Novel substrates for the automated and manual assay of endo-1,4-β-xylanase.
Mangan, D., Cornaggia, C., Liadova, A., McCormack, N., Ivory, R., McKie, V. A., Ormerod, A. & McCleary, D. V. (2017). Carbohydrate Research, 445, 14-22.
endo-1,4-β-Xylanase (EC 126.96.36.199) is employed across a broad range of industries including animal feed, brewing, baking, biofuels, detergents and pulp (paper). Despite its importance, a rapid, reliable, reproducible, automatable assay for this enzyme that is based on the use of a chemically defined substrate has not been described to date. Reported herein is a new enzyme coupled assay procedure, termed the XylX6 assay, that employs a novel substrate, namely 4,6-O-(3-ketobutylidene)-4-nitrophenyl-β-45-O-glucosyl-xylopentaoside. The development of the substrate and associated assay is discussed here and the relationship between the activity values obtained with the XylX6 assay versus traditional reducing sugar assays and its specificity and reproducibility were thoroughly investigated.
Hydrolysis of wheat flour arabinoxylan, acid-debranched wheat flour arabinoxylan and arabino-xylo-oligosaccharides by β-xylanase, α-L-arabinofuranosidase and β-xylosidase.
McCleary, B. V., McKie, V. A., Draga, A., Rooney, E., Mangan, D. & Larkin, J. (2015). Carbohydrate Research, 407, 79-96.
A range of α-L-arabinofuranosyl-(1-4)-β-D-xylo-oligosaccharides (AXOS) were produced by hydrolysis of wheat flour arabinoxylan (WAX) and acid debranched arabinoxylan (ADWAX), in the presence and absence of an AXH-d3 α-L-arabinofuranosidase, by several GH10 and GH11 β-xylanases. The structures of the oligosaccharides were characterised by GC-MS and NMR and by hydrolysis by a range of α-L-arabinofuranosidases and β-xylosidase. The AXOS were purified and used to characterise the action patterns of the specific α-L-arabinofuranosidases. These enzymes, in combination with either Cellvibrio mixtus or Neocallimastix patriciarum β -xylanase, were used to produce elevated levels of specific AXOS on hydrolysis of WAX, such as 32-α-L-Araf-(1-4)-β-D-xylobiose (A3X), 23-α-L-Araf-(1-4)-β-D-xylotriose (A2XX), 33-α-L-Araf-(1-4)-β-D-xylotriose (A3XX), 22-α-L-Araf-(1-4)-β-D-xylotriose (XA2X), 32-α-L-Araf (1-4)-β-D-xylotriose (XA3X), 23-α-L-Araf-(1-4)-β-D-xylotetraose (XA2XX), 33-α-L-Araf-(1-4)-β-D-xylotetraose (XA3XX), 23 ,33-di-α-L-Araf-(1-4)-β-D-xylotriose (A2+3XX), 23,33-di-α-L-Araf-(1-4)-β-D-xylotetraose (XA2+3XX), 24,34-di-α-L-Araf-(1-4)-β-D-xylopentaose (XA2+3XXX) and 33,34-di-α-L-Araf-(1-4)-β-D-xylopentaose (XA3A3XX), many of which have not previously been produced in sufficient quantities to allow their use as substrates in further enzymic studies. For A2,3XX, yields of approximately 16% of the starting material (wheat arabinoxylan) have been achieved. Mixtures of the α-L-arabinofuranosidases, with specific action on AXOS, have been combined with β-xylosidase and β-xylanase to obtain an optimal mixture for hydrolysis of arabinoxylan to L-arabinose and D-xylose.
Preparation of arabinoxylobiose from rye xylan using family 10 Aspergillus aculeatus endo-1,4-β-D-xylanase.
Rantanen, H., Virkki, L., Tuomainen, P., Kabel, M., Schols, H. & Tenkanen, M. (2007). Carbohydrate Polymers, 68(2), 350-359.
