Lin-Feng You1,2, Jia-Jun Huang1, Tao Wei1,3, Shu-Ling Lin1, Bing-Hua Jiang4, Li-Qiong Guo5,6, Jun-Fang Lin7,8. 1. College of Food Science & Institute of Food Biotechnology, South China Agricultural University, Guangzhou, 510640, Guangdong, China. 2. Chongqing Key Laboratory of Catalysis and Functional Organic Molecule, Chongqing Technology and Business University, Chongqing, 400067, China. 3. Research Center for Micro-Ecological Agent Engineering and Technology of Guangdong Province, Guangzhou, 510640, Guangdong, China. 4. Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, 19107, USA. 5. College of Food Science & Institute of Food Biotechnology, South China Agricultural University, Guangzhou, 510640, Guangdong, China. guolq@scau.edu.cn. 6. Research Center for Micro-Ecological Agent Engineering and Technology of Guangdong Province, Guangzhou, 510640, Guangdong, China. guolq@scau.edu.cn. 7. College of Food Science & Institute of Food Biotechnology, South China Agricultural University, Guangzhou, 510640, Guangdong, China. linjf@scau.edu.cn. 8. Research Center for Micro-Ecological Agent Engineering and Technology of Guangdong Province, Guangzhou, 510640, Guangdong, China. linjf@scau.edu.cn.
Abstract
OBJECTIVES: Taxoid 10β-O-acetyl transferase (DBAT) was redesigned to enhance its catalytic activity and substrate preference for baccatin III and taxol biosynthesis. RESULTS: Residues H162, D166 and R363 were determined as potential sites within the catalytic pocket of DBAT for molecular docking and site-directed mutagenesis to modify the activity of DBAT. Enzymatic activity assays revealed that the kcat/KM values of mutant H162A/R363H, D166H, R363H, D166H/R363H acting on 10-deacetylbaccatin III were about 3, 15, 26 and 60 times higher than that of the wild type of DBAT, respectively. Substrate preference assays indicated that these mutants (H162A/R363H, D166H, R363H, D166H/R363H) could transfer acetyl group from unnatural acetyl donor (e.g. vinyl acetate, sec-butyl acetate, isobutyl acetate, amyl acetate and isoamyl acetate) to 10-deacetylbaccatin III. CONCLUSION: Taxoid 10β-O-acetyl transferase mutants with redesigned active sites displayed increased catalytic activities and modified substrate preferences, indicating their possible application in the enzymatic synthesis of baccatin III and taxol.
OBJECTIVES:Taxoid 10β-O-acetyl transferase (DBAT) was redesigned to enhance its catalytic activity and substrate preference for baccatin III and taxol biosynthesis. RESULTS: Residues H162, D166 and R363 were determined as potential sites within the catalytic pocket of DBAT for molecular docking and site-directed mutagenesis to modify the activity of DBAT. Enzymatic activity assays revealed that the kcat/KM values of mutant H162A/R363H, D166H, R363H, D166H/R363H acting on 10-deacetylbaccatin III were about 3, 15, 26 and 60 times higher than that of the wild type of DBAT, respectively. Substrate preference assays indicated that these mutants (H162A/R363H, D166H, R363H, D166H/R363H) could transfer acetyl group from unnatural acetyldonor (e.g. vinyl acetate, sec-butyl acetate, isobutyl acetate, amyl acetate and isoamyl acetate) to 10-deacetylbaccatin III. CONCLUSION:Taxoid 10β-O-acetyl transferase mutants with redesigned active sites displayed increased catalytic activities and modified substrate preferences, indicating their possible application in the enzymatic synthesis of baccatin III and taxol.