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Escudero, V., Jorda, L., Sopena-Torres, S., Melida, H., Miedes, E., Munoz-Barrios, A., . . . Molina, A. (2017). Alteration of cell wall xylan acetylation triggers defense responses that counterbalance the immune deficiencies of plants impaired in the beta-subunit of the heterotrimeric G-protein. The Plant Journal, 92(3), 386-399
Open this publication in new window or tab >>Alteration of cell wall xylan acetylation triggers defense responses that counterbalance the immune deficiencies of plants impaired in the beta-subunit of the heterotrimeric G-protein
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2017 (English)In: The Plant Journal, ISSN 0960-7412, E-ISSN 1365-313X, Vol. 92, no 3, p. 386-399Article in journal (Refereed) Published
Abstract [en]

Arabidopsis heterotrimeric G-protein complex modulates pathogen-associated molecular pattern-triggered immunity (PTI) and disease resistance responses to different types of pathogens. It also plays a role in plant cell wall integrity as mutants impaired in the G- (agb1-2) or G-subunits have an altered wall composition compared with wild-type plants. Here we performed a mutant screen to identify suppressors of agb1-2 (sgb) that restore susceptibility to pathogens to wild-type levels. Out of the four sgb mutants (sgb10-sgb13) identified, sgb11 is a new mutant allele of ESKIMO1 (ESK1), which encodes a plant-specific polysaccharide O-acetyltransferase involved in xylan acetylation. Null alleles (sgb11/esk1-7) of ESK1 restore to wild-type levels the enhanced susceptibility of agb1-2 to the necrotrophic fungus Plectosphaerella cucumerina BMM (PcBMM), but not to the bacterium Pseudomonas syringae pv. tomato DC3000 or to the oomycete Hyaloperonospora arabidopsidis. The enhanced resistance to PcBMM of the agb1-2 esk1-7 double mutant was not the result of the re-activation of deficient PTI responses in agb1-2. Alteration of cell wall xylan acetylation caused by ESK1 impairment was accompanied by an enhanced accumulation of abscisic acid, the constitutive expression of genes encoding antibiotic peptides and enzymes involved in the biosynthesis of tryptophan-derived metabolites, and the accumulation of disease resistance-related secondary metabolites and different osmolites. These esk1-mediated responses counterbalance the defective PTI and PcBMM susceptibility of agb1-2 plants, and explain the enhanced drought resistance of esk1 plants. These results suggest that a deficient PTI-mediated resistance is partially compensated by the activation of specific cell-wall-triggered immune responses. Significance Statement The plant heterotrimeric G protein complex is an essential component of Pathogen Associated Molecular Pattern-triggered immunity (PTI) and of plant disease resistance to several types of pathogens. We found that modification of the degree of xylan acetylation in plant cell walls activates PTI-independent resistance responses that counterbalance the hypersusceptibility to particular pathogens of plants lacking the heterotrimeric G subunit. These data demonstrate that immune deficient response can be partially compensated by the activation of cell wall-triggered immunity that confers specific disease resistance.

Place, publisher, year, edition, pages
WILEY, 2017
Keywords
heterotrimeric G-protein, AGB1, agb1-2, plant cell wall, xylan, necrotrophic fungi, immunity, pathogen-associated molecular pattern, Plectosphaerella cucumerina, Arabidopsis thaliana
National Category
Plant Biotechnology
Identifiers
urn:nbn:se:kth:diva-217023 (URN)10.1111/tpj.13660 (DOI)000412932100005 ()28792629 (PubMedID)2-s2.0-85029405800 (Scopus ID)
Note

QC 20171124

Available from: 2017-11-24 Created: 2017-11-24 Last updated: 2017-11-24Bibliographically approved
Dahlin, P., Srivastava, V., Ekengren, S., McKee, L. S. & Bulone, V. (2017). Comparative analysis of sterol acquisition in the oomycetes Saprolegnia parasitica and Phytophthora infestans. PLoS ONE, 12(2), Article ID e0170873.
Open this publication in new window or tab >>Comparative analysis of sterol acquisition in the oomycetes Saprolegnia parasitica and Phytophthora infestans
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2017 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 2, article id e0170873Article in journal (Refereed) Published
Abstract [en]

