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PDBsum entry 2uwc
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References listed in PDB file
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Key reference
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Title
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Structural evidence for the evolution of xyloglucanase activity from xyloglucan endo-Transglycosylases: biological implications for cell wall metabolism.
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Authors
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M.J.Baumann,
J.M.Eklöf,
G.Michel,
A.M.Kallas,
T.T.Teeri,
M.Czjzek,
H.Brumer.
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Ref.
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Plant Cell, 2007,
19,
1947-1963.
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PubMed id
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Abstract
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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.
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