Download MendeleyStructural Insights into the Catalytic Mechanism of a Plant Diterpene Glycosyltransferase SrUGT76G1.
Liu, Z., Li, J., Sun, Y., Zhang, P., Wang, Y.(2020) Plant Commun 1: 100004-100004
- PubMed: 33404544
- DOI: https://doi.org/10.1016/j.xplc.2019.100004
- Primary Citation of Related Structures:
6KVI, 6KVJ, 6KVK, 6KVL - PubMed Abstract:
Diterpene glycosyltransferase UGT76G1 from Stevia rebaudiana (SrUGT76G1) is key to the generation of economically important steviol glycosides (SGs), a group of natural sweeteners with high-intensity sweetness. SrUGT76G1 accommodates a wide range of steviol-derived substrates and many other small molecules. We report here the crystal structures of SrUGT76G1 in complex with multiple ligands to answer how this enzyme recognizes diterpenoid aglycones and catalyzes the 1,3-sugar chain branching. A spacious pocket for sugar-acceptor binding was observed from the determined SrUGT76G1 structures, which can explain its broad substrate spectrum. Residues Gly87 and Leu204 lining the pocket play key roles in switching between diterpenoid and flavonoid glucosylation. An engineered mutant of SrUGT76G1, T284S, could catalyze a selectively increased production of next-generation sweetener rebaudioside M, with diminished side product of rebaudioside I. Taken together, these resutls provide significant insights into molecular basis of the substrate specificity of scarcely documented diterpenoid glycosyltransferases and would facilitate the structure-guided glycoengineering to produce diversified diterpenoids with new activities.
Organizational Affiliation:
Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
