A Family of Putative Chloride Channels from Arabidopsis and Functional Complementation of a Yeast Strain with a CLC Gene Disruption

Hechenberger, Mirko; Schwappach, Blanche; Fischer, W; Frommer, Wolf B.; Jentsch, Thomas J.; Steinmeyer, Klaus

doi:10.1074/jbc.271.52.33632

Cited by 160 publications

(126 citation statements)

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“…One candidate gene family is the CLC family, because CLC homologs in prokaryotes mediate Cl À flux. However to date, none of the seven CLC family members in Arabidopsis has been localized to the PM or shown to function as an anion channel in planta [84,85]. Another candidate gene family is the ATP-binding cassette (ABC) superfamily [86,87].…”

Section: Anion Channels: Properties and Regulationmentioning

confidence: 99%

Roles of ion channels and transporters in guard cell signal transduction

2007

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Stomatal complexes consist of pairs of guard cells and the pore they enclose. Reversible changes in guard cell volume alter the aperture of the pore and provide the major regulatory mechanism for control of gas exchange between the plant and the environment. Stomatal movement is facilitated by the activity of ion channels and ion transporters found in the plasma membrane and vacuolar membrane of guard cells. Progress in recent years has elucidated the molecular identities of many guard cell transport proteins, and described their modulation by various cellular signal transduction components during stomatal opening and closure prompted by environmental and endogenous stimuli.

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Section: Anion Channels: Properties and Regulationmentioning

confidence: 99%

Roles of ion channels and transporters in guard cell signal transduction

2007

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“…On the other hand, the ability of some Arabidopsis and rice CLCs, upon expression in CLC-depleted yeast mutant cells, to rescue their altered growth phenotype (Hechenberger et al 1996;Gaxiola et al 1998;Nakamura et al 2006;Marmagne et al 2007) suggests that plant CLCs exert a similar function as the yeast CLC. Nevertheless, so far, all the experiments that aimed at demonstrating a transport activity of the AtClCa protein (as well as other plant ClCs) using heterologous expression systems, such as Xenopus oocytes, insect cells or mammalian cells, have failed.…”

Section: The Plant Clc Familymentioning

confidence: 99%

“…After the proteins of the chloride channel (CLC) family were discovered in A. thaliana and Nicotiana tabacum (Hechenberger et al 1996;Lurin et al 1996), it was hypothesized that these proteins might be involved in anion transport across plant membranes.…”

Section: Anion Transport In Plant Cellsmentioning

confidence: 99%

CLC-mediated anion transport in plant cells

Angeli

Monachello

Ephritikhine

et al. 2008

Phil. Trans. R. Soc. B

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Plants need nitrate for growth and store the major part of it in the central vacuole of cells from root and shoot tissues. Based on few studies on the two model plants Arabidopsis thaliana and rice, members of the large ChLoride Channel (CLC) family have been proposed to encode anion channels/transporters involved in nitrate homeostasis. Proteins from the Arabidopsis CLC family (AtClC, comprising seven members) are present in various membrane compartments including the vacuolar membrane (AtClCa), Golgi vesicles (AtClCd and AtClCf ) or chloroplast membranes (AtClCe). Through a combination of electrophysiological and genetic approaches, AtClCa was shown to function as a 2NO 3 K /1H C exchanger that is able to accumulate specifically nitrate into the vacuole, in agreement with the main phenotypic trait of knockout mutant plants that accumulate 50 per cent less nitrate than their wild-type counterparts. The set-up of a functional complementation assay relying on transient expression of AtClCa cDNA in the mutant background opens the way for studies on structure-function relationships of the AtClCa nitrate transporter. Such studies will reveal whether important structural determinants identified in bacterial or mammalian CLCs are also crucial for AtClCa transport activity and regulation.

