His22 of TLXI plays a critical role in the inhibition of glycoside hydrolase family 11 xylanases |
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| Authors: | Sigrid Rombouts Ellen Fierens Elien Vandermarliere Arnout Voet Kurt Gebruers Johnny Beaugrand |
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| Institution: | 1. Laboratory of Gene Technology, Katholieke Universiteit Leuven, Kasteelpark Arenberg 21, B-3001 Leuven, Belgium;2. Laboratory of Food Chemistry and Biochemistry, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium;3. Laboratory for Biocrystallography, Katholieke Universiteit Leuven, Herestraat 49, B-3000 Leuven, Belgium;4. Laboratory of Biomolecular Modeling and BioMacS, Katholieke Universiteit Leuven, Celestijnenlaan 200G, B-3001 Leuven, Belgium |
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| Abstract: | Recently, a novel wheat thaumatin-like protein, TLXI, which inhibits microbial glycoside hydrolase family (GH) 11 xylanases has been identified. It is the first xylanase inhibitor that exerts its inhibition in a non-competitive way. In the present study we gained insight into the interaction between TLXI and xylanases via combined molecular modeling and mutagenic approaches. More specifically, site-specific mutation of His22, situated on a loop which distinguishes TLXI from other, non-inhibiting, thaumatin-like proteins, and subsequent expression of the mutant in Pichia pastoris resulted in a protein lacking inhibition capacity. The mutant protein was unable to form a complex with GH11 xylanases. Based on these findings, the interaction of TLXI with GH11 xylanases is discussed. |
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| Keywords: | Thaumatin-like protein xylanase inhibitor protein–protein interaction site-directed mutagenesis Pichia pastoris |
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