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Lookup NU author(s): Dr Lenka Frankova
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Cell walls are metabolically active components of plant cells. They contain diverse enzymes, including transglycanases (endotransglycosylases), enzymes that cut and paste' certain structural polysaccharide molecules and thus potentially remodel the wall during growth and development. Known transglycanase activities modify several cell-wall polysaccharides (xyloglucan, mannans, mixed-linkage -glucan and xylans); however, no transglycanases were known to act on cellulose, the principal polysaccharide of biomass. We now report the discovery and characterization of hetero-trans--glucanase (HTG), a transglycanase that targets cellulose, in horsetails (Equisetum spp., an early-diverging genus of monilophytes). HTG is also remarkable in predominantly catalysing hetero-transglycosylation: its preferred donor substrates (cellulose or mixed-linkage -glucan) differ qualitatively from its acceptor substrate (xyloglucan). HTG thus generates stable cellulose-xyloglucan and mixed-linkage -glucan-xyloglucan covalent bonds, and may therefore strengthen ageing Equisetum tissues by inter-linking different structural polysaccharides of the cell wall. 3D modelling suggests that only three key amino acid substitutions (Trp Pro, Gly Ser and Arg Leu) are responsible for the evolution of HTG's unique specificity from the better-known xyloglucan-acting homo-transglycanases (xyloglucan endotransglucosylase/hydrolases; XTH). Among land plants, HTG appears to be confined to Equisetum, but its target polysaccharides are widespread, potentially offering opportunities for enhancing crop mechanical properties, such as wind resistance. In addition, by linking cellulose to xyloglucan fragments previously tagged with compounds such as dyes or indicators, HTG may be useful biotechnologically for manufacturing stably functionalized celluloses, thereby potentially offering a commercially valuable green' technology for industrially manipulating biomass.
Author(s): Simmons TJ, Mohler KE, Holland C, Goubet F, Franková L, Houston DR, Hudson AD, Meulewaeter F, Fry SC
Publication type: Article
Publication status: Published
Journal: The Plant Journal
Year: 2015
Volume: 83
Issue: 5
Pages: 753-769
Print publication date: 01/09/2015
Online publication date: 25/08/2015
Acceptance date: 24/06/2015
Date deposited: 23/02/2017
ISSN (print): 0960-7412
ISSN (electronic): 1365-313X
Publisher: Wiley-Blackwell Publishing Ltd.
URL: http://dx.doi.org/10.1111/tpj.12935
DOI: 10.1111/tpj.12935
PubMed id: 26185964
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