title: The Escherichia coli ribosomal protein L11 suppresses release factor 2 but promotes the release factor 1 activities in peptide chain termination.
abstract: The incubation of the 50 S ribosomal subunits of Escherichia coli with 1.5 M LiCl yields 1.5c core particles depleted in 14 proteins and inactive in peptide chain termination. In codon-dependent peptidyl-tRNA hydrolysis the release factor 1 (RF-1)-induced reaction essentially depends on both L11 and L16 whereas the release factor 2 (RF-2)-induced reaction is depressed by L11 and stimulated by L16. Omission of L11 results in a several-fold increase in the specific activity of the RF-2. Functional complexes are formed with RF-2 at an apparent Km (dissociation constant) for the termination codon 5-fold lower than with reconstituted ribosomes containing L11; the Vmax for the hydrolysis is unchanged. L11 suppresses this effect when added to the core at close to molar equivalence. In contrast, RF-1 has a very low activity if ribosomes lack L11 and this can be restored by titration of L11 back to the core. This is the first example of a differential or an opposite effect of a ribosomal component on the activities of the two release factors, and the studies suggest that L11 has a critical role in the binding domain for the two factors.
mesh_terms: D003062:Codon / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D006868:Hydrolysis; D007700:Kinetics; D010443:Peptide Chain Termination, Translational; D010454:Peptide Termination Factors / Q000235:genetics*; D012343:RNA, Transfer / Q000235:genetics; D012346:RNA, Transfer, Amino Acyl; D012269:Ribosomal Proteins / Q000235:genetics*; D012270:Ribosomes / Q000378:metabolism
chemical_list: D003062:Codon; D010454:Peptide Termination Factors; D012346:RNA, Transfer, Amino Acyl; D012269:Ribosomal Proteins; C041460:peptide chain termination release factor 2; C027624:ribosomal protein L11; C019037:tRNA, peptidyl-; D012343:RNA, Transfer