Genetic control of the synthesis of repressible phosphatases in Neurospora crassa.

I N the genetic control of alkaline phosphatase synthesis in Escherichia coli, GAREN and ECHOLS (1962a,b) have presented evidence for the presence of two regulator genes, RI and R2. It was proposed that R1 produces an inducer which has a positive function in controlling the synthesis of alkaline phosphatase and is converted into a repressor in the presence of the R2 product and high concentrations of inorganic phosphate. In Neurospora crassa, it has been shown that the synthesis of an alkaline phosphatase and an acid phosphatase is derepressed by lowering concentrations of inorganic phosphate in the culture medium (NYc, KADNER and CROCKEN 1966; NYC 1967). However, no genetic analysis on the regulation of synthesis of these enzymes has been reported. In previous reports, we described the isolation and characterization of nuclease mutants in N . crassa (ISHIKAWA et al. 1967, 1968, 1969). During the recent study of the utilization of nucleic acid as a source of phosphate in N . crassa, we found that the nuclease mutations showed a pleiotropic effect on the formation of the repressible phosphatases. The present paper reports a relationship between the RNA utilization and a regulatory mechanism of phosphatase formation in N . crassa.