Ribosomal control of translational fidelity in Podospora anserina: A suppressor and an antisuppressor affecting the paromomycin-induced misreading in vitro.

The hypersensitivity to paromomycin dis played by the su 1-60 suppressor, which was thought to be a ribosomal ambiguity mutation, was used to isolate a new antisuppressor, AS 71. This antisuppressor is not specific for ribosomal suppressors, since it is able to act on putative tRNA-type suppressors. Compared to the wild-type, the AS 7-1 mutation produces an increased resistance to paromomycin. In addition, it was found to stop the sporulation process. In the polyuridylic acid-dependant assay, the paromomycin induced misreading was shown to be higher on su 1-60 ribosomes and lower on ribosomes from AS 7-1 mutant and AS 7S-1-su 1-60 double mutant than on wild-type ribosomes. These data confirm that su 1-60 and AS 7-1 mutants are ribosomal mutants involved in the control of translational fidelity.