GRISEA, a copper-modulated transcription factor from Podospora anserina involved in senescence and morphogenesis, is an ortholog of MAC1 in Saccharomyces cerevisiae

Abstract

The initial characterization of Grisea suggested that this gene codes for a transcription factor involved in the genetic control of cellular copper homeostasis in Podospora anserina. Here we demonstrate that GRISEA activates in vivo gene expression in Saccharomyces cerevisiae and is characterized by a modular organization. The DNA-binding domain was mapped to the first 168 N-terminal amino acids and the transactivation domain to the C-terminal half of the protein. Increased levels of copper in the growth medium lead to repression of the transactivation function possibly via intramolecular interactions between parts of the DNA-binding domain and the transactivation domain. The wild-type copy of Grisea was found to complement the phenotype of the mac1-1 mutant of S. cerevisiae. GRISEA is able to bind to the promoter of CTR1, a MAC1 target gene that encodes a high-affinity copper transporter. Taken together, the data reported here and in earlier investigations indicate that GRISEA is an ortholog of the yeast transcription factor MAC1 and suggest at least a partial conservation of the molecular machinery involved in the control of cellular copper homeostasis in eukaryotes. Remarkably, in P. anserina, the spectrum of phenotypes affected by this regulatory protein is much broader than that known in yeast and includes morphogenetic traits as well as lifespan and senescence.