title: Vacuolar-Iron-Transporter1-Like proteins mediate iron homeostasis in Arabidopsis.
abstract: Iron deficiency is a nutritional problem in plants and reduces crop productivity, quality and yield. With the goal of improving the iron (Fe) storage properties of plants, we have investigated the function of three Arabidopsis proteins with homology to Vacuolar Iron Transporter1 (AtVIT1). Heterologous expression of Vacuolar Iron Transporter-Like1 (AtVTL1; At1g21140), AtVTL2 (At1g76800) or AtVTL5 (At3g25190) in the yeast vacuolar Fe transport mutant, Δccc1, restored growth in the presence of 4 mM Fe. Isolated vacuoles from yeast expressing either of the VTL genes in the Δccc1 background had a three- to four-fold increase in Fe concentration compared to vacuoles isolated from the untransformed mutant. Transiently expressed GFP-tagged AtVTL1 was localized exclusively and AtVTL2 was localized primarily to the vacuolar membrane of onion epidermis cells. Seedling root growth of the Arabidopsis nramp3/nramp4 and vit1-1 mutants was decreased compared to the wild type when seedlings were grown under Fe deficiency. When expressed under the 35S promoter in the nramp3/nramp4 or vit1-1 backgrounds, AtVTL1, AtVTL2 or AtVTL5 restored root growth in both mutants. The seed Fe concentration in the nramp3/nramp4 mutant overexpressing AtVTL1, AtVTL2 or AtVTL5 was between 50 and 60% higher than in non-transformed double mutants or wild-type plants. We conclude that the VTL proteins catalyze Fe transport into vacuoles and thus contribute to the regulation of Fe homeostasis in planta.
authors.affiliation: Institute of Biology, Humboldt University Berlin, Berlin, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Gollhofer
authors.affiliation: Institute of Biology, Humboldt University Berlin, Berlin, Germany.
authors.forename: Roman
authors.initials: R
authors.lastname: Timofeev
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy Sciences, Nanjing, PR China.
authors.forename: Ping
authors.initials: P
authors.lastname: Lan
authors.affiliation: Academia Sinica, Institute of Plant and Microbial Biology, Taipei, Taiwan; Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan; Genome and Systems Biology Degree Program, College of Life Science, National Taiwan University, Taipei, Taiwan.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schmidt
authors.affiliation: Institute of Biology, Humboldt University Berlin, Berlin, Germany.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Buckhout
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D030541:Databases, Genetic; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D006706:Homeostasis; D007501:Iron / Q000378:metabolism*; D058977:Molecular Sequence Annotation; D009154:Mutation; D018517:Plant Roots / Q000378:metabolism; D021381:Protein Transport; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; C515257:VIT1 protein, Arabidopsis; D007501:Iron