Download MendeleyStructural Evidence for the Evolution of Xyloglucanase Activity from Xyloglucan Endo-Transglycosylases: Biological Implications for Cell Wall Metabolism.
Baumann, M.J., Eklof, J., Michel, G., Kallasa, A., Teeri, T.T., Czjzek, M., Brumer, H.(2007) Plant Cell 19: 1947
- PubMed: 17557806
- DOI: https://doi.org/10.1105/tpc.107.051391
- Primary Citation of Related Structures:
2UWA, 2UWB, 2UWC - PubMed 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 x Populus tremuloides). Production of the loop deletion variant Tm-NXG1-DeltaYNIIG 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.
Organizational Affiliation:
School of Biotechnology, Royal Institute of Technology, AlbaNova University Center, Stockholm, Sweden.