Commercial xylanase preparation Shearzyme®, which contains the glycoside hydrolase family 10 endo-1,4-β-D-xylanase from Aspergillus aculeatus, was used to prepare short-chain arabinoxylo-oligosaccharides (AXOS) from rye arabinoxylan (AX). A major AXOS was formed as a hydrolysis product. Longer AXOS were also produced as minor products. The pure GH10 xylanase from A. aculeatus was used as a comparison to ensure that the formed AXOS were consequence of the endoxylanase‘s function instead of some side enzymes present in Shearzyme. The major AXOS was purified and the structure confirmed with various analysis methods (TLC, HPAEC-PAD, MALDI-TOF-MS, and one- and two-dimensional NMR spectroscopy with nano-probe) as α-L-Araf-(1→3)-β-D-Xylp-(1→4)-D-Xylp (arabinoxylobiose). This is the first report on 13C NMR data of pure arabinoxylobiose. The yield of arabinoxylobiose was 12% from the quantified hydrolysis products. In conclusion, GH10 endoxylanase from A. aculeatus is thus able to cut efficiently the xylosidic linkage next to the arabinofuranosyl-substituted xylose unit which is not typical for all the GH10 endoxylanases. Interestingly, pure A. aculeatus xylanase showed notably activity towards p-nitrophenyl-β-D-xylopyranose. In previously studies longer AXOS have been produced with Shearzyme but the formation of short-chain AXOS by A. aculeatus GH10 xylanase has not been studied before.
Complete genome of a new Firmicutes species belonging to the dominant human colonic microbiota (‘Ruminococcus bicirculans’) reveals two chromosomes and a selective capacity to utilize plant glucans.
Wegmann, U., Louis, P., Goesmann, A., Henrissat, B., Duncan, S. H. & Flint, H. J. (2014). Environmental Microbiology, 16(9), 2879–2890.
The recently isolated bacterial strain 80/3 represents one of the most abundant 16S rRNA phylotypes detected in the healthy human large intestine and belongs to the Ruminococcaceae family of Firmicutes. The completed genome sequence reported here is the first for a member of this important family of bacteria from the human colon. The genome comprises two large chromosomes of 2.24 and 0.73 Mbp, leading us to propose the name Ruminococcus bicirculans for this new species. Analysis of the carbohydrate active enzyme complement suggests an ability to utilize certain hemicelluloses, especially β-glucans and xyloglucan, for growth that was confirmed experimentally. The enzymatic machinery enabling the degradation of cellulose and xylan by related cellulolytic ruminococci is however lacking in this species. While the genome indicated the capacity to synthesize purines, pyrimidines and all 20 amino acids, only genes for the synthesis of nicotinate, NAD+, NADP+ and coenzyme A were detected among the essential vitamins and co-factors, resulting in multiple growth requirements. In vivo, these growth factors must be supplied from the diet, host or other gut microorganisms. Other features of ecological interest include two type IV pilins, multiple extracytoplasmic function-sigma factors, a urease and a bile salt hydrolase.
A revised architecture of primary cell walls based on biomechanical changes induced by substrate-specific endoglucanases.
Park, Y. B. & Cosgrove, D. J. (2012). Plant Physiology, 158(4), 1933-1943.
Xyloglucan is widely believed to function as a tether between cellulose microfibrils in the primary cell wall, limiting cell enlargement by restricting the ability of microfibrils to separate laterally. To test the biomechanical predictions of this “tethered network” model, we assessed the ability of cucumber (Cucumis sativus) hypocotyl walls to undergo creep (long-term, irreversible extension) in response to three family-12 endo-β-1,4-glucanases that can specifically hydrolyze xyloglucan, cellulose, or both. Xyloglucan-specific endoglucanase (XEG from Aspergillus aculeatus) failed to induce cell wall creep, whereas an endoglucanase that hydrolyzes both xyloglucan and cellulose (Cel12A from Hypocrea jecorina) induced a high creep rate. A cellulose-specific endoglucanase (CEG from Aspergillus niger) did not cause cell wall creep, either by itself or in combination with XEG. Tests with additional enzymes, including a family-5 endoglucanase, confirmed the conclusion that to cause creep, endoglucanases must cut both xyloglucan and cellulose. Similar results were obtained with measurements of elastic and plastic compliance. Both XEG and Cel12A hydrolyzed xyloglucan in intact walls, but Cel12A could hydrolyze a minor xyloglucan compartment recalcitrant to XEG digestion. Xyloglucan involvement in these enzyme responses was confirmed by experiments with Arabidopsis (Arabidopsis thaliana) hypocotyls, where Cel12A induced creep in wild-type but not in xyloglucan-deficient (xxt1/xxt2) walls. Our results are incompatible with the common depiction of xyloglucan as a load-bearing tether spanning the 20- to 40-nm spacing between cellulose microfibrils, but they do implicate a minor xyloglucan component in wall mechanics. The structurally important xyloglucan may be located in limited regions of tight contact between microfibrils.
