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Satoshi Mori - One of the best experts on this subject based on the ideXlab platform.

  • the role of potassium in the secretion of Mugineic Acids family phytosiderophores from iron deficient barley roots
    Plant and Soil, 1999
    Co-Authors: Tamami Sakaguchi, Naoko K. Nishizawa, Hiromi Nakanishi, Etsuro Yoshimura, Satoshi Mori
    Abstract:

    Mugineic acid family phytosiderophores (MAs) are secreted from iron-deficient barley roots with high equimolar correlation of potassium. To determine the form of MAs when it is secreted, we investigated the effect of anion channel blockers and valinomycin on the secretion of MAs. Among the anion channel blockers, anthracene-9-carboxylic acid and phenylglyoxal drastically reduced the amount of secreted MAs, while 4,4-diisothiocyano-2,2- stilbene disulfonate slightly inhibited the MAs secretion. Trifluoromethyl-3-phenylamino-2-nicotinic acid reduced the secreted amount to the half of non-treated. This result suggested that MAs are secreted in the form of anion through an anion channel. The elimination of potassium gradient between the cytoplasm and the cell exterior by treatment with valinomycin reduced the amount of secreted MAs. Analysis of potassium distribution in root by LV-SEM-XMA indicated that potassium in the cortex cells of iron-deficient roots is released with MAs secretion and the amount of potassium in the cortex cells decreases after secretion. These results suggested that MAs are secreted in the form of a monovalent anion via anion channels using the potassium gradient between the cytoplasm and the cell exterior.

  • Iron acquisition by plants
    Current opinion in plant biology, 1999
    Co-Authors: Satoshi Mori
    Abstract:

    In nongraminaceous plants, the FeII-transporter gene and ferric-chelate reductase gene have been cloned from Arabidopsis thaliana, whereas FeIII-reductase has not. In graminaceous monocots, the genes for Mugineic Acids (MAs) synthesis, nas (nicotianamine synthase) and naat (nicotianamine aminotransferase), have been cloned from barley, whereas the FeIII-MAs transporter gene is yet to be cloned. Transferrin absorption in Dunaliella has been reported, suggesting a phagocytotic (endocytotic) Fe-acquisition mechanism. Work to develop transgenic cultivars tolerant to Fe-deficiency in calcareous soils is now in progress.

  • Immunological characterization of a 36 kDa Fe deficiency specific peptide in barley roots
    Biometals, 1997
    Co-Authors: Koichiro Suzuki, Kenji Kanazawa, Kyoko Higuchi, Naoko K. Nishizawa, Satoshi Mori
    Abstract:

    In a previous paper we reported that an acidic 36 kDa peptide is the most strongly induced peptide among several peptides induced by Fe deficiency in barley roots. In this paper, polyclonal antibodies were raised against the 36 kDa peptide. This peptide appeared in the roots of all the graminaceous species tested (barley, rye, wheat, oat, maize, sorghum and rice) in response to Fe deficiency. More of the peptide was found in the roots of graminaceous species which secrete higher amounts of Mugineic Acids (MAs) under Fe deficient nutrition status. Induction of the 36 kDa peptide was first observed on the third day of Fe deficiency, rising to a maximum value on the seventh day. The trend has a positive correlation with secretion of MAs during Fe deficiency. Further, resupply of Fe resulted in a decrease in peptide production on the second day, reaching a control level on the seventh day. The rate of decrease in peptide production was observed to be slower than that of MA secretion. Other nutrient stresses such as B excess, B deficiency, Cu excess, Cu deficiency, Mn excess, Mn deficiency, Zn excess and Zn deficiency induced far less of the peptide. The specific expression of the 36 kDa peptide in roots of graminaceous species under Fe deficiency suggested the positive association of the peptide with a specific Fe deficiency tolerance mechanism in graminaceous plants.

