Naringenin 7- O-methyltransferase involved in the biosynthesis of the flavanone phytoalexin sakuranetin from rice ( Oryza sativa L.)

An inducible S-adenosyl- l-methionine:naringenin 7- O-methyltransferase (NOMT) catalyzing the methylation of naringenin to sakuranetin, a major rice phytoalexin was purified approximately 985-fold from ultraviolet (UV)-irradiated rice leaves. The enzyme is not found in healthy tissues and was purifi...

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Bibliographic Details
Published in:Plant science (Limerick) 2000-06, Vol.155 (2), p.213-221
Main Authors: Rakwal, Randeep, Agrawal, Ganesh Kumar, Yonekura, Masami, Kodama, Osamu
Format: Article
Language:English
Subjects:
Affinity chromatography
Biological and medical sciences
Fundamental and applied biological sciences. Psychology
Fungal plant pathogens
Jasmonic acid
Metabolism
Metabolism. Physicochemical requirements
Naringenin 7- O-methyltransferase
Oryza sativa
Pathology, epidemiology, host-fungus relationships. Damages, economic importance
Phytoalexin
Phytopathology. Animal pests. Plant and forest protection
Plant physiology and development
Sakuranetin
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Summary:An inducible S-adenosyl- l-methionine:naringenin 7- O-methyltransferase (NOMT) catalyzing the methylation of naringenin to sakuranetin, a major rice phytoalexin was purified approximately 985-fold from ultraviolet (UV)-irradiated rice leaves. The enzyme is not found in healthy tissues and was purified to a nearly homogeneous preparation in one step using adenosine-agarose affinity chromatography, with 1 g rice leaves (UV-irradiated) as starting material. Gel filtration chromatography resulted in an almost pure enzyme, as evidenced by a major band migrating to a position corresponding to a molecular mass of approximately 41 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The purified NOMT was strongly inhibited by Mn 2+, Ni 2+, Cu 2+, Zn 2+, Hg 2+, and Cd 2+, and to a low degree by Co 2+, Mg 2+, Ba 2+, Ca 2+ and ethylenediamine tetraacetic acid. The amino acid sequence of a NOMT cyanogen bromide (CNBr)-cleavage peptide was highly homologous to that of a caffeic acid 3- O-methyltransferase from maize, and about 70% of the amino acid sequence was obtained after sequencing the peptides generated by CNBr and/or formic acid hydrolysis. NOMT was also shown to be induced in a time-dependent manner, and purified from rice leaves treated with jasmonic acid and copper chloride.
ISSN:0168-9452
1873-2259
DOI:10.1016/S0168-9452(00)00223-5