Structural basis for entropy-driven cellulose binding by a type-A cellulose-binding module (CBM) and bacterial expansin.
Georgelis, N., Yennawar, N. H. & Cosgrove, D. J. (2012). Proceedings of the National Academy of Sciences, 109(37), 14830-14835.
Components of modular cellulases, type-A cellulose-binding modules (CBMs) bind to crystalline cellulose and enhance enzyme effectiveness, but structural details of the interaction are uncertain. We analyzed cellulose binding by EXLX1, a bacterial expansin with ability to loosen plant cell walls and whose domain D2 has type-A CBM characteristics. EXLX1 strongly binds to crystalline cellulose via D2, whereas its affinity for soluble cellooligosaccharides is weak. Calorimetry indicated cellulose binding was largely entropically driven. We solved the crystal structures of EXLX1 complexed with cellulose-like oligosaccharides to find that EXLX1 binds the ligands through hydrophobic interactions of three linearly arranged aromatic residues in D2. The crystal structures revealed a unique form of ligand-mediated dimerization, with the oligosaccharide sandwiched between two D2 domains in opposite polarity. This report clarifies the molecular target of expansin and the specific molecular interactions of a type-A CBM with cellulose.
Characterization of a new α-L-arabinofuranosidase from Penicillium sp. LYG 0704, and their application in lignocelluloses degradation.
Lee, D. S., Wi, S. G., Lee, Y. G., Cho, E. J., Chung, B. Y. & Bae, H. J. (2011). Molecular Biotechnology, 49(3), 229-239.
A gene (arf) encoding an α-L-arabinofuranosidase (ARF) that hydrolyzes arabinose substituted on xylan was isolated from Penicillium sp. The gene was predicted to encode 339 amino acid residues showing 71–75% homology to GH family 54. E. coli expressed ARF showed optimal activity at 50°C and pH 5–6 on wheat arabinoxylan. The hydrolysis activities on oat spelt xylan by ARF and xylanase were 1.67-fold higher than that of xylanase alone. The synergistic effects of ARF and commercial enzymes (xylanase and cellulase) on popping-pretreated rice straw were 1.15–1.51-fold higher amounts of sugars released in the [ARF + xylanase + cellulase] mixture than in the mixtures [ARF + xylanase], [ARF + cellulase], and [xylanase + cellulase]. Moreover, the liberation of arabinose by ARF was enhanced 2.1–2.9-fold in a reaction with xylanase and cellulase as compared with [xylanase + cellulase] and ARF alone.
In vitro fermentation kinetics and end-products of cereal arabinoxylans and (1,3;1,4)-β-glucans by porcine faeces.
Williams, B. A., Mikkelsen, D., Le Paih, L. & Gidley, M. J. (2011). Journal of cereal science, 53(1), 53-58.
Purified and semi-purified polysaccharides characteristic of cereals were fermented in vitro with a pig faecal inoculum, using the cumulative gas production technique, to examine the kinetics and end-products of fermentation after 48 h. It was shown that arabinoxylan and mixed linkage (1,3;1,4) β-glucan were rapidly fermented if soluble, while less soluble substrates (insoluble arabinoxylan, maize and wheat starch granules, and bacterial cellulose) were more slowly fermented. Relevant monosaccharides were fermented at very similar rates to soluble polymeric arabinoxylan and β-glucan, showing that depolymerisation was not a limiting step, in contrast to some previous studies. Bacterial cellulose is shown to be a useful model substrate for fermentation of plant cellulose which is difficult to obtain without harsh chemical treatments. Fermentation end-products were related to kinetics, with slow carbohydrate fermentation resulting in increased protein fermentation. Ratios of short-chain fatty acid products were similar for all arabinoxylan and β-glucan substrates.
Characterization and pH-dependent substrate specificity of alkalophilic xylanase from Bacillus alcalophilus.
