(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.) > cellular organisms: NE > Bacteria: NE > Proteobacteria: NE > Gammaproteobacteria: NE > Cellvibrionales: NE > Cellvibrionaceae: NE > Teredinibacter: NE > Teredinibacter turnerae: NE
LegendThis sequence has been compared to family alignement (MSA) red => minority aminoacid blue => majority aminoacid color intensity => conservation rate title => sequence position(MSA position)aminoacid rate Catalytic site Catalytic site in the MSA ENLYFQGHMADQDHAQLLHVLGIENLRRGADGNTDSPFAANTDEAKANTA LDSLPPLLTSVSGQAIASATDWEANRPALLNTFSQEIYGYVPGGAPELHW KAGSTTPIDDSGTSAIRQHFTSTLVHPENAALNLSLNFTLVLPKSNKPVP VVVVMSFDPGIWERFRDRMPAERYAQIQADNARWREQVVNAGWGYAEIIP TEFQADSGDGLSQGIIGFVNNGKPRNPTDWGALRAWAWSASQVLTYLQTD SRVAADRISVHGHSRFGKAALVAMAFDNRFAAGFISSSGEGGAKLWRRNF GEQVGNLAGAGEYHWMAGNFVKYAGPKKVNDIPVDAHQLLALCAPRPVLV SVGSQGESWVDPKGMLLAAYHATPAYALFGEQGVTQNELPAVGNGLLAGK LAFRQHEGGHTPAPNWETFITFATRQWASPNRLK
Glucuronoxylans represent a significant fraction of woody biomass, and its decomposition is complicated by the presence of lignin-carbohydrate complexes (LCCs). Herein, LCCs from birchwood were used to investigate the potential coordinated action of a glucuronoyl esterase (TtCE15A) and two alpha-glucuronidases (SdeAgu115A and AxyAgu115A). When supplementing alpha-glucuronidase with equimolar quantities of TtCE15A, total MeGlcpA released after 72 h by SdeAgu115A and AxyAgu115A increased from 52% to 67%, and 61% to 95%, respectively. Based on the combined TtCE15A and AxyAgu115A activities, ~ 34% of MeGlcpA in the extracted birchwood glucuronoxylan was occupied as LCCs. Notably, insoluble LCC fractions reduced soluble alpha-glucuronidase concentrations by up to 70%, whereas reduction in soluble TtCE15A was less than 30%, indicating different tendencies to adsorb onto the LCC substrate.
Glucuronoyl esterases (GEs) catalyze the cleavage of ester linkages found between lignin and glucuronic acid moieties on glucuronoxylan in plant biomass. As such, GEs represent promising biochemical tools in industrial processing of these recalcitrant resources. However, details on how GEs interact with their natural substrates are sparse, calling for thorough structure-function studies. Presented here is the structure and biochemical characterization of a GE, TtCE15A, from the bacterium Teredinibacter turnerae, a symbiont of wood-boring shipworms. To gain deeper insight into enzyme-substrate interactions, inhibition studies were performed with both the WT TtCE15A and variants in which we, by using site-directed mutagenesis, substituted residues suggested to have key roles in binding to or interacting with the aromatic and carbohydrate structures of its uronic acid ester substrates. Our results support the hypothesis that two aromatic residues (Phe-174 and Trp-376), conserved in bacterial GEs, interact with aromatic and carbohydrate structures of these substrates in the enzyme active site, respectively. The solved crystal structure of TtCE15A revealed features previously not observed in either fungal or bacterial GEs, with a large inserted N-terminal region neighboring the active site and a differently positioned residue of the catalytic triad. The findings highlight key interactions between GEs and complex lignin-carbohydrate ester substrates and advance our understanding of the substrate specificities of these enzymes in biomass conversion.
Here we report the complete genome sequence of Teredinibacter turnerae T7901. T. turnerae is a marine gamma proteobacterium that occurs as an intracellular endosymbiont in the gills of wood-boring marine bivalves of the family Teredinidae (shipworms). This species is the sole cultivated member of an endosymbiotic consortium thought to provide the host with enzymes, including cellulases and nitrogenase, critical for digestion of wood and supplementation of the host's nitrogen-deficient diet. T. turnerae is closely related to the free-living marine polysaccharide degrading bacterium Saccharophagus degradans str. 2-40 and to as yet uncultivated endosymbionts with which it coexists in shipworm cells. Like S. degradans, the T. turnerae genome encodes a large number of enzymes predicted to be involved in complex polysaccharide degradation (>100). However, unlike S. degradans, which degrades a broad spectrum (>10 classes) of complex plant, fungal and algal polysaccharides, T. turnerae primarily encodes enzymes associated with deconstruction of terrestrial woody plant material. Also unlike S. degradans and many other eubacteria, T. turnerae dedicates a large proportion of its genome to genes predicted to function in secondary metabolism. Despite its intracellular niche, the T. turnerae genome lacks many features associated with obligate intracellular existence (e.g. reduced genome size, reduced %G+C, loss of genes of core metabolism) and displays evidence of adaptations common to free-living bacteria (e.g. defense against bacteriophage infection). These results suggest that T. turnerae is likely a facultative intracellular ensosymbiont whose niche presently includes, or recently included, free-living existence. As such, the T. turnerae genome provides insights into the range of genomic adaptations associated with intracellular endosymbiosis as well as enzymatic mechanisms relevant to the recycling of plant materials in marine environments and the production of cellulose-derived biofuels.
Teredinibacter turnerae (strain ATCC 39867 / T7901) Carbohydrate esterase family 15 domain protein (TtCE15A)
