title: Heterologous expression and regulation of the Neurospora crassa nit-4 pathway-specific regulatory gene for nitrate assimilation in Aspergillus nidulans.
abstract: The nirA gene of Aspergillus nidulans and the nit-4 gene of Neurospora crassa appear to be equivalent pathway-specific regulatory genes which mediate nitrate induction of nitrate reductase and nitrite reductase (NR and NiR) activities. We have transformed the nit-4 wild-type (wt) gene into the A. nidulans loss-of-function (pleiotropic negative) nirA 1 mutant strain. The nit-4 gene was found to complement the nirA 1 mutation, thus permitting the nirA 1 mutant strain to grow on nitrate or nitrite as the sole source of nitrogen. Integration of the nit-4 gene in transformants appears to have occurred at a number of 'ectopic', i.e. non-nirA, sites. Nitrate is required for the induction of NR activity in nit-4-transformed strains whilst NR production remains markedly subject to nitrogen-metabolite repression. However, NR levels are modestly higher than wt under all growth conditions.
authors.affiliation: Plant Molecular Genetics Unit, University of St. Andrews, Fife, UK.
authors.forename: K L
authors.initials: KL
authors.lastname: Hawker
authors.forename: P
authors.initials: P
authors.lastname: Montague
authors.forename: G A
authors.initials: GA
authors.lastname: Marzluf
authors.forename: J R
authors.initials: JR
authors.lastname: Kinghorn
mesh_terms: D001233:Aspergillus nidulans / Q000201:enzymology / Q000235:genetics*; D005798:Genes, Bacterial; D005809:Genes, Regulator; D008040:Genetic Linkage; D009492:Neurospora crassa / Q000201:enzymology / Q000235:genetics*; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000235:genetics*; D009572:Nitrite Reductases / Q000235:genetics*; D010641:Phenotype; D014169:Transformation, Bacterial
chemical_list: D009565:Nitrate Reductases; D009572:Nitrite Reductases; D050901:Nitrate Reductase