title: Mutations enhance β-cyclodextrin specificity of cyclodextrin glycosyltransferase from Bacillus circulans.
abstract: The effects of amino acid residue at position 31 in the neighborhood of calcium binding site I (CaI) on product specificity of cyclodextrin glycosyltransferase (EC 2.4.1.19, CGTase) were investigated by replacing Ala31 in the CGTase from Bacillus circulans STB01 with arginine, proline, threonine, serine and glycine. The results showed that the mutations A31R, A31P, and A31T resulted in the increases in β-cyclodextrin-forming activity and β-cyclodextrin production, indicating that these mutations enhanced β-cyclodextrin specificity of the CGTase. Especially the mutant A31R displayed approximately 26% increase in β-cyclodextrin production with a concomitant 41% decrease in α-cyclodextrin production when compared to the wild-type CGTase. Thus, it was much more suitable for the industrial production of β-cyclodextrin than the wild-type enzyme. The enhanced β-cyclodextrin specificity of the mutants might be a result of stabilizing CaI, which also suggested that CaI might play an important role in cyclodextrin product specificity of CGTase.
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi 214122, China; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China.
authors.forename: Zhaofeng
authors.initials: Z
authors.lastname: Li
authors.affiliation: School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Ban
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi 214122, China; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China. Electronic address: zhengbiaogu@jiangnan.edu.cn.
authors.forename: Zhengbiao
authors.initials: Z
authors.lastname: Gu
authors.affiliation: School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
authors.forename: Caiming
authors.initials: C
authors.lastname: Li
authors.affiliation: School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
authors.forename: Min
authors.initials: M
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi 214122, China; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Hong
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
authors.forename: Li
authors.initials: L
authors.lastname: Cheng
mesh_terms: D001407:Bacillus / Q000201:enzymology*; D005964:Glucosyltransferases / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D047392:beta-Cyclodextrins / Q000378:metabolism*
chemical_list: D047392:beta-Cyclodextrins; D005964:Glucosyltransferases; C019963:cyclomaltodextrin glucanotransferase
keywords: Alanine 31; Cyclodextrin; Cyclodextrin glycosyltransferase; Mutation; Product specificity