Behaviour of family 10 and 11 xylanases towards arabinoxylans with varying structure

Bonnin, Estelle; Daviet, Stéphanie; Sørensen, Jens F.; Sibbesen, Ole; Goldson, Andrew; Juge, Nathalie; Saulnier, Luc

doi:10.1002/jsfa.2501

Cited by 23 publications

(16 citation statements)

References 27 publications

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“…Indeed, RsgI6-GH10 both binds to and hydrolyzes insoluble and soluble xylan substrates. Although the K m was similar to previously published values for GH10 enzymes on arabinoxylan [29][30][31], the V max value was very low, exhibiting between 0.1-10% of the activity of other characterized xylanases, from C. thermocellum [31,32], as well as from Aspergillus aculeatus, Bacillus subtilis, Geobacillus stearothermophilus, and Themobacillus xylanilyticus [29,30,33]. This indicates that the aYnity for the soluble xylan substrate was similar to those of a typical GH10 enzyme, but the hydrolysis of the substrate was limited.…”

Section: Discussionsupporting

confidence: 85%

Glycoside hydrolases as components of putative carbohydrate biosensor proteins in Clostridium thermocellum

Bahari¹,

Gilad²,

Borovok³

et al. 2010

J Ind Microbiol Biotechnol

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The composition of the cellulase system in the cellulosome-producing bacterium, Clostridium thermocellum, has been reported to change in response to growth on different carbon sources. Recently, an extensive carbohydrate-sensing mechanism, purported to regulate the activation of genes coding for polysaccharide-degrading enzymes, was suggested. In this system, CBM modules, comprising extracellular components of RsgI-like anti-σ factors, were proposed to function as carbohydrate sensors, through which a set of cellulose utilization genes are activated by the associated σ(I)-like factors. An extracellular module of one of these RsgI-like proteins (Cthe_2119) was annotated as a family 10 glycoside hydrolase, RsgI6-GH10, and a second putative anti-σ factor (Cthe_1471), related in sequence to Rsi24, was found to contain a module that resembles a family 5 glycoside hydrolase (termed herein Rsi24C-GH5). The present study examines the relevance of these two glycoside hydrolases as sensors in this signal-transmission system. The RsgI6-GH10 was found to bind xylan matrices but exhibited low enzymatic activity on this substrate. In addition, this glycoside hydrolase module was shown to interact with crystalline cellulose although no hydrolytic activity was detected on cellulosic substrates. Bioinformatic analysis of the Rsi24C-GH5 showed a glutamate-to-glutamine substitution that would presumably preclude catalytic activity. Indeed, the recombinant module was shown to bind to cellulose, but showed no hydrolytic activity. These observations suggest that these two glycoside hydrolases underwent an evolutionary adaptation to function as polysaccharide binding agents rather than enzymatic components and thus serve in the capacity of extracellular carbohydrate sensors.

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Section: Discussionsupporting

confidence: 85%

Glycoside hydrolases as components of putative carbohydrate biosensor proteins in Clostridium thermocellum

Bahari¹,

Gilad²,

Borovok³

et al. 2010

J Ind Microbiol Biotechnol

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“…Another hypothesis is that xylanases drastically change the structure and physicochemical properties of the AX population. Xylanases in the same GH family, i.e., with similar specificities, differ substantially in substrate selectivity, and the classification of GH family alone is not sufficient to predict the breakdown of insoluble AXs by xylanases (8). Although mechanistic information on the catalytic and substrate specificity of xylanases is helpful for comparing xylanase efficiencies, other factors, such as their degree of selectivity toward soluble versus insoluble substrate, may play a role in determining the functionality of these enzymes in the degradation of hemicellulose from raw materials (5).…”

Section: Discussionmentioning

confidence: 99%

Podospora anserina Hemicellulases Potentiate the Trichoderma reesei Secretome for Saccharification of Lignocellulosic Biomass

