XlnR-independent signaling pathway regulates both cellulase and xylanase genes in response to cellobiose in Aspergillus aculeatus
XlnR-independent signaling pathway regulates both cellulase and xylanase genes in response to cellobiose in Aspergillus aculeatus
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DOI：
10.1007/s00294-012-0367-5
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发表时间：
2012-04-01
期刊：
影响因子：
2.5
通讯作者：
Kawaguchi, Takashi
中科院分区：
文献类型：
--
作者：
Tani, Shuji;Kanamasa, Shin;Kawaguchi, Takashi
通过定量RT-PCR （qPCR）比较了宿主菌株与xlnR干扰物之间纤维素酶和木聚糖酶基因的表达水平，以确定xlnR独立信号通路的调控基因。纤维-羧甲基纤维素酶（cmc1）和纤维-木聚糖酶（xynIb）基因的纤维素诱导受XlnR调控；相比之下，fiii -乙酰化酶（chi）、fii -羧甲基纤维素酶（cmc2）和fii -木聚糖酶（xynIa）基因的纤维素诱导则由不依赖xlnr的信号通路控制。为了更深入地了解xlnr独立的信号通路，我们分析了cbhI作为代表性靶基因的表达谱。在由-糖苷键组成的双糖中，纤维素糖与1-脱氧诺吉霉素（DNJ）联合诱导cbi的效率最高。此外，含DNJ的纤维素二糖诱导了cmc2和xynIa的转录，而cmc1和xynIb则未被诱导。对截断和突变的chi启动子的GUS报告子融合分析显示，有效的纤维素诱导转录需要三个区域，所有这些区域都包含CeRE中的保守序列5'-CCGN(2)CCN(7)G(C/A)-3'，该区域已被确定为A. nidulans中eglA表达所必需的上游激活元件（Endo et al. 2008）。因此，这些数据描绘了一种途径，在这种途径中，刺参感知到纤维素二糖的存在，从而激活一个信号通路，在不依赖xlnr的CeRE调控下驱动纤维素酶和半纤维素酶基因的表达。
The expression levels of the cellulase and xylanase genes between the host strain and an xlnR disruptant were compared by quantitative RT-PCR (qPCR) to identify the genes controlled by XlnR-independent signaling pathway. The cellulose induction of the FI-carboxymethyl cellulase (cmc1) and FIb-xylanase (xynIb) genes was controlled by XlnR; in contrast, the cellulose induction of the FIII-avicelase (cbhI), FII-carboxymethyl cellulase (cmc2), and FIa-xylanase (xynIa) genes was controlled by an XlnR-independent signaling pathway. To gain deeper insight into the XlnR-independent signaling pathway, the expression profile of cbhI was analyzed as a representative target gene. Cellobiose together with 1-deoxynojirimycin (DNJ), a glucosidase inhibitor, induced cbhI the most efficiently among disaccharides composed of beta-glucosidic bonds. Furthermore, cellobiose with DNJ induced the transcription of cmc2 and xynIa, whereas cmc1 and xynIb were not induced. GUS reporter fusion analyses of truncated and mutated cbhI promoters revealed that three regions were necessary for effective cellulose-induced transcription, all of which contained the conserved sequence 5'-CCGN(2)CCN(7)G(C/A)-3' within the CeRE, which has been identified as the upstream activating element essential for expression of eglA in A. nidulans (Endo et al. 2008). The data therefore delineate a pathway in which A. aculeatus perceives the presence of cellobiose, thereby activating a signaling pathway that drives cellulase and hemicellulase gene expression under the control of the XlnR-independent regulation through CeRE.