Lee, D. S., Lee, K. H., Cho, E. J., Kim, H. M., Kim, C. S. & Bae, H. J. (2012). Journal of Industrial Microbiology & Biotechnology, 39(10), 1465-1475.
The gene of endo-beta-1-4 xylanase, xynT, was cloned from Bacillus alcalophilus AX2000 and expressed in Escherichia coli. This XynT, which belongs to glycoside hydrolase (GH) family 10, was found to have a molecular weight of approximately 37 kDa and exhibit optimal activity at pH 7–9 and 50°C. It exhibits a high activity towards birchwood xylan and has the ability to bind avicel. Under optimal conditions, XynT hydrolyzes all xylooligomers into xylobiose as an end product with a preference for cleavage sites at the second or third glycosidic bond from the reducing end. XynT has a different substrate affinity on xylooligomers at pH 5.0, which contributes to its low activity toward xylotriose and its derived intermediate products. This low activity may be due to an unstable interaction with the amino acids that constitute subsites of the active site. Interestingly, the addition of Co2+ and Mn2+ led to a significant increase in activity by up to 40 and 50%, respectively. XynT possesses a high binding affinity and hydrolytic activity toward the insoluble xylan, for which it exhibits high activity at pH 7–9, giving rise to its efficient biobleaching effect on Pinus densiflora kraft pulp.
Co-immobilization and stabilization of xylanase, β-xylosidase and α-L-arabinofuranosidase from Penicillium janczewskii for arabinoxylan hydrolysis.
Terrasan, C. R. F., Trobo-Maseda, L., Moreno-Pérez, S., Carmona, E. C., Pessela, B. C. & Guisan, J. M. (2016). Process Biochemistry, 51(5), 614-623.
Differently activated agarose-based supports were evaluated for co-immobilization of a crude extract from Penicillium janczewskii containing xylanase, β-xylosidase and α-L-arabinofuranosidase activities. Adequately selecting support and immobilization conditions (8 h, using agarose with 10% crosslinking) increased enzyme levels substantially, mainly in relation to the xylanase (2-fold). A coating with dextran aldehyde MW 6000 Da, partially oxidized, covalently attached the enzymes to the support. Optimum activity was verified in the pH range 2-4, and at 50, 65 and 80°C for the xylanase, α-L-arabinofuranosidase and β-xylosidase, respectively. The xylanase was highly thermostable retaining more than 70% of activity even after 24 h incubation at 60 and 70°C; and at 80°C its half-life was 1.7 h. The half-lives of the β-xylosidase and α-L-arabinofuranosidase at 50°C were 2.3 and 3.8 h, respectively. The co-immobilization of the enzymes on a single support give raise to a functional multi-enzymatic biocatalyst acting in the complete hydrolysis of different and complex substrates such as oat spelt and wheat arabinoxylans, with xylose yield higher than 40%. The xylanase and the α-L-arabinofuranosidase presented high stability retaining 86.6 and 88.0% of activity after 10 reuse cycles.
Differential growth of bowel commensal Bacteroides species on plant xylans of differing structural complexity.
Centanni, M., Hutchison, J. C., Carnachan, S. M., Daines, A. M., Kelly, W. J., Tannock, G. W. & Sims, I. M. (2017). Carbohydrate Polymers, 157, 1374-1382.
Alterations to the composition of the bowel microbiota (dysbioses) are associated with particular diseases and conditions of humans. There is a need to discover new, indigestible polysaccharides which are selective growth substrates for commensal bowel bacteria. These substrates (prebiotics) could be added to food in intervention studies to correct bowel dysbiosis. A collection of commensal bacteria was screened for growth in culture using a highly-branched xylan produced by New Zealand flax. Two, Bacteroides ovatus ATCC 8483 and Bacteroides xylanisolvens DSM 18836 grew well on this substrate. The utilisation of the xylan was studied chromatographically and by constituent sugar analysis. The two closely related species utilised the xylan in different ways, and differently from their use of wheat arabinoxylan. The growth of Bacteroides species on other plant xylans having differing chemical structures was also investigated. Novel xylans expand the choice of potential prebiotics that could be used to correct bowel dysbioses.
Acidic-alkaline ferulic acid esterase from Chaetomium thermophilum var. dissitum: Molecular cloning and characterization of recombinant enzyme expressed in Pichia pastoris.
