Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Active-site mapping of a Populus xyloglucan endo-transglycosylase with a library of xylogluco-oligosaccharides
KTH, School of Biotechnology (BIO), Glycoscience.
KTH, School of Biotechnology (BIO), Glycoscience.
Show others and affiliations
2008 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 283, no 32, 21853-21863 p.Article in journal (Refereed) Published
Abstract [en]

Restructuring the network of xyloglucan (XG) and cellulose during plant cell wall morphogenesis involves the action of xyloglucan endo-transglycosylases (XETs). They cleave the XG chains and transfer the enzyme-bound XG fragment to another XG molecule, thus allowing transient loosening of the cell wall and also incorporation of nascent XG during expansion. The substrate specificity of a XET from Populus (PttXET16-34) has been analyzed by mapping the enzyme binding site with a library of xylogluco-oligosaccharides as donor substrates using a labeled heptasaccharide as acceptor. The extended binding cleft of the enzyme is composed of four negative and three positive subsites (with the catalytic residues between subsites -1 and + 1). Donor binding is dominated by the higher affinity of the XXXGmoiety (G = Glc beta(1 -> 4) and X = Xyl alpha(1 -> 6)Glc beta(1 -> 4)) of the substrate for positive subsites, whereas negative subsites have a more relaxed specificity, able to bind (and transfer to the acceptor) a cello-oligosaccharyl moiety of hybrid substrates such as GGGGXXXG. Subsite mapping with k(cat)/K-m values for the donor substrates showed that a GG-unit on negative and-XXG on positive subsites are the minimal requirements for activity. Subsites -2 and -3 (for backbone Glc residues) and +2' (for Xyl substitution at Glc in subsite +2) have the largest contribution to transition state stabilization. GalGXXXGXXXG (Gal = Gal beta(1 -> 4)) is the best donor substrate with a "blocked" nonreducing end that prevents polymerization reactions and yields a single transglycosylation product. Its kinetics have unambiguously established that the enzyme operates by a ping-pong mechanism with competitive inhibition by the acceptor.

Place, publisher, year, edition, pages
2008. Vol. 283, no 32, 21853-21863 p.
Keyword [en]
plant-cell wall, glycosyl-enzyme intermediate, endoxyloglucan, transferase, endotransglycosylase, mechanism, acceptor, binding, seeds, purification, nomenclature
Identifiers
URN: urn:nbn:se:kth:diva-17741DOI: 10.1074/jbc.M803058200ISI: 000258114700004Scopus ID: 2-s2.0-52049124583OAI: oai:DiVA.org:kth-17741DiVA: diva2:335786
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Brumer, HarryTeeri, Tuula T.
By organisation
Glycoscience
In the same journal
Journal of Biological Chemistry

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 19 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf