Single amino acid substitution in prokaryote polypeptide release factor 2 permits it to terminate translation at all three stop codons.
Prokaryotic translational release factors, RF1 and RF2, catalyze polypeptide release at UAG/UAA and UGA/UAA stop codons, respectively. In this study, we isolated a bacterial RF2 mutant (RF2*) containing an E167K substitution that restored the growth of a temperature-sensitive RF1 strain of Escherichia coli and the viability of a chromosomal RF1/RF2 double knockout. In both in vivo and in vitro polypeptide termination assays, RF2* catalyzed UAG/UAA termination, as does RF1, as well as UGA termination, showing that RF2* acquired omnipotent release activity. This result suggests that the E167K mutation abolished the putative third-base discriminator function of RF2. These findings are interpreted as indicating that prokaryotic and eukaryotic release factors share the same anticodon moiety and that only one omnipotent release factor is sufficient for bacterial growth, similar to the eukaryotic single omnipotent factor.
Ito
K
K
Department of Tumor Biology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108, Japan.
Uno
M
M
Nakamura
Y
Y
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D018388:Codon, Terminator / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D010454:Peptide Termination Factors / Q000235:genetics*; D014176:Protein Biosynthesis
D018388:Codon, Terminator; D029968:Escherichia coli Proteins; D010454:Peptide Termination Factors; C041460:peptide chain termination release factor 2; C489005:prfA protein, E coli; C489006:prfB protein, E coli