Isolation of nit-4, the minor nitrogen regulatory gene which mediates nitrate induction in Neurospora crassa.

Expression of nitrate reductase in Neurospora crassa requires the positive action of nit-4, a pathway-specific regulatory gene, which mediates nitrate induction. We report the molecular cloning of the nit-4 gene and present results which suggest that the nit-4 gene is constitutively expressed to yield a low-abundance 2.2-kilobase transcript. These results indicate that the nit-2 major control gene and the nit-4 pathway-specific control gene independently regulate the expression of the nitrate assimilatory structural genes.