Furukawa Takanori, Shida Yosuke, Kitagami Naoki, Ota Yuuki, Adachi Masahiro, Nakagawa Shiho, Shimada Ryuichi, Kato Masashi, Kobayashi Tetsuo, Okada Hirofumi, Ogasawara Wataru, Morikawa Yasushi
Department of Bioengineering, Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka, Niigata 940-2188, Japan.
Fungal Genet Biol. 2008 Jul;45(7):1094-102. doi: 10.1016/j.fgb.2008.03.006. Epub 2008 Mar 25.
The xylanase III gene (xyn3) from the filamentous fungus Trichoderma reesei PC-3-7 is only induced by cellulose, its derivatives and L-sorbose, but not by xylan. In this study, we defined three cis-acting elements within the xyn3 upstream region by using detailed deletion and mutation analysis. In addition to the Xyr1/ACEII-binding motif (5'-GGCTAA-3'), the analogous motifs 5'-GGCTAT-3' and 5'-GGCAAA-3' presented as an inverted repeat spaced by 16-bp internal sequences were identified as essential elements for xyn3 expression. Electrophoretic mobility shift assay using heterologously expressed Xyr1 demonstrates that all the identified cis-acting elements are able to interact with Xyr1. Furthermore, no xyn3 transcripts were formed in the xyr1-knockout strain upon induction by sophorose and L-sorbose. These results indicate that xyn3 expression is transcriptionally regulated by Xyr1, and suggest that the 5'-GGCTAT-3' and 5'-GGCAAA-3' motifs play roles in Xyr1-mediated cellulase and xylanase gene expression in T. reesei.
来自丝状真菌里氏木霉PC-3-7的木聚糖酶III基因（xyn3）仅由纤维素、其衍生物和L-山梨糖诱导表达，而不能被木聚糖诱导。在本研究中，我们通过详细的缺失和突变分析确定了xyn3上游区域内的三个顺式作用元件。除了Xyr1/ACEII结合基序（5'-GGCTAA-3'）外，以间隔16个碱基对内部序列的反向重复形式呈现的类似基序5'-GGCTAT-3'和5'-GGCAAA-3'被确定为xyn3表达的必需元件。使用异源表达的Xyr1进行的电泳迁移率变动分析表明，所有鉴定出的顺式作用元件都能够与Xyr1相互作用。此外，在槐糖和L-山梨糖诱导下，xyr1基因敲除菌株中未形成xyn3转录本。这些结果表明，xyn3的表达受Xyr1转录调控，并表明5'-GGCTAT-3'和5'-GGCAAA-3'基序在里氏木霉中Xyr1介导的纤维素酶和木聚糖酶基因表达中发挥作用。