Dotsenko, G., Tong, X., Pilgaard, B., Busk, P. K. & Lange, L. (2016). Biocatalysis and Agricultural Biotechnology, 5, 48-55.
A novel ferulic acid esterase encoding gene CtFae, was successfully cloned from a highly esterase active strain of the thermophile ascomycetous fungus Chaetomium thermophilum var. dissitum; the gene was heterologously expressed in Pichia pastoris KM71H. The recombinant enzyme (CtFae) was purified to homogeneity and subsequently characterized. CtFae was active towards synthetic esters of ferulic, p-coumaric, and caffeic acids, as well as towards wide range of p-nitrophenyl substrates. Its temperature and pH optima were 55°C and pH 6.0, respectively. Enzyme rare features were broad pH optimum, high stability at extended acidic-alkaline pH region, and noticeable thermostability. CtFae released ferulic acid from wheat insoluble arabinoxylan, as well as ferulic and p-coumaric acids from wheat straw and ryegrass, indicating potentials for industrial applications like biomass conversion in biorefineries.
Screening, identification, and characterization of a GH43 family β-xylosidase/α-arabinofuranosidase from a compost microbial metagenome.
Matsuzawa, T., Kaneko, S. & Yaoi, K. (2015). Applied Microbiology and Biotechnology, 99(21), 8943-8954.
A putative glycoside hydrolase family 43 β-xylosidase/α-arabinofuranosidase (CoXyl43) that promotes plant biomass saccharification was isolated via functional screening of a compost microbial metagenomic library and characterized. CoXyl43 promoted the saccharification of plant biomasses, including xylans (xylan and arabinoxylan), rice straw, and Erianthus, by degrading xylooligosaccharide residues to monosaccharide residues. The recombinant CoXyl43 protein exhibited both β-xylosidase and α-arabinofuranosidase activities for chromogenic substrates, with optimal activity at pH 7.5 and 55°C. Both of these activities were inactivated by ethanol, dimethylsulfoxide, and zinc and copper ions but were activated by manganese ions. Only the β-xylosidase activity of recombinant CoXyl43 was enhanced in the presence of calcium ions. These results indicate that CoXyl43 exhibits unique enzymatic properties useful for biomass saccharification.
Optimization of Arundo donax Saccharification by (Hemi) cellulolytic Enzymes from Pleurotus ostreatus.
Liguori, R., Ionata, E., Marcolongo, L., Vandenberghe, L. P. D. S., La Cara, F. & Faraco, V. (2015). BioMed Research International, 2015.
An enzymatic mixture of cellulases and xylanases was produced by Pleurotus ostreatus using microcrystalline cellulose as inducer, partially characterized and tested in the statistical analysis of Arundo donax bioconversion. The Plackett-Burman screening design was applied to identify the most significant parameters for the enzymatic hydrolysis of pretreated A. donax. As the most significant influence during the enzymatic hydrolysis of A. donax was exercised by the temperature (°C), pH, and time, the combined effect of these factors in the bioconversion by P. ostreatus cellulase and xylanase was analyzed by a 33 factorial experimental design. It is worth noting that the best result of 480.10 mg of sugars/gds, obtained at 45°C, pH 3.5, and 96 hours of incubation, was significant also when compared with the results previously reached by process optimization with commercial enzymes.
An ELISA Based Method for Quantifying Arabinoxylan in Wheat Flour.
Hoffstetter, A. L., Griffin, D. P., Brown, L. K., Alan, J. K. & Olson, E. L. (2017). Journal of Cereal Science, , 79, 148-153.
Arabinoxylans (AX) are a type of dietary fiber present in cereal grains. Recent studies have shown consuming water-extractable AX (WE-AX) can reduce blood glucose levels and prevent the growth of pathogenic bacteria in the human gut. WE-AX can affect dough quality by increasing baking absorption and reducing gluten formation. Historically, WE-AX has been quantified using the phloroglucinol assay, however, this method is labor intensive and not amendable to large sample sizes. Enzyme-linked immunosorbent assays (ELISAs) quantify molecules through specific antigen-antibody binding. The monoclonal antibody LM11 specifically binds to wheat WE-AX and can be used in an ELISA based quantification. In this study, an ELISA was developed to quantify WE-AX in whole grain flour. Flour WE-AX content was evaluated using ELISA and the phloroglucinol assay in five varieties and two milling methods using a Retsch osilating mill and a Thomas Wiley mill. Moderate correlations were found between assays and milling methods. The ELISA assay was found to reduce sample processing time by 16.5 min. Twenty soft winter wheat varieties were evaluated for WE-AX content using ELISA. The ELISA developed in this study was found to be a highly accurate method of quantifying WE-AX in large sample sizes.
