title: Molecular cloning of melatonin 3-hydroxylase and its production of cyclic 3-hydroxymelatonin in rice (Oryza sativa).
abstract: Melatonin is metabolized in animals to cyclic 3-hydroxymelatonin (3-OHM) not by an enzymatic pathway, but by interaction with hydroxyl radicals. The production of 3-OHM in animals suggests the possible presence of 3-OHM in plants. Prior to the identification of 3-OHM in plants, we directly cloned the corresponding gene(s) responsible for 3-OHM synthesis using Escherichia coli library strains expressing genes belonging to the 2-oxoglutarate-dependent dioxygenase (2-ODD) superfamily from rice. Three of 35 E. coli library strains supplemented with 1 mmol/L melatonin were found to produce 3-OHM in their extracellular medium, suggestive of three 2-ODD genes involved in 3-OHM production. The purified recombinant 2-ODD 11, 2-ODD 26, and 2-ODD 33 proteins were shown to catalyze the metabolism of melatonin to 3-OHM, with 2-ODD 11 showing the highest melatonin 3-hydroxylase (M3H) catalytic activity. Consistent with the presence of M3H genes, rice leaves supplemented with 5 mmol/L melatonin produced 3-OHM [233 μg/g fresh weight (FW)], 2-hydroxymelatonin (21 μg/g FW), and N1-acetyl-N2-formyl-5-methoxykynuramine (5 μg/g FW). Three M3H transcripts were induced upon the treatment of rice leaves with cadmium followed by an increase in M3H enzyme activity. Cloning of M3H genes in plants has paved the way for the studies of melatonin in plants in terms of its multiple physiological roles.
authors: Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, South Korea.
authors: Kyungjin
authors: K
authors: Lee
authors: Faculty of Chemistry, University of Warsaw, Warsaw, Poland.
authors: Anna
authors: A
authors: Zawadzka
authors: Faculty of Chemistry, University of Warsaw, Warsaw, Poland.
authors: Zbigniew
authors: Z
authors: Czarnocki
authors: Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors: Russel J
authors: RJ
authors: Reiter
authors: Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, South Korea. kback@chonnam.ac.kr.
authors: Kyoungwhan
authors: K
authors: Back
mesh_terms: D002104:Cadmium / Q000494:pharmacology*; D003001:Cloning, Molecular; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D008550:Melatonin / Q000031:analogs & derivatives* / Q000096:biosynthesis; D006899:Mixed Function Oxygenases / Q000096:biosynthesis / Q000235:genetics; D012275:Oryza / Q000201:enzymology / Q000235:genetics; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics
chemical_list: D002104:Cadmium; C052611:1-acetyl-1,2,3,3a,8,8a-hexahydro-8a-hydroxy-5-methoxypyrrolo(2,3-b)indole; D006899:Mixed Function Oxygenases; D008550:Melatonin
keywords: 2-hydroxymelatonin; 2-oxoglutarate-dependent dioxygenase; N-acetyl-5-methoxykynurenamine; N1-acetyl-N2-formyl-5-methoxykynuramine; cyclic 3-hydroxymelatonin; melatonin catabolism