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Substrate specificity and subsite mobility in T. aurantiacus xylanase 10A
L Lo Leggio1, S Kalogiannis, K Eckert
1Centre for Crystallographic Studies, Chemical Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark. leila@ccs.ki.ku.dk
FEBS Letters
|December 14, 2001
Summary
Thermoascus aurantiacus xylanase 10A (TAX) structural and biochemical studies reveal substrate specificity. Xylobiose binding stabilizes key enzyme regions, explaining specificity at subsites -1 and -2.
Area of Science:
- Biochemistry
- Structural Biology
- Enzymology
Background:
- Xylanases are crucial enzymes for biomass degradation.
- Thermoascus aurantiacus xylanase 10A (TAX) is a family 10 xylanase with industrial applications.
- Understanding enzyme-substrate interactions is key to enzyme engineering.
Purpose of the Study:
- To investigate the substrate specificity of TAX.
- To elucidate the structural basis of TAX's interaction with xylobiose.
- To correlate structural findings with enzyme function and specificity.
Main Methods:
- Biochemical assays to determine substrate specificity.
- High-resolution X-ray crystallography at 291 K and 100 K.
- Analysis of enzyme-ligand complexes (TAX-xylobiose).
Main Results:
- Xylobiose binds to TAX in its alpha anomeric conformation.
- Structural data rationalize specificity for p-nitrophenyl glycosides at -1 and -2 subsites.
- Binding of xylobiose stabilizes the disordered Trp 275 residue.
- Two structural subsets of family 10 xylanases are identified based on a loop variation.
Conclusions:
- The study provides structural insights into TAX substrate specificity.
- The role of Trp 275 mobility in xylanase function is highlighted.
- Identified structural differences may influence xylanase activity and substrate preference.
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