Structural basis for glucosylsucrose synthesis by a member of theα-1,2-glucosyltransferase family  

作　　者：Qiuyu Han Yuan Yao Yuhan Liu Wenlu Zhang Jinyi Yu Heya Na Tianhao Liu Kevin HMayo Jiyong Su 

机构地区：[1]Engineering Research Center of Glycoconjugates Ministry of Education,Jilin Provincial Key Laboratory of Chemistry and Biology of Changbai Mountain Natural Drugs,School of Life Sciences,Northeast Normal University,Changchun 130024,China [2]Media Academy,Jilin Engineering Normal University,Changchun 130052,China [3]Department of Biochemistry,Molecular Biology&Biophysics,University of Minnesota,Minneapolis,MN 55455,USA

出　　处：《Acta Biochimica et Biophysica Sinica》2022年第4期537-547,共11页生物化学与生物物理学报（英文版）

基　　金：the grants from the National Natural Science Foundation of China(No.32171255);the Fundamental Research Funds for the Central Universities(No.2412020ZD011);Industrialization Cultivation Planning Project of Jilin Provincial Department of Education(No.JJKH20221168CY)。

摘　　要：Glucosylsucroses are potentially useful as additives in cosmetic and pharmaceutical formulations.Although enzymatic synthesis of glucosylsucroses is the most efficient method for their production,the key enzyme that produces them has remained unknown.Here,we report that glucosylsucrose synthase from Thermosynechococcus elongatus(TeGSS)catalyzes the synthesis of glucosylsucrose using sucrose and UDP-glucose as substrates.These saccharides are homologous to glucosylsucroses produced by Nostoc sp.PCC 7120(referred to as protein alr1000).When the ratio of UDP-glucose to sucrose is relatively high,TeGSS from cyanobacteria can hydrolyze excess UDP-glucose to UDP and glucose,indicating that sucrose provides a feedback mechanism for the control of glucosylsucrose synthesis.In the present study,we solved the crystal structure of TeGSS bound to UDP and sucrose.Our structure shows that the catalytic site contains a circular region that may allow glucosylsucroses with a right-hand helical structure to enter the catalytic site.Because active site residues Tyr18 and Arg179 are proximal to UDP and sucrose,we mutate these residues(i.e.,Y18F and R179A)and show that they exhibit very low activity,supporting their role as catalytic groups.Overall,our study provides insight into the catalytic mechanism of TeGSS.

关 键 词：catalytic mechanism crystal structure glucosylsucrose UDP-GLUCOSE α-1 2-glucosyltransferase 

分 类 号：O64[理学—物理化学]