Cross-Pathway Regulation: Histidine-Mediated Control of Histidine, Tryptophan, and Arginine Biosynthetic Enzymes in Neurospora crassa

Abstract

In Neurospora crassa , histidine starvation of histidine mutants resulted in derepression of histidine, tryptophan, and arginine biosynthetic enzymes. The same tripartite derepression occurred in wild-type strain 74A when it was grown in medium supplemented with 3-amino-1,2,4-triazole, an inhibitor of histidine biosynthesis. Histidine-mediated derepression of tryptophan and arginine biosynthetic enzymes was not due to a lowered intracellular concentration of tryptophan or arginine, respectively. A discussion of possible mechanisms and of similar studies in prokaryotic and eukaryotic organisms is presented.