Genome-wide transcriptional changes induced by Cd2+ in Aspergillus nidulans

Cd2+ pollution represents a serious global environmental risk. Understanding how microbes survive cadmium stress can facilitate the development of techniques to clean our environment and to prevent accumulation of this toxic heavy metal in the food chain. Genome-wide transcriptional changes induced by CdCl2 were determined and evaluated in Aspergillus nidulans. In addition to the reference strain, a atfA gene deletion mutant was also investigated to collect data on the regulatory role of AtfA transcription factor in this model organism. Up-regulation of the crpA Cu2+/Cd2+ pump and AN7729 putative bis(glutathionato)-cadmium transporter genes as well as transcriptional changes aiming to increase intracellular Cys availability were important parts of the efficient adaptation in both strains. Although deletion of atfA did not alter the cadmium tolerance of the fungus, the cadmium stress response of the mutant substantially differed from that of the reference strain. Promoter and transcriptional analyses of the “Two component signal transduction system” genes suggest that the AtfA-dependent regulation of these genes can be relevant in this phenomenon. We concluded that the regulatory network of A. nidulans has a high flexibility allowing the fungus to adapt efficiently to stress both in the presence and absence of this important transcription factor. two strains (TNJ92 atfA gene deletion mutant and THS30 reference strain) were examined under two conditions (CdCl2 treated and untreated cultures) with three biological replicates (altogether 12 samples)

镉（Cd²⁺）污染是一类严峻的全球性环境风险。解析微生物耐受镉胁迫的机制，可助力环境修复技术的研发，并阻断该有毒重金属在食物链中的富集。本研究对构巢曲霉（Aspergillus nidulans）中氯化镉（CdCl₂）诱导的全基因组转录变化进行了检测与分析。除参考菌株外，本研究同时对ΔatfA基因缺失突变体开展了实验分析，以探究AtfA转录因子在该模式生物中的调控功能。两种菌株均通过上调crpA编码的Cu²⁺/Cd²⁺转运泵、AN7729推定的双谷胱甘肽配位镉转运蛋白基因，以及增强细胞内半胱氨酸（Cys）可用性的相关转录调控通路，作为高效适应镉胁迫的核心策略。尽管atfA基因缺失并未改变构巢曲霉的镉耐受能力，但该突变体的镉胁迫应答模式与参考菌株存在显著差异。针对“双组分信号转导系统（Two component signal transduction system）”基因的启动子与转录分析结果表明，AtfA依赖的这些基因调控或与该应答差异密切相关。本研究最终得出结论：构巢曲霉的转录调控网络具有高度灵活性，无论该关键转录因子是否存在，该真菌均可高效适应镉胁迫环境。本实验针对两种菌株开展分析：TNJ92（ΔatfA基因缺失突变体）与THS30（参考菌株）；设置两种培养条件：氯化镉处理组与未处理对照组；每组均设置3次生物学重复，总计12个样本。