Repression of the acid ZrfA/ZrfB zinc-uptake system of Aspergillus fumigatus mediated by PacC under neutral, zinc-limiting conditions.

The ZrfA and ZrfB transporters are components of a zinc-uptake system of Aspergillus fumigatus that mainly operates under acidic, zinc-limiting conditions. Expression of the genes zrfA and zrfB is up-regulated by the transcriptional activator ZafA in both acidic and neutral, zinc-limiting media. The transcription of zafA is not influenced by PacC, which is the transcriptional regulator involved in regulating pH homeostasis in Aspergillus. However, at neutral pH the expression of both zrfA and zrfB is significantly reduced. In this work, the repression of zrfA and zrfB in neutral and alkaline, zinc-limiting media was found to be mediated by the transcriptional regulator PacC.