Nitrate reductase and nitrite reductase transcript levels in various mutants of Aspergillus nidulans: confirmation of autogenous regulation.

The regulation of the expression of the A. nidulans niiA and niaD genes (encoding nitrite reductase and nitrate reductase activities, respectively) was investigated by Northern blotting. It was demonstrated that expression of the niiA and niaD genes is controlled at the level of mRNA accumulation and that mutations within the nirA and areA regulatory genes, as well as certain mutations within niaD itself or cnxE (for its molybdenum cofactor), markedly affect niiA and niaD transcript levels.