mycoCLAP, the database for characterized lignocellulose-active proteins of fungal origin: resource and text mining curation support (original) (raw)
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Cellulose, 2009
Genome sequencing of a variety of fungi is a major initiative currently supported by the Department of Energy's Joint Genome Institute. Encoded within the genomes of many fungi are upwards of 200? enzymes called glycoside hydrolases (GHs). GHs are known for their ability to hydrolyze the polysaccharide components of lignocellulosic biomass. Production of ethanol and ''next generation'' biofuels from lignocellulosic biomass represents a sustainable route to biofuels production. However, this process has to become more economical before large scale operations are put into place. Identifying and characterizing GHs with improved properties for biomass degradation is a key factor for the development of cost effective processes to convert biomass to fuels and chemicals. With the recent explosion in the number of GH encoding genes discovered by fungal genome sequencing projects, it has become apparent that improvements in GH gene annotation processes have to be developed. This will enable more informed and efficient decision making with regard to selection and utilization of these important enzymes in bioprocess that produce fuels and chemicals from lignocellulosic feedstocks.
Background: Fungal glucose dehydrogenases (GDHs) are FAD-dependent enzymes belonging to the glucose-methanol-choline oxidoreductase superfamily. These enzymes are classified in the “Auxiliary Activity” family 3 (AA3) of the Carbohydrate-Active enZymes database, and more specifically in subfamily AA3_2, that also includes the closely related flavoenzymes aryl-alcohol oxidase and glucose 1-oxidase. Based on sequence similarity to known fungal GDHs, an AA3_2 enzyme active on glucose was identified in the genome of Pycnoporus cinnabarinus, a model Basidiomycete able to completely degrade lignin.Results: In our work, substrate screening and functional characterization showed an unexpected preferential activity of this enzyme toward oligosaccharides containing a b(1à3) glycosidic bond, with the highest efficiency observed for the disaccharide laminaribiose. Despite its sequence similarity to GDHs, we defined a novel enzymatic activity, namely oligosaccharide dehydrogenase (ODH), for this ...
Scientific reports, 2017
In this study, a high-throughput sequencing approach was applied to discover novel biocatalysts for lignocellulose hydrolysis from three dedicated energy crops, Arundo donax, Eucalyptus camaldulensis and Populus nigra, after natural biodegradation. The microbiomes of the three lignocellulosic biomasses were dominated by bacterial species (approximately 90%) with the highest representation by the Streptomyces genus both in the total microbial community composition and in the microbial diversity related to GH families of predicted ORFs. Moreover, the functional clustering of the predicted ORFs showed a prevalence of poorly characterized genes, suggesting these lignocellulosic biomasses are potential sources of as yet unknown genes. 1.2%, 0.6% and 3.4% of the total ORFs detected in A. donax, E. camaldulensis and P. nigra, respectively, were putative Carbohydrate-Active Enzymes (CAZymes). Interestingly, the glycoside hydrolases abundance in P. nigra (1.8%) was higher than that detected ...
BMC Genomics, 2012
Background: Filamentous fungi are potent biomass degraders due to their ability to thrive in ligno(hemi)celluloserich environments. During the last decade, fungal genome sequencing initiatives have yielded abundant information on the genes that are putatively involved in lignocellulose degradation. At present, additional experimental studies are essential to provide insights into the fungal secreted enzymatic pools involved in lignocellulose degradation. Results: In this study, we performed a wide analysis of 20 filamentous fungi for which genomic data are available to investigate their biomass-hydrolysis potential. A comparison of fungal genomes and secretomes using enzyme activity profiling revealed discrepancies in carbohydrate active enzymes (CAZymes) sets dedicated to plant cell wall. Investigation of the contribution made by each secretome to the saccharification of wheat straw demonstrated that most of them individually supplemented the industrial Trichoderma reesei CL847 enzymatic cocktail. Unexpectedly, the most striking effect was obtained with the phytopathogen Ustilago maydis that improved the release of total sugars by 57% and of glucose by 22%. Proteomic analyses of the best-performing secretomes indicated a specific enzymatic mechanism of U. maydis that is likely to involve oxido-reductases and hemicellulases. Conclusion: This study provides insight into the lignocellulose-degradation mechanisms by filamentous fungi and allows for the identification of a number of enzymes that are potentially useful to further improve the industrial lignocellulose bioconversion process.
BMC Genomics, 2015
Background: Various saprotrophic microorganisms, especially filamentous fungi, can efficiently degrade lignocellulose that is one of the most abundant natural materials on earth. It consists of complex carbohydrates and aromatic polymers found in the plant cell wall and thus in plant debris. Aspergillus fumigatus Z5 was isolated from compost heaps and showed highly efficient plant biomass-degradation capability. Results: The 29-million base-pair genome of Z5 was sequenced and 9540 protein-coding genes were predicted and annotated. Genome analysis revealed an impressive array of genes encoding cellulases, hemicellulases and pectinases involved in lignocellulosic biomass degradation. Transcriptional responses of A. fumigatus Z5 induced by sucrose, oat spelt xylan, Avicel PH-101 and rice straw were compared. There were 444, 1711 and 1386 significantly differently expressed genes in xylan, cellulose and rice straw, respectively, when compared to sucrose as a control condition. Conclusions: Combined analysis of the genomic and transcriptomic data provides a comprehensive understanding of the responding mechanisms to the most abundant natural polysaccharides in A. fumigatus. This study provides a basis for further analysis of genes shown to be highly induced in the presence of polysaccharide substrates and also the information which could prove useful for biomass degradation and heterologous protein expression.
