Impact and efficiency of GH10 and GH11 thermostable endoxylanases on wheat bran and alkali-extractable arabinoxylans

Beaugrand, Johnny; Chambat, G.; Wong, Vivian W.Y.; Goubet, Florence; Rémond, Caroline; Paës, Gabriel; Benamrouche, Samina; Debeire, Philippe; O’Donohue, Michael; Chabbert, Brigitte

doi:10.1016/j.carres.2004.08.012

Cited by 133 publications

(81 citation statements)

References 41 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: 83%

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: 83%

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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“…However, it is well known that arabinosyl substitutions can be unevenly distributed along the xylose backbone (Chanliaud et al 1995;Dervilly et al 2000;Adams et al 2004;Dervilly-Pinel et al 2004). In the case of pericarp AX, this would appear to be true because the use of alkalineextracted AX from XYL11-WT residual bran as substrate for XYL11-WT has revealed weak but detectable activity (Beaugrand et al 2004b). Likewise, one might expect the occurence of limited enzyme-specific zones devoid of arabinose on pericarp AX that could be labelled when using antibodies raised against unsubstituted xylon or xylanase.…”

Section: Discussionmentioning

confidence: 96%

“…In the glycoside hydrolase classification system (Henrissat 1991;Davies and Henrissat 1995), xylanases (EC 3.2.1.8) are mainly grouped in two families, GH10 and GH11. However, owing to their high efficiency towards insoluble lignocellulosic materials (Re´mond-Zilliox et al 1997;Beaugrand et al 2004b), GH11 xylanases are better candidates for depolymerization of an AX, embedded in a complex composite such as the caryopsis outer layers. In a recent study on the enzymatic degradation of WB using a thermostable GH11 xylanase, we revealed differential tissue and cell wall susceptibility to enzyme action, which could be related to the distribution of the enzyme's substrate (i.e.…”

Section: Introductionmentioning

confidence: 99%

Probing the cell wall heterogeneity of micro-dissected wheat caryopsis using both active and inactive forms of a GH11 xylanase

Beaugrand

Paës

Reis³

et al. 2005

Planta

Self Cite

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The external envelope of wheat grain (Triticum aestivum L. cv. Isengrain) is a natural composite whose tissular and cellular heterogeneity constitute a significant barrier for enzymatic cell wall disassembly. To better understand the way in which the cell wall network and tissular organization hamper enzyme penetration, we have devised a strategy based on in situ visualization of an active and an inactive form of a xylanase in whole-wheat bran and in three micro-dissected layers (the outer bran, the inner bran and the aleurone layer). The main aims of this study were to (1) evaluate the role of cuticular layers as obstacles to enzyme diffusion, (2) assess the impact of the cell wall network on xylanase penetration, (3) highlight wall heterogeneity. To conduct this study, we created by in vitro mutagenesis a hydrolytically inactive xylanase that displayed full substrate binding ability, as demonstrated by the calculation of dissociation constants (K(d)) using fluorescence titration. To examine enzyme penetration and action, immunocytochemical localization of the xylanases and of feebly substituted arabinoxylans (AXs) was performed following incubation of the bran layers, or whole bran with active and inactive isoforms of the enzyme for different time periods. The data obtained showed that the micro-dissected layers provided an increased accessible surface for the xylanase and that the enzyme-targeted cell walls were penetrated more quickly than those in intact bran. Examination of immunolabelling of xylanase indicated that the cuticle layers constitute a barrier for enzyme penetration in bran. Moreover, our data indicated that the cell wall network by itself physically restricts enzyme penetration. Inactive xylanase penetration was much lower than that of the active form, whose penetration was facilitated by the concomitant depletion of AXs in enzyme-sensitive cell walls.

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“…There was no obvious general preference for the FAE acting with a particular family of xylanases in releasing FA from waterunextractable arabinoxylan. Feruloyl esters were not a problem in the hydrolysis of WB aleurone and nucellar layers by a GH11 xylanase, but the pericarp stayed intact (Beaugrand et al 2004), suggesting diferuloylation and arabinose branching is a more important impediment to a better utilisation of cereal brans. Enzymatic release of FA from brewer's spent grain (BSG) appears to augment the action of other glycoside hydrolases in addition to xylanases in comparison to the two enzyme system on WB, suggesting a more complicated interaction between wall polymers in barley compared to wheat (Faulds et al 2002).…”

Section: Deconstruction Of Plant Cell Walls and Potential Uses In Biomentioning

confidence: 99%

What can feruloyl esterases do for us?

Faulds

2009

Phytochem Rev

105

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The role of feruloyl esterases in plant wall development, in gut health, and in the breakdown of plant biomass for the production of bioactive phytochemicals and biofuel is covered in this review. These enzymes have potential roles in stomatal cell function and the phenolic substitutions and crosslinkages between plant cell wall components. As more plant genomes are sequenced, the role of ferulic acid and feruloyl esterases in planta may be better understood. In human and ruminal digestion, these enzymes are important to de-esterify dietary fibre, releasing hydroxycinnamates and derivatives which have been shown to have positive health effects, such as antioxidant, anti-inflammatory and anti-microbial activities. They are also involved in colonic fermentation where their extracellular and intracellular activities in the microbiota improve the breakdown of polysaccharides and increase microbial production of short chain fatty acids. Their specificity can also be employed to synthesize bioactive compounds for cosmetic and health applications. The enzymatic disassembly of cereal straws is greatly enhanced when feruloyl esterase activity is present, although the substrate specificity of the esterase appears to have some bearing on its optimal application. The involvement of feruloyl esterases in the improved enzymatic and microbial saccharification of cerealderived material demonstrates a high importance for these enzymes in animal feed preparation and bioalcohol production.

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Impact and efficiency of GH10 and GH11 thermostable endoxylanases on wheat bran and alkali-extractable arabinoxylans

Cited by 133 publications

References 41 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

Probing the cell wall heterogeneity of micro-dissected wheat caryopsis using both active and inactive forms of a GH11 xylanase

What can feruloyl esterases do for us?

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