title: Mutations in cyclodextrin glycosyltransferase from Bacillus circulans enhance β-cyclization activity and β-cyclodextrin production.
abstract: Cyclodextrin glycosyltransferase (EC 2.4.1.19, CGTase) is used to produce cyclodextrins, which are cyclic glucans with many industrial applications. In the present study, the effects of the amino acid residue at position 577, which is located in calcium-binding site III (CaIII), on cyclization activity and cyclodextrin production were investigated by replacing Asp577 in CGTase from Bacillus circulans STB01 with glutamate, arginine, lysine, and histidine. The results showed that mutations D577E and D577R significantly increased the β-cyclization activity. The D577R mutant, in particular, displayed a 30.7% increase in the β-cyclization activity when compared to the wild-type CGTase. Furthermore, under conditions resembling industrial production processes, the D577R and D577E mutants displayed 9.1 and 2.0% enhancement in β-cyclodextrin production, respectively. More importantly, the higher β-cyclization activities resulted in a significant reduction in the amount of mutant protein required during the process. Thus, the two mutants were much more suitable for the industrial production of β-cyclodextrin than the wild-type enzyme.
authors.affiliation: State Key Laboratory of Food Science and Technology, ‡School of Food Science and Technology, and §Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University , Wuxi, Jiangsu 214122, People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Huang
authors.forename: Caiming
authors.initials: C
authors.lastname: Li
authors.forename: Zhengbiao
authors.initials: Z
authors.lastname: Gu
authors.forename: Li
authors.initials: L
authors.lastname: Cheng
authors.forename: Yan
authors.initials: Y
authors.lastname: Hong
authors.forename: Zhaofeng
authors.initials: Z
authors.lastname: Li
mesh_terms: D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001665:Binding Sites; D055162:Biocatalysis; D003500:Cyclization; D005964:Glucosyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D020125:Mutation, Missense; D047392:beta-Cyclodextrins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D047392:beta-Cyclodextrins; D005964:Glucosyltransferases; C019963:cyclomaltodextrin glucanotransferase; C031215:betadex
keywords: Asp577; cyclization activity; cyclodextrin; cyclodextrin glycosyltransferase; mutation