The PHO-2A mutant of neurospora crassa which is deficient in PI-repressible alkaline phosphatase (EC 3.1.3.1) is also defective in PI-represssible acid phosphatase (EC 3.1.3.2)

ABSTRACT

The mycelial Pi-repressible acid phosphatase presented p-nitrophenylphosphatase activity with negative cooperativity and Michaelian behavior when synthesized by the wild-type and pho-2A mutant strains of Neurospora crassa, respectively. The major acid phosphatase present in cell extracts of the pho-2A mutant of N. crassa grown in low Pi medium is more thermolabile (t½= 4 min at 54 grade C, pH 5.4) than that of the wild strain (stable for at least 80 min at 54 grade C, pH 5.4). The pho-2A mutant of N. crassa secreted a more thermobabile acid phosphatase (t½=30 min at 50 grade C, pH 5.4) than the wild strain (t½ of at least 80 min at 50 grade C, pH 5.4). The pho-2A mutant of N. crassa synthesized a more thermolabile acid phosphatase (t½=37 min at 54 grade C, pH 5.4) than the wild strain in high Pi medium (t½=14 min at 54 grade C, pH 5.4). The pleiotropic nature of the pho-2 locus and its possible involement in the mechanism of phosphatase secretion by N. crassa are proposed