  • Nicotianamine aminotransferase activities are correlated to the phytosiderophore secretions under Fe-deficient conditions in Gramineae
    Journal of Experimental Botany, 1994
    Co-Authors: Kenji Kanazawa, Kyoko Higuchi, Naoko-kishi Nishizawa, Shinji Fushiya, Mitsuo Chino, Satoshi Mori
    Abstract:

    The activities of nicotianamine aminotransferase, one of the enzymes for the biosynthesis of Mugineic acid-family phytosiderophores, were examined in six graminaceous species. The enzyme activities were induced by Fe-deficiency treatments in all species tested and had a considerable correlation to the amounts of secreted Mugineic Acids

  • Enhancement of ferric-Mugineic acid uptake by iron deficient barley roots in the presence of excess free Mugineic acid in the medium
    Plant and Soil, 1991
    Co-Authors: S. Mihashi, Satoshi Mori, Naoko K. Nishizawa
    Abstract:

    To investigate the mechanism of Mugineic acid-FeIII uptake by barley roots, plasma membrane fractions were isolated from Fe-deficient barley roots using an aqueous two-phase partition method. Utilizing the plasma membrane vesicles, we developed an assay system for studying Mugineic acid-55FeIII binding to the plasma membrane. However, no efficient active transport of Mugineic acid-55FeIII into the plasma membrane vesicle was detected, because of large amount of non-specific adsorption of 55FeIII onto the vesicle. And the adsorption could be decreased by adding excess amount of free Mugineic acid to the assay system. From the results it is speculated that an excess of free Mugineic Acids is necessary in the medium for effective uptake of Mugineic acid-FeIII by Fe-deficient barley roots. Support for this speculation came from a multi-compartment transport box experiment with excised roots of Fe-deficient barley.

Kyosuke Nomoto - One of the best experts on this subject based on the ideXlab platform.

  • Genes controlling hydroxylations of phytosiderophores are located on different chromosomes in barley (Hordeum vulgare L.)
    Planta, 1999
    Co-Authors: Jian Feng, Shin Taketa, Yi Chieh Chang, Kazuyoshi Takeda, Hideaki Matsumoto, Takashi Iwashita, Kyosuke Nomoto
    Abstract:

    Phytosiderophores, Mugineic Acids, have been demonstrated to be involved in Fe acquisition in gramineous plants. In this study, chromosomal arm locations of genes encoding for biosynthesis of various phytosiderophores were identified in a cultivar of barley (Hordeum vulgare L. cv. Betzes). Using wheat (Triticum aestivum L. cv. Chinese Spring)-barley (cv. Betzes) ditelosomic addition lines for 4HS and 4HL, a gene for hydroxylation of 2′-deoxyMugineic acid to Mugineic acid was localized to the long arm of barley chromosome 4H. To locate the gene for hydroxylation of Mugineic acid to 3-epihydroxyMugineic acid, hybrids between the 4H addition line and other wheat-barley addition lines were studied. Only a hybrid between 4H and 7H addition lines produced 3-epihydroxyMugineic acid. The gene was further localized to the long arm of chromosome 7H by feeding Mugineic acid to ditelosomic addition lines for 7HS and 7HL. A new phytosiderophore was discovered in both 7H and 7HL addition lines, which was identified to be 3-epihydroxy-2′-deoxyMugineic acid by detailed nuclear magnetic resonance studies. These results revealed that in barley there are two pathways from 2′-deoxyMugineic acid to 3-epihydroxyMugineic acid: 2′-deoxyMugineic acid → Mugineic acid → 3-epihydroxyMugineic acid and 2′-deoxyMugineic acid → 3-epihydroxy-2′-deoxyMugineic acid → 3-epihydroxyMugineic acid. Barley genes encoding for the hydroxylations of phytosiderophores are located in different chromosomes and each gene hydroxylates different C-positions: the long arm of chromosome 4H carries the gene for hydroxylating the C-2′ position and the long arm of chromosome 7H carries the gene for hydroxylating the C-3 position of the azetidine ring.

