A fusion protein strategy for soluble expression of Stevia glycosyltransferase UGT76G1 in Escherichia coli

作者：Chen, Liangliang; Sun, Ping; Li, Yan^*; Yan, Ming; Xu, Lin; Chen, Kequan; Ouyang, Pingkai

来源：3 Biotech, 2017, 7(6): 356.

DOI：10.1007/s13205-017-0943-y

• Fusion partner
• Inclusion body
• Rebaudioside A
• Stevioside
• UGT76G1
• Glucosyltransferase

The UDP-glucosyltransferase UGT76G1 from Stevia rebaudiana converts stevioside to rebaudioside A via a one-step glycosylation reaction, which increases the amount of sweet-tasting rebaudioside A and decreases the amount of stevioside that has a bitter aftertaste. This enzyme could, therefore, conceivably be used to improve the organoleptic properties of steviol glycosides and offer a cost-effective preparation of high-purity rebaudioside A. Producing soluble enzymes by overexpression is a prerequisite for large-scale biocatalysis. However, most of the UGT76G1 overexpressed in Escherichia coli is in inclusion bodies. In this study, three N-terminal fusion partners, 3'-phosphoadenosine-5'-phosphatase (CysQ), 2-keto-3-deoxy-6-phosphogluconate aldolase (EDA) and N-utilisation substance A (NusA), were tested to improve UGT76G1 expression and solubility in E. coli. Compared with the fusion-free protein, the solubility of UGT76G1 was increased 40% by fusion with CysQ, and the glucosyltransferase activity of the crude extract was increased 82%. This successful CysQ fusion strategy could be applied to enhance the expression and solubility of other plant-derived glucosyltransferases and presumably other unrelated proteins in the popular, convenient and cost-effective E. coli host.

• 出版日期2017-10-3
• 单位三峡大学