AN ADDITIONAL COPY OF THE ADENYLATE CYCLASE-ENCODING GENE RELIEVES DEVELOPMENTAL DEFECTS PRODUCED BY A MUTATION IN A VEGETATIVE INCOMPATIBILITY-CONTROLLING GENE IN PODOSPORA-ANSERINA

To identify cellular functions involved in vegetative incompatibility in filamentous fungi, we have initiated the cloning of Podospora anser ina (Pa) mod genes. These genes interfere with the lethal reaction tri ggered by interaction between incompatible het genes. A gene (Pa AC) h as been cloned by complementation of developmental defects caused by a mutation in the mod-D gene. This gene encodes a protein of 2145 amino acids (aa) that exhibits strong similarities with many adenylate cycl ases (AC). About 65% aa identity has been found between the sequence o f the polypeptide encoded by this Pa AC gene and the AC of Neurospora crassa. The organization of peptidic domains in the polypeptide encode d by Pa AC is closely related to that of Saccharomyces cerevisiae CYR1 . Restriction-fragment-length polymorphism (RFLP) and genetic analysis have shown that Pa AC and mod-D are distinct genes.