title: Molecular dynamic analysis of mutant Y195I α-cyclodextrin glycosyltransferase with switched product specificity from α-cyclodextrin to γ-cyclodextrin.
abstract: Alpha-cyclodextrin (α-CD) glycosyltransferase (α-CGTase) can convert starch into α-CD blended with various proportions of β-cyclodextrin (β-CD) and/or γ-cyclodextrin (γ-CD). In this study, we verified the catalytic characteristics of purified Y195I α-CGTase and elucidated the mechanism of action with molecular dynamic (MD) simulations. We found that purified Y195I α-CGTase produced less α-CD, slightly more β-CD, and significantly more γ-CD than wild-type α-CGTase. Correspondingly, α-CD-based K m values increased, and β-CD- and γ-CD-based K m values decreased. MD simulation studies revealed that the dynamic trajectories of the substrate oligosaccharide chain in the mutant CGTase binding site were significantly different from those in the wild-type enzyme, with reduced hydrophobic interaction, finally resulting in different product specificity and more γ-CD formation.
authors.affiliation: Center for Quantitative Biology, AAIS, Peking University, Beijing, China, 100871.
authors.forename: Fangjin
authors.initials: F
authors.lastname: Chen
authors.forename: Ting
authors.initials: T
authors.lastname: Xie
authors.forename: Yang
authors.initials: Y
authors.lastname: Yue
authors.forename: Shijun
authors.initials: S
authors.lastname: Qian
authors.forename: Yapeng
authors.initials: Y
authors.lastname: Chao
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Pei
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005964:Glucosyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D020125:Mutation, Missense; D013379:Substrate Specificity; D046950:Thermoanaerobacterium / Q000201:enzymology; D047391:alpha-Cyclodextrins / Q000378:metabolism*; D047408:gamma-Cyclodextrins / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D047391:alpha-Cyclodextrins; D047408:gamma-Cyclodextrins; D005964:Glucosyltransferases; C019963:cyclomaltodextrin glucanotransferase; C023792:gamma-cyclodextrin; C032613:alpha-cyclodextrin