  • effective regulation of iron acquisition in graminaceous plants the role of Mugineic Acids as phytosiderophores
    Physiologia Plantarum, 1996
    Co-Authors: Jian Feng, Kyosuke Nomoto
    Abstract:

    Discovery of Mugineic Acids as phytosiderophores has shown that some graminaceous monocotyledonous plants have a different iron acquisition strategy (strategy II) from dicotyledonous and nongraminaceous monocotyledonous plants (strategy I). The process of iron acquisition by strategy II plants can be divided into four main steps: biosynthesis, secretion, solubilization, and uptake, all of which are effectively regulated by different systems. The biosynthesis of Mugineic Acids is controlled by an on-off system which is operated under the control of iron demand in the plant. All Mugineic Acids share the same biosynthetic pathway from L-methionine to 2'-deoxyMugineic acid, but the subsequent steps differ among plant species and even cultivars. The biosynthesis of Mugineic Acids is associated with the methionine recycling pathway. The secretion of Mugineic Acids shows a distinct diumal rhythm. Mugineic Acids solubilize sparingly soluble inorganic iron by chelation and possess a high chelation affinity for iron, but not for other polyvalent ions such as Ca 2+ , Mg 2+ and Al 3+ . The iron uptake process is regulated by a specific uptake system that transports the Mugineic acid-Fe(III) complex as an intact molecule. This system specifically recognizes the Mugineic acid-Fe(III) complexes, but not other Mugineic acid-metal or synthetic chelator-Fe(III) complexes, suggesting that binding sites with strict recognition for stereostructure of the complex are located on the plasma membrane. All these regulatory systems are considered to represent an efficient strategy to acquire adequate amounts of iron and to avoid factors unfavorable for iron acquisition such as high pH, high concentrations of bicarbonate, Ca 2+ and Mg 2+ , microbial degradation, and uptake of other metals that are common in calcareous soils.

  • biosynthesis of phytosiderophores Mugineic Acids associated with methionine cycling
    Journal of Biological Chemistry, 1995
    Co-Authors: Jian Feng, Tetsuro Shinada, Chitose Matsuda, Kyosuke Nomoto
    Abstract:

    Abstract The biosynthesis of 2′-deoxyMugineic acid, a key phytosiderophore, was examined in association with the putative methionine recycling pathway in the roots of wheat using labeling experiments and structural analysis. Feeding with D-[1-C]ribose did not result in C enrichment of 2′-deoxyMugineic acid, while D-[2-C]ribose resulted in C enrichment at the C-4″, −1, −4′ positions, and D-[5-C]ribose did in C-1′, −4, and −1″ positions of 2′-deoxyMugineic acid, respectively. Furthermore, two isotope-labeled intermediates of the methionine recycling pathway, 5-[5-2H2]methylthioribose and 2-[1-C]keto-4-methylthiobutyric acid, were synthesized, and their incorporation into 2′-deoxyMugineic Acids was investigated. Six deuterium atoms at the C-4, −1′, and −1″ positions of 2′-deoxyMugineic acid were observed after feeding with 5-[5-2H2]methylthioribose. Feeding with 2-[1-C]keto-4-methylthiobutyric acid yielded 2′-deoxyMugineic acid enriched with C at the C-4′, −1, and −4″ positions. These results demonstrated for the first time that the biosynthesis of 2′-deoxyMugineic acid is associated with the methionine recycling pathway. This association system functions to recycle methionine required for continued synthesis of Mugineic Acids in the roots of gramineous plants.

  • Two Related Biosynthetic Pathways of Mugineic Acids in Gramineous Plants.
    Plant physiology, 1993
    Co-Authors: Jian Feng, Kyosuke Nomoto
    Abstract:

    The biosynthesis of Mugineic Acids was studied by feeding 2H- or 13C-labeled compounds to water-cultured roots in several gramineous plants. The fate of labeled compounds was monitored by using 2H- and 13C-nuclear magnetic resonance. On investigating the proton changes during biosynthesis by feeding D,L-[3,3,4,4-d4]-methionine (98.6% 2H), 2H-labeled 2[prime]-deoxyMugineic, Mugineic, and 3-epihydroxyMugineic Acids were isolated from root washings of wheat (Triticum aestivum L. cv Minori), barley (Hordeum vulgare L. cv Minorimugi), and beer barley (Hordeum vulgare L. cv AM Nijo Tochigi), respectively. The 2H-nuclear magnetic resonance study indicated that 12 deuteriums were incorporated into the labeled 2[prime]-deoxyMugineic acid, suggesting that three molecules of L-[3,3,4,4-d4]methionine were combined. In comparison, one of the deuteriums at C-2[prime] position in the Mugineic acid, and one each of the deuteriums at C-2[prime] and C-3 positions in the 3-epihydroxyMugineic acid, were lost. However, all other deuteriums were incorporated in a manner similar to that of the labeled 2[prime]-deoxyMugineic acid. When [1,4[prime],4″-13C3]2[prime]-deoxyMugineic acid (20% 13C) was fed to oat roots (Avena sativa L. cv Amuri II), avenic acid A, which was 13C enriched at the corresponding positions, was obtained. These results revealed that L-methionine was the precursor for all these Mugineic Acids and that cleavage of the azetidine ring or hydroxylation of the 2[prime]-deoxyMugineic acid produced two related biosynthetic pathways in different gramineous plant species: L-methionine -> 2[prime]-deoxyMugineic acid -> avenic acid A in oat; and L-methionine -> 2[prime]-deoxyMugineic acid -> Mugineic acid -> 3-epihydroxyMugineic acid in barley and beer barley.

