@article { ISI:000248451900017,
	title = {Structural evidence for the evolution of xyloglucanase activity from xyloglucan endo-transglycosylases: Biological implications for cell wall metabolism},
	journal = {PLANT CELL},
	volume = {19},
	number = {6},
	year = {2007},
	month = {JUN},
	pages = {1947-1963},
	type = {Article},
	abstract = {<p>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.</p>},
	issn = {1040-4651},
	doi = {10.1105/tpc.107.051391},
	author = {Baumann, Martin J. and Eklof, Jens M. and Michel, Gurvan and Kallas, Asa M. and Teeri, Tuula T. and Czjzek, Mirjam and Brumer, Harry}
}
