title: UGT74D1 catalyzes the glucosylation of 2-oxindole-3-acetic acid in the auxin metabolic pathway in Arabidopsis.
abstract: IAA is a naturally occurring auxin that plays a crucial role in the regulation of plant growth and development. The endogenous concentration of IAA is spatiotemporally regulated by biosynthesis, transport and its inactivation in plants. Previous studies have shown that the metabolism of IAA to 2-oxindole-3-acetic acid (OxIAA) and OxIAA-glucoside (OxIAA-Glc) may play an important role in IAA homeostasis, but the genes involved in this metabolic pathway are still unknown. In this study, we show that UGT74D1 catalyzes the glucosylation of OxIAA in Arabidopsis. By screening yeasts transformed with Arabidopsis UDP-glycosyltransferase (UGT) genes, we found that OxIAA-Glc accumulates in the culture media of yeasts expressing UGT74D1 in the presence of OxIAA. Further, we showed that UGT74D1 expressed in Escherichia coli converts OxIAA to OxIAA-Glc. The endogenous concentration of OxIAA-Glc decreased by 85% while that of OxIAA increased 2.5-fold in ugt74d1-deficient mutants, indicating the major role of UGT74D1 in OxIAA metabolism. Moreover, the induction of UGT74D1 markedly increased the level of OxIAA-Glc and loss of root gravitropism. These results indicate that UGT74D1 catalyzes a committed step in the OxIAA-dependent IAA metabolic pathway in Arabidopsis.
authors.affiliation: United Graduate School of Agricultural Science, Tokyo University of Agriculture & Technology, Tokyo, 183-8509 Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Tanaka
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Hayashi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Natsume
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kamiya
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sakakibara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawaide
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kasahara
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D055162:Biocatalysis / Q000187:drug effects; D053898:Biosynthetic Pathways / Q000187:drug effects / Q000235:genetics; D004790:Enzyme Induction / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism*; D006031:Glycosylation / Q000187:drug effects; D016695:Glycosyltransferases / Q000096:biosynthesis; D018522:Gravitropism / Q000187:drug effects; D007210:Indoleacetic Acids / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D053858:Metabolic Networks and Pathways / Q000187:drug effects / Q000235:genetics; D000078183:Oxindoles; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D000078183:Oxindoles; C003013:2-oxindole-3-acetic acid; D016695:Glycosyltransferases; D005964:Glucosyltransferases; C000591372:UGT74D1 protein, Arabidopsis
keywords: Arabidopsis; Auxin; Glucosyltransferase; Metabolism; Plant hormone