Regulation of freA , acoA , lysF , and cycA Expression by Iron Availability in Aspergillus nidulans

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Abstract
In the filamentous fungus Aspergillus nidulans , iron homeostasis is regulated at the transcriptional level by the negative-acting GATA factor SREA. In this study the expression of a putative heme-containing metalloreductase-encoding gene, freA , was found to be upregulated by iron limitation independently of SREA, demonstrating the existence of an iron-regulatory mechanism which does not involve SREA. In contrast to freA , various other genes encoding proteins in need of iron-containing cofactors— acoA , lysF , and cycA —were downregulated in response to iron depletion. Remarkably, SREA deficiency led to increased expression of acoA , lysF , and cycA under iron-replete growth conditions.