Oligosaccharide binding to family 11 xylanases: both covalent intermediate and mutant product complexes display B-2,B-5 conformations at the active centre

E Sabini, K S Wilson, S Danielsen, M Schulein, G J Davies

Research output: Contribution to journalArticlepeer-review

Abstract

The glycoside hydrolase sequence-based classification reveals two families of enzymes which hydrolyse the beta -1,4-linked backbone of xylan, xylanases, termed families GH-10 and GH-11. Family GH-11 xylanases are intriguing in that catalysis is performed via a covalent intermediate adopting an unusual B-2,B-5 (boat) conformation, a conformation which also fulfils the stereochemical constraints of the oxocarbenium ion-like transition state. Here, the 1.9 Angstrom structure of a nucleophile, E94A, mutant of the Xyn11 from Bacillus agaradhaerens in complex with xylotriose is presented. Intriguingly, this complex also adopts the B-2,B-5 conformation in the -1 subsite, with the vacant space provided by the Glu --> Ala mutation allowing the sugar to adopt the alpha -configuration at C1. The structure of the covalent 2-deoxy-2-fluoroxylobiosyl-enzyme intermediate has been extended to atomic (1.1 Angstrom) resolution.

Original languageEnglish
Pages (from-to)1344-1347
Number of pages4
JournalActa Crystallographica. Section D, Biological Crystallography
Volume57
Publication statusPublished - Sept 2001

Keywords

  • GLYCOSYL-ENZYME INTERMEDIATE
  • CRYSTAL-STRUCTURE
  • MACROMOLECULAR STRUCTURES
  • XYLANASE
  • SPECIFICITY
  • REFINEMENT
  • CATALYSIS
  • SITE

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