Structure and function of a glycoside hydrolase family 8 endoxylanase from Teredinibacter turnerae

Claire A Fowler, Glyn R Hemsworth, Fiona Cuskin, Sam Hart, Johan Turkenburg, Harry J. Gilbert, Paul H Walton, Gideon J Davies

Research output: Contribution to journalArticlepeer-review


The biological conversion of lignocellulosic matter into high-value chemicals or biofuels is of increasing industrial importance as the sector slowly transitions away from nonrenewable sources. Many industrial processes involve the use of cellulolytic enzyme cocktails - a selection of glycoside hydrolases and, increasingly, polysaccharide oxygenases - to break down recalcitrant plant polysaccharides. ORFs from the genome of Teredinibacter turnerae, a symbiont hosted within the gills of marine shipworms, were identified in order to search for enzymes with desirable traits. Here, a putative T. turnerae glycoside hydrolase from family 8, hereafter referred to as TtGH8, is analysed. The enzyme is shown to be active against β-1,4-xylan and mixed-linkage (β-1,3,β-1,4) marine xylan. Kinetic parameters, obtained using high-performance anion-exchange chromatography with pulsed amperometric detection and 3,5-dinitrosalicyclic acid reducing-sugar assays, show that TtGH8 catalyses the hydrolysis of β-1,4-xylohexaose with a k cat/K m of 7.5 × 10 7  M -1  min -1 but displays maximal activity against mixed-linkage polymeric xylans, hinting at a primary role in the degradation of marine polysaccharides. The three-dimensional structure of TtGH8 was solved in uncomplexed and xylobiose-, xylotriose- and xylohexaose-bound forms at approximately 1.5 Å resolution; the latter was consistent with the greater k cat/K m for hexasaccharide substrates. A 2,5B boat conformation observed in the -1 position of bound xylotriose is consistent with the proposed conformational itinerary for this class of enzyme. This work shows TtGH8 to be effective at the degradation of xylan-based substrates, notably marine xylan, further exemplifying the potential of T. turnerae for effective and diverse biomass degradation.

Original languageEnglish
Pages (from-to)946-955
Number of pages10
JournalActa crystallographica. Section D, Structural biology
Issue numberPt 10
Publication statusPublished - 5 Oct 2018

Bibliographical note

© 2018, The Author(s).


  • Biofuels
  • Biomass
  • Cellulolytic enzymes
  • Glycoside hydrolase
  • Marine polysaccharides
  • Shipworms
  • Teredinibacter turnerae
  • Xylans/metabolism
  • Plants/chemistry
  • Polysaccharides/metabolism
  • Gram-Negative Facultatively Anaerobic Rods/enzymology
  • Gammaproteobacteria/enzymology
  • Endo-1,4-beta Xylanases/chemistry
  • Protein Conformation
  • Bacterial Proteins/chemistry
  • Kinetics
  • Glycoside Hydrolases/chemistry
  • Plant Cells/metabolism

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