  • Phytosiderophores structures and properties of Mugineic Acids and their metal complexes
    Siderophores from Microorganisms and Plants, 1
    Co-Authors: Yukio Sugiura, Kyosuke Nomoto
    Abstract:

    In graminaceous plants such as barley, oats, and wheat, novel iron-chelating amino Acids are secreted from the roots. A typical example is Mugineic acid. A phytosiderophore, Mugineic acid significantly stimulates iron-uptake and chlorophyll synthesis in rice plants. Most microbial siderophores have hydroxamate or phenolate groups as Fe(III)-coordination donors, while phytosiderophores consist of carboxyl, amine, and hydroxyl groups as the ligand functional groups. The Mugineic acid-Fe(III) complex and its structurally analogous Co(III) complex have been characterized by some spectroscopic and X-ray diffraction methods. The coordination of Mugineic acid to Co(III) and Fe(III) ions involves the azetidine nitrogen, secondary amine nitrogen, both terminal carboxylate oxygens as basal planar donors, and the hydroxyl oxygen and intermediate carboxylate oxygen as axial donors in nearly octahedral configuration. The Mossbauer (ΔEQ = 0.24 and δ Fe = + 0.39 mm/sec) and ESR (g = 9.4, 4.51, 4.44, and 4.31) parameters of the Mugineic acid-Fe(III) complex are characteristic of high-spin (S = 5/2) ferric type. Of special interest is the apparent high reduction potential (E1/2 = − 102 mV vs. NHE) of the Mugineic acid-Fe(III) complex, as compared to those of the microbial hydroxamates and ferric enterobactin. The mechanism of iron-absorption and -transport in gramineous plants probably includes Fe(III)-solubilization by Mugineic acid and reduction from the thermodynamically stable ferric Mugineic acid complex (log K ML M = 18.1) to the weakly bound ferrous complex (log K ML M = 8.1).

Jian Feng - One of the best experts on this subject based on the ideXlab platform.

  • Genes controlling hydroxylations of phytosiderophores are located on different chromosomes in barley (Hordeum vulgare L.)
    Planta, 1999
    Co-Authors: Jian Feng, Shin Taketa, Yi Chieh Chang, Kazuyoshi Takeda, Hideaki Matsumoto, Takashi Iwashita, Kyosuke Nomoto
    Abstract:

    Phytosiderophores, Mugineic Acids, have been demonstrated to be involved in Fe acquisition in gramineous plants. In this study, chromosomal arm locations of genes encoding for biosynthesis of various phytosiderophores were identified in a cultivar of barley (Hordeum vulgare L. cv. Betzes). Using wheat (Triticum aestivum L. cv. Chinese Spring)-barley (cv. Betzes) ditelosomic addition lines for 4HS and 4HL, a gene for hydroxylation of 2′-deoxyMugineic acid to Mugineic acid was localized to the long arm of barley chromosome 4H. To locate the gene for hydroxylation of Mugineic acid to 3-epihydroxyMugineic acid, hybrids between the 4H addition line and other wheat-barley addition lines were studied. Only a hybrid between 4H and 7H addition lines produced 3-epihydroxyMugineic acid. The gene was further localized to the long arm of chromosome 7H by feeding Mugineic acid to ditelosomic addition lines for 7HS and 7HL. A new phytosiderophore was discovered in both 7H and 7HL addition lines, which was identified to be 3-epihydroxy-2′-deoxyMugineic acid by detailed nuclear magnetic resonance studies. These results revealed that in barley there are two pathways from 2′-deoxyMugineic acid to 3-epihydroxyMugineic acid: 2′-deoxyMugineic acid → Mugineic acid → 3-epihydroxyMugineic acid and 2′-deoxyMugineic acid → 3-epihydroxy-2′-deoxyMugineic acid → 3-epihydroxyMugineic acid. Barley genes encoding for the hydroxylations of phytosiderophores are located in different chromosomes and each gene hydroxylates different C-positions: the long arm of chromosome 4H carries the gene for hydroxylating the C-2′ position and the long arm of chromosome 7H carries the gene for hydroxylating the C-3 position of the azetidine ring.

