Mode of action and properties of the β-xylosidases fromTalaromyces emersonii andTrichoderma reesei

Rasmussen, Louise Enggaard; Sørensen, Henrik Rokkjær; Vind, Jesper; Viksø-Nielsen, Anders

doi:10.1002/bit.20908

Cited by 46 publications

(25 citation statements)

References 25 publications

(40 reference statements)

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“…In addition, BxTW1 showed activity against beechwood xylan, something uncommon among most of the known ␤-xylosidases. These behaviors have been previously reported, and they are considered a typical feature of exo-type xylanolytic enzymes (34,44), in contrast to classical ␤-xylosidases (45). Exo-type xylanases (EC 3.2.1.156) are also called reducing-end xylose-releasing exo-oligoxylanases (Rex enzymes), and they share with ␤-xylosidases (EC 3.2.1.37) the exo-attack of substrates.…”

Section: Discussionsupporting

confidence: 57%

“…Very few characterized ␤-xylosidases, such as BXTE from T. emersonii (34), had a slightly lower K m value toward this substrate. Nevertheless, BxTW1 demonstrated better kinetic properties: its V max is 22-fold higher than that of Xyl I, and the k cat against pNPX was 173 s Ϫ1 , more than 700-fold higher than that reported for BXTE.…”

Section: Discussionmentioning

confidence: 97%

“…Sequence alignments of BxTW1 and closely related GH3 xylosidases (data not shown) revealed no changes in the catalytic environment that would explain the low optimum pH of BxTW1. However, Rasmussen et al (34) reported that ␤-xylosidases from T. emersonii and T. reesei changed their optimum pH from pH 4.0 to pH 3.0 to 3.5 when they were expressed in Aspergillus oryzae, for which high N-glycosylation potential has been reported (35). This observation could suggest that this posttranslational modification might modulate the pH sensitivity of glycoside hydrolases.…”

Section: Discussionmentioning

confidence: 99%

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Novel pH-Stable Glycoside Hydrolase Family 3 β-Xylosidase from Talaromyces amestolkiae: an Enzyme Displaying Regioselective Transxylosylation

Nieto-Domínguez

Eugenio

Barriuso

et al. 2015

Appl Environ Microbiol

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This paper reports on a novel ␤-xylosidase from the hemicellulolytic fungus Talaromyces amestolkiae. The expression of this enzyme, called BxTW1, could be induced by beechwood xylan and was purified as a glycoprotein from culture supernatants. We characterized the gene encoding this enzyme as an intronless gene belonging to the glycoside hydrolase gene family 3 (GH3). BxTW1 exhibited transxylosylation activity in a regioselective way. This feature would allow the synthesis of oligosaccharides or other compounds not available from natural sources, such as alkyl glycosides displaying antimicrobial or surfactant properties. Regioselective transxylosylation, an uncommon combination, makes the synthesis reproducible, which is desirable for its potential industrial application. BxTW1 showed high pH stability and Cu 2؉ tolerance. The enzyme displayed a pI of 7.6, a molecular mass around 200 kDa in its active dimeric form, and K m and V max values of 0.17 mM and 52.0 U/mg, respectively, using commercial p-nitrophenyl-␤-D-xylopyranoside as the substrate. The catalytic efficiencies for the hydrolysis of xylooligosaccharides were remarkably high, making it suitable for different applications in food and bioenergy industries. P lant biomass represents the most abundant renewable energy resource available on earth. It is composed mainly of cellulose and hemicellulose, two polysaccharides that constitute the raw material for the so-called second-generation (2G) bioethanol industry. The production of this biofuel has received special attention in recent years because it is based on the use of nonfood sources of cellulosic biomass (1). It has been pointed out that energy crops should be restricted to metal-contaminated soils in order to avoid cultivation competition against the food industry (2, 3).In order to make the production of this biofuel economically viable, many modifications have been introduced into the industrial process in recent years. Among them, the strategy of combining enzymatic hydrolysis of lignocellulose with ethanol fermentation in a single process known as simultaneous saccharification and fermentation (SSF) is a significant step forward, but reduced production costs and improved yields are still necessary (1). Most studies have been using agricultural wastes as raw materials, usually after a physicochemical pretreatment to disrupt the lignocellulose structure to enhance cellulose and hemicellulose accessibility. Nevertheless, the industrial procedure currently used to produce 2G ethanol consists of fermenting glucose, which is enzymatically released from cellulose by using Saccharomyces cerevisiae as a biocatalyst (4). To increase process yields, hemicellulose hydrolysis and pentose fermentation are extremely relevant. Within this heterogeneous group of polysaccharides, xylans are most abundant in hardwoods and grass. They are composed of a backbone of ␤-1,4-linked D-xylopyranosyl units highly substituted with arabinofuranose, glucose, glucuronic or methyl-glucuronic acid, and acetyl side groups. The enz...

