title: HMA1 and PAA1, two chloroplast-envelope PIB-ATPases, play distinct roles in chloroplast copper homeostasis.
abstract: Copper is an essential micronutrient but it is also potentially toxic as copper ions can catalyse the production of free radicals, which result in various types of cell damage. Therefore, copper homeostasis in plant and animal cells must be tightly controlled. In the chloroplast, copper import is mediated by a chloroplast-envelope PIB-type ATPase, HMA6/PAA1. Copper may also be imported by HMA1, another chloroplast-envelope PIB-ATPase. To get more insights into the specific functional roles of HMA1 and PAA1 in copper homeostasis, this study analysed the phenotypes of plants affected in the expression of both HMA1 and PAA1 ATPases, as well as of plants overexpressing HMA1 in a paa1 mutant background. The results presented here provide new evidence associating HMA1 with copper homeostasis in the chloroplast. These data suggest that HMA1 and PAA1 behave as distinct pathways for copper import and targeting to the chloroplast. Finally, this work also provides evidence for an alternative route for copper import into the chloroplast mediated by an as-yet unidentified transporter that is neither HMA1 nor PAA1.
authors: CNRS, Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, 17 rue des Martyrs, F-38054 Grenoble, France.
authors: Sylvain
authors: S
authors: Boutigny
authors: Emeline
authors: E
authors: Sautron
authors: Giovanni
authors: G
authors: Finazzi
authors: Corinne
authors: C
authors: Rivasseau
authors: Annie
authors: A
authors: Frelet-Barrand
authors: Marinus
authors: M
authors: Pilon
authors: Norbert
authors: N
authors: Rolland
authors: Daphné
authors: D
authors: Seigneurin-Berny
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D025222:Chloroplast Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D003300:Copper / Q000378:metabolism*; D015870:Gene Expression; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D006706:Homeostasis; D009154:Mutation; D010641:Phenotype; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified; D036226:Seedlings / Q000201:enzymology / Q000235:genetics / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D003300:Copper; D000251:Adenosine Triphosphatases; C509978:HMA1 protein, Arabidopsis; D025222:Chloroplast Proton-Translocating ATPases; C477511:PAA1 protein, Arabidopsis
keywords: Arabidopsis; PIB ATPase.; chloroplast; copper; envelope transporter; metal homeostasis