Structural evidence for the evolution of xyloglucanase activity from xyloglucan endo-transglycosylases: Biological implications for cell wall metabolism

Martin J. Baumann, Jens M. Eklof, Gurvan Michel, Asa M. Kallas, Tuula T. Teeri, Mirjam Czjzek*, Harry Brumer

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

High-resolution, three-dimensional structures of the archetypal glycoside hydrolase family 16 (GH16) endo-xyloglucanases Tm-NXG1 and Tm-NXG2 from nasturtium (Tropaeolum majus) have been solved by x-ray crystallography. Key structural features that modulate the relative rates of substrate hydrolysis to transglycosylation in the GH16 xyloglucan-active enzymes were identified by structure-function studies of the recombinantly expressed enzymes in comparison with data for the strict xyloglucan endo-transglycosylase Ptt-XET16-34 from hybrid aspen ( Populus tremula 3 Populus tremuloides). Production of the loop deletion variant Tm-NXG1-Delta YNIIG yielded an enzyme that was structurally similar to Ptt- XET16-34 and had a greatly increased transglycosylation: hydrolysis ratio. Comprehensive bioinformatic analyses of XTH gene products, together with detailed kinetic data, strongly suggest that xyloglucanase activity has evolved as a gain of function in an ancestral GH16 XET to meet specific biological requirements during seed germination, fruit ripening, and rapid wall expansion.

Original languageEnglish
Pages (from-to)1947-1963
Number of pages17
JournalPLANT CELL
Volume19
Issue number6
DOIs
Publication statusPublished - Jun 2007
MoE publication typeA1 Journal article-refereed

Keywords

  • TROPAEOLUM-MAJUS L
  • GERMINATED NASTURTIUM SEEDS
  • GLYCOSIDE HYDROLASES
  • EXPRESSION ANALYSIS
  • KAPPA-CARRAGEENASE
  • SEQUENCE ALIGNMENT
  • CRYSTAL-STRUCTURES
  • PICHIA-PASTORIS
  • HYBRID ASPEN
  • ENDOTRANSGLYCOSYLASE

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