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“…In mammals, the roles of plasma membrane CLC Cl Ϫ channels include transepithelial transport (2)(3)(4)(5) and control of muscle excitability (6), whereas vesicular CLC exchangers may facilitate endocytosis (7) and lysosomal function (8 -10) by electrically shunting vesicular proton pump currents (11). In the plant Arabidopsis thaliana, there are seven CLC isoforms (AtClC-a-AtClC-g) 2 (12)(13)(14)(15), which may mostly reside in intracellular membranes. AtClC-a uses the pH gradient across the vacuolar membrane to transport the nutrient nitrate into that organelle (16).…”

Section: /Hmentioning

confidence: 99%

Residues Important for Nitrate/Proton Coupling in Plant and Mammalian CLC Transporters

Bergsdorf

Zdebik

Jentsch

2009

Journal of Biological Chemistry

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107

127

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CLC proteins are found in all phyla from bacteria to humans and either mediate electrogenic anion/proton exchange or function as chloride channels (1). In mammals, the roles of plasma membrane CLC Cl Ϫ channels include transepithelial transport (2-5) and control of muscle excitability (6), whereas vesicular CLC exchangers may facilitate endocytosis (7) and lysosomal function (8 -10) by electrically shunting vesicular proton pump currents (11). In the plant Arabidopsis thaliana, there are seven CLC isoforms (AtClC-a-AtClC-g) 2 (12-15), which may mostly reside in intracellular membranes. AtClC-a uses the pH gradient across the vacuolar membrane to transport the nutrient nitrate into that organelle (16). This secondary active transport requires a tightly coupled NO 3 Ϫ /H ϩ exchange. Astonishingly, however, mammalian ClC-4 and -5 and bacterial EcClC-1 (one of the two CLC isoforms in Escherichia coli) display tightly coupled Cl Ϫ /H ϩ exchange, but anion flux is largely uncoupled from H ϩ when NO 3 Ϫ is transported (17-21). The lack of appropriate expression systems for plant CLC transporters (12) has so far impeded structure-function analysis that may shed light on the ability of AtClC-a to perform efficient NO 3 Ϫ /H ϩ exchange. This dearth of data contrasts with the extensive mutagenesis work performed with CLC proteins from animals and bacteria.The crystal structure of bacterial CLC homologues (22, 23) and the investigation of mutants (17, 19 -21, 24 -29) have yielded important insights into their structure and function. CLC proteins form dimers with two largely independent permeation pathways (22,25,30,31). Each of the monomers displays two anion binding sites (22). A third binding site is observed when a certain key glutamate residue, which is located halfway in the permeation pathway of almost all CLC proteins, is mutated to alanine (23). Mutating this gating glutamate in CLC Cl Ϫ channels strongly affects or even completely suppresses single pore gating (23), whereas CLC exchangers are transformed by such mutations into pure anion conductances that are not coupled to proton transport (17,19,20). Another key glutamate, located at the cytoplasmic surface of the CLC monomer, seems to be a hallmark of CLC anion/proton exchangers. Mutating this proton glutamate to nontitratable amino acids uncouples anion transport from protons in the bacterial EcClC-1 protein (27) but seems to abolish transport altogether in mammalian . In those latter proteins, anion transport could be restored by additionally introducing an uncoupling mutation at the gating glutamate (21).The functional complementation by 32) 2 The abbreviations used are: AtCIC-n, member n of the CLC family of Cl Ϫ channels and transporters in the plant Arabidopsis thaliana; CIC-n, member n of the CLC family of chloride channel and transporters (in animals); pH i , intracellular pH; pH 0 , extracellular pH; I(NO 3 Ϫ ) and I(Cl Ϫ ), current in the presence of NO 3 Ϫ and Cl Ϫ , respectively, which in CLC exchangers also involves an H ϩ component; WT, wild-type...

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A Family of Putative Chloride Channels from Arabidopsis and Functional Complementation of a Yeast Strain with a CLC Gene Disruption

Abstract: We have cloned four novel members of the CLC family of chloride channels from Arabidopsis thaliana. The four plant genes are homologous to a recently isolated chloride channel gene from tobacco (CLC-Nt1; Lurin, C., Geelen, D., Barbier-Brygoo, H., Guern, J., and Maurel, C.

Cited by 160 publications

References 63 publications

Roles of ion channels and transporters in guard cell signal transduction

Roles of ion channels and transporters in guard cell signal transduction

CLC-mediated anion transport in plant cells

Residues Important for Nitrate/Proton Coupling in Plant and Mammalian CLC Transporters

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