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Published on: June 11, 2010
Iridoid-specific glucosyltransferase from Gardenia jasminoides
Mai Nagatoshi1, Kazuyoshi Terasaka, Akito Nagatsu
1Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan.
The Journal of Biological Chemistry
|July 30, 2011
Summary
Scientists discovered a new enzyme, UDP-glucose:iridoid glucosyltransferase (UGT85A24), in Gardenia jasminoides. This enzyme is key to iridoid biosynthesis, specifically glucosylation, and shows high specificity for iridoid compounds.
Area of Science:
- Plant biochemistry
- Metabolic engineering
- Medicinal plant research
Background:
- Iridoids are vital plant secondary metabolites with pharmacological activity.
- They are precursors to important alkaloid classes.
- The glucosylation step in iridoid biosynthesis is poorly understood.
Purpose of the Study:
- To identify the enzyme responsible for iridoid glucosylation in Gardenia jasminoides.
- To elucidate the role of this enzyme in the biosynthesis of geniposide.
Main Methods:
- Isolation of a cDNA encoding UDP-glucose:iridoid glucosyltransferase (UGT85A24).
- Enzyme activity assays using various iridoid substrates.
- Analysis of UGT85A24 mRNA levels in response to methyl jasmonate treatment.
Main Results:
- UGT85A24 preferentially glucosylated 7-deoxyloganetin and genipin at the 1-O-hydroxyl group.
- The enzyme demonstrated high specificity for iridoid aglycones.
- UGT85A24 mRNA levels correlated with increased genipin glucosylation activity and iridoid accumulation.
Conclusions:
- UGT85A24 is a key enzyme in the iridoid biosynthetic pathway, specifically for geniposide production in G. jasminoides.
- Glucosylation likely occurs after methylation in the geniposide pathway.
- The enzyme's specificity suggests a targeted role in iridoid metabolism.
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