The oomycete class includes pathogens of animals and plants which are responsible for some of the most significant global losses in agriculture and aquaculture. There is a need to replace traditional chemical means of controlling oomycete growth with more targeted approaches, and the inhibition of sterol synthesis is one promising area. To better direct these efforts, we have studied sterol acquisition in two model organisms: the sterol-autotrophic Saprolegnia parasitica, and the sterol-heterotrophic Phytophthora infestans. We first present a comprehensive reconstruction of a likely sterol synthesis pathway for S. parasitica, causative agent of the disease saprolegniasis in fish. This pathway shows multiple potential routes of sterol synthesis, and draws on several avenues of new evidence: bioinformatic mining for genes with sterol-related functions, expression analysis of these genes, and analysis of the sterol profiles in mycelium grown in different media. Additionally, we explore the extent to which P. infestans, which causes the late blight in potato, can modify exogenously provided sterols. We consider whether the two very different approaches to sterol acquisition taken by these pathogens represent any specific survival advantages or potential drug targets.

Place, publisher, year, edition, pages
PUBLIC LIBRARY SCIENCE, 2017
National Category
Biological Sciences
Identifiers
urn:nbn:se:kth:diva-204090 (URN)10.1371/journal.pone.0170873 (DOI)000396161200053 ()2-s2.0-85011382600 (Scopus ID)
Note

QC 20170329

Available from: 2017-03-29 Created: 2017-03-29 Last updated: 2017-11-29Bibliographically approved
McKee, L. S. (2017). Measuring enzyme kinetics of glycoside hydrolases using the 3,5-dinitrosalicylic acid assay. In: Methods in Molecular Biology: (pp. 27-36). Humana Press Inc.
Open this publication in new window or tab >>Measuring enzyme kinetics of glycoside hydrolases using the 3,5-dinitrosalicylic acid assay
2017 (English)In: Methods in Molecular Biology, Humana Press Inc. , 2017, p. 27-36Conference paper (Refereed)
Abstract [en]

Use of the 3,5-dinitrosalicylic acid reagent allows the simple and rapid quantification of reducing sugars. The method can be used for analysis of biological samples or in the characterization of enzyme reactions. Presented here is an application of the method in measuring the kinetics of a glycoside hydrolase reaction, including the optimization of the DNSA reagent, and the production of a standard curve of absorbance and sugar concentration.

Place, publisher, year, edition, pages
Humana Press Inc., 2017
Keywords
3, 5-dinitrosalicylic acid, Enzyme kinetics, Glycoside hydrolase, Reducing sugars, UV–visible spectrophotometry, 3, 5 dinitrosalicylic acid, glycosidase, reagent, salicylic acid derivative, sugar, unclassified drug, assay, enzyme mechanism, chemistry, enzyme assay, kinetics, metabolism, procedures, Enzyme Assays, Glycoside Hydrolases, Salicylates
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:kth:diva-216559 (URN)10.1007/978-1-4939-6899-2_3 (DOI)2-s2.0-85018584524 (Scopus ID)
Note

Funding details: Knut och Alice Wallenbergs Stiftelse; Funding details: KTH, Kungliga Tekniska Högskolan; Funding details: Svenska Forskningsrådet Formas; Funding text: The author thanks the support of the Knut and Alice Wallenberg Foundation through the Wallenberg Wood Science Centre, Sweden, as well as the KTH Carbohydrate Materials Consortium (CarboMat) supported by the Swedish Research Council FORMAS.

QC 20171108

Available from: 2017-11-08 Created: 2017-11-08 Last updated: 2017-11-08Bibliographically approved
Larsbrink, J., Tuveng, T. R., Pope, P. B., Bulone, V., Eijsink, V. G. .., Brumer, H. & McKee, L. S. (2017). Proteomic data on enzyme secretion and activity in the bacterium Chitinophaga pinensis. Data in Brief, 11, 484-490
Open this publication in new window or tab >>Proteomic data on enzyme secretion and activity in the bacterium Chitinophaga pinensis
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2017 (English)In: Data in Brief, E-ISSN 2352-3409, Vol. 11, p. 484-490Article in journal (Refereed) Published
Abstract [en]

