Translation termination in eukaryotes: Polypeptide release factor eRF1 is composed of functionally and structurally distinct domains

Class-1 polypeptide chain release factors (RFs) trigger hydrolysis of peptidyl-tRNA at the ribosomal peptidyl transferase center mediated by one of the three termination codons. In eukaryotes, apart from catalyzing the translation termination reaction, eRF1 binds to and activates another factor, eRF...

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Bibliographic Details
Published in:RNA (Cambridge) 2000-03, Vol.6 (3), p.381-390, Article S135583820099143X
Main Authors: FROLOVA, LUDMILA YU, MERKULOVA, TATYANA I., KISSELEV, LEV L.
Format: Article
Language:English
Subjects:
Amino Acid Sequence
eRF1 protein
Eukaryotic Cells - chemistry
Eukaryotic Cells - metabolism
Eukaryotic Cells - physiology
Humans
Molecular Sequence Data
Peptide Chain Termination, Translational
Peptide Termination Factors - chemistry
Peptide Termination Factors - genetics
Peptide Termination Factors - metabolism
Peptide Termination Factors - physiology
peptidyl-tRNA
polypeptide chain release factors
Protein Structure, Tertiary
Sequence Deletion
tRNA
Two-Hybrid System Techniques
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Summary:Class-1 polypeptide chain release factors (RFs) trigger hydrolysis of peptidyl-tRNA at the ribosomal peptidyl transferase center mediated by one of the three termination codons. In eukaryotes, apart from catalyzing the translation termination reaction, eRF1 binds to and activates another factor, eRF3, which is a ribosome-dependent and eRF1-dependent GTPase. Because peptidyl-tRNA hydrolysis and GTP hydrolysis could be uncoupled in vitro, we suggest that the two main functions of eRF1 are associated with different domains of the eRF1 protein. We show here by deletion analysis that human eRF1 is composed of two physically separated and functionally distinct domains. The “core” domain is fully competent in ribosome binding and termination-codon-dependent peptidyl-tRNA hydrolysis, and encompasses the N-terminal and middle parts of the polypeptide chain. The C-terminal one-third of eRF1 binds to eRF3 in vivo in the absence of the core domain, but both domains are required to activate eRF3 GTPase in the ribosome. The calculated isoelectric points of the core and C domains are 9.74 and 4.23, respectively. This highly uneven charge distribution between the two domains implies that electrostatic interdomain interaction may affect the eRF1 binding to the ribosome and eRF3, its activity in the termination reaction and activation of eRF3 GTPase. The positively charged core of eRF1 may interact with negatively charged rRNA and peptidyl-tRNA phosphate backbones at the ribosomal eRF1 binding site and exhibit RNA-binding ability. The structural and functional dissimilarity of the core and eRF3-binding domains implies that evolutionarily eRF1 originated as a product of gene fusion.
ISSN:1355-8382
1469-9001
DOI:10.1017/S135583820099143X