Chow Sih Yao, Wang Yung Lin, Hsieh Yu Chiao, Lee Guan Chiun, Liaw Shwu Huey
Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei 11221, Taiwan.
Department of Life Science, National Taiwan Normal University, No. 162, Sec. 1, Heping East Road, Taipei 11677, Taiwan.
Acta Crystallogr F Struct Biol Commun. 2017 Nov 1;73(Pt 11):588-594. doi: 10.1107/S2053230X17014303. Epub 2017 Oct 20.
Trehalose synthase (TS) catalyzes the reversible conversion of maltose to trehalose and belongs to glycoside hydrolase family 13 (GH13). Previous mechanistic analysis suggested a rate-limiting protein conformational change, which is probably the opening and closing of the active site. Consistently, crystal structures of Deinococcus radiodurans TS (DrTS) in complex with the inhibitor Tris displayed an enclosed active site for catalysis of the intramoleular isomerization. In this study, the apo structure of the DrTS N253F mutant displays a new open conformation with an empty active site. Analysis of these structures suggests that substrate binding induces a domain rotation to close the active site. Such a substrate-induced domain rotation has also been observed in some other GH13 enzymes.
海藻糖合酶（TS）催化麦芽糖向海藻糖的可逆转化，属于糖苷水解酶家族13（GH13）。先前的机理分析表明存在限速蛋白构象变化，这可能是活性位点的打开和关闭。一致地，与抑制剂Tris复合的耐辐射球菌TS（DrTS）的晶体结构显示出用于催化分子内异构化的封闭活性位点。在本研究中，DrTS N253F突变体的无配体结构显示出具有空活性位点的新开放构象。对这些结构的分析表明，底物结合会诱导结构域旋转以关闭活性位点。在其他一些GH13酶中也观察到了这种底物诱导的结构域旋转。
