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Publication Abstract from PubMed

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 beta-1,4-xylan and mixed-linkage (beta-1,3,beta-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 beta-1,4-xylohexaose with a kcat/Km of 7.5 x 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 A resolution; the latter was consistent with the greater kcat/Km for hexasaccharide substrates. A (2,5)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.

Structure and function of a glycoside hydrolase family 8 endoxylanase from Teredinibacter turnerae.,Fowler CA, Hemsworth GR, Cuskin F, Hart S, Turkenburg J, Gilbert HJ, Walton PH, Davies GJ Acta Crystallogr D Struct Biol. 2018 Oct 1;74(Pt 10):946-955. doi:, 10.1107/S2059798318009737. Epub 2018 Oct 2. PMID:30289404^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.