2drq | pdb_00002drq
Crystal structure of reducing-end-xylose releasing exo-oligoxylanase D263G mutant
Structural highlights
FunctionREOX_HALH5 Hydrolyzes xylooligosaccharides with a degree of polymerization of greater than or equal to 3, releasing xylose from the reducing end. Only hydrolyzes the beta anomers of xylooligosaccharides, with inversion of anomeric configuration. Hydrolyzes the glucose and xylose-based trisaccharides where xylose is located at the -1 subsite, GXX, XXG and GXG. Does not hydrolyze xylan, chitosan, lichenan, curdlan or carboxymethylcellulose.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedGlycosynthases are engineered glycoside hydrolases (GHs) that catalyse the synthesis of glycoside from glycosyl-fluoride donors and suitable acceptors. We have determined five crystal structures of the glycosynthase mutants reducing-end xylose-releasing exo-oligoxylanase, an inverting GH, that exhibit various levels of glycosynthetic activities. At the active site of the Y198F mutant, the most efficient glycosynthase, a water molecule is observed at the same position as nucleophilic water (NW) in the parent enzyme, and the loss of the fixation of the direction of the lone pair of water molecules in the mutant drastically decreases hydrolytic activity. Water molecules were also observed at each active site of the general base mutant, but they were shifted 1.0-3.0 A from the NW in the wild type. Their positions exhibited a strong correlation with the strength of glycosynthase activity. Here, we propose that a structural prerequisite for the sufficient glycosynthase reaction is the presence of a water molecule at the NW position, and mutation at the NW holder provides a general strategy for inverting GHs. The idea on the position of a water molecule may also be applicable to the design of efficient glycosynthases from retaining GHs. Structural explanation for the acquisition of glycosynthase activity.,Hidaka M, Fushinobu S, Honda Y, Wakagi T, Shoun H, Kitaoka M J Biochem. 2010 Feb;147(2):237-44. Epub 2009 Oct 9. PMID:19819900[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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