The secretion of carbohydrate-degrading enzymes by a bacterium sourced from a softwood forest environment has been investigated by mass spectrometry. The findings are discussed in full in the research article “Proteomic insights into mannan degradation and protein secretion by the forest floor bacterium Chitinophaga pinensis” in Journal of Proteomics by Larsbrink et al. ([1], doi: 10.1016/j.jprot.2017.01.003). The bacterium was grown on three carbon sources (glucose, glucomannan, and galactomannan) which are likely to be nutrient sources or carbohydrate degradation products found in its natural habitat. The bacterium was grown on solid agarose plates to mimic the natural behaviour of growth on a solid surface. Secreted proteins were collected from the agarose following trypsin-mediated hydrolysis to peptides. The different carbon sources led to the secretion of different numbers and types of proteins. Most carbohydrate-degrading enzymes were found in the glucomannan-induced cultures. Several of these enzymes may have biotechnological potential in plant cell wall deconstruction for biofuel or biomaterial production, and several may have novel activities. A subset of carbohydrate-active enzymes (CAZymes) with predicted activities not obviously related to the growth substrates were also found in samples grown on each of the three carbohydrates. The full dataset is accessible at the PRIDE partner repository (ProteomeXchange Consortium) with the identifier PXD004305, and the full list of proteins detected is given in the supplementary material attached to this report.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Bacterium; Carbohydrate-active enzymes; Mass spectrometry; Plant biomass deconstruction; Protein secretion
National Category
Natural Sciences
Identifiers
urn:nbn:se:kth:diva-203316 (URN)10.1016/j.dib.2017.02.032 (DOI)2-s2.0-85014713718 (Scopus ID)
Note

QC 20170321

Available from: 2017-03-15 Created: 2017-03-15 Last updated: 2018-02-12Bibliographically approved
Larsbrink, J., Tuveng, T. R., Pope, P. B., Bulone, V., Eijsink, V. G., Brumer, H. & McKee, L. S. (2017). Proteomic insights into mannan degradation and protein secretion by the forest floor bacterium Chitinophaga pinensis. Journal of Proteomics, 156, 63-74
Open this publication in new window or tab >>Proteomic insights into mannan degradation and protein secretion by the forest floor bacterium Chitinophaga pinensis
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2017 (English)In: Journal of Proteomics, ISSN 1874-3919, E-ISSN 1876-7737, Vol. 156, p. 63-74Article in journal (Refereed) Published
Abstract [en]

Together with fungi, saprophytic bacteria are central to the decomposition and recycling of biomass in forest environments. The Bacteroidetes phylum is abundant in diverse habitats, and several species have been shown to be able to deconstruct a wide variety of complex carbohydrates. The genus Chitinophaga is often enriched in hotspots of plant and microbial biomass degradation. We present a proteomic assessment of the ability of Chitinophaga pinensis to grow on and degrade mannan polysaccharides, using an agarose plate-based method of protein collection to minimise contamination with exopolysaccharides and proteins from lysed cells, and to reflect the realistic setting of growth on a solid surface. We show that select Polysaccharide Utilisation Loci (PULs) are expressed in different growth conditions, and identify enzymes that may be involved in mannan degradation. By comparing proteomic and enzymatic profiles, we show evidence for the induced expression of enzymes and PULs in cells grown on mannan polysaccharides compared with cells grown on glucose. In addition, we show that the secretion of putative biomass-degrading enzymes during growth on glucose comprises a system for nutrient scavenging, which employs constitutively produced enzymes. Significance of this study Chitinophaga pinensis belongs to a bacterial genus which is prominent in microbial communities in agricultural and forest environments, where plant and fungal biomass is intensively degraded. Such degradation is hugely significant in the recycling of carbon in the natural environment, and the enzymes responsible are of biotechnological relevance in emerging technologies involving the deconstruction of plant cell wall material. The bacterium has a comparatively large genome, which includes many uncharacterised carbohydrate-active enzymes. We present the first proteomic assessment of the biomass-degrading machinery of this species, focusing on mannan, an abundant plant cell wall hemicellulose. Our findings include the identification of several novel enzymes, which are promising targets for future biochemical characterisation. In addition, the data indicate the expression of specific Polysaccharide Utilisation Loci, induced in the presence of different growth substrates. We also highlight how a constitutive secretion of enzymes which deconstruct microbial biomass likely forms part of a nutrient scavenging process.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
CAZyme, Chitinophaga pinensis, Galactoglucomannan, Label-free quantification, Secretome
National Category
Microbiology
Identifiers
urn:nbn:se:kth:diva-208034 (URN)10.1016/j.jprot.2017.01.003 (DOI)2-s2.0-85010866780 (Scopus ID)
Note

