Increase of translational fidelity blocks sporulation in the fungus Podospora anserina

Summary AS7-1 and AS7-2 are antisuppressor mutations reducing the miscoding capacity of ribosomes. Strains carrying and AS7 mutation do not sporulate. We have investigated whether the sporulation deficiency is due to the decrease of translational ambiguity. Two major findings argue in favour of this assumption. First, a significant sporulation level is restored in the presence of paromomycin. Second, three mutations which restore the sporulation of AS7-2 increase the ribosomal misreading in vitro. They define two new loci for ribosomal suppressors, su11 and su12. The two ribosomal proteins altered by su11-1 and su12-1 have been identified by electrophoresis. The results are discussed in the context of a more general hypothesis proposed by Picard-Bennoun (1982).