Download MendeleyFirst crystal structure of an endo-inulinase, INU2, from Aspergillus ficuum: Discovery of an extra-pocket in the catalytic domain responsible for its endo-activity.
Pouyez, J., Mayard, A., Vandamme, A.M., Roussel, G., Perpete, E.A., Wouters, J., Housen, I., Michaux, C.(2012) Biochimie 94: 2423-2430
- PubMed: 22750808
- DOI: https://doi.org/10.1016/j.biochi.2012.06.020
- Primary Citation of Related Structures:
3RWK, 3SC7 - PubMed Abstract:
Endo-inulinase is a member of glycosidase hydrolase family 32 (GH32) degrading fructans of the inulin type with an endo-cleavage mode and is an important class of industrial enzyme. In the present study, we report the first crystal structure of an endo-inulinase, INU2, from Aspergillus ficuum at 1.5 Å. It was solved by molecular replacement with the structure of exo-inulinase as search model. The 3D structure presents a bimodular arrangement common to other GH32 enzymes: a N-terminal 5-fold β-propeller catalytic domain with four β-sheets and a C-terminal β-sandwich domain organized in two β-sheets with five β-strands. The structural analysis and comparison with other GH32 enzymes reveal the presence of an extra pocket in the INU2 catalytic site, formed by two loops and the conserved motif W-M(I)-N-D(E)-P-N-G. This cavity would explain the endo-activity of the enzyme, the critical role of Trp40 and particularly the cleavage at the third unit of the inulin(-like) substrates. Crystal structure at 2.1 Å of INU2 complexed with fructosyl molecules, experimental digestion data and molecular modelling studies support these hypotheses.
Organizational Affiliation:
Unité de Chimie Physique Théorique et Structurale, Chemistry Department, University of Namur, 61 rue de Bruxelles, B-5000 Namur, Belgium.
