Gating of human ClC‐2 chloride channels and regulation by carboxy‐terminal domains

Garcia‐Olivares, Jennie; Alekov, Alexi K.; Boroumand, Mohammad Reza; Begemann, Birgit; Hidalgo, Patricia; Fahlke, Christoph

doi:10.1113/jphysiol.2008.158097

Cited by 53 publications

(69 citation statements)

References 46 publications

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“…In this study, the effects on the subcellular distribution were only studied by confocal imaging, and none of the truncated hClC-1 exhibited major changes on this parameter (48). For hClC-2, ATP binding to the CBS domains results in longer slow gate closures (51), and removal of the full carboxyl terminus accelerates hClC-2 gating by preventing slow gate closures (50). Multiple partial carboxyl-terminal truncations and deletions constitutively locked hClC-2 in a closed conformation, without any effect on surface membrane insertion (50).…”

Section: Discussionmentioning

confidence: 99%

“…For hClC-2, ATP binding to the CBS domains results in longer slow gate closures (51), and removal of the full carboxyl terminus accelerates hClC-2 gating by preventing slow gate closures (50). Multiple partial carboxyl-terminal truncations and deletions constitutively locked hClC-2 in a closed conformation, without any effect on surface membrane insertion (50). For CLC anion/ proton antiporters that normally reside in intracellular cell organelles crucial roles for correct trafficking and sorting have been assigned to the carboxyl terminus (52)(53)(54)(55).…”

Section: Discussionmentioning

confidence: 99%

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Carboxyl-terminal Truncations of ClC-Kb Abolish Channel Activation by Barttin Via Modified Common Gating and Trafficking

Stölting

Bungert-Plümke

Franzen

et al. 2015

Journal of Biological Chemistry

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Background: Carboxyl-terminal truncations of hClC-Kb cause Bartter syndrome. Results: hClC-Kb channels lacking the carboxyl terminus still associate with barttin, but are neither stabilized in the membrane nor activated. Conclusion: Truncated hClC-Kb channels are not regulated by barttin. Significance: Elucidating the role of the carboxyl terminus of hClC-Kb significantly improves our understanding of CLC-K regulation by barttin.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Carboxyl-terminal Truncations of ClC-Kb Abolish Channel Activation by Barttin Via Modified Common Gating and Trafficking

Stölting

Bungert-Plümke

Franzen

et al. 2015

Journal of Biological Chemistry

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“…They have also been suggested to play a role in CLC trafficking (29,30), in the regulation of epithelial Na þ channels by CLC-2 (31), and in the regulation of CLC-Kb by the accessory protein barttin (32). CBS domains also participate, in a poorly defined way, in CLC common gating (33,34). Mutations in CLC CBS domains cause myotonia, Dent's disease, osteopetrosis, and Bartter syndrome (18,35).…”

Section: Introductionmentioning

confidence: 99%

Role of CBS and Bateman Domains in Phosphorylation-Dependent Regulation of a CLC Anion Channel

Yamada

Krzeminski

Bozóky

et al. 2016

Biophysical Journal

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Eukaryotic CLC anion channels and transporters are homodimeric proteins composed of multiple a-helical membrane domains and large cytoplasmic C-termini containing two cystathionine-b-synthase domains (CBS1 and CBS2) that dimerize to form a Bateman domain. The Bateman domains of adjacent CLC subunits interact to form a Bateman domain dimer. The functions of CLC CBS and Bateman domains are poorly understood. We utilized the Caenorhabditis elegans CLC-1/2/Ka/ Kb anion channel homolog CLH-3b to characterize the regulatory roles of CLC cytoplasmic domains. CLH-3b activity is reduced by phosphorylation or deletion of a 14-amino-acid activation domain (AD) located on the linker connecting CBS1 and CBS2. We demonstrate here that phosphorylation-dependent reductions in channel activity require an intact Bateman domain dimer and concomitant phosphorylation or deletion of both ADs. Regulation of a CLH-3b AD deletion mutant is reconstituted by intracellular perfusion with recombinant 14-amino-acid AD peptides. The sulfhydryl reactive reagent 2-(trimethylammonium)ethyl methanethiosulfonate bromide (MTSET) alters in a phosphorylation-dependent manner the activity of channels containing single cysteine residues that are engineered into the short intracellular loop connecting membrane a-helices H and I (H-I loop), the AD, CBS1, and CBS2. In contrast, MTSET has no effect on channels in which cysteine residues are engineered into intracellular regions that are dispensable for regulation. These studies together with our previous work suggest that binding and unbinding of the AD to the Bateman domain dimer induces conformational changes that are transduced to channel membrane domains via the H-I loop. Our findings provide new, to our knowledge, insights into the roles of CLC Bateman domains and the structurefunction relationships that govern the regulation of CLC protein activity by diverse ligands and signaling pathways.

