Structural Evidence for the Evolution of Xyloglucanase Activity from Xyloglucan Endo-Transglycosylases: Biological Implications for Cell Wall Metabolism[W]
| Autor: | Harry Brumer, Martin J. Baumann, Mirjam Czjzek, Jens M. Eklöf, Tuula T. Teeri, Åsa M. Kallas, Gurvan Michel |
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| Jazyk: | angličtina |
| Rok vydání: | 2007 |
| Předmět: |
DNA
Complementary Glycoside Hydrolases Molecular Sequence Data Static Electricity Oligosaccharides Plant Science Biology Nasturtium Crystallography X-Ray Catalysis Protein Structure Secondary Substrate Specificity Cell wall Evolution Molecular chemistry.chemical_compound Structure-Activity Relationship Tropaeolum Cell Wall Glycoside hydrolase Xyloglucan:xyloglucosyl transferase Cloning Molecular Glucans Research Articles Phylogeny Plant Proteins chemistry.chemical_classification Cell Biology Xyloglucan endotransglucosylase biology.organism_classification Recombinant Proteins Tropaeolum majus Xyloglucan Kinetics Enzyme chemistry Biochemistry Mutagenesis Chromatography Gel Mutant Proteins Xylans Gene Deletion |
| Popis: | 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 × Populus tremuloides). Production of the loop deletion variant Tm-NXG1-ΔYNIIG 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. |
| Databáze: | OpenAIRE |
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