Conversion of omnipotent translation termination factor eRF1 into ciliate-like UGA-only unipotent eRF1.
In eukaryotic ribosomes, termination of translation is triggered by class 1 polypeptide release factor, eRF1. In organisms with a universal code, eRF1 responds to three stop codons, whereas, in ciliates with variant codes, only one or two codon(s) remain(s) as stop signals. By mutagenesis of the Y-C-F minidomain of the N domain, we converted an omnipotent human eRF1 recognizing all three stop codons into a unipotent 'ciliate-like' UGA-only eRF1. The conserved Cys127 located in the Y-C-F minidomain plays a critical role in stop codon recognition. The UGA-only response has also been achieved by concomitant substitutions of four other amino acids located at the Y-C-F and NIKS minidomains of eRF1. We suggest that for eRF1 the stop codon decoding is of a non-linear (non-protein-anticodon) type and explores a combination of positive and negative determinants. We assume that stop codon recognition is profoundly different by eukaryotic and prokaryotic class 1 RFs.
Engelhardt Institute of Molecular Biology, Moscow, Russia.
Alim
A
Seit-Nebi
Ludmila
L
Frolova
Lev
L
Kisselev
D000595:Amino Acid Sequence; D000818:Animals; D003062:Codon; D003545:Cysteine / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010454:Peptide Termination Factors / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012270:Ribosomes / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D003062:Codon; D018076:DNA, Complementary; C489002:ETF1 protein, human; D010454:Peptide Termination Factors; D003545:Cysteine