Couturier

Haon²,

Coutinho

et al. 2011

Appl Environ Microbiol

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To improve the enzymatic hydrolysis (saccharification) of lignocellulosic biomass by Trichoderma reesei, a set of genes encoding putative polysaccharide-degrading enzymes were selected from the coprophilic fungus Podospora anserina using comparative genomics. Five hemicellulase-encoding genes were successfully cloned and expressed as secreted functional proteins in the yeast Pichia pastoris. These novel fungal CAZymes belonging to different glycoside hydrolase families (PaMan5A and PaMan26A mannanases, PaXyn11A xylanase, and PaAbf51A and PaAbf62A arabinofuranosidases) were able to break down their predicted cognate substrates. Although PaMan5A and PaMan26A displayed similar specificities toward a range of mannan substrates, they differed in their end products, suggesting differences in substrate binding. The N-terminal CBM35 module of PaMan26A displayed dual binding specificity toward xylan and mannan. PaXyn11A harboring a C-terminal CBM1 module efficiently degraded wheat arabinoxylan, releasing mainly xylobiose as end product. PaAbf51A and PaAbf62A arabinose-debranching enzymes exhibited differences in activity toward arabinose-containing substrates. Further investigation of the contribution made by each P. anserina auxiliary enzyme to the saccharification of wheat straw and spruce demonstrated that the endo-acting hemicellulases (PaXyn11A, PaMan5A, and PaMan26A) individually supplemented the secretome of the industrial T. reesei CL847 strain. The most striking effect was obtained with PaMan5A that improved the release of total sugars by 28% and of glucose by 18%, using spruce as lignocellulosic substrate.Lignocellulosic biomass is a desirable feedstock for the supply of second-generation bioethanol, being the largest renewable source of carbohydrates, but the recalcitrance of raw materials makes biotechnological conversion complex and costly (34).The main components of plant cell walls are cellulose, lignin, and hemicellulose, which form a tight complex with varying proportions between plants (for a review, see reference 45). Cellulose microfibrils are formed by crystalline-like combination of linear and highly ordered polymer chains of ␤-1,4-linked D-glucose residues, and lignin consists of an amorphous aromatic heteropolymer with hydrophobic properties. Hemicellulose is a combined designation of a diverse set of noncrystalline carbohydrate polymers from plant tissues that form closely associated networks with cellulose microfibrils and lignin (6, 24). Typically, the most abundant component of hemicellulose in the cell walls of monocots (e.g., cereals) is ␤-1,4-xylan, which consists of ␤-1,4-linked D-xylose residues substituted with L-arabinosyl, 4-O-methyl-glucuronosyl and acetyl side chains (46,53). Arabinofuranosyl residues of arabinoxylan may also be esterified with hydroxycinnamic acid residues, e.g., ferulic and p-coumaric acids (53). In softwoods (gymnosperms), the main hemicellulose component is ␤-1,4-mannan, which consists of a backbone formed by ␤-1,4-linked D-mannose and D-glucose residues substitu...

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“…These enzymes are mainly classified in the glycosyl hydrolase (GH) families 10 and 11 [16,64,65], although putative xylanase activities have been reported in GH families 5, 7, 8 and 43 [84,85]. GH10 xylanases are regarded to have broader substrate specificity and release shorter fragments compared to GH11 xylanases, while the latter enzymes are more susceptible to steric hindrance by arabinose substituents [86,87]. In addition, different endogenous xylanase inhibitors occur in cereals: Triticum aestivum L. xylanase inhibitor (TAXI) [88,89], xylanase inhibitor proteins (XIP-type inhibitors) [90] and TLXI-type (thaumatin-like endoxylanase inhibitors) [91].…”

Section: Hemicellulasesmentioning

confidence: 99%

Enzymes in Bakery: Current and Future Trends

Miguel¹,

Martins-Meyer²,

Figueiredo³

et al. 2013

Food Industry

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Behaviour of family 10 and 11 xylanases towards arabinoxylans with varying structure

Cited by 23 publications

References 27 publications

Glycoside hydrolases as components of putative carbohydrate biosensor proteins in Clostridium thermocellum

Glycoside hydrolases as components of putative carbohydrate biosensor proteins in Clostridium thermocellum

Podospora anserina Hemicellulases Potentiate the Trichoderma reesei Secretome for Saccharification of Lignocellulosic Biomass

Enzymes in Bakery: Current and Future Trends

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