TAP CHI SINH HOC 2020, 42(1): 21–29 DOI: 10.15625/0866-7160/v42n1.13833 21 EXPRESSION OF GENE ENCODING FLAVONOL SYNTHASE ISOLATING FROM TRUNG DU XANH TEA (Camellia sinensis var. macrophylla) IN E. coli Hoang Thi Thu Yen 1,* , Vu Thi Lan 1 , Huynh Thi Thu Hue 2 1 University of Sciences, Thai Nguyen University, Thai Nguyen, Vietnam 2 Institute of Genome Research, VAST, Vietnam Received 20 May 2019, accepted 10 January 2020 ABSTRACT Common flavonols in plants including quercetin, kaempferol and myricetin are synthesized from dihydroflavonols (dihydroquercetin-DHQ, dihydrokaempferol-DHK and dihydromyricetin- DHM) by flavonol synthase (FLS). In tea, FLS has been shown to metabolize dihydroquercetin to quercetin. The FLS gene was cloned and sequenced from the cultivated tea (Camellia sinensis var. macrophylla) in Thai Nguyen province. In this study, we presented the results of optimizing and designing an expression vector for recombinant FLS (recombinant FLS-rFLS). The FLS gene was ligated completely to the pET32a (+) vector, then expressed in E. coli Rosetta1 and Rosetta2 strain. Using 1mM IPTG to induce the expression of rFLS at 37 o C, rFLS was obtained with 52.83 kDa in size and existed predominantly as insoluble form. E. coli Rosetta1 pET32a (+)_FLS produces rFLS in the soluble fraction than E. coli Rosetta2 pET32a (+)_FLS. Next, E. coli Rosetta1 pET32a (+)_FLS was optimized for expression at temperatures of 30 o C, 23 o C and 16 o C (24 and 48 hours). After being induced for expression with 1mM IPTG in 48 hours and cultured at 16 o C, E. coli Rosetta1 strain containing pET32a (+) FLS produced the largest amount of rFLS in the soluble form. Keywords: Camelia sinensis, dihydroquercetin metabolism, flavonol synthase, recombinant FLS. Citation: Hoang Thi Thu Yen, Vu Thi Lan, Huynh Thi Thu Hue, 2020. Expression of gene encoding flavonol synthase isolating from trung du xanh tea (Camellia sinensis var. macrophylla) in E. coli. Tap chi Sinh hoc, 42(1): 21–29. https://doi.org/10.15625/0866-7160/v42n1.13833. *Corresponding author email: yenhtt@tnus.edu.vn ©2020 Vietnam Academy of Science and Technology (VAST)