DIRECT ANALYSIS OF NATIVE AND CHIMERIC GATA SPECIFIC DNA-BINDING PROTEINS FROM ASPERGILLUS-NIDULANS

In Aspergillus nidulans the regulatory gene areA is responsible for mediating nitrogen metabolite repression. The areA product (AREA) represents an example of the GATA family of DNA binding proteins, which are characterised by the presence of a GATA domain consisting of a zinc finger within a highly conserved region of 52 amino acids. Among the other transcription factors included in this family is the principal erythroid transcription factor, GATA-1, which contains two GATA domains. In order to demonstrate high specificity binding of native AREA to DNA containing the sequence -GATA-, and investigate the presence in A.nidulans of other proteins with related specificities, we have used gel mobility shift assays. Both AREA-dependent and independent complexes have been identified. Two strains bearing chimeric genes were also characterised. In these, the region encoding the native GATA domain of AREA was replaced by sequences from murine GATA-1 cDNA encoding either the equivalent C-terminal domain or both the N and C-terminal domains. Strains bearing the areA::NC-GATA construct, which includes the sequence encoding both the N and C-terminal domains of GATA-1, leads to a pronounced increase in one of two AREA-dependent complexes and implicates the N-terminal domain of GATA-1 in mediating protein-protein interactions.