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266 a.a.
Key reference
DOI no: 10.1105/tpc.107.051391 Plant Cell 19:1947-1963 (2007) PubMed id: 17557806
Structural evidence for the evolution of xyloglucanase activity from xyloglucan endo-transglycosylases: biological implications for cell wall metabolism. M.J.Baumann, J.M.Eklöf, G.Michel, A.M.Kallas, T.T.Teeri, M.Czjzek, H.Brumer. 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.
Literature references that cite this PDB file's key reference
PubMed id Reference
19635745 A.Maris, D.Suslov, S.C.Fry, J.P.Verbelen, and K.Vissenberg (2009).
Enzymic characterization of two recombinant xyloglucan endotransglucosylase/hydrolase (XTH) proteins of Arabidopsis and their effect on root growth and cell wall extension.J Exp Bot, 60, 3959-3972.
19189377 B.Mertz, X.Gu, and P.J.Reilly (2009).
Analysis of functional divergence within two structurally related glycoside hydrolase families.Biopolymers, 91, 478-495.
19076217 M.Hrmova, V.Farkas, A.J.Harvey, J.Lahnstein, B.Wischmann, N.Kaewthai, I.Ezcurra, T.T.Teeri, and G.B.Fincher (2009).
Substrate specificity and catalytic mechanism of a xyloglucan xyloglucosyl transferase HvXET6 from barley (Hordeum vulgare L.).FEBS J, 276, 437-456.
19454593 R.Schröder, R.G.Atkinson, and R.J.Redgwell (2009).
Re-interpreting the role of endo-beta-mannanases as mannan endotransglycosylase/hydrolases in the plant cell wall.Ann Bot (Lond), 104, 197-204.
18757879 E.J.Mellerowicz, P.Immerzeel, and T.Hayashi (2008).
Xyloglucan: the molecular muscle of trees.Ann Bot (Lond), 102, 659-665.
18043802 K.Piens, A.M.Henriksson, F.Gullfot, M.Lopez, R.Fauré, F.M.Ibatullin, T.T.Teeri, H.Driguez, and H.Brumer (2007).
Glycosynthase activity of hybrid aspen xyloglucan endo-transglycosylase PttXET16-34 nucleophile mutants.Org Biomol Chem, 5, 3971-3978. The most recent references are shown first. Citation data come partly from CiteXplore and partly from an automated harvesting procedure. Note that this is likely to be only a partial list as not all journals are covered by either method. However, we are continually building up the citation data so more and more references will be included with time.
