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

Abstract

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.

PaPro1 and IDC4, Two Genes Controlling Stationary Phase, Sexual Development and Cell Degeneration in Podospora anserina

“…In previous analyses [ 2 , 45 ], we positioned IDC proteins with respect to PDC1 by double mutant analysis. PDC1 encodes a repressor within the PaMpk1/PaNox1 pathway and is positioned between the PaMpk1/PaMpk2 MAP kinases and the other members of the cascade ( Figure 7 ).…”

“…PDC1 encodes a repressor within the PaMpk1/PaNox1 pathway and is positioned between the PaMpk1/PaMpk2 MAP kinases and the other members of the cascade ( Figure 7 ). To position PaPro1 and IDC4 within the cascade, we constructed the PaPro1 Δ PDC1 Δ and IDC 508 PDC 2205 double mutants; PDC 2205 is a null allele of PDC1 [ 45 ]. Phenotypic analyses of these mutants ( Figure 8 ) showed that both lacked pigments, aerial hyphae and were female sterile, yet both developed CG sector on M2.…”

“… Scheme of the IDC signaling cascade. PDC1 encodes a repressor of the cascade, which was shown to likely repress the positive regulatory loop of the PaMpk1 MAPK cascade [ 45 ]. Double mutants of PDC1 and either PaMpk1 or PaMpk2 never present CG.…”