title: Molecular and biochemical characterization of the Fe(III) chelate reductase gene family in Arabidopsis thaliana.
abstract: Iron chelate reductase is required for iron acquisition from soil and for metabolism in plants. In the genome of Arabidopsis thaliana there are eight genes classified into the iron chelate reductase gene family (AtFROs) based on sequence homology with AtFRO2 (a ferric chelate reductase in Arabidopsis). They are localized on chromosome 1 (three AtFROs) and chromosome 5 (five AtFROs) of Arabidopsis and show a high level of amino acid sequence similarity to each other. An assay for ferric chelate reductase activity revealed that AtFRO2, AtFRO3, AtFRO4, AtFRO5, AtFRO7 and AtFRO8 conferred significantly increased iron reduction activity compared with the control when expressed in yeast cells, indicating that the six AtFROs encode iron chelate reductases functioning in iron homeostasis in Arabidopsis. AtFRO2 displayed the highest iron reduction activity among the AtFROs investigated, further demonstrating that AtFRO2 is a major iron reductase gene in Arabidopsis. AtFRO2 and AtFRO3 were mainly expressed in roots of Arabidopsis, AtFRO5 and AtFRO6 in shoots and flowers, and AtFRO7 in cotyledons and trichomes, whereas the transcription of AtFRO8 was specific for leaf veins. Considering the tissue-specific expression profiles of AtFRO genes, we suggest that AtFRO2 and AtFRO3 are two Fe(III) chelate reductases mainly functioning in iron acquisition and metabolism in Arabidopsis roots, while AtFRO5, AtFRO6, AtFRO7 and AtFRO8 are required for iron homeostasis in different tissues of shoots.
authors: State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, PR China.
authors: Huilan
authors: H
authors: Wu
authors: Lihua
authors: L
authors: Li
authors: Juan
authors: J
authors: Du
authors: Youxi
authors: Y
authors: Yuan
authors: Xudong
authors: X
authors: Cheng
authors: Hong-Qing
authors: HQ
authors: Ling
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D032461:Chromosomes, Plant; D038181:FMN Reductase / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D018506:Gene Expression Regulation, Plant; D005966:Glucuronidase / Q000378:metabolism; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D038181:FMN Reductase; C023903:ferric citrate iron reductase; D005966:Glucuronidase