Glycosynthase activity of hybrid aspen xyloglucan endo-transglycosylase PttXET16-34 nucleophile mutants

Kathleen Piens*, Anna-Maria Henriksson, Fredrika Gullfot, Marie Lopez, Egis Faure, Farid M. Ibatullin, Tuula T. Teeri, Hugues Driguez, Harry Brumer

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Glycosynthases are active-site mutants of glycoside hydrolases that catalyse glycosyl transfer using suitable activated donor substrates without competing product hydrolysis ( S. M. Hancock, M. D. Vaughan and S. G. Withers, Curr. Opin. Chem. Biol., 2006, 10, 509-519). Site-directed mutagenesis of the catalytic nucleophile, Glu-85, of a Populus tremula x tremuloides xyloglucan endo-transglycosylase (PttXET16-34, EC 2.4.1.207) into alanine, glycine, and serine yielded enzymes with glycosynthase activity. Product analysis indicated that PttXET16-34 E85A in particular was able to catalyse regio- and stereospecific homo- and hetero- condensations of alpha-xylogluco-oligosaccharyl fluoride donors XXXG alpha F andXLLG alpha F to produce xyloglucans with regular sidechain substitution patterns. This substrate promiscuity contrasts that of the Humicola insolens Ce17B E197A glycosynthase, which was not able to polymerise the di-galactosylated substrate XLLG alpha F. The production of the PttXET16-34 E85A xyloglucosynthase thus expands the repertoire of glycosynthases to include those capable of synthesising structurally homogenenous xyloglucans

Original languageEnglish
Pages (from-to)3971-3978
Number of pages8
JournalORGANIC AND BIOMOLECULAR CHEMISTRY
Volume5
Issue number24
DOIs
Publication statusPublished - 2007
MoE publication typeA1 Journal article-refereed

Keywords

  • OLIGOSACCHARIDE SYNTHESIS
  • CRYSTAL-STRUCTURES
  • BETA-GLUCOSIDASE
  • CELL-WALLS
  • GLYCOSIDASES
  • ENDOTRANSGLYCOSYLASE
  • CELLULASE
  • GLYCOSYLTRANSFERASES
  • POLYSACCHARIDES
  • SPECIFICITY

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