  • effective regulation of iron acquisition in graminaceous plants the role of Mugineic Acids as phytosiderophores
    Physiologia Plantarum, 1996
    Co-Authors: Jian Feng, Kyosuke Nomoto
    Abstract:

    Discovery of Mugineic Acids as phytosiderophores has shown that some graminaceous monocotyledonous plants have a different iron acquisition strategy (strategy II) from dicotyledonous and nongraminaceous monocotyledonous plants (strategy I). The process of iron acquisition by strategy II plants can be divided into four main steps: biosynthesis, secretion, solubilization, and uptake, all of which are effectively regulated by different systems. The biosynthesis of Mugineic Acids is controlled by an on-off system which is operated under the control of iron demand in the plant. All Mugineic Acids share the same biosynthetic pathway from L-methionine to 2'-deoxyMugineic acid, but the subsequent steps differ among plant species and even cultivars. The biosynthesis of Mugineic Acids is associated with the methionine recycling pathway. The secretion of Mugineic Acids shows a distinct diumal rhythm. Mugineic Acids solubilize sparingly soluble inorganic iron by chelation and possess a high chelation affinity for iron, but not for other polyvalent ions such as Ca 2+ , Mg 2+ and Al 3+ . The iron uptake process is regulated by a specific uptake system that transports the Mugineic acid-Fe(III) complex as an intact molecule. This system specifically recognizes the Mugineic acid-Fe(III) complexes, but not other Mugineic acid-metal or synthetic chelator-Fe(III) complexes, suggesting that binding sites with strict recognition for stereostructure of the complex are located on the plasma membrane. All these regulatory systems are considered to represent an efficient strategy to acquire adequate amounts of iron and to avoid factors unfavorable for iron acquisition such as high pH, high concentrations of bicarbonate, Ca 2+ and Mg 2+ , microbial degradation, and uptake of other metals that are common in calcareous soils.

  • biosynthesis of phytosiderophores Mugineic Acids associated with methionine cycling
    Journal of Biological Chemistry, 1995
    Co-Authors: Jian Feng, Tetsuro Shinada, Chitose Matsuda, Kyosuke Nomoto
    Abstract:

    Abstract The biosynthesis of 2′-deoxyMugineic acid, a key phytosiderophore, was examined in association with the putative methionine recycling pathway in the roots of wheat using labeling experiments and structural analysis. Feeding with D-[1-C]ribose did not result in C enrichment of 2′-deoxyMugineic acid, while D-[2-C]ribose resulted in C enrichment at the C-4″, −1, −4′ positions, and D-[5-C]ribose did in C-1′, −4, and −1″ positions of 2′-deoxyMugineic acid, respectively. Furthermore, two isotope-labeled intermediates of the methionine recycling pathway, 5-[5-2H2]methylthioribose and 2-[1-C]keto-4-methylthiobutyric acid, were synthesized, and their incorporation into 2′-deoxyMugineic Acids was investigated. Six deuterium atoms at the C-4, −1′, and −1″ positions of 2′-deoxyMugineic acid were observed after feeding with 5-[5-2H2]methylthioribose. Feeding with 2-[1-C]keto-4-methylthiobutyric acid yielded 2′-deoxyMugineic acid enriched with C at the C-4′, −1, and −4″ positions. These results demonstrated for the first time that the biosynthesis of 2′-deoxyMugineic acid is associated with the methionine recycling pathway. This association system functions to recycle methionine required for continued synthesis of Mugineic Acids in the roots of gramineous plants.

