Inverting character of family GH115 α‐glucuronidases

Kolenová, Katarína; Ryabova, Olena B.; Vršanská, Mária; Biely, Peter

doi:10.1016/j.febslet.2010.08.031

Cited by 26 publications

(16 citation statements)

References 30 publications

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“…The agu115 gene is highly expressed on xylans to a level similar to that of agu67A, and neither of these genes include sequences corresponding to a signal peptide. GH115 ␣-glucuronidases from the prokaryotic Gram-negative bacterium Bacteroides ovatus ATCC 8483 (34) and eukaryotic Pichia stipitis CBS 6054 (35) have been shown to have a preference for the aldopentauronate generated by GH11 endoxylanases. Agu115 from the Gram-positive bacterium Pjdr2 also shows activity on MeGX 4 generated by Xyn11 digestion of MeGX n (unpublished data).…”

Section: Resultsmentioning

confidence: 99%

Transcriptomic Analysis of Xylan Utilization Systems in Paenibacillus sp. Strain JDR-2

Sawhney

Crooks

John

et al. 2015

Appl Environ Microbiol

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b Xylans, including methylglucuronoxylans (MeGX n ) and methylglucuronoarabinoxylans (MeGAX n ), are the predominant polysaccharides in hemicellulose fractions of dicots and monocots available for conversion to biofuels and chemicals. Paenibacillus sp. strain JDR-2 (Pjdr2) efficiently depolymerizes MeGX n and MeGAX n and assimilates the generated oligosaccharides, resulting in efficient saccharification and subsequent metabolism of these polysaccharides. A xylan utilization regulon encoding a cellassociated GH10 (glycoside hydrolase family 10) endoxylanase, transcriptional regulators, ABC (ATP binding cassette) transporters, an intracellular GH67 ␣-glucuronidase, and other glycoside hydrolases contributes to complete metabolism. This GH10/GH67 system has been proposed to account for preferential utilization of xylans compared to free oligo-and monosaccharides. To identify additional genes contributing to MeGX n and MeGAX n utilization, the transcriptome of Pjdr2 has been sequenced following growth on each of these substrates as well as xylose and arabinose. Increased expression of genes with different substrates identified pathways common or unique to the utilization of MeGX n or MeGAX n . Coordinate upregulation of genes comprising the GH10/GH67 xylan utilization regulon is accompanied with upregulation of genes encoding a GH11 endoxylanase and a GH115 ␣-glucuronidase, providing evidence for a novel complementary pathway for processing xylans. Elevated expression of genes encoding a GH43 arabinoxylan arabinofuranohydrolase and an arabinose ABC transporter on MeGAX n but not on MeGX n supports a process in which arabinose may be removed extracellularly followed by its rapid assimilation. Further development of Pjdr2 for direct conversion of xylans to targeted products or introduction of these systems into fermentative strains of related bacteria may lead to biocatalysts for consolidated bioprocessing of hemicelluloses released from lignocellulose.

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Section: Resultsmentioning

confidence: 99%

Transcriptomic Analysis of Xylan Utilization Systems in Paenibacillus sp. Strain JDR-2

Sawhney

Crooks

John

et al. 2015

Appl Environ Microbiol

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“…What makes Rex8A unique among the characterized reducing-end xylose-releasing exo-oligoxylanases is its activity on branched oligomers, which could facilitate the release of MeGlcA substitutions by ␣-glucuronidases. In fact, the characterized GH115 ␣-glucuronidase of Pichia stipitis has shown increasing activity on branched oligomers of decreasing length (37).…”

Section: Fig 6 Analysis Of Hydrolysis Products From Branched Xylooligmentioning

confidence: 99%

The Glycoside Hydrolase Family 8 Reducing-End Xylose-Releasing Exo-oligoxylanase Rex8A from Paenibacillus barcinonensis BP-23 Is Active on Branched Xylooligosaccharides

