Structural genes for phosphatases in Aspergillus nidulans

Abstract

Although the fungus Aspergillus nidulans has a multiplicity of phosphatases and of genes where mutations affect one or more phosphatases, we have succeeded in identifying structural genes for three phosphatases as well as one other gene which might encode a fourth. Using both conditional and non-conditional mutations, palD has been shown to be the structural gene for a phosphate-repressible alkaline phosphatase, palG to be the structural gene for a non-repressible alkaline phosphatase which apparently exists in two electrophoretically distinct forms (but whose rates of thermal inactivation are apparently very similar) and pacA to be the structural gene for both intracellular and secreted forms of a phosphate-repressible acid phosphatase. Colony staining techniques for the enzymes specified by palD and pacA have been described previously but we have now shown that the enzyme specified by palG can be detected by staining toluene-permeabilized colonies. Mutations in pacG lead to loss of non-repressible acid phosphatase as judged by colony staining and electrophoretic patterns but their effects on assays of activity in cell-free extracts are only marginal. Under phosphate-limited, but not phosphate-starved or phosphate-sufficient, conditions, pacG− mutations also affect the regulation of other, phosphate-repressible phosphatases. None of these phosphatases, alone or in combination, plays an essential role. © 1986, Cambridge University Press. All rights reserved.