Identification and characterization of the first β-1, 3-D-xylosidase from a gram-positive bacterium, Streptomyces sp. SWU10.
Phuengmaung, P., Fujiwara, D., Sukhumsirichart, W. & Sakamoto, T. (2017). Enzyme and Microbial Technology, 112, 72-78.
In previous reports, we characterized four endo-xylanases produced by Streptomyces sp. strain SWU10 that degrade xylans to several xylooligosaccharides. To obtain a set of enzymes to achieve complete xylan degradation, a β-D-xylosidase gene was cloned and expressed in Escherichia coli, and the recombinant protein, named rSWU43A, was characterized. SWU43A is composed of 522 amino acids and does not contain a signal peptide, indicating that the enzyme is an intracellular protein. SWU43A was revealed to contain a Glyco_hydro_43 domain and possess the three conserved amino acid residues of the glycoside hydrolase family 43 proteins. The molecular mass of rSWU43A purified by Ni-affinity column chromatography was estimated to be 60 kDa. The optimum reaction conditions of rSWU43A were pH 6.5 and 40°C. The enzyme was stable up to 40°C over a wide pH range (3.1-8.9). rSWU43A activity was enhanced by Fe2+ and Mn2+ and inhibited by various metals (Ag+, Cd2+ , Co2+, Cu2+, Hg2+, Ni2+, and Zn2+), D-xylose, and L-arabinose. rSWU43A showed activity on p-nitrophenyl-β-D-xylopyranoside and p-nitrophenyl-α-L-arabinofuranoside substrates, with specific activities of 0.09 and 0.06 U/mg, respectively, but not on any xylosidic or arabinosidic polymers. rSWU43A efficiently degraded β-1,3-xylooligosaccharides to produce xylose but showed little activity towards β-1,4-xylobiose, with specific activities of 1.33 and 0.003 U/mg, respectively. These results demonstrate that SWU43A is a β-1,3-D-xylosidase (EC 188.8.131.52), which to date has only been described in the marine bacterium Vibrio sp. Therefore, rSWU43A of Streptomyces sp. is the first β-1,3-xylosidase found in gram-positive bacteria. SWU43A could be useful as a specific tool for the structural elucidation and production of xylose from β-1,3-xylan in seaweed cell walls.
Performance, egg quality, nutrient digestibility, and excreta microbiota shedding in laying hens fed corn-soybean-meal-wheat-based diets supplemented with xylanase.
Lei, X. J., Lee, K. Y. & Kim, I. H. (2018). Poultry Science, 97(6), 2071-2077.
The aim of this study was to evaluate the effects of dietary levels of xylanase on production performance, egg quality, nutrient digestibility, and excreta microbiota shedding of laying hens in a 12-week trial. Two-hundred-forty Hy-Line brown laying hens (44 wk old) were distributed according to a randomized block experimental design into one of 4 dietary treatments with 10 replicates of 6 birds each. The 4 dietary treatments were corn-soybean-meal-wheat-based diets supplemented with 0, 225, 450, or 900 U/kg xylanase. Daily feed intake, egg production, egg weight, egg mass, feed conversion ratio, and damaged egg rate showed no significant response to increasing xylanase supplementation during any phase (P > 0.05). No significant responses were observed for apparent total tract digestibility of dry matter, nitrogen, or gross energy (P > 0.05). A significant linear increase to increasing xylanase supplementation was seen for lactic acid bacteria numbers, although coliforms and Salmonella counts were not affected. Increasing the dietary xylanase resulted in a significant linear increase in eggshell thickness in wk 3, 6, 9, and 12 (P < 0.05). In addition, a significant linear increase occurred for Haugh unit and albumen height in wk 12 (P < 0.05). In summary, the inclusion of xylanase in corn-soybean-meal-wheat-based diets increased eggshell thickness, Haugh unit, albumen height, and excreta lactic acid bacteria count but had no effect on production performance or nutrient digestibility.
