Mutations affecting cyclic phosphodiesterases and adenylate cyclase in Neurospora.

Two regulatory mutants in orthophosphate-regulated cyclic phosphodiesterase (cPDase), cpd-3 and cpd-4, were isolated and mapped proximal to arg-1 on L.G. IC and distal to arg-12 on L.G. IIR, respectively. cpd-3 showed short aerial hyphae with dense formation of conidia. The morphology was very similar to that of cr-1, cpd-3 and cr-1 had reduced levels of cyclic 3',5'-AMP, adenylate cyclase and cPDases (CPDase I, II and III in low phosphate condition) but had elevated levels of cyclic 3',5'-GMP. Although cr-1 showed an enhanced level and enhanced activation of heat activated cyclic phosphodiesterase (ha-PDE), this enzyme was not activated in cpd-3. cpd-4, nuc-1 and nuc-2 produced neither cPDase I, II, III, alkaline phosphatase nor ribonuclease N1 in low phosphate media. These mutants did not produce aerial hyphae or conidia when grown in low phosphate liquid medium. Activation of ha-PDE occurred in cpd-4, but not in nuc-1 and nuc-2.