QC 20170601

Available from: 2017-06-01 Created: 2017-06-01 Last updated: 2017-06-01Bibliographically approved
Mattsson, T., Azhar, S., Eriksson, S., Helander, M., Henriksson, G., Jedvert, K., . . . Theliander, H. (2017). The Development of a Wood-based Materials-biorefinery. BioResources, 12(4), 9152-9182
Open this publication in new window or tab >>The Development of a Wood-based Materials-biorefinery
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2017 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 4, p. 9152-9182Article in journal (Refereed) Published
Abstract [en]

Several different methods for the extraction, separation, and purification of wood constituents were combined in this work as a unified process with the purpose of achieving a high overall efficiency of material extraction and utilization. This study aimed to present a laboratory-scale demonstrator biorefinery that illustrated how the different wood constituents could be separated from the wood matrix for later use in the production of new bio-based materials and chemicals by combining several approaches. This study builds on several publications and ongoing activities within the Wallenberg Wood Science Center (WWSC) in Sweden on the theme "From wood to material components." Combining the approaches developed in these WWSC projects - including mild steam explosion, membrane and chromatographic separation, enzymatic treatment and leaching, ionic liquid extraction, and fractionation together with Kraft pulping - formed an outline for a complete materials-biorefinery. The process steps involved were tested as integral steps in a linked process. The scale of operations ranged from the kilogram-scale to the gram-scale. The feasibility and efficiency of these process steps in a biorefinery system were assessed, based on the data, beginning with whole wood.

Place, publisher, year, edition, pages
North Carolina State University, 2017
Keywords
Biorefinery, Wood components, Separation, Demonstrator
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:kth:diva-223311 (URN)000422879900158 ()2-s2.0-85032700916 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20180216

Available from: 2018-02-16 Created: 2018-02-16 Last updated: 2018-06-19Bibliographically approved
Dahlin, P., Müller, M. C., Ekengren, S., McKee, L. S. & Bulone, V. (2017). The Impact of Steroidal Glycoalkaloids on the Physiology of Phytophthora infestans, the Causative Agent of Potato Late Blight. Molecular Plant-Microbe Interactions, 30(7), 531-542
Open this publication in new window or tab >>The Impact of Steroidal Glycoalkaloids on the Physiology of Phytophthora infestans, the Causative Agent of Potato Late Blight
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2017 (English)In: Molecular Plant-Microbe Interactions, ISSN 0894-0282, E-ISSN 1943-7706, Vol. 30, no 7, p. 531-542Article in journal (Refereed) Published
Abstract [en]

Steroidal glycoalkaloids (SGAs) are plant secondary metabolites known to be toxic to animals and humans and that have putative roles in defense against pests. The proposed mechanisms of SGA toxicity are sterol-mediated disruption of membranes and inhibition of cholinesterase activity in neurons. It has been suggested that phytopathogenic microorganisms can overcome SGA toxicity by enzymatic deglycosylation of SGAs. Here, we have explored SGA-mediated toxicity toward the invasive oomycete Phytophthora infestans, the causative agent of the late blight disease in potato and tomato, as well as the potential for SGA deglycosylation by this species. Our growth studies indicate that solanidine, the nonglycosylated precursor of the potato SGAs a-chaconine and a-solanine, has a greater physiological impact than its glycosylated forms. All of these compounds were incorporated into the mycelium, but only solanidine could strongly inhibit the growth of P. infestans in liquid culture. Genes encoding several glycoside hydrolases with potential activity on SGAs were identified in the genome of P. infestans and were shown to be expressed. However, we found no indication that deglycosylation of SGAs takes place. We present additional evidence for apparent host-specific adaptation to potato SGAs and assess all results in terms of future pathogen management strategies.

Place, publisher, year, edition, pages
AMER PHYTOPATHOLOGICAL SOC, 2017
National Category
Biological Sciences
Identifiers
urn:nbn:se:kth:diva-211001 (URN)10.1094/MPMI-09-16-0186-R (DOI)000404048400002 ()28510502 (PubMedID)2-s2.0-85021335851 (Scopus ID)
Funder
Swedish Research Council Formas, 2013-1427
Note

QC 20170713

Available from: 2017-07-13 Created: 2017-07-13 Last updated: 2017-07-13Bibliographically approved
McKee, L. S., Sunner, H., Anasontzis, G. E., Toriz, G., Gatenholm, P., Bulone, V., . . . Olsson, L. (2016). A GH115 alpha-glucuronidase from Schizophyllum commune contributes to the synergistic enzymatic deconstruction of softwood glucuronoarabinoxylan. Biotechnology for Biofuels, 9, Article ID 2.
Open this publication in new window or tab >>A GH115 alpha-glucuronidase from Schizophyllum commune contributes to the synergistic enzymatic deconstruction of softwood glucuronoarabinoxylan
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2016 (English)In: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 9, article id 2Article in journal (Refereed) Published
Abstract [en]

