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Regiospecific hydroxylation of isoflavones by cytochrome P450 81E enzymes from Medicago truncatula
Author(s) -
Liu ChangJun,
Huhman David,
Sumner Lloyd W.,
Dixon Richard A.
Publication year - 2003
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2003.01893.x
Subject(s) - medicago truncatula , cytochrome p450 , biology , isoflavonoid , hydroxylation , biochemistry , endoplasmic reticulum , yeast , isoflavones , complementary dna , subfamily , microsome , enzyme , gene , genetics , flavonoid , antioxidant , symbiosis , bacteria
Summary Mining of Medicago truncatula EST databases and screening of a root cDNA library led to the identification of three cytochrome P450 81E subfamily members. Two were functionally characterized by expression in yeast. The recombinant enzymes in yeast microsomes utilized the same isoflavone substrates, but produced different products hydroxylated at the 2′ and/or 3′ positions of the B‐ring. When transiently expressed in alfalfa leaves, green fluorescent protein (GFP) fusions of the isoflavone 2′‐ and 3′‐hydroxylases localized to the endoplasmic reticulum. The isoflavone 2′‐hydroxylase was functional when expressed in Arabidopsis. Differential tissue‐specific and biotic/abiotic stress‐dependent expression patterns were observed for the isoflavone 2′‐hydroxylase and 3′‐hydroxylase genes, suggesting differential involvement of 2′‐ and 3′‐hydroxylated isoflavonoids in pathogen defense and insect‐induced responses, respectively, in Medicago .