title: AtHMA3, a P1B-ATPase allowing Cd/Zn/Co/Pb vacuolar storage in Arabidopsis.
abstract: The Arabidopsis (Arabidopsis thaliana) Heavy Metal Associated3 (AtHMA3) protein belongs to the P1B-2 subgroup of the P-type ATPase family, which is involved in heavy metal transport. In a previous study, we have shown, using heterologous expression in the yeast Saccharomyces cerevisiae, that in the presence of toxic metals, AtHMA3 was able to phenotypically complement the cadmium/lead (Cd/Pb)-hypersensitive strain ycf1 but not the zinc (Zn)-hypersensitive strain zrc1. In this study, we demonstrate that AtHMA3 in planta is located in the vacuolar membrane, with a high expression level in guard cells, hydathodes, vascular tissues, and the root apex. Confocal imaging in the presence of the Zn/Cd fluorescent probe BTC-5N revealed that AtHMA3 participates in the vacuolar storage of Cd. A T-DNA insertional mutant was found more sensitive to Zn and Cd. Conversely, ectopic overexpression of AtHMA3 improved plant tolerance to Cd, cobalt, Pb, and Zn; Cd accumulation increased by about 2- to 3-fold in plants overexpressing AtHMA3 compared with wild-type plants. Thus, AtHMA3 likely plays a role in the detoxification of biological (Zn) and nonbiological (Cd, cobalt, and Pb) heavy metals by participating in their vacuolar sequestration, an original function for a P1B-2 ATPase in a multicellular eukaryote.
authors.affiliation: l'Energie Atomique, DSV, IBEB, Lab Echanges Membran and Signalisation, Saint-Paul-lez-Durance F-13108, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Morel
authors.forename: Jérôme
authors.initials: J
authors.lastname: Crouzet
authors.forename: Antoine
authors.initials: A
authors.lastname: Gravot
authors.forename: Pascaline
authors.initials: P
authors.lastname: Auroy
authors.forename: Nathalie
authors.initials: N
authors.lastname: Leonhardt
authors.forename: Alain
authors.initials: A
authors.lastname: Vavasseur
authors.forename: Pierre
authors.initials: P
authors.lastname: Richaud
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity; D003300:Copper / Q000378:metabolism / Q000633:toxicity; D018744:DNA, Plant / Q000235:genetics; D004361:Drug Tolerance; D008658:Inactivation, Metabolic; D007854:Lead / Q000378:metabolism / Q000633:toxicity; D026901:Membrane Transport Proteins / Q000378:metabolism*; D019216:Metals, Heavy / Q000378:metabolism / Q000633:toxicity*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D014617:Vacuoles / Q000187:drug effects / Q000201:enzymology*; D015032:Zinc / Q000378:metabolism / Q000633:toxicity
chemical_list: D029681:Arabidopsis Proteins; D018744:DNA, Plant; D026901:Membrane Transport Proteins; D019216:Metals, Heavy; D011993:Recombinant Fusion Proteins; D002104:Cadmium; D007854:Lead; D003300:Copper; D000251:Adenosine Triphosphatases; C484509:HMA3 protein, Arabidopsis; D015032:Zinc