The Aspergillus nidulans metZ gene encodes a transcription factor involved in regulation of sulfur metabolism in this fungus and other Eurotiales

In Aspergillus nidulans, expression of sulfur metabolism genes is activated by the MetR transcription factor containing a basic region and leucine zipper domain (bZIP). Here we identified and characterized MetZ, a new transcriptional regulator in Aspergillus nidulans and other Eurotiales. It contains a bZIP domain similar to the corresponding region in MetR and this similarity suggests that MetZ could potentially complement the MetR deficiency. The metR and metZ genes are interrupted by unusually long introns. Transcription of metZ, unlike that of metR, is controlled by the sulfur metabolite repression system (SMR) dependent on the MetR protein. Overexpression of metZ from a MetR-independent promoter in a metR strain, activates transcription of genes encoding sulfate permease, homocysteine synthase and methionine permease, partially complementing the phenotype of the metR mutation. Thus, MetZ appears to be a second transcription factor involved in regulation of sulfur metabolism genes. Comparison of transcriptomes of the filamentous fungus Aspergillus nidulans two congenic strains, K1 (delmetR,pyr-4+) and TZ12(delmetR,trpCpr::metZ,pyr-4+). Four biological replicates of K1 vs TZ12 were performed. Each biological replicate had two technical replicates with dye swapping.