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Section: Discussionsupporting

confidence: 57%

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

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Novel pH-Stable Glycoside Hydrolase Family 3 β-Xylosidase from Talaromyces amestolkiae: an Enzyme Displaying Regioselective Transxylosylation

Nieto-Domínguez

Eugenio

Barriuso

et al. 2015

Appl Environ Microbiol

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“…␤-Xylosidases hydrolyze ␤-1,4-D-xylans, oligomers, and xylobiose to remove successive single D-xylose residues from the nonreducing terminus. GH3 xylosidases follow xylanases, with a retaining mechanism of hydrolysis, while GH43 xylosidases are inverting enzymes (160). Talaromyces emersonii (␤-XTE) and T. reesei (␤-XTR) hydrolyze xylobiose, producing ␤-D-xylose (160).…”

Section: Hemicellulasesmentioning

confidence: 99%

Genomics Review of Holocellulose Deconstruction by Aspergilli

Segato

Damásio

Lucas

et al. 2014

Microbiol Mol Biol Rev

113

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SUMMARY Biomass is constructed of dense recalcitrant polymeric materials: proteins, lignin, and holocellulose, a fraction constituting fibrous cellulose wrapped in hemicellulose-pectin. Bacteria and fungi are abundant in soil and forest floors, actively recycling biomass mainly by extracting sugars from holocellulose degradation. Here we review the genome-wide contents of seven Aspergillus species and unravel hundreds of gene models encoding holocellulose-degrading enzymes. Numerous apparent gene duplications followed functional evolution, grouping similar genes into smaller coherent functional families according to specialized structural features, domain organization, biochemical activity, and genus genome distribution. Aspergilli contain about 37 cellulase gene models, clustered in two mechanistic categories: 27 hydrolyze and 10 oxidize glycosidic bonds. Within the oxidative enzymes, we found two cellobiose dehydrogenases that produce oxygen radicals utilized by eight lytic polysaccharide monooxygenases that oxidize glycosidic linkages, breaking crystalline cellulose chains and making them accessible to hydrolytic enzymes. Among the hydrolases, six cellobiohydrolases with a tunnel-like structural fold embrace single crystalline cellulose chains and cooperate at nonreducing or reducing end termini, splitting off cellobiose. Five endoglucanases group into four structural families and interact randomly and internally with cellulose through an open cleft catalytic domain, and finally, seven extracellular β-glucosidases cleave cellobiose and related oligomers into glucose. Aspergilli contain, on average, 30 hemicellulase and 7 accessory gene models, distributed among 9 distinct functional categories: the backbone-attacking enzymes xylanase, mannosidase, arabinase, and xyloglucanase, the short-side-chain-removing enzymes xylan α-1,2-glucuronidase, arabinofuranosidase, and xylosidase, and the accessory enzymes acetyl xylan and feruloyl esterases.

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“…Based on press releases, patents, talks at scientific meetings, and presentations scattered across the Internet, the companies are taking several approaches to reduce the cost of enzymes. These include screening new organisms (mainly fungi) for superior versions of current enzymes and for enzymes that act synergistically with existing commercial enzymes, continued strain improvement by conventional and molecular mutagenesis, enzyme improvement by protein engineering and directed evolution, and improved efficiencies in industrial-scale enzyme production [1,11,40,48,49,56].…”

Section: The Research Landscape Of Biomass Enzymesmentioning

confidence: 99%

Improving Enzymes for Biomass Conversion: A Basic Research Perspective

2010

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The cost of enzymes for converting plant biomass materials to fermentable sugars is a major impediment to the development of a practical lignocellulosic ethanol industry. Research on enzyme optimization with the goal of reducing the cost of converting biomass materials such as corn stover into glucose, xylose, and other sugars is being actively pursued in private industry, academia, and government laboratories. Under the auspices of the Department of Energy Great Lakes Bioenergy Research Center, we are taking several approaches to address this problem, including "bioprospecting" for superior key enzymes, protein engineering, and high-level expression in plants. A particular focus is the development of synthetic enzyme mixtures, in order to learn which of the hundreds of known enzymes are important and in what ratios. A core set comprises cellobiohydrolase, endoglucanase, β-glucosidase, endoxylanase, and β-glucosidase. Accessory enzymes include esterases, proteases, nonhydrolytic proteins, and glycosyl hydrolases that cleave the less frequent chemical linkages found in plant cell walls.

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Mode of action and properties of the β-xylosidases fromTalaromyces emersonii andTrichoderma reesei

Cited by 46 publications

References 25 publications

Novel pH-Stable Glycoside Hydrolase Family 3 β-Xylosidase from Talaromyces amestolkiae: an Enzyme Displaying Regioselective Transxylosylation

Novel pH-Stable Glycoside Hydrolase Family 3 β-Xylosidase from Talaromyces amestolkiae: an Enzyme Displaying Regioselective Transxylosylation

Genomics Review of Holocellulose Deconstruction by Aspergilli

Improving Enzymes for Biomass Conversion: A Basic Research Perspective

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