  • Two Related Biosynthetic Pathways of Mugineic Acids in Gramineous Plants.
    Plant physiology, 1993
    Co-Authors: Jian Feng, Kyosuke Nomoto
    Abstract:

    The biosynthesis of Mugineic Acids was studied by feeding 2H- or 13C-labeled compounds to water-cultured roots in several gramineous plants. The fate of labeled compounds was monitored by using 2H- and 13C-nuclear magnetic resonance. On investigating the proton changes during biosynthesis by feeding D,L-[3,3,4,4-d4]-methionine (98.6% 2H), 2H-labeled 2[prime]-deoxyMugineic, Mugineic, and 3-epihydroxyMugineic Acids were isolated from root washings of wheat (Triticum aestivum L. cv Minori), barley (Hordeum vulgare L. cv Minorimugi), and beer barley (Hordeum vulgare L. cv AM Nijo Tochigi), respectively. The 2H-nuclear magnetic resonance study indicated that 12 deuteriums were incorporated into the labeled 2[prime]-deoxyMugineic acid, suggesting that three molecules of L-[3,3,4,4-d4]methionine were combined. In comparison, one of the deuteriums at C-2[prime] position in the Mugineic acid, and one each of the deuteriums at C-2[prime] and C-3 positions in the 3-epihydroxyMugineic acid, were lost. However, all other deuteriums were incorporated in a manner similar to that of the labeled 2[prime]-deoxyMugineic acid. When [1,4[prime],4″-13C3]2[prime]-deoxyMugineic acid (20% 13C) was fed to oat roots (Avena sativa L. cv Amuri II), avenic acid A, which was 13C enriched at the corresponding positions, was obtained. These results revealed that L-methionine was the precursor for all these Mugineic Acids and that cleavage of the azetidine ring or hydroxylation of the 2[prime]-deoxyMugineic acid produced two related biosynthetic pathways in different gramineous plant species: L-methionine -> 2[prime]-deoxyMugineic acid -> avenic acid A in oat; and L-methionine -> 2[prime]-deoxyMugineic acid -> Mugineic acid -> 3-epihydroxyMugineic acid in barley and beer barley.

Kosuke Namba - One of the best experts on this subject based on the ideXlab platform.

  • Transgenic petunia with the iron(III)-phytosiderophore transporter gene acquires tolerance to iron deficiency in alkaline environments.
    PloS one, 2015
    Co-Authors: Yoshiko Murata, Takashi Iwashita, Yoshiyuki Itoh, Kosuke Namba
    Abstract:

    Iron is an essential nutrient for all plants. However, terrestrial plants often suffer from iron deficiency in alkaline soil due to its extremely low solubility. Alkaline soil accounts for about 30% of all cultivated ground in the world. Plants have evolved two distinct strategies, I and II, for iron uptake from the soil. Dicots and non-graminaceous monocots use Strategy I, which is primarily based on the reduction of iron(III) to iron(II) and the uptake of iron(II) by the iron-regulated transporter, IRT1. In contrast, graminaceous plants use Strategy II to efficiently acquire insoluble iron(III). Strategy II comprises the synthesis and secretion of iron-chelating phytosiderophores, such as Mugineic Acids and the Yellow Stripe 1 transporter proteins of the iron(III)-phytosiderophore complex. Barley, which exhibits the highest tolerance to iron deficiency in alkaline soil among graminaceous plants, utilizes Mugineic Acids and the specific iron(III)-Mugineic Acids transporter, HvYS1. In this study, we established the transgenic plant Petunia hybrida, which originally had only Strategy I, by introducing the HvYS1 transporter gene derived from barley. When the transgenic plants were grown hydroponically in media containing the iron(III)-2′-deoxyMugineic acid complex, free 2′-deoxyMugineic acid and its iron(III) complex were detected in the root extract of the transgenic plant by electrospray ionization-Fourier transform-ion cyclotron resonance mass spectrometry. The growth of the transgenic petunia was significantly better than that of the control host in alkaline conditions. Consequently, the transgenic plant acquired a significantly enhanced tolerance to alkaline hydroponic media in the presence of the iron(III)-2′-deoxyMugineic acid complex. Furthermore, the flower color of the transgenic plant deepened. The results showed that iron-phytosiderophore complexes and their transporters can potentially be utilized to overcome the worldwide iron uptake problems to diverse plant species that are found in areas with alkaline conditions.

