Mutagenesis of super-suppressors in yeast.

Abstract

A new class of mutations, referred to as “nonsense” mutations, has been described in phages and bacteria in recent years (Benzer and Champe, 1962; Garen and Siddiqi, 1962). It is characterized by two major properties: a drastic effect on protein synthesis (A cistron of the rII region in phage T4, Benzer and Champe, 1962; alkaline phosphatase in E. coli, Garen and Siddiqi, 1962) produced by a polypeptide chain termination at the site of the mutational lesion (Sarabhai et al., 1964), and by responsiveness to external suppressors which can give rise to a wild or pseudo-wild phenotype (ambivalent rII mutants, Benzer and Champe, 1961; host-dependent defective mutations in phage λ, Campbell, 1961; alkaline phosphatase in E. coli, Garen and Siddiqi, 1962; amber mutations in phage T4, Epstein et al., 1963).