Mäntylä Arja, Paloheimo Marja, Hakola Satu, Lindberg Emilia, Leskinen Sanna, Kallio Jarno, Vehmaanperä Jari, Lantto Raija, Suominen Pirkko
Roal Oy, 05201, Rajamäki, Finland.
Appl Microbiol Biotechnol. 2007 Aug;76(2):377-86. doi: 10.1007/s00253-007-1020-y. Epub 2007 May 30.
Three endoxylanase genes were cloned from the thermophilic fungus Chaetomium thermophilum CBS 730.95. All genes contained the typical consensus sequence of family 11 glycoside hydrolases. Genomic copies of Ct xyn11A, Ct xyn11B, and Ct xyn11C were expressed in the filamentous fungus T. reesei under the control of the strong T. reesei cel7A (cellobiohydrolase 1, cbh1) promoter. The molecular masses of the Ct Xyn11A, Ct Xyn11B, and Ct Xyn11C proteins on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were 27, 23, and 22 kDa, respectively. Ct Xyn11A was produced almost as efficiently as the homologous xylanase II from a corresponding single-copy transformant strain. Ct Xyn11B production level was approximately half of that of Ct Xyn11A. The amount of Ct Xyn11C was remarkably lower. Ct Xyn11A had the highest temperature optimum and stability of the recombinant xylanases and the highest activity at acid-neutral pH (pH 5-7). It was the most suitable for industrial bleaching of kraft pulp at high temperature.
从嗜热真菌嗜热毛壳菌CBS 730.95中克隆出三个内切木聚糖酶基因。所有基因都含有11家族糖苷水解酶的典型共有序列。Ct xyn11A、Ct xyn11B和Ct xyn11C的基因组拷贝在里氏木霉强cel7A（纤维二糖水解酶1，cbh1）启动子的控制下在丝状真菌里氏木霉中表达。在十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS-PAGE）上，Ct Xyn11A、Ct Xyn11B和Ct Xyn11C蛋白的分子量分别为27、23和22 kDa。Ct Xyn11A的产生效率几乎与相应单拷贝转化菌株的同源木聚糖酶II相同。Ct Xyn11B的产生水平约为Ct Xyn11A的一半。Ct Xyn11C的量明显更低。Ct Xyn11A在重组木聚糖酶中具有最高的最适温度和稳定性，并且在酸中性pH（pH 5-7）下具有最高活性。它最适合用于高温下硫酸盐浆的工业漂白。
