Function of the anion transporter AtCLC-d in the trans-Golgi network.
Anion transporting proteins of the CLC type are involved in anion homeostasis in a variety of organisms. CLCs from Arabidopsis have been shown to participate in nitrate accumulation and storage. In this study, the physiological role of the functional chloride transporter AtCLC-d from Arabidopsis was investigated. AtCLC-d is weakly expressed in various tissues, including the root. When transiently expressed as a GFP fusion in protoplasts, it co-localized with the VHA-a1 subunit of the proton-transporting V-type ATPase in the trans-Golgi network (TGN). Stable expression in plants showed that it co-localized with the endocytic tracer dye FM4-64 in a brefeldin A-sensitive compartment. Immunogold electron microscopy confirmed the localization of AtCLC-d to the TGN. Disruption of the AtCLC-d gene by a T-DNA insertion did not affect the nitrate and chloride contents. The overall morphology of these clcd-1 plants was similar to that of the wild-type, but root growth on synthetic medium was impaired. Moreover, the sensitivity of hypocotyl elongation to treatment with concanamycin A, a blocker of the V-ATPase, was stronger in the clcd-1 mutant. These phenotypes could be complemented by overexpression of AtCLC-d in the mutant background. The results suggest that the luminal pH in the trans-Golgi network is adjusted by AtCLC-d-mediated transport of a counter anion such as Cl(-) or NO(3)(-).
von der Fecht-Bartenbach
Jennifer
J
Zentrum für Molekularbiologie der Pflanzen (ZMBP), Pflanzenphysiologie, Universität Tübingen, Auf der Morgenstelle 1, D-72076 Tübingen, Germany.
Bogner
Martin
M
Krebs
Melanie
M
Stierhof
York-Dieter
YD
Schumacher
Karin
K
Ludewig
Uwe
U
D027321:Anion Transport Proteins / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D018118:Chloride Channels / Q000378:metabolism*; D017353:Gene Deletion; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018942:Macrolides / Q000494:pharmacology; D021381:Protein Transport; D036226:Seedlings / Q000254:growth & development; D021601:trans-Golgi Network / Q000378:metabolism*
D027321:Anion Transport Proteins; D029681:Arabidopsis Proteins; C000592782:CLCd protein, Arabidopsis; D018118:Chloride Channels; D018942:Macrolides; C036978:concanamycin A