3zxk

Engineering the active site of a GH43 glycoside hydrolase generates a biotechnologically significant enzyme that displays both endo- xylanase and exo-arabinofuranosidase activity

spinqualitylabelsall models 3zxk, resolution 1.44Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3zxk is a 2 chain structure with sequence from Humicola insolens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.44Å Ligands: AHR, EPE, XYP Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed The degradation of the plant cell wall by glycoside hydrolases is central to environmentally sustainable industries. The major polysaccharides of the plant cell wall are cellulose and xylan, a highly decorated beta-1,4-xylopyranose polymer. Glycoside hydrolases displaying multiple catalytic functions may simplify the enzymes required to degrade plant cell walls, increasing the industrial potential of these composite structures. Here we test the hypothesis that glycoside hydrolase family 43 (GH43) provides a suitable scaffold for introducing additional catalytic functions into enzymes that target complex structures in the plant cell wall. We report the crystal structure of Humicola insolens AXHd3 (HiAXHd3), a GH43 arabinofuranosidase that hydrolyses O3-linked arabinose of doubly substituted xylans, a feature of the polysaccharide that is recalcitrant to degradation. HiAXHd3 displays an N-terminal five-bladed beta-propeller domain and a C-terminal beta-sandwich domain. The interface between the domains comprises a xylan binding cleft that houses the active site pocket. Substrate specificity is conferred by a shallow arabinose binding pocket adjacent to the deep active site pocket, and through the orientation of the xylan backbone. Modification of the rim of the active site introduces endo-xylanase activity, whereas the resultant enzyme variant, Y166A, retains arabinofuranosidase activity. These data show that the active site of HiAXHd3 is tuned to hydrolyse arabinofuranosyl or xylosyl linkages, and it is the topology of the distal regions of the substrate binding surface that confers specificity. This report demonstrates that GH43 provides a platform for generating bespoke multifunctional enzymes that target industrially significant complex substrates, exemplified by the plant cell wall. Introducing endo-xylanase activity into an exo-acting arabinofuranosidase that targets side chains.,McKee LS, Pena MJ, Rogowski A, Jackson A, Lewis RJ, York WS, Krogh KB, Vikso-Nielsen A, Skjot M, Gilbert HJ, Marles-Wright J Proc Natl Acad Sci U S A. 2012 Apr 24;109(17):6537-42. Epub 2012 Apr 6. PMID:22492980 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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