Ohnishi Yuka, Nagase Mitsutoshi, Ichiyanagi Tsuyoshi, Kitamoto Yutaka, Aimi Tadanori
Faculty of Agriculture, Tottori University, Tottori-shi, Tottori, Japan.
FEMS Microbiol Lett. 2007 Sep;274(2):218-25. doi: 10.1111/j.1574-6968.2007.00831.x. Epub 2007 Jun 30.
In the current study, the genomic and cDNA clones encoding the endoglucanase (cel4) of Polyporus arcularius were sequenced and characterized. The amino acid sequence of Cel4 indicated that it is a glycosyl hydrolase family 5 protein. The expressions of the previously cloned endoglucanase cel3A and cel4 were induced by Avicel (microcrystalline cellulose) and cellopentaose but repressed by glucose, cellobiose, cellotriose, and cellotetraose. There was a low level of transcription of both genes regardless of the carbon source. These results suggest that P. arcularius cells constitutively express a very low level of cellulase that can degrade insoluble crystalline cellulose and that the transcription of cel3A and cel4 in the cells is induced by products produced by these endoglucanases such as cellooligosaccharides.
在当前研究中，对编码拱状多孔菌内切葡聚糖酶（cel4）的基因组和cDNA克隆进行了测序和表征。Cel4的氨基酸序列表明它是一种糖基水解酶家族5蛋白。先前克隆的内切葡聚糖酶cel3A和cel4的表达受到微晶纤维素（Avicel）和纤维五糖的诱导，但受到葡萄糖、纤维二糖、纤维三糖和纤维四糖的抑制。无论碳源如何，这两个基因的转录水平都很低。这些结果表明，拱状多孔菌细胞组成性地表达非常低水平的纤维素酶，该酶可降解不溶性结晶纤维素，并且细胞中cel3A和cel4的转录受到这些内切葡聚糖酶产生的产物（如纤维寡糖）的诱导。
