Molecular cloning and characterization of UDP-glucose: furaneol glucosyltransferase gene from Japanese

Abstract

2,5-Dimethyl-4-hydroxy-3(2H)-furanone (furaneol) is an important aroma compound in fruits, such as pineapple and strawberry, and is reported to contribute to the strawberry-like note in some wines. Several grapevine species are used in winemaking, and furaneol is one of the characteristic aroma compounds in wines made from American grape (Vitis labrusca) and its hybrid grape, similar to methyl anthranilate. Muscat Bailey A is a hybrid grape variety [V. labrusca (Bailey) x V. vinifera (Muscat Hamburg)], and its wine is one of the most popular in Japan. The inclusion of Muscat Bailey A in the ‘International List of Vine and Varieties and their Synonyms’ managed by the ‘International Organisation of Vine and Wine (OIV)’ in 2013 has further fueled its popularity among winemakers and researchers worldwide. Most Muscat Bailey A wines have unique characters, such as a light mouth feel which is derived from the low concentration of proanthocyanidins (1). In addition, Muscat Bailey A grapes also biosynthesize and accumulate furaneol, suggesting that furaneol might be essential for the characteristic flavor of this wine (2). The previous study identified furaneol glucoside from the juice of Muscat Bailey A, using high-performance liquid chromatography–tandem mass spectrometry, and this was followed by its isolation from some fruits such as strawberry and tomato (3). Furaneol glucoside is a significant ‘aroma precursor of wine’ because furaneol is liberated from it during alcoholic fermentation. In this study, we have identified a glucosyltransferase gene from Muscat Bailey A (UGT85K14), which is responsible for the glucosylation of furaneol (4). Recombinant UGT85K14 expressed in Escherichia coli is able to transfer a glucose moiety from UDP-glucose to the hydroxy group of furaneol, indicating that this gene might be UDP-glucose: furaneol glucosyltransferase in Muscat Bailey A. Furaneol glucoside content in Muscat Bailey A berry during maturation might be controlled by the expression of UGT85K14 along with the biosynthesis of furaneol. On the other hand, UGT85K14 was expressed in the representative grape cultivars regardless of species. In addition to Muscat Bailey A, the corresponding genes from Pinot Noir (V. vinifera) and Concord (V. labrusca) have been identified and characterized. Sequence analysis and the characterization of recombinant proteins demonstrated that furaneol glucoside content was regulated by the biosynthesis of furaneol in grape species (V. vinifera and V. labrusca), and both species might have evolved and diverged after the molecular evolution of this gene.

References
1. Ichikawa, M. et al. (2011) Food Sci. Technol. Res. 17, 335-339. 2. Kobayashi, H. et al. (2013) Vitis 52, 9-11. 3. Sasaki, K. et al. (2015) Am. J. Enol. Vitic. 66, 91-94. 4. Sasaki, K. et al. (2015) J. Exp. Bot. 66, 6167-6174.