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An endo β‐1,4 glucanse, PtEG16‐1 from black cottonwood (Populustrichocarpa) represents an evolutionary link between bacterial lichenases and XTH geneproducts
KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
(engelsk)Artikkel i tidsskrift (Annet vitenskapelig) Submitted
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-31985OAI: oai:DiVA.org:kth-31985DiVA, id: diva2:407928
Merknad
QS 20120326Tilgjengelig fra: 2011-04-01 Laget: 2011-04-01 Sist oppdatert: 2012-03-26bibliografisk kontrollert
Inngår i avhandling
1. Plant and microbial xyloglucanases: Function, Structure and Phylogeny
Åpne denne publikasjonen i ny fane eller vindu >>Plant and microbial xyloglucanases: Function, Structure and Phylogeny
2011 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

In this thesis, enzymes acting on the primary cell wall hemicellulose xyloglucan are studied.  Xyloglucans are ubiquitous in land plants which make them an important polysaccharide to utilise for microbes and a potentially interesting raw material for various industries.  The function of xyloglucans in plants is mainly to improve primary cell wall characteristics by coating and tethering cellulose microfibrils together.  Some plants also utilise xyloglucans as storage polysaccharides in their seeds.

In microbes, a variety of different enzymes for degrading xyloglucans have been found.  In this thesis, the structure-function relationship of three different microbial endo-xyloglucanases from glycoside hydrolase families 5, 12 and 44 are probed and reveal details of the natural diversity found in xyloglucanases.  Hopefully, a better understanding of how xyloglucanases recognise and degrade their substrate can lead to improved saccharification processes of plant matter, finding uses in for example biofuel production.

In plants, xyloglucans are modified in muro by the xyloglucan transglycosylase/hydrolase (XTH) gene products.  Interestingly, closely related XTH gene products catalyse either transglycosylation (XET activity) or hydrolysis (XEH activity) with dramatically different effects on xyloglucan and on cell wall characteristics.  The strict transglycosylases transfer xyloglucan segments between individual xyloglucan molecules while the hydrolases degrade xyloglucan into oligosaccharides.  Here, we describe and determine, a major determinant of transglycosylation versus hydrolysis in XTH gene products by solving and comparing the first 3D structure of an XEH, Tm-NXG1 and a XET, PttXET16-34.  The XEH activity was hypothesised, and later confirmed to be restricted to subset of the XTH gene products.  The in situ localisation of XEH activity in roots and hypocotyls of Arabidopsis was also visualised for the first time.  Furthermore, an evolutionary scheme for how XTH gene products developed from bacterial beta-1,3;1,4 glucanases was also presented based on the characterisation of a novel plant endo-glucanase, PtEG16-1. The EG16s are proposed to predate XTH gene products and are with activity on both xyloglucan and beta-1,3;1,4 glucans an “intermediate” in the evolution from beta-1,3;1,4 glucanases to XTH gene products.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2011. s. 61
Serie
Trita-BIO-Report, ISSN 1654-2312 ; 2011:07
Emneord
xyloglucan, xyloglucanases, XTH, XET, XEH, endoglucanases, EG16
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-31677 (URN)978-91-7415-932-5 (ISBN)
Disputas
2011-04-15, FR4, Albanova Universitetscentrum, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Merknad
QC 20110401Tilgjengelig fra: 2011-04-01 Laget: 2011-03-22 Sist oppdatert: 2011-11-03bibliografisk kontrollert

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