4lgx

Structure of Chitinase D from Serratia proteamaculans revealed an unusually constrained substrate binding site

spinqualitylabelsall models 4lgx, resolution 1.49Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4lgx is a 1 chain structure with sequence from Serratia proteamaculans 568. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.49Å Ligands: ACT, GOL, OMT Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function A8GFD6_SERP5 Publication Abstract from PubMed Serratia proteamaculans chitinase-D (SpChiD) has a unique combination of hydrolytic and transglycosylation (TG) activities. The TG activity of SpChiD can be used for large-scale production of chito-oligosaccharides (CHOS). The multiple activities (hydrolytic and/or chitobiase activities and TG) of SpChiD appear to be strongly influenced by the substrate-binding cleft. Here, we report the unique property of SpChiD substrate-binding cleft, wherein, the residues Tyr28, Val35 and Thr36 control chitobiase activity and the residues Trp160 and Trp290 are crucial for TG activity. Mutants with reduced (V35G and T36G/F) or no (SpChiDDelta30-42 and Y28A) chitobiase activity produced higher amounts of the quantifiable even-chain TG product with degree of polymerization (DP)-6, indicating that the chitobiase and TG activities are inversely related. In addition to its unprecedented catalytic properties, unlike other chitinases, the single modular SpChiD showed dual unfolding transitions. Ligand-induced thermal stability studies with the catalytically inactive mutant of SpChiD (E153A) showed that the transition temperature increased upon binding of CHOS with DP2-6. Isothermal titration calorimetry experiments revealed the exceptionally high binding affinities for E153A to CHOS with DP2-6. These observations strongly support that the architecture of SpChiD substrate-binding cleft adopted to control chitobiase and TG activities, in addition to usual chitinase-mediated hydrolysis. Inverse relationship between chitobiase and transglycosylation activities of chitinase-D from Serratia proteamaculans revealed by mutational and biophysical analyses.,Madhuprakash J, Bobbili KB, Moerschbacher BM, Singh TP, Swamy MJ, Podile AR Sci Rep. 2015 Oct 23;5:15657. doi: 10.1038/srep15657. PMID:26493546 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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