Engineering in Life Sciences
Lignocellulose degradation: An overview of fungi and fungal enzymes involved in lignocellulose degradation This review aims to present current knowledge of the fungi involved in lignocellulose degradation with an overview of the various classes of lignocellulose-acting enzymes engaged in the pretreatment and saccharification step. Fungi have numerous applications and biotechnological potential for various industries including chemicals, fuel, pulp, and paper. The capability of fungi to degrade lignocellulose containing raw materials is due to their highly effective enzymatic system. Along with the hydrolytic enzymes consisting of cellulases and hemicellulases, responsible for polysaccharide degradation, they have a unique nonenzymatic oxidative system which together with ligninolytic enzymes is responsible for lignin modification and degradation. An overview of the enzymes classification is given by the Carbohydrate-Active enZymes (CAZy) database as the major database for the identification of the lignocellulolytic enzymes by their amino acid sequence similarity. Finally, the recently discovered novel class of recalcitrant polysaccharide degraders-lytic polysaccharide monooxygenases (LPMOs) are presented, because of these enzymes importance in the cellulose degradation process.
Frontiers in Bioengineering and Biotechnology, 2020
Given the global abundance of plant biomass residues, potential exists in biorefinerybased applications with lignocellulolytic fungi. Frequently isolated from agricultural cellulosic materials, Aspergillus terreus is a fungus efficient in secretion of commercial enzymes such as cellulases, xylanases and phytases. In the context of biomass saccharification, lignocellulolytic enzyme secretion was analyzed in a strain of A. terreus following liquid culture with sugarcane bagasse (SB) (1% w/v) and soybean hulls (SH) (1% w/v) as sole carbon source, in comparison to glucose (G) (1% w/v). Analysis of the fungal secretome revealed a maximum of 1.017 UI.mL −1 xylanases after growth in minimal medium with SB, and 1.019 UI.mL −1 after incubation with SH as carbon source. The fungal transcriptome was characterized on SB and SH, with gene expression examined in comparison to equivalent growth on G as carbon source. Over 8000 genes were identified, including numerous encoding enzymes and transcription factors involved in the degradation of the plant cell wall, with significant expression modulation according to carbon source. Eighty-nine carbohydrate-active enzyme (CAZyme)-encoding genes were identified following growth on SB, of which 77 were differentially expressed. These comprised 78% glycoside hydrolases, 8% carbohydrate esterases, 2.5% polysaccharide lyases, and 11.5% auxiliary activities. Analysis of the glycoside hydrolase family revealed significant up-regulation for genes encoding 25 different GH family proteins, with predominance for families GH3, 5, 7, 10, and 43. For SH, from a total of 91 CAZyme-encoding genes, 83 were also significantly up-regulated in comparison to G. These comprised 80% glycoside hydrolases, 7% carbohydrate esterases, 5% polysaccharide lyases, 7% auxiliary activities (AA), and 1% glycosyltransferases. Similarly, within the glycoside hydrolases, significant up-regulation was observed for genes encoding 26 different GH family proteins, with predominance again for families GH3, 5, 10, 31, and 43. A. terreus is a promising species for production
Distribution and diversity of enzymes for polysaccharide degradation in fungi (R. Berlemont*)
Background: Glycoside hydrolases (GH) targeting cellulose, xylan, and chitin are common in the bacterial genomes that have been sequenced. Little is known, however, about the architecture of multi-domain and multi-activity glyco-side hydrolases. In these enzymes, combined catalytic domains act synergistically and thus display overall improved catalytic efficiency, making these proteins of high interest for the biofuel technology industry. Results: Here, we identify the domain organization in 40,946 proteins targeting cellulose, xylan, and chitin derived from 11,953 sequenced bacterial genomes. These bacteria are known to be capable, or to have the potential, to degrade polysaccharides, or are newly identified potential degraders (e.g., Actinospica, Hamadaea, Cystobacter, and Microbispora). Most of the proteins we identified contain a single catalytic domain that is frequently associated with an accessory non-catalytic domain. Regarding multi-domain proteins, we found that many bacterial strains have unique GH protein architectures and that the overall protein organization is not conserved across most genera. We identified 217 multi-activity proteins with at least two GH domains for cellulose, xylan, and chitin. Of these proteins, 211 have GH domains targeting similar or associated substrates (i.e., cellulose and xylan), whereas only six proteins target both cellulose and chitin. Fifty-two percent of multi-activity GHs are hetero-GHs. Finally, GH6, −10, −44 and −48 domains were mostly C-terminal; GH9, −11, −12, and −18 were mostly N-terminal; and GH5 domains were either Nor C-terminal. Conclusion: We identified 40,946 multi-domain/multi-activity proteins targeting cellulase, chitinase, and xylanase in bacterial genomes and proposed new candidate lineages and protein architectures for carbohydrate processing that may play a role in biofuel production.
