Characterization of cpd-1 and cpd-2 mutants which affect the activity of orthophosphate regulated cyclic phosphodiesterase in Neurospora.

Enzymatic and genetic characterization of cpd-1 and cpd-2, which exhibit rhythmic conidiation in liquid media and on solid media, were described with band (bd) strain as a reference. Cpd-1 and cpd-2 showed reduced growth in orthophosphate-free cyclic 3',5'-AMP media, while bd showed wild-type level of growth in the media. In low-phosphate media, cpd-1 and cpd-2 produced 19.2% and 9.8% of orthophosphate-regulated cyclic phosphodiesterase (cPDase) in culture media, while bd produced 123%. The intracellular levels of cPDase with Km of 1 x 10(-5) M in high-phosphate media in cpd-1, cpd-2 and bd were about 20%, 15%, and 10% of that in wild-type, respectively. In low-phosphate media roughly equal levels of cPDase with Km of 1 x 10(-5) M were produced in all strains, whereas the production of cPDase with Km of 2 x 10(-3) M was reduced in cpd-2, and that of cPDase with Km of 1 x 10(-2) was reduced in cpd-1 and cpd-2. The levels of intracellular cyclic 3',5'-AMP in cpd-1, cpd-2, and bd in high-phosphate media were 13.1%, 10.1%, and 69.6% of that in wild-type. Adenylate cyclase activity in cpd-1, cpd-2, bd, and cr-1 was 69.3%, 34.0%, 63.2%, and 20.3% of that of wild-type (74A). The levels of Mg++-stimulated cyclic phosphodiesterase in cpd-1, cpd-2, bd, and cr-1 at 0.2 microM cyclic 3',5'-AMP were 199%, 137%, 329%, and 293% of that of wild-type.(ABSTRACT TRUNCATED AT 250 WORDS)