title: Functional cloning and characterization of a plant efflux carrier for multidrug and heavy metal detoxification.
abstract: We have identified a detoxifying efflux carrier from Arabidopsis using a functional cloning strategy. A bacterial mutant, KAM3, is deficient in multidrug resistance and does not survive on medium containing norfloxacin. After transformation of KAM3 cells with an Arabidopsis cDNA library, transformants were selected for restored growth on the toxic medium. One cDNA clone that complemented KAM3 encodes a novel protein with twelve putative transmembrane domains and contains limited sequence homology to a multidrug and toxin efflux carrier from bacteria. We named this Arabidopsis protein AtDTX1 (for Arabidopsis thaliana Detoxification 1). A large gene family of at least 56 members encoding related proteins was identified from the Arabidopsis genome. Further functional analysis of AtDTX1 protein in KAM3 mutant demonstrated that AtDTX1 serves as an efflux carrier for plant-derived alkaloids, antibiotics, and other toxic compounds. Interestingly, AtDTX1 was also capable of detoxifying Cd(2+), a heavy metal. Further experiments suggest that AtDTX1 is localized in the plasma membrane in plant cells thereby mediating the efflux of plant-derived or exogenous toxic compounds from the cytoplasm.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.
authors.forename: Legong
authors.initials: L
authors.lastname: Li
authors.forename: Zengyong
authors.initials: Z
authors.lastname: He
authors.forename: Girdhar K
authors.initials: GK
authors.lastname: Pandey
authors.forename: Tomofusa
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Sheng
authors.initials: S
authors.lastname: Luan
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics*; D001599:Berberine / Q000494:pharmacology; D001692:Biological Transport; D015152:Blotting, Northern; D002104:Cadmium / Q000378:metabolism; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics*; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism; D004996:Ethidium / Q000494:pharmacology; D015723:Gene Library; D005816:Genetic Complementation Test; D049452:Green Fluorescent Proteins; D006863:Hydrogen-Ion Concentration; D007364:Intercalating Agents / Q000494:pharmacology; D008164:Luminescent Proteins / Q000378:metabolism; D008670:Metals / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009643:Norfloxacin / Q000494:pharmacology; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D018076:DNA, Complementary; C449804:DTX1 protein, Arabidopsis; D004791:Enzyme Inhibitors; D007364:Intercalating Agents; D008164:Luminescent Proteins; D008670:Metals; D010940:Plant Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D014475:Uncoupling Agents; D002104:Cadmium; D001599:Berberine; D049452:Green Fluorescent Proteins; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D004996:Ethidium; D009643:Norfloxacin