Nitrogen nutrient utilization genes are regulated in Aspergillus nidulans by the GATA DNA-binding transcription activator AreA. The transcriptional activity of AreA is highly regulated by multiple mechanisms including autogenous transcriptional regulation, differential areA transcript stability, interaction of AreA with the corepressor NmrA, and repression by the negative-acting GATA factor AreB. In addition, AreA shows regulated nuclear accumulation. AreA accumulates in the nucleus specifically during nitrogen starvation, and is rapidly exported to the cytoplasm upon addition of nitrogen nutrients to nitrogen-starved cells. I will focus on recent developments in our understanding of AreA nuclear import and nuclear export, the key control points of regulated AreA nuclear accumulation. We have shown that the six conserved nuclear localization signals (NLSs) in AreA show redundancy and collaborate to mediate nuclear import. In contrast, a single CrmA exportin-dependent nuclear export signal (NES) in AreA is required for nuclear export. We have shown that fusion of the AreA NES to a constitutively nuclear protein confers nucleocytoplasmic localization and a loss of function phenotype. We have exploited this phenotype to select mutants defective in the AreA-CrmA interaction.
Full conference title:
27th Fungal Genetics Conference
- Fungal Genetics Conference 27th (2013)