title: Arsenic tolerance in Arabidopsis is mediated by two ABCC-type phytochelatin transporters.
abstract: Arsenic is an extremely toxic metalloid causing serious health problems. In Southeast Asia, aquifers providing drinking and agricultural water for tens of millions of people are contaminated with arsenic. To reduce nutritional arsenic intake through the consumption of contaminated plants, identification of the mechanisms for arsenic accumulation and detoxification in plants is a prerequisite. Phytochelatins (PCs) are glutathione-derived peptides that chelate heavy metals and metalloids such as arsenic, thereby functioning as the first step in their detoxification. Plant vacuoles act as final detoxification stores for heavy metals and arsenic. The essential PC-metal(loid) transporters that sequester toxic metal(loid)s in plant vacuoles have long been sought but remain unidentified in plants. Here we show that in the absence of two ABCC-type transporters, AtABCC1 and AtABCC2, Arabidopsis thaliana is extremely sensitive to arsenic and arsenic-based herbicides. Heterologous expression of these ABCC transporters in phytochelatin-producing Saccharomyces cerevisiae enhanced arsenic tolerance and accumulation. Furthermore, membrane vesicles isolated from these yeasts exhibited a pronounced arsenite [As(III)]-PC(2) transport activity. Vacuoles isolated from atabcc1 atabcc2 double knockout plants exhibited a very low residual As(III)-PC(2) transport activity, and interestingly, less PC was produced in mutant plants when exposed to arsenic. Overexpression of AtPCS1 and AtABCC1 resulted in plants exhibiting increased arsenic tolerance. Our findings demonstrate that AtABCC1 and AtABCC2 are the long-sought and major vacuolar PC transporters. Modulation of vacuolar PC transporters in other plants may allow engineering of plants suited either for phytoremediation or reduced accumulation of arsenic in edible organs.
authors.affiliation: Department of Integrative Bioscience and Biotechnology, University of Zurich Cooperative Laboratory, World Class University Program, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Won-Yong
authors.initials: WY
authors.lastname: Song
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Park
authors.forename: David G
authors.initials: DG
authors.lastname: Mendoza-Cózatl
authors.forename: Marianne
authors.initials: M
authors.lastname: Suter-Grotemeyer
authors.forename: Donghwan
authors.initials: D
authors.lastname: Shim
authors.forename: Stefan
authors.initials: S
authors.lastname: Hörtensteiner
authors.forename: Markus
authors.initials: M
authors.lastname: Geisler
authors.forename: Barbara
authors.initials: B
authors.lastname: Weder
authors.forename: Philip A
authors.initials: PA
authors.lastname: Rea
authors.forename: Doris
authors.initials: D
authors.lastname: Rentsch
authors.forename: Julian I
authors.initials: JI
authors.lastname: Schroeder
authors.forename: Youngsook
authors.initials: Y
authors.lastname: Lee
authors.forename: Enrico
authors.initials: E
authors.lastname: Martinoia
mesh_terms: D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism; D001151:Arsenic / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002614:Chelating Agents; D004361:Drug Tolerance; D026901:Membrane Transport Proteins / Q000378:metabolism*; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism*; D054811:Phytochelatins / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D001151:Arsenic; D002614:Chelating Agents; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D054811:Phytochelatins; C421109:multidrug resistance-associated protein 1