A Flavone-5-O-glycosyltransferase Obtained through Domain Shuffling and Its Application in the Bioproduction of Luteolin-5-O-glucoside

Luteolin-5-O-glucoside is a rare luteolin glycoside compound with enormous potential for application. In order to promote sustainability and a circular economy, environmentally friendly catalysts and catalytic processes are in demand to produce luteolin-5-O-glucoside. Using glycosyltransferase transformation is an efficient method for synthesizing glycosylated flavonoids. However, most reported glycosyltransferases have not been able to catalyze glycosylation on the 5-OH site, and a method for the sustainable production of luteolin-5-O-glucoside has not been established. In this paper, a glycosyltransferase DoUGT71A15 was cloned from Dichanthelium oligosanthes. The N-terminal fragment of ZmUGT707A8 (Met1–Met93) was inserted into the N-terminus of DoUGT71A15 by domain shuffling, and a biological catalyst ZmDo was obtained. ZmDo could convert luteolin to luteolin-5-O-glucoside with Km and kcat/Km values of 0.13 mM and 1355.8 s–1·M–1, respectively. Then, the catalytic mechanism of region selectivity of ZmDo was studied by using bioinformatics methods, and the key site E89 was identified through alanine scanning. Finally, the strain BSZ containing the UDPG circulatory system, which could use cellobiose as a substrate and recycle UDP to synthesize UDPG, was used for efficient production of luteolin-5-O-glucoside, with a yield of 2253 mg/L and a molar conversion rate of 95.8%. This research obtained a novel flavone-5-OH glycosyltransferase and produced luteolin-5-O-glucoside by bioconversion, which provided the possibility for sustainable production and application of luteolin-5-O-glucoside.