Triticum aestivum Xylanase Inhibitor (TAXI), a New Class of Enzyme Inhibitor Affecting Breadmaking Performance

Debyser, Winok; Wj, Peumans; Damme, Ejm Van; Delcour, Jan A.

doi:10.1006/jcrs.1999.0272

Cited by 133 publications

(81 citation statements)

References 16 publications

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“…A glycoprotein was identified in kiwi fruit that inhibits the action of a different pectindegrading enzyme, pectin methylesterase (55,127). In addition, several plant proteins have been isolated that inhibit the activity of endoxylanases (77,255,317). One of these studies also produced evidence for the production of an arabinofuranosidase inhibitor by wheat (317).…”

Section: Discussionmentioning

confidence: 99%

AspergillusEnzymes Involved in Degradation of Plant Cell Wall Polysaccharides

Vries

Visser

2001

Microbiol Mol Biol Rev

878

585

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SUMMARY Degradation of plant cell wall polysaccharides is of major importance in the food and feed, beverage, textile, and paper and pulp industries, as well as in several other industrial production processes. Enzymatic degradation of these polymers has received attention for many years and is becoming a more and more attractive alternative to chemical and mechanical processes. Over the past 15 years, much progress has been made in elucidating the structural characteristics of these polysaccharides and in characterizing the enzymes involved in their degradation and the genes of biotechnologically relevant microorganisms encoding these enzymes. The members of the fungal genus Aspergillus are commonly used for the production of polysaccharide-degrading enzymes. This genus produces a wide spectrum of cell wall-degrading enzymes, allowing not only complete degradation of the polysaccharides but also tailored modifications by using specific enzymes purified from these fungi. This review summarizes our current knowledge of the cell wall polysaccharide-degrading enzymes from aspergilli and the genes by which they are encoded.

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Section: Discussionmentioning

confidence: 99%

AspergillusEnzymes Involved in Degradation of Plant Cell Wall Polysaccharides

Vries

Visser

2001

Microbiol Mol Biol Rev

878

585

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“…Since then, three types of wheat endogenous xylanase inhibitors have been described, i.e. Triticum aestivum xylanase inhibitor (TAXI) [8], xylanase inhibitor protein (XIP) [9], and thaumatin-like xylanase inhibitor (TLXI) [10].…”

Section: Introductionmentioning

confidence: 99%

“…Form A consists of one single polypeptide chain with a M r of approximately 40,000, while form B is made up of two peptide chains; one with a M r of approximately 29,000 is linked to the other with a M r of approximately 11,000 by one single disulfide bridge (Cys167 TAXICys378 TAXI ). Form B is derived from form A in planta, possibly by the action of specific proteases [8]. TAXI proteins consist of two ß-barrel domains with a few helical segments divided by an extended cleft.…”

Section: Introductionmentioning

confidence: 99%

Biochemical and structural characterization of TLXI, the Triticum aestivum L. thaumatin-like xylanase inhibitor

Fierens

Gebruers

Voet

et al. 2009

Journal of Enzyme Inhibition and Medicinal Chemistry

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Thaumatin-like xylanase inhibitors (TLXI) are recently discovered wheat proteins. They belong to the family of the thaumatin-like proteins and inhibit glycoside hydrolase family 11 endoxylanases commonly used in different cereal based (bio)technological processes. We here report on the biochemical characterisation of TLXI. Its inhibition activity is temperature-and pH-dependent and shows a maximum at approximately 408C and pH 5.0. The TLXI structure model, generated with the crystal structure of thaumatin as template, shows the occurrence of five disulfide bridges and three b-sheets. Much as in the structures of other short-chain thaumatin-like proteins, no a-helix is present. The circular dichroism spectrum of TLXI confirms the absence of a-helices and the presence of antiparallel b-sheets. All ten cysteine residues in TLXI are involved in disulfide bridges. TLXI is stable for at least 120 min between pH 1-12 and for at least 2 hours at 1008C, making it much more stable than the other two xylanase inhibitors from wheat, i.e. Triticum aestivum xylanase inhibitor (TAXI) and xylanase inhibitor protein (XIP). This high stability can probably be ascribed to the high number of disulfide bridges, much as seen for other thaumatin-like proteins.

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“…They are monomeric glycosylated proteins with molecular masses of ϳ29 kDa and pI values of 8.7-8.9. The second type are the Triticum aestivum L. xylanase inhibitor (TAXI)-like inhibitors (36). They are high pI, nonglycosylated proteins with molecular masses of ϳ40 kDa.…”

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confidence: 99%

Specific Characterization of Substrate and Inhibitor Binding Sites of a Glycosyl Hydrolase Family 11 Xylanase fromAspergillus niger

Tahir

Berrin

Flatman

et al. 2002

Journal of Biological Chemistry

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The importance of aromatic and charged residues at the surface of the active site of a family 11 xylanase from Aspergillus niger was evaluated using site-directed mutagenesis. Ten mutant proteins were heterologously produced in Pichia pastoris, and their biochemical properties and kinetic parameters were determined. The specific activity of the Y6A, Y10A, Y89A, Y164A, and W172A mutant enzymes was drastically reduced. The low specific activities of Y6A and Y89A were entirely accounted for by a change in k cat and K m , respectively, whereas the lower values of Y10A, Y164A, and W172A were due to a combination of increased K m and decreased k cat . Tyr 6 , Tyr 10 , Tyr 89 , Tyr 164 , and Trp 172 are proposed as substrate-binding residues, a finding consistent with structural sequence alignments of family 11 xylanases and with the three-dimensional structure of the A. niger xylanase in complex with the modeled xylobiose. All other variants, D113A, D113N, N117A, E118A, and E118Q, retained full wild-type activity. Only N117A lost its sensitivity to xylanase inhibitor protein I (XIP-I), a protein inhibitor isolated from wheat, and this mutation did not affect the fold of the xylanase as revealed by circular dichroism. The N117A variant showed kinetics, pH stability, hydrolysis products pattern, substrate specificity, and structural properties identical to that of the wild-type xylanase. The loss of inhibition, as measured in activity assays, was due to abolition of the interaction between XIP-I and the mutant enzyme, as demonstrated by surface plasmon resonance and electrophoretic titration. A close inspection of the threedimensional structure of A. niger xylanase suggests that the binding site of XIP-I is located at the conserved "thumb" hairpin loop of family 11 xylanases.

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Triticum aestivum Xylanase Inhibitor (TAXI), a New Class of Enzyme Inhibitor Affecting Breadmaking Performance

Cited by 133 publications

References 16 publications

AspergillusEnzymes Involved in Degradation of Plant Cell Wall Polysaccharides

AspergillusEnzymes Involved in Degradation of Plant Cell Wall Polysaccharides

Biochemical and structural characterization of TLXI, the Triticum aestivum L. thaumatin-like xylanase inhibitor

Specific Characterization of Substrate and Inhibitor Binding Sites of a Glycosyl Hydrolase Family 11 Xylanase fromAspergillus niger

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