Carbamyl phosphate synthesis in Neurospora Crassa II. Genetics, metabolic position, and regulation of arginine-specific carbamyl phosphokinase

Abstract

The sole demonstrated enzyme of carbamyl phosphate synthesis in Neurospora appears to serve only the arginine pathway. The enzyme is completely absent in arg-3 mutants, which require arginine. While pyrimidine synthesis requires carbamyl phosphate, pyrimidine synthesis is unimpaired in arg-3 mutants. This suggests the existence of a pyrimidine-specific mode of carbamyl phosphate synthesis, and gene interaction experiments in support of this notion are presented. The regulatory behavior of argine and pyrimidine enzymes in mutant strains also reinforces the hypothesis that dual modes of carbamyl phosphate synthesis prevail in this organism.