Crystal structures of D-psicose 3-epimerase from Clostridium cellulolyticum H10 and its complex with ketohexose sugars.
10.1007/s13238-012-2026-5
- Author:
Hsiu-Chien CHAN
1
;
Yueming ZHU
;
Yumei HU
;
Tzu-Ping KO
;
Chun-Hsiang HUANG
;
Feifei REN
;
Chun-Chi CHEN
;
Yanhe MA
;
Rey-Ting GUO
;
Yuanxia SUN
Author Information
1. Industrial Enzymes National Engineering Laboratory, Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
- Publication Type:Journal Article
- MeSH:
Binding Sites;
Biocatalysis;
Catalytic Domain;
Clostridium cellulolyticum;
enzymology;
Hexoses;
chemistry;
Manganese;
chemistry;
Protein Structure, Quaternary;
Racemases and Epimerases;
chemistry;
metabolism;
Substrate Specificity
- From:
Protein & Cell
2012;3(2):123-131
- CountryChina
- Language:English
-
Abstract:
D-psicose 3-epimerase (DPEase) is demonstrated to be useful in the bioproduction of D-psicose, a rare hexose sugar, from D-fructose, found plenty in nature. Clostridium cellulolyticum H10 has recently been identified as a DPEase that can epimerize D-fructose to yield D-psicose with a much higher conversion rate when compared with the conventionally used DTEase. In this study, the crystal structure of the C. cellulolyticum DPEase was determined. The enzyme assembles into a tetramer and each subunit shows a (β/α)(8) TIM barrel fold with a Mn(2+) metal ion in the active site. Additional crystal structures of the enzyme in complex with substrates/products (D-psicose, D-fructose, D-tagatose and D-sorbose) were also determined. From the complex structures of C. cellulolyticum DPEase with D-psicose and D-fructose, the enzyme has much more interactions with D-psicose than D-fructose by forming more hydrogen bonds between the substrate and the active site residues. Accordingly, based on these ketohexose-bound complex structures, a C3-O3 proton-exchange mechanism for the conversion between D-psicose and D-fructose is proposed here. These results provide a clear idea for the deprotonation/protonation roles of E150 and E244 in catalysis.
