Enzymatic and structural characterization of hydrolysis of gibberellin A4 glucosyl ester by a rice β-d-glucosidase

- Os3BGlu6 was identified as a gibberellin A4 glucosyl ester β-glucosidase.
- Os3BGlu6 acid-base mutants transfer glucose from its gibberellin A4 ester to azide.
- A covalent intermediate with glucose builds-up in the Os3BGlu6 E178Q mutant.
- The X-ray structure of the intermediate clarifies critical H-bonding at glucose O2.
- H-bonding at glucosyl O2 was unclear in previous structures with 2-fluoroglucoside.