REGULATION OF HEXOKINASE AND PHOSPHOGLUCOMUTASE ACTIVITY IN ASPERGILLUS-NIDULANS

The levels of G-6-P and 6-phosphogluconate dehydrogenase in wild type cells of A. nidulans varied with the C and N source. In general, hexokinase activity did not vary with C or N source. The ammonium derepressed mutant amrA1 had only 50% of the wild type level of kexokinase. Phosphoglucomutase activity was low in wild type cells grown with nitrate, but high in cells grown with ammonium when glucose was the C source. A non-inducible mutant, nirA-1, in the regulatory gene for nitrate reductase, had high phosphoglucomutase activity when grown with nitrate or ammonium. A constitutive mutant nirAc1, in the regulatory gene for nitrate reductase, had low phosphoglucomutase activity when grown with nitrate or ammonium. The mutants nir-1 and nirAc1 are recessive and semi-dominant for abnormal phosphoglucomutase activity, respectively.