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

In Neurospora crassa, the starvation of tryptophan mutants for tryptophan resulted in the derepression of tryptophan, histidine, and arginine biosynthetic enzymes. This tryptophan-mediated derepression of histidine and arginine biosynthetic enzymes occurred despite the fact that the tryptophan-starved cells had a higher intracellular concentration of histidine and arginine than did nonstarved cells.