Identification and characterization of PDC1， a novel protein involved in the epigenetic cell degeneration Crippled Growth in Podospora anserina.

The model fungus Podospora anserina exhibits Crippled Growth (CG)， a cell degeneration process linked to the spreading of a prion-like hereditary element. Previous work has shown that the PaMpk1 MAP kinase and the PaNox1 NADPH oxidase are key player in setting up CG. Here， we identified PDC1， a new gene that negatively regulates the PaMpk1 pathway， by identifying the gene mutated in the PDC mutant. This mutant exhibits strong CG in conditions where the wild-type does not. PDC1 encodes a small protein conserved in other Pezizomycotina. The protein contains four evolutionary-conserved cysteines， a tryptophan and a histidine; all six amino-acid are essential for function. PDC1 is located in the cytosol and is present in lower amounts in stationary hyphae in accordance with its role as a repressor. Epistasis analyses place PDC1 between PaMpk1 and PaNox1.