Cloning and expression of a novel α-1, 3-arabinofuranosidase from Penicillium oxalicum sp. 68.
Hu, Y., Yan, X., Zhang, H., Liu, J., Luo, F., Cui, Y., Wang, W. & Zhou, Y. (2018). AMB Express, 8(1), 51.
The discovery and creation of biocatalysts for plant biomass conversion are essential for industrial demand and scientific research of the plant cell wall. α-1,2 and α-1,3-L-arabinofuranosidases are debranching enzymes that catalyzing hydrolytic release of α-L-arabinofuranosyl residues in plant cell wall. Gene database analyses shows that GH62 family only contains specific α-L-arabinofuranosidases that play an important role in the degradation and structure of the plant cell wall. At present, there are only 22 enzymes in this group has been characterized. In this study, we cloned a novel α-1,3-arabinofuranosidase gene (poabf62a) belonging to glycoside hydrolase family 62 from Penicillium oxalicum sp. 68 and expressed it in Pichia pastoris. The molecular mass of recombinant PoAbf62A was estimated to be 32.9 kDa. Using p-nitrophenyl-α-L-arabinofuranoside (pNPαAbf) as substrate, purified PoAbf62A exhibited an optimal pH of 4.5 and temperature of 35°C. Results of methylation and 13 C NMR analyses showed that PoAbf62A was exclusively α-1,3-arabinofuranosidase, specific for cleavage of α-1,3-arabinofuranosyl residues, and with the absence of activity towards α-1,2-arabinofuranose and α-1,5-arabinofuranose. Therefore, PoAbf62A exhibits high activity on sugar beet arabinan and wheat arabinoxylan, because their branched side chain are decorated with α-1,3-arabinofuranose. On the other hand, there is a lack of activity with linear-α-L-1,5-arabinan and xylan that only contained α-L-1,5-arabinofuranose or β-1,4-xylose. The α-1,3-arabinofuranosidase activity identified here provides a new biocatalytic tool to degrade hemicellulose and analyze the structure of plant cell walls.
Cloning and expression of a novel α-1, 3-arabinofuranosidase from Penicillium oxalicum sp. 68.
Hu, Y., Yan, X., Zhang, H., Liu, J., Luo, F., Cui, Y., Wang, W. & Zhou, Y. (2018). AMB Express, 8(1), 51
The discovery and creation of biocatalysts for plant biomass conversion are essential for industrial demand and scientific research of the plant cell wall. α-1,2 and α-1,3-L-arabinofuranosidases are debranching enzymes that catalyzing hydrolytic release of α-L-arabinofuranosyl residues in plant cell wall. Gene database analyses shows that GH62 family only contains specific α-L-arabinofuranosidases that play an important role in the degradation and structure of the plant cell wall. At present, there are only 22 enzymes in this group has been characterized. In this study, we cloned a novel α-1,3-arabinofuranosidase gene (poabf62a) belonging to glycoside hydrolase family 62 from Penicillium oxalicum sp. 68 and expressed it in Pichia pastoris. The molecular mass of recombinant PoAbf62A was estimated to be 32.9 kDa. Using p-nitrophenyl-α-L-arabinofuranoside (pNPαAbf) as substrate, purified PoAbf62A exhibited an optimal pH of 4.5 and temperature of 35°C. Results of methylation and 13C NMR analyses showed that PoAbf62A was exclusively α-1,3-arabinofuranosidase, specific for cleavage of α-1,3-arabinofuranosyl residues, and with the absence of activity towards α-1,2-arabinofuranose and α-1,5-arabinofuranose. Therefore, PoAbf62A exhibits high activity on sugar beet arabinan and wheat arabinoxylan, because their branched side chain are decorated with α-1,3-arabinofuranose. On the other hand, there is a lack of activity with linear-α-L-1,5-arabinan and xylan that only contained α-L-1,5-arabinofuranose or β-1,4-xylose. The α-1,3-arabinofuranosidase activity identified here provides a new biocatalytic tool to degrade hemicellulose and analyze the structure of plant cell walls.