Mutational Analysis of AREA, a Transcriptional Activator Mediating Nitrogen Metabolite Repression in Aspergillus nidulans and a Member of the “Streetwise” GATA Family of Transcription Factors

Abstract

SUMMARY The transcriptional activator AREA is a member of the GATA family of transcription factors and mediates nitrogen metabolite repression in the fungus Aspergillus nidulans. The nutritional versatility of A. nidulans and its amenability to classical and reverse genetic manipulations make the AREA DNA binding domain (DBD) a useful model for analyzing GATA family DBDs, particularly as structures of two AREA-DNA complexes have been determined. The 109 extant mutant forms of the AREA DBD surveyed here constitute one of the highest totals of eukaryotic transcription factor DBD mutants, are discussed in light of the roles of individual residues, and are compared to corresponding mutant sequence changes in other fungal GATA factor DBDs. Other topics include delineation of the DBD using both homology and mutational truncation, use of frameshift reversion to detect regions of tolerance to mutational change, the finding that duplication of the DBD can apparently enhance AREA function, and use of the AREA system to analyze a vertebrate GATA factor DBD. Some major points to emerge from work on the AREA DBD are (i) tolerance to sequence change (with retention of function) is surprisingly great, (ii) mutational changes in a transcription factor can have widely differing, even opposing, effects on expression of different structural genes so that monitoring expression of one or even several structural genes can be insufficient and possibly misleading, and (iii) a mutational change altering local hydrophobic packing and DNA binding target specificity can markedly influence the behavior of mutational changes elsewhere in the DBD.

Molecular analysis of the cercosporin biosynthetic gene cluster in Cercospora nicotianae

“…The consensus TATA sequence was found in the promoters of CTB1, CTB2, CTB4, CTB5, CTB7 and ORF11 but not in CTB3 , CTB6 , ORF9 and ORF12. All the promoter regions have one or multiple putative GATA motifs found in the AreA (nitrogen regulatory protein) gene of E. nidulans (Wilson and Arst, 1998), whereas none of the CTB clustered gene promoters has the CreA (carbon regulatory protein) binding site (Panozzo et al ., 1998). All but CTB1 , CTB2 , CTB5 and ORF10 have a putative pH regulatory protein PacC binding motif (Espeso and Arst, 2000).…”

EMILIANIA HUXLEYI(PRYMNESIOPHYCEAE): NITROGEN-METABOLISM GENES AND THEIR EXPRESSION IN RESPONSE TO EXTERNAL NITROGEN SOURCES

“…AreA and NIT2 are positive regulators belonging to the GATA protein family (Marzluf 1997). In the absence of a preferred nitrogen source, often NH 4 + , they recognize and bind to consensus GATA sites in the promoter region of various genes coding for enzymes or permeases required for the catabolism of secondary nitrogen sources, thus promoting their transcription (Wilson and Arst 1998). A regulation of N metabolism by global nitrogen regulators suggests the presence of a nitrogen preference hierarchy.…”

Transcriptional control of nmrA by the bZIP transcription factor MeaB reveals a new level of nitrogen regulation in Aspergillus nidulans

“…This global transcriptional activator, which is conserved in filamentous ascomycetes, is encoded by the areA and nit‐2 genes in Aspergillus nidulans and Neurospora crassa respectively. Loss‐of‐function mutations in these genes result in an inability to grow on nitrogen sources except ammonium and glutamine (Fu and Marzluf, 1990; Kudla et al ., 1990; Wilson and Arst, 1998).…”