Temperature-sensitive mutations in various genes of Escherichia coli K12 can be suppressed by the ssrA gene for 10Sa RNA (tmRNA).
An Escherichia coli strain with a deletion in the ssrA gene that encodes 10Sa RNA (tmRNA) was used to screen for temperature-sensitive (ts) mutants whose ts phenotypes were suppressible by introduction of the wild-type ssrA gene. Mutants in four different genes were isolated. Ts mutants of this type were also obtained in a screen for mutations in thyA, the structural gene for thymidylate synthase. The ThyA activity in crude extracts prepared from the ts mutants was temperature-sensitive. The presence of the ssrA gene caused an increase in the total amount of the temperature-sensitive enzyme expressed, rather than suppressing the ts activity of the enzyme itself. SsrA-DD, a mutant form of 10Sa RNA, suppressed the ts phenotype of a thyA mutant, suggesting that degradation of a tagged peptide was not required for suppression of the ts phenotype. Considering the fact that ssrA-suppressible mutants could be isolated as temperature-sensitive mutants with mutations in different genes, it seems evident that trans-translation can occur on mRNA that is not lacking its stop codon.
Nakano
H
H
Department of Biophysics, Graduate School of Science, Kyoto University, Japan.
Goto
S
S
Nakayashiki
T
T
Inokuchi
H
H
D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000235:genetics; D018388:Codon, Terminator; D004926:Escherichia coli / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D009154:Mutation; D010641:Phenotype; D017354:Point Mutation; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000235:genetics / Q000502:physiology*; D012268:Ribose-Phosphate Pyrophosphokinase / Q000235:genetics; D017384:Sequence Deletion; D013489:Suppression, Genetic; D013696:Temperature; D013940:Thymidylate Synthase / Q000235:genetics
D001426:Bacterial Proteins; D018388:Codon, Terminator; D012329:RNA, Bacterial; C096222:tmRNA; D013940:Thymidylate Synthase; D012268:Ribose-Phosphate Pyrophosphokinase