Background: Lignocellulosic biomass from softwood represents a valuable resource for the production of biofuels and bio-based materials as alternatives to traditional pulp and paper products. Hemicelluloses constitute an extremely heterogeneous fraction of the plant cell wall, as their molecular structures involve multiple monosaccharide components, glycosidic linkages, and decoration patterns. The complete enzymatic hydrolysis of wood hemicelluloses into monosaccharides is therefore a complex biochemical process that requires the activities of multiple degradative enzymes with complementary activities tailored to the structural features of a particular substrate. Glucuronoarabinoxylan (GAX) is a major hemicellulose component in softwood, and its structural complexity requires more enzyme specificities to achieve complete hydrolysis compared to glucuronoxylans from hardwood and arabinoxylans from grasses. Results: We report the characterisation of a recombinant alpha-glucuronidase (Agu115) from Schizophyllum commune capable of removing (4-O-methyl)-glucuronic acid ((Me) GlcA) residues from polymeric and oligomeric xylan. The enzyme is required for the complete deconstruction of spruce glucuronoarabinoxylan (GAX) and acts synergistically with other xylan-degrading enzymes, specifically a xylanase (Xyn10C), an alpha-l-arabinofuranosidase (AbfA), and a beta-xylosidase (XynB). Each enzyme in this mixture showed varying degrees of potentiation by the other activities, likely due to increased physical access to their respective target monosaccharides. The exo-acting Agu115 and AbfA were unable to remove all of their respective target side chain decorations from GAX, but their specific activity was significantly boosted by the addition of the endo-Xyn10C xylanase. We demonstrate that the proposed enzymatic cocktail (Agu115 with AbfA, Xyn10C and XynB) achieved almost complete conversion of GAX to arabinofuranose (Araf), xylopyranose (Xylp), and MeGlcA monosaccharides. Addition of Agu115 to the enzymatic cocktail contributes specifically to 25 % of the conversion. However, traces of residual oligosaccharides resistant to this combination of enzymes were still present after deconstruction, due to steric hindrances to enzyme access to the substrate. Conclusions: Our GH115 alpha-glucuronidase is capable of finely tailoring the molecular structure of softwood GAX, and contributes to the almost complete saccharification of GAX in synergy with other exo- and endo-xylan-acting enzymes. This has great relevance for the cost-efficient production of biofuels from softwood lignocellulose.

Place, publisher, year, edition, pages
BioMed Central, 2016
Keywords
Lignocellulosic biomass, Glucuronoarabinoxylan, Glycoside hydrolases (GH), alpha-Glucuronidase, Agu115
National Category
Industrial Biotechnology
Identifiers
urn:nbn:se:kth:diva-181362 (URN)10.1186/s13068-015-0417-6 (DOI)000367513300002 ()26734072 (PubMedID)2-s2.0-84954121323 (Scopus ID)
Funder
Knut and Alice Wallenberg FoundationSwedish Research Council, 621-2014-5295Chalmers Energy initiative
Note

QC 20160205

Available from: 2016-02-05 Created: 2016-02-01 Last updated: 2017-11-30Bibliographically approved
McKee, L. S. & Brumer, H. (2015). Growth of Chitinophaga pinensis on Plant Cell Wall Glycans and Characterisation of a Glycoside Hydrolase Family 27 beta-L-Arabinopyranosidase Implicated in Arabinogalactan Utilisation. PLoS ONE, 10(10), Article ID e0139932.
Open this publication in new window or tab >>Growth of Chitinophaga pinensis on Plant Cell Wall Glycans and Characterisation of a Glycoside Hydrolase Family 27 beta-L-Arabinopyranosidase Implicated in Arabinogalactan Utilisation
2015 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 10, article id e0139932Article in journal (Refereed) Published
Abstract [en]

