| Summary: | Cadmium is an exceptionally toxic industrial and environmental pollutant classified as a human carcinogen. In order to provide insight into how we can keep our environment safe from cadmium contamination and prevent the accumulation of it in the food chain, we aim to elucidate how <i>Aspergillus nidulans</i>, one of the most abundant fungi in soil, survives and handles cadmium stress. As AtfA is the main transcription factor governing stress responses in <i>A. nidulans</i>, we examined genome-wide expression responses of wild-type and the <i>atfA</i> null mutant exposed to CdCl<sub>2</sub>. Both strains showed up-regulation of the <i>crpA</i> Cu<sup>2+</sup>/Cd<sup>2+</sup> pump gene and AN7729 predicted to encode a putative bis(glutathionato)-cadmium transporter, and transcriptional changes associated with elevated intracellular Cys availability leading to the efficient adaptation to Cd<sup>2+</sup>. Although the deletion of <i>atfA</i> did not alter the cadmium tolerance of the fungus, the cadmium stress response of the mutant differed from that of a reference strain. Promoter and transcriptional analyses of the “Phospho-relay response regulator” genes suggest that the AtfA-dependent regulation of these genes can be relevant in this phenomenon. We concluded that the regulatory network of <i>A. nidulans</i> has a high flexibility allowing the fungus to adapt efficiently to stress both in the presence and absence of this important transcription factor.
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