Characterization of amber and ochre suppressors in Salmonella typhimurium.

Amber and ochre suppressor mutations in Salmonella typhimurium were selected. The amino acid insertions directed by the suppressors were inferred from suppression patterns of Escherichia coli lacI amber mutations. These amber mutations only respond to nonsense suppressors that direct the insertion of particular amino acids. Four Salmonella amber suppressors characterized insert serine, glutamine, tyrosine, and (probably) leucine. Of the three ochre suppressors characterized, two direct the insertion of tyrosine and one directs that of lysine. Of the three amber and two ochre suppressors which have been mapped by phage P22 cotransduction, all are located in the same relative position on the Salmonella map as the analogous E. coli suppressors are on the E. coli map.