title: Inhibition of the release factor-dependent termination reaction on ribosomes by DnaJ and the N-terminal peptide of rhodanese.
abstract: A peptide consisting of the 17 N-terminal amino acids of native bovine rhodanese in combination with the chaperone DnaJ specifically inhibits release factor- and stop codon-dependent hydrolysis of N-formylmethionine from N(formyl)-methionyl-tRNA bound with AUG to salt-washed ribosomes. Neither the peptide nor DnaJ by itself causes this inhibition. The N-terminal peptide and DnaJ both singularly and combined do not affect the peptidyltransferase reaction per se. The total amount of rhodanese synthesized in the cell-free coupled transcription-translation system is reduced by the peptide, with concomitant accumulation of full-length enzymatically inactive rhodanese polypeptides on ribosomes. In combination with DnaJ, the N-terminal polypeptide inhibits the termination and release of full-length rhodanese peptides that have accumulated on Escherichia coli ribosomes during the course of uninhibited coupled transcription-translation in the cell-free system. This inhibition appears to involve release factor 2-mediated termination at the UGA termination codon in the coding sequence for rhodanese. It is suggested that the N-terminal peptide inhibits the binding of the release factor to ribosomes. These data appear to provide the first report of differential inhibition of the termination reaction on ribosomes without inhibition of the peptidyltransferase reaction and peptide elongation.
authors.affiliation: Department of Chemistry and Biochemistry, University of Texas, Austin 78712, USA.
authors.forename: W
authors.initials: W
authors.lastname: Kudlicki
authors.forename: O W
authors.initials: OW
authors.lastname: Odom
authors.forename: G
authors.initials: G
authors.lastname: Merrill
authors.forename: G
authors.initials: G
authors.lastname: Kramer
authors.forename: B
authors.initials: B
authors.lastname: Hardesty
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002474:Cell-Free System; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D018388:Codon, Terminator; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000494:pharmacology*; D018832:Molecular Chaperones / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010443:Peptide Chain Termination, Translational / Q000187:drug effects; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology; D010454:Peptide Termination Factors / Q000502:physiology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D012358:RNA, Transfer, Met / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D012276:Ricin / Q000096:biosynthesis; D013762:Tetrahydrofolate Dehydrogenase / Q000096:biosynthesis; D013884:Thiosulfate Sulfurtransferase / Q000096:biosynthesis / Q000494:pharmacology*
chemical_list: D018388:Codon, Terminator; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D010446:Peptide Fragments; D010454:Peptide Termination Factors; D011500:Protein Synthesis Inhibitors; D012358:RNA, Transfer, Met; C089238:fMet-tRNA(fMet); C041460:peptide chain termination release factor 2; D012276:Ricin; D013762:Tetrahydrofolate Dehydrogenase; D015500:Chloramphenicol O-Acetyltransferase; D013884:Thiosulfate Sulfurtransferase