The range of amino acids whose limitation activates general amino-acid control in Neurospora crassa.

Several amino-acid synthetic enzymes, belonging to arginine, glutamine, leucine, lysine and phenylalanine biosynthesis, respectively, were investigated under conditions of reduced availability of any one of 16 out of the 20 amino acids represented in proteins. The enzymes showed simultaneous derepression under each condition, albeit to different degrees. Derepression was abolished and the remaining basal enzyme levels reduced by mutations at the cpc-1 locus which governs general amino-acid control in Neurospora. Glutamine synthetase was shown to be under cpc-1 and additional controls. The evidence emphasizes the global nature of general amino-acid control.