title: TamA interacts with LeuB, the homologue of Saccharomyces cerevisiae Leu3p, to regulate gdhA expression in Aspergillus nidulans.
abstract: Previous studies have shown that expression of the gdhA gene, encoding NADP-linked glutamate dehydrogenase (NADP-GDH), in Aspergillus nidulans is regulated by the major nitrogen regulatory protein AreA and its co-activator TamA. We show here that loss of TamA function has a more severe effect on the levels of gdhA expression than loss of AreA function. Using TamA as the bait in a yeast two-hybrid screen, we have identified a second protein that interacts with TamA. Sequencing analysis and functional studies have shown that this protein, designated LeuB, is a transcriptional activator with similar function to the homologous Leu3p of Saccharomyces cerevisiae. Inactivation of leuB revealed that this gene is involved in the regulation of gdhA, and an areA; leuB double mutant was shown to have similar NADP-GDH levels to a tamA single mutant. The requirement for TamA function to promote gdhA expression is likely to be due to its dual interaction with AreA and LeuB.
authors.affiliation: Department of Genetics, The University of Melbourne, 3010 Parkville, Australia.
authors.forename: R
authors.initials: R
authors.lastname: Polotnianka
authors.forename: B J
authors.initials: BJ
authors.lastname: Monahan
authors.forename: M J
authors.initials: MJ
authors.lastname: Hynes
authors.forename: M A
authors.initials: MA
authors.lastname: Davis
mesh_terms: D000595:Amino Acid Sequence; D001233:Aspergillus nidulans / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015152:Blotting, Northern; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D040461:Gene Components; D015966:Gene Expression Regulation, Fungal; D005816:Genetic Complementation Test; D018086:Glutamate Dehydrogenase (NADP+) / Q000378:metabolism*; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015534:Trans-Activators / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C063667:LEU3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C099751:TamA protein, Aspergillus nidulans; D015534:Trans-Activators; D018086:Glutamate Dehydrogenase (NADP+)