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J Biosci Bioeng

Title:		Characterization of an O-methyltransferase specific to guaiacol-type benzenoids from the flowers of loquat (Eriobotrya japonica)
Author(s):		Koeduka T; Kajiyama M; Furuta T; Suzuki H; Tsuge T; Matsui K;
Address:		"Department of Biological Chemistry, Faculty of Agriculture and Division of Agricultural Sciences, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi 753-8515, Japan. Electronic address: takaori@yamaguchi-u.ac.jp. Department of Biological Chemistry, Faculty of Agriculture and Division of Agricultural Sciences, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi 753-8515, Japan. Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. Department of Research and Development, Kazusa DNA Research Institute, Chiba 292-0818, Japan"
Journal Title:		J Biosci Bioeng
Year:		2016
Volume:		20160726
Issue:		6
Page Number:		679 - 684
DOI:		10.1016/j.jbiosc.2016.06.012
ISSN/ISBN:		1347-4421 (Electronic) 1347-4421 (Linking)
Abstract:		"Volatile benzenoids, including methyl p-methoxybenzoate, p-anisaldehyde, and p-anisalcohol, are responsible for the sweet and characteristic fragrance of loquat (Eriobotrya japonica, Rosaceae) flowers. Although the full pathway of volatile benzenoid synthesis has yet to be elucidated, their chemical structures suggest that O-methyltransferases are present in loquat and function in the methylation of the para-OH groups. In the present study, we used RNA-sequencing to identify four loquat genes (EjOMT1, EjOMT2, EjOMT3, and EjOMT4) that encode O-methyltransferases. We found that EjOMT1 was highly expressed in floral tissues, with an expression pattern that coincided with changes in intracellular volatile benzenoids during flower development. Recombinant EjOMT1 protein expressed in Escherichia coli showed the highest activity towards guaiacol with a K(m) value of 35 muM. Furthermore, the protein also showed lesser activities towards guaiacol-type benzenoids including eugenol, isoeugenol, vanillin, and ferulic acid, in addition to much weaker activities towards catechol and p-hydroxybenzenoid derivatives. However, no activity was shown towards phenylpropenes without m-methoxy substitution, t-anol and chavicol. Taken together, our findings indicate that EjOMT1 has a broad substrate specificity towards compounds with both para-OH and meta-OCH(3) groups, unlike previously characterized O-methyltransferases for volatile benzenoid/phenylpropanoid biosynthesis"
Keywords:		"Amino Acid Sequence Benzaldehydes/metabolism Cloning, Molecular Eriobotrya/enzymology/*genetics Eugenol/analogs & derivatives/metabolism Flowers/chemistry/genetics/metabolism Guaiacol/*metabolism Methyltransferases/*genetics/*metabolism Phylogeny Sequence;"
Notes:		"MedlineKoeduka, Takao Kajiyama, Mami Furuta, Takumi Suzuki, Hideyuki Tsuge, Tomohiko Matsui, Kenji eng Japan 2016/07/31 J Biosci Bioeng. 2016 Dec; 122(6):679-684. doi: 10.1016/j.jbiosc.2016.06.012. Epub 2016 Jul 26"