Applied and environmental microbiology, 2018
Fungi play a key role cycling nutrients in forest ecosystems but the mechanisms remain uncertain. To clarify the enzymatic processes involved in wood decomposition, metatranscriptomics and metaproteomics of extensively decayed lodgepole pine were examined by RNAseq and LC-MS/MS, respectively. Following metatranscriptome assembly, 52,011 contigs were searched for functional domains and homology to database entries. Contigs similar to to basidiomycete transcripts dominated and many of these were most closely related to ligninolytic white rot fungi or cellulolytic brown rot fungi. A diverse array of carbohydrate active enzymes (CAzymes) representing a total of 132 families or subfamilies were identified. Among these were 672 glycoside hydrolases including highly expressed cellulases or hemicellulases. The CAzymes also included 162 genes encoding redox enzymes classified within Auxiliary Activity (AA) families. Eighteen of these were manganese peroxidases, key components of ligninolytic...
Distribution and diversity of enzymes for polysaccharide degradation in fungi OPEN
Fungi are important polysaccharide degraders in the environment and for biotechnology. Here, the increasing number of sequenced fungal genomes allowed for systematic identification of genes and proteins involved in polysaccharide degradation in 218 fungi. Globally, 9,003 sequences for glycoside hydrolases and lytic polysaccharide mono-oxygenases targeting cellulose, xylan, and chitin, were identified. Although abundant in most lineages, the distribution of these enzymes is variable even between organisms from the same genus. However, most fungi are generalists possessing several enzymes for polysaccharide deconstruction. Most identified enzymes were small proteins with simple domain organization or eventually consisted of one catalytic domain associated with a non-catalytic accessory domain. Thus unlike bacteria, fungi's ability to degrade polysaccharides relies on apparent redundancy in functional traits and the high frequency of lytic polysaccharide mono-oxygenases, as well as other physiological adaptation such as hyphal growth. Globally, this study provides a comprehensive framework to further identify enzymes for polysaccharide deconstruction in fungal genomes and will help identify new strains and enzymes with potential for biotechnological application. Glycoside hydrolases (GHs) and lytic polysaccharide mono-oxygenases (LPMOs) with other carbohydrate active enzymes (e.g., polysaccharide lyases), are essential for the processing of polysaccharides 1. Among the many identified polysaccharides, cellulose and xylan from plants represent the major source of carbon in land ecosystems. Chitin, produced by arthropods and fungi, is an important source of carbon and nitrogen in both marine and land ecosystems. The enzymatic degradation of these polysaccharides is essential for many ecosystem-processes including nutrient cycling (e.g., carbon cycling) 2 and herbivores nutrition 3. In order to degrade polysaccharides, many enzymes with synergistic action are required. For example GHs with an endo-mode of action (e.g., endo-cellulase) and GHs active on extremities (e.g., exo-cellulase) act syner-gistically to release short oligosaccharides. Finally some GHs are involved in the processing of these shorter degradation products (e.g., β-glucosidase). In consequence, most identified polysaccharide degraders are equipped with several GH families 1, 4, 5. Often, polysaccharides associate and form complex superstructures (e.g., cellulose and xylan in plant cell walls); the deconstruction of these complex structure requires further synergy between enzymes targeting chemically distinct but physically associated substrates. Hence, many degraders often target several substrates (e.g., cellulose and xylan) 5, 6. In the environment, the hydrolysis of cellulose, xylan, and chitin is mostly supported by bacteria and fungi. Several strategies have been described: the production of (i) individual enzymes, sometimes associated with non-catalytic accessory domains (i.e., multidomain GHs) 7, 8 , (ii) the production of multiactivity GHs with several catalytic domains associated; and (iii) the synthesis of non-covalent multi-protein complexes called cellulosomes 9, 10. Multidomain/activity GHs, and cellulosomes are promising tools for improving the deconstruction of biopol-ymers and biofuel industries 9, 11–13. Beside GHs, CAZymes include some proteins with " auxiliary activities " (AAs), among others. The proteins are involved in lignin deconstruction and oxidative degradation of cellulose and chitin (i.e., lytic polysaccharide mono-oxygenases, LPMOs) 1. Proteins from AA family 9 and 10 are LPMOs, previously classified as GH family 61 and CBM33, respectively. According to CAZy DB 1 , AA family 9 is exclusively observed in eukaryote whereas AA family 10 is found mostly in bacteria. Finally, AA13 is the third family of enzyme with LPMO activity and contains only a few identified sequences.