Specific xyloglucanases as a new class of polysaccharide-degrading enzymes

Grishutin, Sergey G; Gusakov, Alexander V.; Марков, А. В.; Ustinov, Boris B.; Семенова, М. В.; Sinitsyn, A. P.

doi:10.1016/j.bbagen.2004.07.001

Cited by 133 publications

(80 citation statements)

References 35 publications

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“…While some endoglucanases are promiscuous and can hydrolyze both unbranched and branched ␤-1,4-glucan chains (189), xyloglucan-specific endoglucanases (XEGs) constitute a relatively new class of enzymes (190) and were described as EC 3.2.1.151 and EC 3.2.1.150 enzymes (191).…”

Section: Hemicellulasesmentioning

confidence: 99%

Genomics Review of Holocellulose Deconstruction by Aspergilli

Segato

Damásio

Lucas

et al. 2014

Microbiol Mol Biol Rev

105

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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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Section: Hemicellulasesmentioning

confidence: 99%

Genomics Review of Holocellulose Deconstruction by Aspergilli

Segato

Damásio

Lucas

et al. 2014

Microbiol Mol Biol Rev

105

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“…Enzyme activities were determined as described (Grishutin et al, 2004) using xyloglucan and b-glucan (Megazyme) as substrates. Assays were performed in 96-well microplates.…”

Section: Enzyme Activity Assaysmentioning

confidence: 99%

A Phytophthora sojae Glycoside Hydrolase 12 Protein Is a Major Virulence Factor during Soybean Infection and Is Recognized as a PAMP

et al. 2015

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We identified a glycoside hydrolase family 12 (GH12) protein, XEG1, produced by the soybean pathogen Phytophthora sojae that exhibits xyloglucanase and b-glucanase activity. It acts as an important virulence factor during P. sojae infection but also acts as a pathogen-associated molecular pattern (PAMP) in soybean (Glycine max) and solanaceous species, where it can trigger defense responses including cell death. GH12 proteins occur widely across microbial taxa, and many of these GH12 proteins induce cell death in Nicotiana benthamiana. The PAMP activity of XEG1 is independent of its xyloglucanase activity. XEG1 can induce plant defense responses in a BAK1-dependent manner. The perception of XEG1 occurs independently of the perception of ethylene-inducing xylanase. XEG1 is strongly induced in P. sojae within 30 min of infection of soybean and then slowly declines. Both silencing and overexpression of XEG1 in P. sojae severely reduced virulence. Many P. sojae RXLR effectors could suppress defense responses induced by XEG1, including several that are expressed within 30 min of infection. Therefore, our data suggest that PsXEG1 contributes to P. sojae virulence, but soybean recognizes PsXEG1 to induce immune responses, which in turn can be suppressed by RXLR effectors. XEG1 thus represents an apoplastic effector that is recognized via the plant's PAMP recognition machinery.

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“…The enzyme turnover rate, K cat , and the catalytic efficiency (K cat /K m ) were also higher for xyloglucan. It is possible that this enzyme might be considered a specific xyloglucanase, because its activity against xyloglucan is more than 10 times higher than its activity against CMC (24). However, further analyses are required for confirmation.…”

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confidence: 99%

Activity-Based Metagenomic Screening and Biochemical Characterization of Bovine Ruminal Protozoan Glycoside Hydrolases

Findley

Mormile

Sommer-Hurley

et al. 2011

Appl Environ Microbiol

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The rumen, the foregut of herbivorous ruminant animals such as cattle, functions as a bioreactor to process complex plant material. Among the numerous and diverse microbes involved in ruminal digestion are the ruminal protozoans, which are single-celled, ciliated eukaryotic organisms. An activity-based screen was executed to identify genes encoding fibrolytic enzymes present in the metatranscriptome of a bovine ruminal protozoan-enriched cDNA expression library. Of the four novel genes identified, two were characterized in biochemical assays. Our results provide evidence for the effective use of functional metagenomics to retrieve novel enzymes from microbial populations that cannot be maintained in axenic cultures.To process fibrous plant materials, the rumen harbors a collection of diverse microorganisms, including bacteria, archaea, fungi, and protozoa (reviewed in references 33 and 45). While the diversity and functions of the thousands of microbial species of this unique ecosystem (32) are interesting from both the evolutionary and functional perspectives, the rumen also represents a rich resource of enzymes for converting lignocellulosic feedstocks into biofuel (35, 43) and other applications (19). A range of inexpensive, robust enzymes with a broad range of specificities will likely be required for efficient industrial processing of highly complex plant polysaccharides. Identification of such enzymes that microorganisms use to break down plant materials has been greatly facilitated by metagenomics (42), both in the form of activity-based screens (20, 52) and also through increasingly powerful, high-throughput genomic DNA sequencing approaches (28, 57). As evident in numerous studies (28,39,41), metagenomics has proven to be particularly effective for identification of carbohydrate-active genes of fiber-adherent bacterial species of the rumen.In addition to bacteria and archaea, the rumen also hosts eukaryotic species, namely, anaerobic fungi and ciliate protozoans (reviewed in reference 33). Addressing the function of ruminal protozoans, in particular, has been a challenge due to the difficulty of maintaining these organisms in axenic cultures (55). Thus, assessing the diversity and dynamics of ruminal protozoans has been addressed historically in morphogenic studies (reviewed in reference 12) and by molecular phylogenetics (e.g., by using 18S rDNA markers [47]). Ruminal protozoans are known to contribute to fiber degradation in their hosts (21), and determination and characterization of their ability to directly process plant material have been addressed by diverse strategies, such as direct, biochemical detection of specific fibrolytic enzymes (e.g., cellulases) in extracts derived from individual protozoan species (38, 54), by molecular cloning studies to directly identify genes encoding enzymes capable of degrading cellulose or hemicellulose (49, 50) and, most recently, by sequencing of protozoan-derived expressed sequence tag (EST) libraries (41). Early studies to establish the capacity of protozoan ...

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Specific xyloglucanases as a new class of polysaccharide-degrading enzymes

Cited by 133 publications

References 35 publications

Genomics Review of Holocellulose Deconstruction by Aspergilli

Genomics Review of Holocellulose Deconstruction by Aspergilli

A Phytophthora sojae Glycoside Hydrolase 12 Protein Is a Major Virulence Factor during Soybean Infection and Is Recognized as a PAMP

Activity-Based Metagenomic Screening and Biochemical Characterization of Bovine Ruminal Protozoan Glycoside Hydrolases

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