Topic
Xyne
About: Xyne is a research topic. Over the lifetime, 8 publications have been published within this topic receiving 357 citations.
Papers
TL;DR: These findings indicate that at least two distinct dockerin-binding specificities are involved in the novel organization of plant cell wall-degrading enzymes in this species and suggest that different scaffoldins and perhaps multiple enzyme complexes may exist in R. flavefaciens.
Abstract: The DNA sequence coding for putative cellulosomal scaffolding protein ScaA from the rumen cellulolytic anaerobe Ruminococcus flavefaciens 17 was completed. The mature protein exhibits a calculated molecular mass of 90,198 Da and comprises three cohesin domains, a C-terminal dockerin, and a unique N-terminal X domain of unknown function. A novel feature of ScaA is the absence of an identifiable cellulose-binding module. Nevertheless, native ScaA was detected among proteins that attach to cellulose and appeared as a glycosylated band migrating at around 130 kDa. The ScaA dockerin was previously shown to interact with the cohesin-containing putative surface-anchoring protein ScaB. Here, six of the seven cohesins from ScaB were overexpressed as histidine-tagged products in E. coli; despite their considerable sequence differences, each ScaB cohesin specifically recognized the native 130-kDa ScaA protein. The binding specificities of dockerins found in R. flavefaciens plant cell wall-degrading enzymes were examined next. The dockerin sequences of the enzymes EndA, EndB, XynB, and XynD are all closely related but differ from those of XynE and CesA. A recombinant ScaA cohesin bound selectively to dockerin-containing fragments of EndB, but not to those of XynE or CesA. Furthermore, dockerin-containing EndB and XynB, but not XynE or CesA, constructs bound specifically to native ScaA. XynE- and CesA-derived probes did however bind a number of alternative R. flavefaciens bands, including an ∼110-kDa supernatant protein expressed selectively in cultures grown on xylan. Our findings indicate that in addition to the ScaA dockerin-ScaB cohesin interaction, at least two distinct dockerin-binding specificities are involved in the novel organization of plant cell wall-degrading enzymes in this species and suggest that different scaffoldins and perhaps multiple enzyme complexes may exist in R. flavefaciens.
86 citations
TL;DR: The initial rate data from the hydrolysis of short xylo-oligosaccharides indicated that the catalytic efficiency increased with increasing degree of polymerisation of oligomer up to 6, suggesting that the specificity region of XynE and XynF spans at least six xylose residues.
Abstract: The filamentous fungus Talaromyces versatilis produces a wide range of cellulolytic and hemicellulolytic enzymes such as xylanases. The recent accessibility to the T. versatilis genome allows identifying two new genes, xynE and xynF, encoding glycoside-hydrolases from family GH11. Both genes were cloned and expressed in the methylotrophic yeast Pichia pastoris in order to compare these new xylanases with two other GH11 xylanases from T. versatilis (XynB and XynC) that were previously reported. High-level expression of recombinant enzymes was obtained for the four enzymes that were purified to homogeneity. The XynB, XynC, XynE and XynF enzymes have molecular masses of 34, 22, 45 and 23 kDa, an optimal pH between 3.5 and 4.5 and an optimal temperature between 50 °C and 60 °C. Interestingly, XynF has shown the best thermal stability at 50 °C for at least 180 min with a weak loss of activity. The four xylanases catalysed hydrolysis of low viscosity arabinoxylan (LVAX) with K
m(app) between 11.5 and 23.0 mg.mL−1 and k
cat/K
m(app) 170 and 3,963 s−1 mg−1.mL. Further investigations on the rate and pattern of hydrolysis of the four enzymes on LVAX showed the predominant production of xylose, xylobiose and some (arabino)xylo-oligosaccharides as end products. The initial rate data from the hydrolysis of short xylo-oligosaccharides indicated that the catalytic efficiency increased with increasing degree of polymerisation of oligomer up to 6, suggesting that the specificity region of XynE and XynF spans at least six xylose residues. Because of their attractive properties, T. versatilis xylanases might be considered for biotechnological applications.
32 citations
TL;DR: The biochemical characterisation upon recombinant expression in Escherichia coli revealed that the protein is a thermostable endoxylanase, named Xyn141E, which is the first xylanase in this new family of biomass-degrading enzymes.
Abstract: Enzymes that cleave polysaccharides in lignocellulose, i. e., cellulases, xylanases, and accessory enzymes, play crucial roles in the natural decomposition of plant-derived biomass and its efficient and sustainable processing into biofuels or other bulk chemicals. The analysis of open reading frame cthe_2195 from the thermophilic, cellulolytic anaerobe Clostridium thermocellum (also known as ‘Ruminiclostridium thermocellum’) suggested that it encoded a cellulosomal protein comprising a dockerin-I module, a carbohydrate-binding module, and a module of previously unknown function. The biochemical characterisation upon recombinant expression in Escherichia coli revealed that the protein is a thermostable endoxylanase, named Xyn141E with an optimal pH of 6.0–6.5 and a temperature optimum of 67–75 °C. The substrate spectrum of Xyn141E resembles that of GH10 xylanases, because of its side activities on carboxymethyl cellulose, barley β-glucan, and mannan. Conversely, the product spectrum of Xyn141E acting on arabinoxylan is similar to those of GH11, as established by HPAEC-PAD analysis. Xyn141E is weakly related (20.7% amino acid sequence identity) to the founding member of the recently established GH family 141 and is the first xylanase in this new family of biomass-degrading enzymes.
32 citations
TL;DR: A xylanase gene (xynE) encoding XynE (110 kDa) was cloned from a lambda phage genomic library of Aeromonas caviae ME-1 which is a multiple-xylanase-producing bacterium and was found to be similar to endo-beta-1,4- xylanases which are categorized to glycosyl hydrolase family 10.
11 citations
TL;DR: An extracellular 72-kDa xylanase from an Escherichia coli transformant that harbored pXED30 carrying xynE of Aeromonas caviae ME-1 was purified by extraction following SDS-PAGE to electrophoretic homogeneity and found to have the same sequence as that of the N-terminal 10 amino acid residues.
6 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2017 | 1 |
| 2014 | 1 |
| 2007 | 1 |
| 2003 | 3 |
| 2000 | 1 |
| 1995 | 1 |