2drs

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spinqualitylabelsall models 2drs, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of reducing-end-xylose releasing exo-oligoxylanase D263S mutant

Overview

Reducing end xylose-releasing exooligoxylanase (Rex, EC 3.2.1.156) is an, inverting GH that hydrolyzes xylooligosaccharides (> or = X3) to release, X1 at their reducing end. The wild-type enzyme exhibited the Hehre, resynthesis hydrolysis mechanism, in which alpha-X2F was hydrolyzed to X2, and HF in the presence of X1 as an acceptor molecule. However, the, transglycosidation product (X3) was not detectable in the reaction. To, convert reducing end xylose-releasing exooligoxylanase to glycosynthase, derivatives with mutations in the catalytic base (Asp-263) were, constructed by saturation random mutagenesis. Nine amino acid residue, mutants (Asp-263 to Gly, Ala, Val, Thr, Leu, Asn, Cys, Pro, or Ser) were, found to possess glycosynthase activity forming X3 from alpha-X2F and X1., Among them, D263C showed the highest level of X3 production, and D263N, exhibited the fastest consumption of alpha-X2F. The D263C mutant showed, 10-fold lower hydrolytic activity than D263N, resulting in the highest, yield of X3. X2 was formed from the early stage of the reaction of the, D263C mutant, indicating that a portion of the X3 formed by condensation, was hydrolyzed before its release from the enzyme. To acquire, glycosynthase activity from inverting enzymes, it is important to minimize, the decrease in F(-)-releasing activity while maximizing the decrease in, the hydrolytic activity. The present study expands the possibility of, conversion of glycosynthases from inverting enzymes.

About this Structure

2DRS is a Single protein structure of sequence from Bacillus halodurans with and as ligands. Active as Oligosaccharide reducing-end xylanase, with EC number 3.2.1.156 Full crystallographic information is available from OCA.

Reference

The first glycosynthase derived from an inverting glycoside hydrolase., Honda Y, Kitaoka M, J Biol Chem. 2006 Jan 20;281(3):1426-31. Epub 2005 Nov 21. PMID:16301312

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