Valenzuela

López

Biely

et al. 2016

Appl Environ Microbiol

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A GH8 family enzyme involved in xylan depolymerization has been characterized. The enzyme, Rex8A, is a reducing-end xylosereleasing exo-oligoxylanase (Rex) that efficiently hydrolyzes xylooligosaccharides and shows minor activity on polymeric xylan. Rex8A hydrolyzes xylooligomers of 3 to 6 xylose units to xylose and xylobiose in long-term incubations. Kinetic constants of Rex8A were determined on xylotriose, showing a K m of 1.64 ؎ 0.03 mM and a k cat value of 118.8 s ؊1 . Besides linear xylooligosaccharides, the enzyme hydrolyzed decorated xylooligomers. The catalytic activity on branched xylooligosaccharides, i.e., the release of xylose from the reducing end, is a newly described trait of xylose-releasing exo-oligoxylanases, as the exo-activity on these substrates has not been reported for the few of these enzymes characterized to date. Modeling of the three-dimensional (3D) structure of Rex8A shows an (␣/␣) 6 barrel fold where the loops connecting the ␣-helices contour the active site. These loops, which show high sequence diversity among GH8 enzymes, shape a catalytic cleft with a ؊2 subsite that can accommodate methyl-glucuronic acid decorations. The hydrolytic ability of Rex8A on branched oligomers can be crucial for the complete depolymerization of highly substituted xylans, which is indispensable to accomplish biomass deconstruction and to generate efficient catalysts. IMPORTANCEA GH8 family enzyme involved in xylan depolymerization has been characterized. The Rex8A enzyme from Paenibacillus barcinonensis is involved in depolymerization of glucuronoxylan, a major component of the lignocellulosic substrates. The study shows that Rex8A is a reducing-end xylose-releasing exo-oligoxylanase that efficiently hydrolyzes xylose from neutral and acidic xylooligosaccharides generated by the action of other xylanases also secreted by the strain. The activity of a Rex enzyme on branched xylooligosaccharides has not been described to date. This report provides original and useful information on the properties of a new example of the rarely studied Rex enzymes. Depolymerization of highly substituted xylans is crucial for biomass valorization as a platform for generation of biofuels, chemicals, and solvents. P lant biomass is the most abundant source of organic carbon on the planet; therefore, it has become one of the most powerful and sustainable alternatives to petroleum as a platform for generation of biofuels, chemicals, and solvents (1). Nevertheless, plant cell walls are recalcitrant to biological depolymerization, as the extensive interactions between polysaccharides, and between polysaccharides and lignin, restrict access to the battery of degrading enzymes that break down these composite structures (2, 3). Celluloses and hemicelluloses are the most abundant polysaccharides in plants; thus, their separation and degradation are crucial for biomass valorization. Xylan is the major component of hemicelluloses, and it is composed of a backbone of ␤-D-xylopyranosyl residues that can be variably acetylated an...

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“…Hydrogels were obtained by selective removal of arabinose from extracted arabinoglucuronoxylans using the ␣-l-arabinofuranosidase enzyme from family GH54 (AbfB), produced by expression in Aspergillus niger (Chimphango et al, 2012a). Similar precipitation was achieved by removal of MeGlcA from polymeric glucuronoxylans by the ␣-d-glucuronidase enzyme from family GH115 (Agu), expressed in Scheffersomyces stipites (Kolenova, Ryabova, Vrsanska, & Biely, 2010). The sidechain removal activities of AbfB and Agu enzymes are not limited to oligomeric xylans, as observed for the majority of ␣-d-glucuronidases and ␣-l-arabinofuranosidase enzymes (De Vries, Poulsen, Madrid, & Visser, 1998;Tenkanen & Siika-aho, 2000).…”

Section: Introductionmentioning

confidence: 99%

Modifying solubility of polymeric xylan extracted from Eucalyptus grandis and sugarcane bagasse by suitable side chain removing enzymes

Gomes

Chimphango

Görgens

2015

Carbohydrate Polymers

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Inverting character of family GH115 α‐glucuronidases

Cited by 26 publications

References 30 publications

Transcriptomic Analysis of Xylan Utilization Systems in Paenibacillus sp. Strain JDR-2

Transcriptomic Analysis of Xylan Utilization Systems in Paenibacillus sp. Strain JDR-2

The Glycoside Hydrolase Family 8 Reducing-End Xylose-Releasing Exo-oligoxylanase Rex8A from Paenibacillus barcinonensis BP-23 Is Active on Branched Xylooligosaccharides

Modifying solubility of polymeric xylan extracted from Eucalyptus grandis and sugarcane bagasse by suitable side chain removing enzymes

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