Xylanases: Characteristics, Sources, Production, and Applications

Panagiotou, Gianni; Christakopoulos, Paul

doi:10.1002/9781118642047.ch9

Cited by 5 publications

(2 citation statements)

References 144 publications

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“…Here the gene cluster of interest includes a putative xylanase gene which might or might not be effectively active on its host (human) as the host lacks the substrate xylan. 1,4-β-Xylanase involves in xylan degradation pathway and degrades xylan into xylose and/or its xylooligosaccharides [34]. Presence of a putative xylanase gene in the gene cluster suggests that the transcriptional regulation of the gene cluster is influenced by xylan and/or other intermediates of the xylan degradation pathway.…”

Section: Discussionmentioning

confidence: 99%

MxyR of Mycobacterium tuberculosis Responds to Xylan; an Unusual Ligand for a MarR Family Transcriptional Regulator

Mauran

Perera

2021

Mol Biol

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Among the repertoire of MarR family transcriptional regulators in Mycobacterium tuberculosis, gene rv3095 (mxyR) encodes Mycobacterial Xylan Regulator, MxyR. Gene mxyR is divergently oriented from a hydrolase (rv3094c), oxidoreductase (rv3093c) and an ABC transporter (rv3092c) and convergently oriented with xylanase (rv3096). Xylanase is commonly used by plant pathogenic microbes where they degrade xylan, the major component of hemicellulose. We have purified the transcriptional regulatory protein encoded by rv3095 and its molecular interactions were studied in detail using electrophoretic mobility shift assay. MxyR interacts with its upstream intergenic region mxyO with high specificity and at a dissociation constant of 5.01 ± 0.017 nM. Notably, this binding is attenuated by specific carbohydrate ligands such as xylan, L-Arabinose and D-Galactose with an IC 50 values of 22.7 ± 1.02 ng/μL, 360.8 ± 24.25 ng/μL and 2320.0 ± 96.97 μg/μL, respectively. Consequently, it is evident that this association changes the conformation of the DNA binding helix α4 making the transcriptional regulator incompatible with binding to its cognate DNA, allowing xylanase and other genes to be transcribed. This study establishes the natural ligands of MxyR of M. tuberculosis providing insight on metabolic regulation of the carbohydrate, xylan.

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Section: Discussionmentioning

confidence: 99%

MxyR of Mycobacterium tuberculosis Responds to Xylan; an Unusual Ligand for a MarR Family Transcriptional Regulator

Mauran

Perera

2021

Mol Biol

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“…Xylanases belonging to GH10 and GH11 families have been widely investigated in literature with GH10 xylanases exhibiting less substrate specificity than GH11 xylanases. Therefore, the former enzymes are able to catalyze the hydrolysis of a wide spectrum of xylans, while the latter are known to preferentially cleave unsubstituted regions of arabinoxylan [4].…”

Section: Introductionmentioning

confidence: 99%

A novel fungal GH30 xylanase with xylobiohydrolase auxiliary activity

Katsimpouras

Dedes

Thomaidis

et al. 2019

Biotechnol Biofuels

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Background The main representatives of hemicellulose are xylans, usually decorated β-1,4-linked d -xylose polymers, which are hydrolyzed by xylanases. The efficient utilization and complete hydrolysis of xylans necessitate the understanding of the mode of action of xylan degrading enzymes. The glycoside hydrolase family 30 (GH30) xylanases comprise a less studied group of such enzymes, and differences regarding the substrate recognition have been reported between fungal and bacterial GH30 xylanases. Besides their role in the utilization of lignocellulosic biomass for bioenergy, such enzymes could be used for the tailored production of prebiotic xylooligosaccharides (XOS) due to their substrate specificity. Results The expression of a putative GH30_7 xylanase from the fungus Thermothelomyces thermophila (synonyms Myceliophthora thermophila , Sporotrichum thermophile ) in Pichia pastoris resulted in the production and isolation of a novel xylanase with unique catalytic properties. The novel enzyme designated Tt Xyn30A, exhibited an endo- mode of action similar to that of bacterial GH30 xylanases that require 4- O -methyl- d -glucuronic acid (MeGlcA) decorations, in contrast to most characterized fungal ones. However, Tt Xyn30A also exhibited an exo-acting catalytic behavior by releasing the disaccharide xylobiose from the non-reducing end of XOS. The hydrolysis products from beechwood glucuronoxylan were MeGlcA substituted XOS, and xylobiose. The major uronic XOS (UXOS) were the aldotriuronic and aldotetrauronic acid after longer incubation indicating the ability of Tt Xyn30A to cleave linear parts of xylan and UXOS as well. Conclusions Hereby, we reported the heterologous production and biochemical characterization of a novel fungal GH30 xylanase exhibiting endo- and exo-xylanase activity. To date, considering its novel catalytic properties, Tt Xyn30A shows differences with most characterized fungal and bacterial GH30 xylanases. The discovered xylobiohydrolase mode of action offers new insights into fungal enzymatic systems that are employed for the utilization of lignocellulosic biomass. The recombinant xylanase could be used for the production of X2 and UXOS from glucuronoxylan, which in turn would be utilized as prebiotics carrying manifold health benefits. Electronic supplementary material The online version of this article (10.1186/s13068-019-1455-2) contains supplementary material, which is available to authorized users.

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