State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology, Shanghai, 200237, China.
The Key Laboratory of Industrial Biotechnology of Ministry of Education, Jiangnan University, Wuxi, 214122, China.
Mol Genet Genomics. 2020 Sep;295(5):1269-1279. doi: 10.1007/s00438-020-01700-x. Epub 2020 Jun 19.
Aspergillus nidulans nrtA encodes a nitrate transporter that plays an important role in the [Formula: see text] assimilatory process. Many studies have focused on protein functions rather than gene regulation. The knowledge of nrtA[Formula: see text] uptake process, particularly in the regulation mechanism of transcription factors AreA and NirA on nrtA transcription, is very limited. Herein, we investigated the transcriptional regulation of nrtA in response to various N-sources in detail and characterized the promoter activity of nrtA. We confirmed that nrtA was induced by [Formula: see text] and repressed by preferred N-sources. Additionally, for the first time, we found that the transcription of nrtA increased under N-starvation conditions. AreA mediates nrtA transcription under both [Formula: see text] and N-starvation conditions, while NirA is effective only under [Formula: see text] conditions. All of the proposed AreA and NirA binding sites in the promoter region were capable of binding to their corresponding transcription factors in vitro. In vivo, all of the NirA binding sites showed regulation activities, but to AreA, only several of the initiation-codon-proximal binding sites participated in nrtA transcription. Moreover, the active binding sites contributed in different degrees of regulation strength to nrtA transcription, which is unrelated to the distance between the binding sites and initiation codon. These results provided an extensive map of nrtA promoter, defining the functional regulatory elements of A. nidulans nrtA.
构巢曲霉 nrtA 编码一种硝酸盐转运蛋白，在[公式：见文本]同化过程中发挥重要作用。许多研究都集中在蛋白质功能上，而不是基因调控上。关于 nrtA[公式：见文本]摄取过程的知识，特别是转录因子 AreA 和 NirA 对 nrtA 转录的调控机制，知之甚少。在此，我们详细研究了 nrtA 对各种 N 源的转录调控，并对 nrtA 启动子的活性进行了表征。我们证实 nrtA 被[公式：见文本]诱导，被优先 N 源抑制。此外，我们首次发现 nrtA 在 N 饥饿条件下转录增加。AreA 在[公式：见文本]和 N 饥饿条件下介导 nrtA 转录，而 NirA 仅在[公式：见文本]条件下有效。启动子区域中所有提议的 AreA 和 NirA 结合位点均能够在体外与相应的转录因子结合。在体内，所有的 NirA 结合位点都表现出调节活性，但对于 AreA，只有几个起始密码子近端结合位点参与 nrtA 转录。此外，活性结合位点对 nrtA 转录的调节强度不同，与结合位点与起始密码子之间的距离无关。这些结果提供了 nrtA 启动子的广泛图谱，确定了 A 的功能调节元件。nidulans nrtA。
