A family 11 xylanase from Penicillium funiculosum is strongly inhibited by three wheat xylanase inhibitors

Steady-state kinetic approaches were used to investigate the binding of a novel Penicillium funiculosum xylanase, XYNC, with three known xylanase inhibitor proteins from wheat ( Triticum aestivum). The xylanase gene ( xynC) was cloned from a P. funiculosum genomic library and the deduced amino acid...

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Bibliographic Details
Published in:	Biochimica et biophysica acta Vol. 1598; no. 1; pp. 24 - 29
Main Authors:	Furniss, Caroline S.M, Belshaw, Nigel J, Alcocer, Marcos J.C, Williamson, Gary, Elliott, Giles O, Gebruers, Kurt, Haigh, Nigel P, Fish, Neville M, Kroon, Paul A
Format:	Journal Article
Language:	English
Published:	Netherlands Elsevier B.V 29-07-2002
Subjects:	Amino Acid Sequence Arabinoxylan Cloning, Molecular DNA Primers Enzyme Inhibitors - isolation & purification Enzyme Inhibitors - pharmacology Filamentous fungus Genetic Vectors Glycosyl hydrolase Kinetics Penicillium - enzymology Plant cell wall Polymerase Chain Reaction Recombinant Proteins - antagonists & inhibitors Reverse Transcriptase Polymerase Chain Reaction Triticum - chemistry Triticum aestivum Xylan Endo-1,3-beta-Xylosidase Xylosidases - antagonists & inhibitors Xylosidases - genetics Xylosidases - isolation & purification Glycosyl hydrolase Plant cell wall Filamentous fungus Triticum aestivum Arabinoxylan
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Summary:	Steady-state kinetic approaches were used to investigate the binding of a novel Penicillium funiculosum xylanase, XYNC, with three known xylanase inhibitor proteins from wheat ( Triticum aestivum). The xylanase gene ( xynC) was cloned from a P. funiculosum genomic library and the deduced amino acid sequence of XYNC exhibited high sequence similarity with fungal family 11 xylanases. xynC was overexpressed in P. funiculosum and the product (XYNC: M r=23.6 kDa; p I=3.7) purified and shown to efficiently degrade birchwood xylan [ K m=0.47% w/v, V max=2540 μmol xylose min −1 (mg protein) −1 at pH 5.5 and 30 °C] and soluble wheat arabinoxylans [ K m=1.45% w/v, V max=7190 μmol xylose min −1 mg protein) −1 at pH 5.5 and 30 °C]. The xylanase activity of XYNC was inhibited strongly by three xylanase inhibitor proteins from wheat; XIP-I, TAXI I and TAXI II. The inhibition for each was competitive, with very tight binding ( K i=3.4, 16 and 17 nM, respectively) equivalent to free energy changes (Δ G°) of −49, −45 and −45 kJ mol −1. This is the first report describing a xylanase that is inhibited by all three wheat xylanase inhibitor proteins described to date.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	1570-9639 0006-3002 1878-1454
DOI:	10.1016/S0167-4838(02)00366-7