The genome of the soil bacterium Chitinophaga pinensis encodes a diverse array of carbohydrate active enzymes, including nearly 200 representatives from over 50 glycoside hydrolase (GH) families, the enzymology of which is essentially unexplored. In light of this genetic potential, we reveal that C. pinensis has a broader saprophytic capacity to thrive on plant cell wall polysaccharides than previously reported, and specifically that secretion of beta-L-arabinopyranosidase activity is induced during growth on arabinogalactan. We subsequently correlated this activity with the product of the Cpin_5740 gene, which encodes the sole member of glycoside hydrolase family 27 (GH27) in C. pinensis, CpArap27. Historically, GH27 is most commonly associated with alpha-D-galactopyranosidase and alpha-D-N-acetylgalactosaminidase activity. A new phylogenetic analysis of GH27 highlighted the likely importance of several conserved secondary structural features in determining substrate specificity and provides a predictive framework for identifying enzymes with the less common beta-L-arabinopyranosidase activity.

Place, publisher, year, edition, pages
[McKee, Lauren S.; Brumer, Harry] Royal Inst Technol KTH, AlbaNova Univ Ctr, Div Glycosci, Sch Biotechnol, S-10691 Stockholm, Sweden. [McKee, Lauren S.; Brumer, Harry] Wallenberg Wood Sci Ctr, S-10044 Stockholm, Sweden. [Brumer, Harry] Univ British Columbia, Michael Smith Labs, Vancouver, BC V6T 1Z4, Canada. [Brumer, Harry] Univ British Columbia, Dept Chem, Vancouver, BC V6T 1Z4, Canada.: , 2015
National Category
Medical Biotechnology Medical Biotechnology
Identifiers
urn:nbn:se:kth:diva-176339 (URN)10.1371/journal.pone.0139932 (DOI)000362511000066 ()26448175 (PubMedID)2-s2.0-84948698182 (Scopus ID)
Note

QC 20151109

Available from: 2015-11-09 Created: 2015-11-03 Last updated: 2017-12-01Bibliographically approved
Larsbrink, J., Rogers, T. E., Hemsworth, G. R., McKee, L. S., Tauzin, A. S., Spadiut, O., . . . Brumer, H. (2014). A discrete genetic locus confers xyloglucan metabolism in select human gut Bacteroidetes. Nature, 506(7489), 498-502
Open this publication in new window or tab >>A discrete genetic locus confers xyloglucan metabolism in select human gut Bacteroidetes
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2014 (English)In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 506, no 7489, p. 498-502Article in journal (Refereed) Published
Abstract [en]

A well-balanced human diet includes a significant intake of non-starch polysaccharides, collectively termed 'dietary fibre', from the cell walls of diverse fruits and vegetables(1). Owing to the paucity of alimentary enzymes encoded by the human genome(2), our ability to derive energy from dietary fibre depends on the saccharification and fermentation of complex carbohydrates by the massive microbial community residing in our distal gut(3,4). The xyloglucans (XyGs) are a ubiquitous family of highly branched plant cell wall polysaccharides(5,6) whose mechanism(s) of degradation in the human gut and consequent importance in nutrition have been unclear(1,7,8). Here we demonstrate that a single, complex gene locus in Bacteroides ovatus confers XyG catabolism in this common colonic symbiont. Through targeted gene disruption, biochemical analysis of all predicted glycoside hydrolases and carbohydrate-binding proteins, and three-dimensional structural determination of the vanguard endo-xyloglucanase, we reveal the molecular mechanisms through which XyGs are hydrolysed to component monosaccharides for further metabolism. We also observe that orthologous XyG utilization loci (XyGULs) serve as genetic markers of XyG catabolism in Bacteroidetes, that XyGULs are restricted to a limited number of phylogenetically diverse strains, and that XyGULs are ubiquitous in surveyed human metagenomes. Our findings reveal that the metabolism of even highly abundant components of dietary fibre may be mediated by niche species, which has immediate fundamental and practical implications for gut symbiont population ecology in the context of human diet, nutrition and health(9-12).

Keywords
Carbohydrate-Binding Modules, Intestinal Bacteria, Maximum-Likelihood, Human Microbiome, Reducing Sugar, Active Enzymes, Cell Walls, Recognition, Proteins, Reagent
National Category
Other Biological Topics
Identifiers
urn:nbn:se:kth:diva-143987 (URN)10.1038/nature12907 (DOI)000332165100040 ()24463512 (PubMedID)2-s2.0-84896734943 (Scopus ID)
Funder
FormasSwedish Research Council
Note

QC 20140407

Available from: 2014-04-07 Created: 2014-04-04 Last updated: 2017-12-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3372-8773

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