we identified I109 as the residue that exhibits the greatest conformational coupling to water wire formation and experimentally tested the effects of mutating this residue. The results, by providing a detailed microscopic view of the dynamics of water wire formation and confirming the involvement of specific protein residues, offer a mechanism for the coupled transport of H + and Cl − ions in CLC transporters. membrane transporters | membrane proteins | membrane exchangers | antiporters | coupling mechanism T he chloride channel (CLC) family (1, 2) includes both passive Cl − channels and secondary active H + -coupled Cl − transporters (3-8). The latter, also known as H + /Cl − exchangers, drive uphill movement of H + by coupling the process to downhill movement of Cl − or vice versa, thereby exchanging the two types of ions across the membrane at fixed stoichiometry (9). ClC-ec1, a CLC from Escherichia coli, has served as the prototype CLC for biophysical studies because of its known crystal structures (10, 11), its tractable biochemical behavior, and its structural and mechanistic similarities to mammalian CLC transporters (3)(4)(5)(6)(7)(8)(12)(13)(14)(15)(16)(17). Detailed structural and functional studies of 11,[18][19][20][21][22][23][24][25][26][27] have shed light on some of its key mechanistic aspects. Most prominently, these studies have characterized the Cl − permeation pathway and its lining residues (10,18,25) and established the role of E148, also known as Glu ex , as the extracellular gate for the Cl − pathway (9, 11).Although much less is known about the H + translocation pathway (and mechanism), experimental studies have provided key information ...

show abstract