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The structure and function of an arabinan-specific alpha-1,2-arabinofuranosidase identified from screening the activities of bacterial GH43 glycoside hydrolases
KTH, School of Biotechnology (BIO). University of Georgia, United States.ORCID iD: 0000-0002-3372-8773
KTH, School of Biotechnology (BIO), Glycoscience.
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2011 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 286, no 17Article in journal (Refereed) Published
Abstract [en]

Reflecting the diverse chemistry of plant cell walls, microorganisms that degrade these composite structures synthesize an array of glycoside hydrolases. These enzymes are organized into sequence-, mechanism-, and structure-based families. Genomic data have shown that several organisms that degrade the plant cell wall contain a large number of genes encoding family 43 (GH43) glycoside hydrolases. Here we report the biochemical properties of the GH43 enzymes of a saprophytic soil bacterium, Cellvibrio japonicus, and a human colonic symbiont, Bacteroides thetaiotaomicron. The data show that C. japonicus uses predominantly exo-acting enzymes to degrade arabinan into arabinose, whereas B. thetaiotaomicron deploys a combination of endo-and side chain-cleaving glycoside hydrolases. Both organisms, however, utilize an arabinan-specific alpha-1,2-arabinofuranosidase in the degradative process, an activity that has not previously been reported. The enzyme can cleave alpha-1,2-arabinofuranose decorations in single or double substitutions, the latter being recalcitrant to the action of other arabinofuranosidases. The crystal structure of the C. japonicus arabinan-specific alpha-1,2-arabinofuranosidase, CjAbf43A, displays a five-bladed beta-propeller fold. The specificity of the enzyme for arabinan is conferred by a surface cleft that is complementary to the helical backbone of the polysaccharide. The specificity of CjAbf43A for alpha-1,2-L-arabinofuranose side chains is conferred by a polar residue that orientates the arabinan backbone such that O2 arabinose decorations are directed into the active site pocket. A shelflike structure adjacent to the active site pocket accommodates O3 arabinose side chains, explaining how the enzyme can target O2 linkages that are components of single or double substitutions.

Place, publisher, year, edition, pages
American Society for Biochemistry and Molecular Biology, 2011. Vol. 286, no 17
National Category
Biochemistry and Molecular Biology
Identifiers
URN: urn:nbn:se:kth:diva-179859DOI: 10.1074/jbc.M110.215962ISI: 000289788300076ScopusID: 2-s2.0-79955415550OAI: oai:DiVA.org:kth-179859DiVA: diva2:890552
Note

QC 20160126

Available from: 2016-01-04 Created: 2016-01-04 Last updated: 2016-01-26Bibliographically approved
In thesis
1. Strategies for the Discovery of Carbohydrate-Active Enzymes from Environmental Bacteria
Open this publication in new window or tab >>Strategies for the Discovery of Carbohydrate-Active Enzymes from Environmental Bacteria
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The focus of this thesis is a comparative study of approaches in discovery of carbohydrate-active enzymes (CAZymes). CAZymes synthesise, bind to, and degrade all the multitude of carbohydrates found in nature. As such, when aiming for sustainable methods to degrade plant biomass for the generation of biofuels, for which there is a strong drive in society, CAZymes are a natural source of environmentally friendly molecular tools.

In nature, microorganisms are the principal degraders of carbohydrates. Not only do they degrade plant matter in forests and aquatic habitats, but also break down the majority of carbohydrates ingested by animals. These symbiotic microorganisms, known as the microbiota, reside in animal digestive tracts in immense quantities, where one of the key nutrient sources is complex carbohydrates. Thus, microorganisms are a plentiful source of CAZymes, and strategies in the discovery of new enzymes from bacterial sources have been the basis for the work presented here, combined with biochemical characterisation of several enzymes.

Novel enzymatic activities for the glycoside hydrolase family 31 have been described as a result of the initial projects of the thesis. These later evolved into projects studying bacterial multi-gene systems for the partial or complete degradation of the heterogeneous plant polysaccharide xyloglucan. These systems contain, in addition to various hydrolytic CAZymes, necessary binding-, transport-, and regulatory proteins. The results presented here show, in detail, how very complex carbohydrates can efficiently be degraded by bacterial enzymes of industrial relevance.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. viii, 82 p.
Series
TRITA-BIO-Report, ISSN 1654-2312 ; 2013:13
Keyword
CAZyme discovery, xyloglucan, polysaccharide-utilisation locus, microbiota, α-xylosidase, GH31, transglucosidase, human gut
National Category
Biochemistry and Molecular Biology
Research subject
SRA - Molecular Bioscience
Identifiers
urn:nbn:se:kth:diva-126956 (URN)978-91-7501-834-8 (ISBN)
Public defence
2013-09-13, Oskar Klein Auditoriet, FR4, 10:00, Albanova Universitetscentrum, Roslagstullsbacken 21, Stockholm, 15:00 (English)
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QC 20130826

Available from: 2013-08-26 Created: 2013-08-23 Last updated: 2016-01-26Bibliographically approved

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