The PAC-3 transcription factor critically regulates phenotype-associated genes in Neurospora crassa

Abstract Transcription factors play an important role in fungal environmental adaptive process by promoting adjustment to challenging stimuli via gene modulation and activation of signaling networks. The transcription factor encoded by the pac-3/rim101/pacC gene is involved in pH regulation and is associated with a wide variety of cellular functions. The deletion of pac-3 affects fungal development. In Neurospora crassa, the Δpac-3 strain presents diminished aerial growth and reduced conidiation. However, the PAC-3-regulated genes associated with this altered phenotype have not been elucidated. In this study, we used RNA-seq to analyze the phenotypic plasticity induced after pac-3 deletion in the filamentous fungus N. crassa cultivated in media supplemented with sufficient or limited inorganic phosphate. Genes related to morphology, hyphal development, and conidiation were of particular interest in this study. Our results suggest a pac-3 dependency in gene regulation in a Pi-dependent manner. Furthermore, our analysis suggested that the fungus attempts to overcome the deletion effects in a Δpac-3 mutant through a complex combined regulatory mechanism. Finally, the modulatory responses observed in the Δpac-3 strain, a double mutant generated based on the Δmus-52 mutant strain, is strain-specific, highlighting that the phenotypic impact may be attributed to pac-3 absence despite the combined mus-52 deletion.

摘要 转录因子（Transcription factors）通过调控基因表达、激活信号网络以帮助真菌适应逆境刺激，在真菌环境适应过程中发挥重要作用。由pac-3/rim101/pacC基因编码的转录因子参与pH调控，并与多种细胞功能相关。敲除pac-3会影响真菌的生长发育。在粗糙脉孢霉（Neurospora crassa）中，Δpac-3突变株的气生生长能力减弱，产孢量降低。然而，与该异常表型相关的PAC-3调控靶基因尚未得到阐明。本研究采用RNA测序（RNA-seq）技术，分析了培养于添加充足或限量无机磷酸盐的培养基中的粗糙脉孢霉在pac-3敲除后诱导的表型可塑性。本研究重点关注与形态建成、菌丝发育及产孢相关的基因。研究结果表明，pac-3对基因的调控具有无机磷酸盐（Pi）依赖特性。进一步分析显示，该真菌可通过复杂的联合调控机制，试图弥补Δpac-3突变体中pac-3缺失带来的影响。最后，本研究使用的Δpac-3菌株是基于Δmus-52突变株构建的双突变体，其调控应答具有菌株特异性，这表明尽管存在mus-52的联合缺失，表型差异仍可归因于pac-3的缺失。