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“…We employed a variation of stationary noise analysis (22)(23)(24)28). Steady-state current variances (…”

Section: D117a Modifies Time and Voltage Dependence Of Eaat4mentioning

confidence: 99%

A Conserved Aspartate Determines Pore Properties of Anion Channels Associated with Excitatory Amino Acid Transporter 4 (EAAT4)

Kovermann

Machtens

Ewers

et al. 2010

Journal of Biological Chemistry

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Excitatory amino acid transporter (EAAT) glutamate transporters function not only as secondary active glutamate transporters but also as anion channels. Recently, a conserved aspartic acid (Asp 112 ) within the intracellular loop near to the end of transmembrane domain 2 was proposed as a major determinant of substrate-dependent gating of the anion channel associated with the glial glutamate transporter EAAT1. We studied the corresponding mutation (D117A) in another EAAT isoform, EAAT4, using heterologous expression in mammalian cells, whole cell patch clamp, and noise analysis. In EAAT4, D117A modifies unitary conductances, relative anion permeabilities, as well as gating of associated anion channels. EAAT4 anion channel gating is characterized by two voltage-dependent gating processes with inverse voltage dependence. In wild type EAAT4, external L-glutamate modifies the voltage dependence as well as the minimum open probabilities of both gates, resulting in concentration-dependent changes of the number of open channels. Not only transport substrates but also anions affect wild type EAAT4 channel gating. External anions increase the open probability and slow down relaxation constants of one gating process that is activated by depolarization. D117A abolishes the anion and glutamate dependence of EAAT4 anion currents and shifts the voltage dependence of EAAT4 anion channel activation by more than 200 mV to more positive potentials. D117A is the first reported mutation that changes the unitary conductance of an EAAT anion channel. The finding that mutating a pore-forming residue modifies gating illustrates the close linkage between pore conformation and voltage-and substrate-dependent gating in EAAT4 anion channels. Glial and neuronal excitatory amino acid transporters (EAATs)2 remove glutamate from the synaptic cleft to ensure low resting glutamate levels and to prevent neuronal damage by excessive glutamate receptor activation. EAATs are not only secondary active glutamate transporters but also anion-selective channels (1). For some EAAT isoforms, anion currents are much smaller than electrogenic uptake currents. For other isoforms, anion currents represent the predominant transportermediated current component (2-5). These differences suggest that some EAATs might play physiological roles as substrategated anion channels involved in the regulation of cellular excitability, and others may play roles as glutamate transporters (6, 7).Whereas key processes underlying glutamate transport have been identified in recent years (8 -15), molecular determinants of the EAAT anion conductance still need to be clarified. For other transport proteins, studies that focused on the functional consequences of single point mutations greatly improved our understanding of basic mechanisms of operation (16 -18). We took a similar approach on EAAT anion channels and focused on a point mutation that was first reported by Vandenberg and co-workers (19). Neutralizing a conserved aspartate between TM2 and TM3 (D112A) abolished the substrat...

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Gating of human ClC‐2 chloride channels and regulation by carboxy‐terminal domains

Cited by 53 publications

References 46 publications

Carboxyl-terminal Truncations of ClC-Kb Abolish Channel Activation by Barttin Via Modified Common Gating and Trafficking

Carboxyl-terminal Truncations of ClC-Kb Abolish Channel Activation by Barttin Via Modified Common Gating and Trafficking

Role of CBS and Bateman Domains in Phosphorylation-Dependent Regulation of a CLC Anion Channel

A Conserved Aspartate Determines Pore Properties of Anion Channels Associated with Excitatory Amino Acid Transporter 4 (EAAT4)

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