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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. [ABSTRACT FROM AUTHOR]

Arl6/BBS3 is a small GTPase, mutations in which are implicated in the human ciliopathy Bardet-Biedl Syndrome (BBS). Arl6 is proposed to facilitate the recruitment of a large protein complex known as the BBSome to the base of the primary cilium, mediating specific trafficking of molecules to this important sensory organelle. Orthologues of Arl6 and the BBSome core subunits have been identified in the genomes of trypanosomes. Flagellum function and motility are crucial to the survival of Trypanosoma brucei, the causative agent of human African sleeping sickness, in the human bloodstream stage of its lifecycle and so the function of the BBSome proteins in trypanosomes warrants further study. RNAi knockdown of T. brucei Arl6 ( TbArl6) has recently been shown to result in shortening of the trypanosome flagellum. Here we present the crystal structure of TbArl6 with the bound non-hydrolysable GTP analog GppNp at 2.0 Å resolution and highlight important differences between the trypanosomal and human proteins. Analysis of the TbArl6 active site confirms that it lacks the key glutamine that activates the nucleophile during GTP hydrolysis in other small GTPases. Furthermore, the trypanosomal proteins are significantly shorter at their N-termini suggesting a different method of membrane insertion compared to humans. Finally, analysis of sequence conservation suggests two surface patches that may be important for protein-protein interactions. Our structural analysis thus provides the basis for future biochemical characterisation of this important family of small GTPases. [ABSTRACT FROM AUTHOR]