title: Expression of peptide chain release factor 2 requires high-efficiency frameshift.
abstract: Peptide chain release factors are soluble proteins that participate in the stop codon-dependent termination of polypeptide biosynthesis. In Escherichia coli, two release factors are necessary for peptide chain termination: release factor 1 (RF1) specifies UAG- and UAA-dependent termination whereas release factor 2 (RF2) specifies UGA- and UAA-dependent termination. Release factors are found in low concentrations relative to other translation factors, suggesting that their expression is tightly regulated and, accordingly, making the study of their structure-function relationship difficult. RF1 and RF2 exhibit significant sequence homology, probably reflecting their similar functions and perhaps a common evolutionary origin. DNA and peptide sequencing have suggested the existence of a unique mechanism for the autogenous regulation of RF2 in which an in-frame UGA stop codon requires an obligatory +1 frameshift within the coding region of the RF2 gene. In this report we present in vitro experimental results consistent with the autogenous regulation of RF2. Additionally, we used RF2-lacZ gene fusions to demonstrate that autogenous regulation occurs, at least in part, by premature termination at the in-frame stop codon, since deletion of this stop codon leads to overproduction of the RF2-LacZ fusion protein. Frameshifting at this premature termination codon occurs at the remarkably high rate of 50%.
mesh_terms: D003062:Codon / Q000235:genetics*; D029968:Escherichia coli Proteins; D005246:Feedback; D005786:Gene Expression Regulation / Q000187:drug effects; D010454:Peptide Termination Factors / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D014176:Protein Biosynthesis / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis; D012689:Sequence Homology, Nucleic Acid
chemical_list: D003062:Codon; D029968:Escherichia coli Proteins; D010454:Peptide Termination Factors; D012333:RNA, Messenger; D011994:Recombinant Proteins; C041460:peptide chain termination release factor 2; C489005:prfA protein, E coli; C489006:prfB protein, E coli