Structures of trehalose synthase from Deinococcus radiodurans reveal that a closed conformation is involved in catalysis of the intramolecular isomerization

Yung Lin Wang, Sih Yao Chow, Yi Ting Lin, Yu Chiao Hsieh, Guan Chiun Lee, Shwu Huey Liaw

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Trehalose synthase catalyzes the simple conversion of the inexpensive maltose into trehalose with a side reaction of hydrolysis. Here, the crystal structures of the wild type and the N253A mutant of Deinococcus radiodurans trehalose synthase (DrTS) in complex with the inhibitor Tris are reported. DrTS consists of a catalytic (β/α)8 barrel, subdomain B, a C-terminal β domain and two TS-unique subdomains (S7 and S8). The C-terminal domain and S8 contribute the majority of the dimeric interface. DrTS shares high structural homology with sucrose hydrolase, amylosucrase and sucrose isomerase in complex with sucrose, in particular a virtually identical active-site architecture and a similar substrate-induced rotation of subdomain B. The inhibitor Tris was bound and mimics a sugar at the -1 subsite. A maltose was modelled into the active site, and subsequent mutational analysis suggested that Tyr213, Glu320 and Glu324 are essential within the +1 subsite for the TS activity. In addition, the interaction networks between subdomains B and S7 seal the active-site entrance. Disruption of such networks through the replacement of Arg148 and Asn253 with alanine resulted in a decrease in isomerase activity by 8-9-fold and an increased hydrolase activity by 1.5-1.8-fold. The N253A structure showed a small pore created for water entry. Therefore, our DrTS-Tris may represent a substrate-induced closed conformation that will facilitate intramolecular isomerization and minimize disaccharide hydrolysis.

Original languageEnglish
Pages (from-to)3144-3154
Number of pages11
JournalActa Crystallographica Section D: Biological Crystallography
Volume70
Issue number12
DOIs
Publication statusPublished - 2014 Dec 1

Keywords

  • conformational change
  • enzyme mechanism
  • glycoside hydrolase family 13
  • intramolecular isomerization
  • trehalose synthase

ASJC Scopus subject areas

  • Structural Biology

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