The dual nature of the wheat xylanase protein inhibitor XIP-I: Structural basis for the inhibition of family 10 and family 11 xylanases

Françoise Payan, Philippe Leone, Sophie Porciero, Caroline Furniss, Tariq Tahir, Gary Williamson, Anne Durand, Paloma Manzanares, Harry J. Gilbert, Nathalie Juge, Alain Roussel

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110 Citations (Scopus)


The xylanase inhibitor protein I (XIP-I) from wheat Triticum aestivum is the prototype of a novel class of cereal protein inhibitors that inhibit fungal xylanases belonging to glycoside hydrolase families 10 (GH10) and 11 (GH11). The crystal structures of XIP-I in complex with Aspergillus nidulans (GH10) and Penicillium funiculosum (GH11) xylanases have been solved at 1.7 and 2.5 Å resolution, respectively. The inhibition strategy is novel because XIP-I possesses two independent enzyme-binding sites, allowing binding to two glycoside hydrolases that display a different fold. Inhibition of the GH11 xylanase is mediated by the insertion of an XIP-I ∏-shaped loop (Lα4β5) into the enzyme active site, whereas residues in the helix α7 of XIP-I, pointing into the four central active site subsites, are mainly responsible for the reversible inactivation of GH10 xylanases. The XIP-I strategy for inhibition of xylanases involves substrate-mimetic contacts and interactions occluding the active site. The structural determinants of XIP-I specificity demonstrate that the inhibitor is able to interact with GH10 and GH11 xylanases of both fungal and bacterial origin. The biological role of the xylanase inhibitors is discussed in light of the present structural data.

Original languageEnglish
Pages (from-to)36029-36037
Number of pages9
JournalJournal of Biological Chemistry
Issue number34
Publication statusPublished - 20 Aug 2004
Externally publishedYes

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