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Publication Abstract from PubMed

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 A. 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 beta-propeller catalytic domain with four beta-sheets and a C-terminal beta-sandwich domain organized in two beta-sheets with five beta-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 A of INU2 complexed with fructosyl molecules, experimental digestion data and molecular modelling studies support these hypotheses.

First 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 AM, Roussel G, Perpete EA, Wouters J, Housen I, Michaux C Biochimie. 2012 Jun 28. PMID:22750808^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.