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KMID : 0545120120220081118
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Journal of Microbiology and Biotechnology
2012 Volume.22 No. 8 p.1118 ~ p.1126
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Characterization of the Four GH12 Endoxylanases from the Plant Pathogen Fusarium graminearum
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Olivier Habrylo
Xinghan Song
Anne Forster
Jean-Marc Jeltsch
Vincent Phalip
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Abstract
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Four putative GH12 genes were found in the Fusarium graminearum genome. The corresponding proteins were expressed in Escherichia coli, purified, and evaluated. FGSG_05851 and FGSG_11037 displayed high activities towards xyloglucan (Vmax of 4 and 11 μmol/min, respectively), whereas FGSG_07892 and FGSG_16349 were much less active with this substrate (0.081 and 0.004 μmol/min, respectively). However, all four of these enzymes had a similar binding affinity for xyloglucan. Xyloglucan was the substrate preferred by FGSG_05851, in contrast to the three other enzymes, which preferred β-glucan or lichenan. Therefore, FGSG_05851 is a xyloglucan-specific glucanase (E.C. 3.2.1.151) rather than an endoglucanase (E.C. 3.2.1.4) with broad substrate specificity. FGSG_11037 displayed a peculiar behavior in that the xyloglucan binding was highly cooperative, with a Hill coefficient of 2.5. Finally, FGSG_05851 essentially degraded xyloglucan into hepta-, octa-, and nonasaccharides, whereas the three other enzymes yielded hepta- and octa-saccharides as well as larger molecules.
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KEYWORD
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xyloglucanase, fusarium, glycosyl hydrolase, cooperativity
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