The enzyme is involved in the biosynthesis of the protective and allelophatic benzoxazinoid DIMBOA [(2R)-4-hydroxy-7-methoxy-3-oxo-3,4-dihydro-2H-1,4-benzoxazin] in some plants, most commonly from the family of Poaceae (grasses).
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The expected taxonomic range for this enzyme is: Zea mays
The enzyme is involved in the biosynthesis of the protective and allelophatic benzoxazinoid DIMBOA [(2R)-4-hydroxy-7-methoxy-3-oxo-3,4-dihydro-2H-1,4-benzoxazin] in some plants, most commonly from the family of Poaceae (grasses).
the only substance that serves as a substrate for the recombinant Bx7 is TRIBOA-Glc, neither the aglucone TRIBOA nor well-known substrates of plant O-methyltransferases are efficiently converted by the enzyme. In case of quercetin, a minor activity is detected. BX7 has no catalytic activity toward phenylpropanoids and flavonoids, e.g. apigenin is no substrate
i.e. TRIMBOA-Glc, enzyme BX7 methylates the C-7 hydroxyl group of TRIBOA-Glc. Recombinant BX7 also accepts TRIMBOA-Glc as substrate and methylates the hydroxyl group at C-7
gene Bx7 is part of a small gene family consisting of 15 members with higher sequence similarity to each other (62 to 99%), BX7 shows high similarity to BX14
Bx7 is required for biosynthesis of the benzoxazinoid pesticide 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one, i.e. DIMBOA, that is synthesized in seedlings and stored as glucoside in maize
the enzyme is involved in benzoxazinoid formation in maize, overview. A 2-oxoglutarate-dependent dioxygenase (BX13, UniProt ID A0A1P8SET2) catalyzes the conversion of 2-(2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one)-beta-D-glucopyranose (DIMBOA-Glc) into a benzoxazinoid intermediate, 2-(2,4,7-trihydroxy-8-methoxy-1,4-benzoxazin-3-one)-beta-D-glucopyranose (TRIMBOA-Glc), by an uncommon reaction involving hydroxylation and a likely ortho-rearrangement of a methoxy group. TRIMBOA-Glc is then converted to 2-(2,4-dihydroxy-7,8-dimethoxy-1,4-benzoxazin-3-one)-beta-D-glucopyranose (DIM2BOA-Glc) by an O-methyltransferase BX7. Furthermore, an O-methyltransferase BX14 (UniProt ID A0A1P8SEU3) converts DIM2BOA-Glc to 2-(2-hydroxy-4,7,8-trimethoxy-1,4-benzoxazin-3-one)-beta-D-glucopyranose (HDM2BOA-Glc). HDM2BOA-Glc is known to be induced by biotic stresses such as pathogen infestation and insect feeding. The inducibility of HDM2BOA-Glc is associated with a stronger induction of genes Bx13 and Bx14. DIM2BOA-Glc and HDM2BOA-Glc specifically increase plant resistance against aphids
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CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
DNA and amino acid sequence determination and analysis, Bx7 maps to the cluster of Bx genes on the short arm of chromosome 4, Bx7 is located 9 cM distal to the marker adh2 at position 47, phylogenetic analysis, expression as His-tagged enzyme in Escherichia coli
gene BX7, DNA and amino acid sequence determination and analysis, the QTL Bb3 on chromosome 4 comprises the O-methyltransferase gene Bx7, identifies by quantitative trait locus (QTL) mapping, overview, phylogenetic tree, functional recombinant expression of N-terminally His-tagged enzyme in Escherichia coli