The GATA factors AREA and AREB together with the co-repressor NMRA, negatively regulate arginine catabolism in Aspergillus nidulans in response to nitrogen and carbon source

Abstract

The filamentous fungus Aspergillus nidulans can utilize arginine both as a nitrogen and carbon source. Analysis of areA and areB single and double mutants has shown that the two GATA transcription factors AREA and AREB negatively regulate the expression of arginine catabolism genes agaA and otaA under nitrogen repressing conditions. AREA is necessary for the ammonium repression of agaA and otaA under carbon repressing conditions, while AREB is involved under carbon-limiting conditions. The ability of both AREA and AREB to sense the status of carbon metabolism is most probably dependent on NMRA, and not on the transcription factor CREA, which mediates general carbon catabolite repression in A. nidulans. NMRA is a co-repressor which has previously been shown to bind the C-terminus of AREA and inhibits its activity under conditions of nitrogen sufficiency, in response to high intracellular glutamine levels. We therefore propose a novel function for NMRA, the modulation of AREA and AREB activity in response to the carbon status of the cell.