Chemistry:Nicotianamine
Nicotianamine is a metal-chelating molecule ubiquitous in higher plants.[1] It is also used as a precursor for the synthesis of phytosiderophores which play a key role in iron uptake from the soil in graminaceous plants.[2] Biochemically, it is synthesized by the enzyme nicotianamine synthase, which uses three molecules of S-adenosylmethionine.[3]
Biosynthesis
The enzyme nicotianamine synthase converts three units of its substrate, S-adenosyl methionine, into nicotianamine and three units of 5′-methylthioadenosine as a by-product.[4]
Metabolism
Nicotianamine binds efficiently to iron II but much less well to the iron III mainly found in soil.[2]: 199 Plants convert it into other phytosiderophores which are more efficient in scavenging iron III and other ions. For example, the enzymes nicotianamine aminotransferase (NAAT)[5] and 3-deamino-3-oxonicotianamine reductase (DOR)[6] give two additional compounds:
Further additions of hydroxyl groups, catalysed by alpha-ketoglutarate-dependent hydroxylases, convert 2'-deoxymugineic acid to mugineic acid and related phytosiderophores.[1][2][7]
References
- ↑ 1.0 1.1 Takahashi, Michiko; Terada, Yasuko; Nakai, Izumi et al. (2003). "Role of Nicotianamine in the Intracellular Delivery of Metals and Plant Reproductive Development". The Plant Cell 15 (6): 1263–1280. doi:10.1105/tpc.010256. PMID 12782722.
- ↑ 2.0 2.1 2.2 Marschner, Horst (2012). Marschner's Mineral Nutrition of Higher Plants. London Waltham, MA: Academic Press. ISBN 978-0-12-384905-2. https://www.google.co.uk/books/edition/Marschner_s_Mineral_Nutrition_of_Higher/_a-hKcXXQuAC?hl=en&gbpv=1&printsec=frontcover&bsq=nicotianamine.
- ↑ "Nicotianamine, a novel enhancer of rice iron bioavailability to humans". PLOS ONE 5 (4). 2010. doi:10.1371/journal.pone.0010190. PMID 20419136. Bibcode: 2010PLoSO...510190Z.
- ↑ Higuchi, Kyoko; Kanazawa, Kenji; Nishizawa, Naoko-Kishi; Chino, Mitsuo; Mori, Satoshi (1994). "Purification and characterization of nicotianamine synthase from Fe-deficient barley roots". Plant and Soil 165 (2): 173–179. doi:10.1007/BF00008059.
- ↑ Takahashi, Michiko; Yamaguchi, Hirotaka; Nakanishi, Hiromi et al. (1999). "Cloning Two Genes for Nicotianamine Aminotransferase, a Critical Enzyme in Iron Acquisition (Strategy II) in Graminaceous Plants". Plant Physiology 121 (3): 947–956. doi:10.1104/pp.121.3.947. PMID 10557244.
- ↑ Shojima, Shinsuke; Nishizawa, Naoko-Kishi; Fushiya, Shinji et al. (1990). "Biosynthesis of Phytosiderophores". Plant Physiology 93 (4): 1497–1503. doi:10.1104/pp.93.4.1497. PMID 16667646.
- ↑ Kobayashi, Takanori; Nakanishi, Hiromi; Takahashi, Michiko; Kawasaki, Shinji; Nishizawa, Naoko-Kishi; Mori, Satoshi (2001). "In vivo evidence that Ids3 from Hordeum vulgare encodes a dioxygenase that converts 2′-deoxymugineic acid to mugineic acid in transgenic rice". Planta 212 (5–6): 864–871. doi:10.1007/s004250000453. PMID 11346963.
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