  • Toward mechanistic elucidation of iron acquisition in barley: efficient synthesis of Mugineic Acids and their transport activities.
    Chemical record (New York N.Y.), 2010
    Co-Authors: Kosuke Namba, Yoshiko Murata
    Abstract:

    Iron acquisition of graminaceous plants is characterized by the synthesis and secretion of iron-chelating compounds, Mugineic Acids (MAs), and by a specific uptake system for MAs-iron(III) complexes. We identified a transporter, HvYS1 (Hordeum vulgare L. yellow stripe 1), that is highly specific for MAs-iron(III) in barley roots. In this article we outline the characterization of HvYS1, and our recent work on the practical syntheses of MAs and investigations into the molecular basis of the specific transport of their iron(III) complexes by HvYS1. 2′-DeoxyMugineic acid (DMA) was synthesized in a good overall yield from commercially available Boc-l-allylglycine using a minimal number of short simple operations with minimal protecting groups and work-up/purification procedures. The same strategy was also successfully applied to β-hydroxy-l-allylglycine, which was obtained by an allylic oxidation of l-allylglycine derivatives, to give MA and 2′-epi-MA efficiently. HvYS1 transported the iron(III) complexes of all three synthetic specimens with efficiency similar to that of a natural Mugineic acid complex. With sufficient quantities of MAs in hand, we analyzed the function of HvYS1 and revealed by preparing chimeric transporters that the sixth outer membrane loop of the transporter plays a vital role in substrate specificity. © 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 10: 140–150; 2010: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.200900028

Kenji Kanazawa - One of the best experts on this subject based on the ideXlab platform.

  • Immunological characterization of a 36 kDa Fe deficiency specific peptide in barley roots
    Biometals, 1997
    Co-Authors: Koichiro Suzuki, Kenji Kanazawa, Kyoko Higuchi, Naoko K. Nishizawa, Satoshi Mori
    Abstract:

    In a previous paper we reported that an acidic 36 kDa peptide is the most strongly induced peptide among several peptides induced by Fe deficiency in barley roots. In this paper, polyclonal antibodies were raised against the 36 kDa peptide. This peptide appeared in the roots of all the graminaceous species tested (barley, rye, wheat, oat, maize, sorghum and rice) in response to Fe deficiency. More of the peptide was found in the roots of graminaceous species which secrete higher amounts of Mugineic Acids (MAs) under Fe deficient nutrition status. Induction of the 36 kDa peptide was first observed on the third day of Fe deficiency, rising to a maximum value on the seventh day. The trend has a positive correlation with secretion of MAs during Fe deficiency. Further, resupply of Fe resulted in a decrease in peptide production on the second day, reaching a control level on the seventh day. The rate of decrease in peptide production was observed to be slower than that of MA secretion. Other nutrient stresses such as B excess, B deficiency, Cu excess, Cu deficiency, Mn excess, Mn deficiency, Zn excess and Zn deficiency induced far less of the peptide. The specific expression of the 36 kDa peptide in roots of graminaceous species under Fe deficiency suggested the positive association of the peptide with a specific Fe deficiency tolerance mechanism in graminaceous plants.

  • Nicotianamine aminotransferase activities are correlated to the phytosiderophore secretions under Fe-deficient conditions in Gramineae
    Journal of Experimental Botany, 1994
    Co-Authors: Kenji Kanazawa, Kyoko Higuchi, Naoko-kishi Nishizawa, Shinji Fushiya, Mitsuo Chino, Satoshi Mori
    Abstract:

    The activities of nicotianamine aminotransferase, one of the enzymes for the biosynthesis of Mugineic acid-family phytosiderophores, were examined in six graminaceous species. The enzyme activities were induced by Fe-deficiency treatments in all species tested and had a considerable correlation to the amounts of secreted Mugineic Acids