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

DOI: 10.1107/S2059798318009737 DOI Help

Authors: Claire A. Fowler (The University of York) , Glyn R. Hemsworth (University of Leeds) , Fiona Cuskin (Newcastle University) , Sam Hart (The University of York) , Johan Turkenburg (The University of York) , Harry J. Gilbert (Newcastle University) , Paul H. Walton (The University of York) , Gideon J. Davies (The University of York)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acta Crystallographica Section D Structural Biology , VOL 74 , PAGES 946 - 955

State: Published (Approved)
Published: October 2018
Diamond Proposal Number(s): 9948 , 13587

Open Access Open Access

Abstract: 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 kcat/Km of 7.5 × 107 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 kcat/Km 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.

Journal Keywords: glycoside hydrolase; biomass; biofuels; marine polysaccharides; cellulolytic enzymes; shipworms; Teredinibacter turnerae

Diamond Keywords: Biofuel; Enzymes

Subject Areas: Biology and Bio-materials, Energy, Chemistry

Instruments: I02-Macromolecular Crystallography , I04-Macromolecular Crystallography

Added On: 11/10/2018 14:49


Discipline Tags:

Catalysis Earth Sciences & Environment Climate Change Energy Bioenergy Sustainable Energy Systems Engineering & Technology Biotechnology Life Sciences & Biotech Structural biology Chemistry Biochemistry

Technical Tags:

Diffraction Macromolecular Crystallography (MX)