6G0N

Crystal Structure of a GH8 catalytic mutant xylohexaose complex xylanase from Teredinibacter turnerae

Summary for 6G0N

• Entry DOI: 10.2210/pdb6g0n/pdb
• Related: 6G00 6G09 6G0B
• Descriptor: Glycoside hydrolase family 8 domain protein, beta-D-xylopyranose-(1-4)-beta-D-xylopyranose-(1-4)-beta-D-xylopyranose-(1-4)-beta-D-xylopyranose-(1-4)-beta-D-xylopyranose, beta-D-xylopyranose, ... (5 entities in total)
• Functional Keywords: xylanse, mutant, carbohydrate, hydrolase
• Biological source: Teredinibacter turnerae (strain ATCC 39867 / T7901)
• Total number of polymer chains: 1
• Total formula weight: 46032.72

Authors

Fowler, C.A.,Davies, G.J.,Walton, P.H. (deposition date: 2018-03-19, release date: 2018-10-10, Last modification date: 2024-05-08)

Primary citation

Fowler, C.A.,Hemsworth, G.R.,Cuskin, F.,Hart, S.,Turkenburg, J.,Gilbert, H.J.,Walton, P.H.,Davies, G.J.
Structure and function of a glycoside hydrolase family 8 endoxylanase from Teredinibacter turnerae.
Acta Crystallogr D Struct Biol, 74:946-955, 2018

PubMed 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 k/K of 7.5 × 10 M min 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/K for hexasaccharide substrates. A B 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.

PubMed: 30289404
DOI: 10.1107/S2059798318009737

Experimental method

X-RAY DIFFRACTION (1.8 Å)