Cloning and characterization of the multifunctional his-3 gene of Neurospora crassa.

We have cloned the his-3 gene of Neurospora crassa and determined its nucleotide sequence. The gene specifies a protein of 863 amino acids (aa) and contains a 59-bp intron which interrupts aa 800, a proline residue. The 5' end of the his-3 transcript is heterogeneous with major starts 122 and 124 bp upstream from the start codon. There are three possible polyadenylation sites, 119, 120 and 121 bp after the UAA stop codon. The protein shows two regions of homology to the yeast HIS4 gene which correspond to the hisIE and hisD genes of Escherichia coli and Salmonella typhimurium. Northern analysis shows that the level of his-3 mRNA increases severalfold in cultures subjected to histidine starvation.