Departamento de Biotecnología, Universidad Autónoma Metropolitana Unidad Iztapalapa, Iztapalapa, Ciudad de México, México.
INBIOTEC, Instituto de Biotecnología de León, Parque Científico de León, León, Spain.
Microb Cell Fact. 2022 Apr 2;21(1):50. doi: 10.1186/s12934-022-01765-w.
Reactive oxygen species (ROS) trigger different morphogenic processes in filamentous fungi and have been shown to play a role in the regulation of the biosynthesis of some secondary metabolites. Some bZIP transcription factors, such as Yap1, AtfA and AtfB, mediate resistance to oxidative stress and have a role in secondary metabolism regulation. In this work we aimed to get insight into the molecular basis of this regulation in the industrially important fungus Penicillium chrysogenum through the characterization of the role played by two effectors that mediate the oxidative stress response in development and secondary metabolism.
In P. chrysogenum, penicillin biosynthesis and conidiation are stimulated by the addition of HO to the culture medium, and this effect is mediated by the bZIP transcription factors PcYap1 and PcRsmA. Silencing of expression of both proteins by RNAi resulted in similar phenotypes, characterized by increased levels of ROS in the cell, reduced conidiation, higher sensitivity of conidia to HO and a decrease in penicillin production. Both PcYap1 and PcRsmA are able to sense HO-generated ROS in vitro and change its conformation in response to this stimulus. PcYap1 and PcRsmA positively regulate the expression of brlA, the first gene of the conidiation central regulatory pathway. PcYap1 binds in vitro to a previously identified regulatory sequence in the promoter of the penicillin gene pcbAB: TTAGTAA, and to a TTACTAA sequence in the promoter of the brlA gene, whereas PcRsmA binds to the sequences TGAGACA and TTACGTAA (CRE motif) in the promoters of the pcbAB and penDE genes, respectively.
bZIP transcription factors PcYap1 and PcRsmA respond to the presence of HO-generated ROS and regulate oxidative stress response in the cell. Both proteins mediate ROS regulation of penicillin biosynthesis and conidiation by binding to specific regulatory elements in the promoters of key genes. PcYap1 is identified as the previously proposed transcription factor PTA1 (Penicillin Transcriptional Activator 1), which binds to the regulatory sequence TTAGTAA in the pcbAB gene promoter. This is the first report of a Yap1 protein directly regulating transcription of a secondary metabolism gene. A model describing the regulatory network mediated by PcYap1 and PcRsmA is proposed.
活性氧（ROS）在丝状真菌中引发不同的形态发生过程，并已被证明在调节某些次生代谢物的生物合成中发挥作用。一些 bZIP 转录因子，如 Yap1、AtfA 和 AtfB，介导氧化应激抗性，并在次级代谢调控中发挥作用。在这项工作中，我们旨在通过研究两种效应子在发育和次级代谢中的氧化应激反应中的作用，深入了解工业上重要的真菌青霉产黄青霉中这种调控的分子基础。
在青霉产黄青霉中，向培养基中添加 HO 可刺激青霉素生物合成和产孢，这种作用是由 bZIP 转录因子 PcYap1 和 PcRsmA 介导的。通过 RNAi 沉默这两种蛋白的表达导致了相似的表型，其特征是细胞内 ROS 水平升高、产孢减少、孢子对 HO 的敏感性增加以及青霉素产量降低。PcYap1 和 PcRsmA 都能够在体外感知 HO 产生的 ROS，并响应此刺激改变其构象。PcYap1 和 PcRsmA 正向调节调控途径中第一个基因 brlA 的表达。PcYap1 在体外与青霉素基因 pcbAB 启动子中先前鉴定的调节序列 TTAGTAA 以及 brlA 基因启动子中的 TTACTAA 序列结合，而 PcRsmA 分别与 pcbAB 和 penDE 基因启动子中的序列 TGAGACA 和 TTACGTAA（CRE 基序）结合。
bZIP 转录因子 PcYap1 和 PcRsmA 响应 HO 产生的 ROS 的存在，并调节细胞中的氧化应激反应。这两种蛋白通过结合关键基因启动子中的特定调节元件，介导 ROS 对青霉素生物合成和产孢的调节。PcYap1 被鉴定为先前提出的转录因子 PTA1（青霉素转录激活因子 1），它与 pcbAB 基因启动子中的调节序列 TTAGTAA 结合。这是首次报道 Yap1 蛋白直接调节次级代谢基因的转录。提出了一个描述由 PcYap1 和 PcRsmA 介导的调节网络的模型。
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