title: Enzymatic activities for lignin monomer intermediates highlight the biosynthetic pathway of syringyl monomers in Robinia pseudoacacia.
abstract: Most of the known 4-coumarate:coenzyme A ligase (4CL) isoforms lack CoA-ligation activity for sinapic acid. Therefore, there is some doubt as to whether sinapic acid contributes to sinapyl alcohol biosynthesis. In this study, we characterized the enzyme activity of a protein mixture extracted from the developing xylem of Robinia pseudoacacia. The crude protein mixture contained at least two 4CLs with sinapic acid 4-CoA ligation activity. The crude enzyme preparation displayed negligible sinapaldehyde dehydrogenase activity, but showed ferulic acid 5-hydroxylation activity and 5-hydroxyferulic acid O-methyltransferase activity; these activities were retained in the presence of competitive substrates (coniferaldehyde and 5-hydroxyconiferaldehyde, respectively). 5-Hydroxyferulic acid and sinapic acid accumulated in the developing xylem of R. pseudoacacia, suggesting, in part at least, sinapic acid is a sinapyl alcohol precursor in this species.
authors.affiliation: Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Shigeto
authors.affiliation: Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
authors.forename: Yukie
authors.initials: Y
authors.lastname: Ueda
authors.affiliation: Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Sasaki
authors.affiliation: Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
authors.forename: Koki
authors.initials: K
authors.lastname: Fujita
authors.affiliation: Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan. y-tsutsu@agr.kyushu-u.ac.jp.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tsutsumi
mesh_terms: D053898:Biosynthetic Pathways; D003066:Coenzyme A Ligases / Q000235:genetics / Q000378:metabolism; D003373:Coumaric Acids / Q000378:metabolism*; D006900:Hydroxylation; D008031:Lignin / Q000096:biosynthesis*; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D010666:Phenylpropionates / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D031301:Robinia / Q000737:chemistry / Q000201:enzymology*; D052584:Xylem / Q000737:chemistry / Q000201:enzymology
chemical_list: D003373:Coumaric Acids; D010666:Phenylpropionates; D010940:Plant Proteins; C071744:5-hydroxyferulic acid; C073734:sinapinic acid; C496130:sinapyl alcohol; D008031:Lignin; C004999:ferulic acid; D008780:Methyltransferases; C019608:caffeate O-methyltransferase; D003066:Coenzyme A Ligases; C019943:4-coumarate-CoA ligase
keywords: 4-Coumarate:coenzyme A ligase (4CL); Lignin biosynthesis; Robinia pseudoacacia; Sinapic acid; Syringyl lignin