5j3c | pdb_00005j3c
Thermus thermophilus 70S termination complex containing E. coli RF1
Structural highlights
FunctionRL2_THET8 One of the primary rRNA binding proteins. Required for association of the 30S and 50S subunits to form the 70S ribosome, for tRNA binding and peptide bond formation. It has been suggested to have peptidyltransferase activity; this is somewhat controversial (By similarity). Makes several contacts with the 16S rRNA (forming bridge B7b) in the 70S ribosome.[HAMAP-Rule:MF_01320_B] Publication Abstract from PubMedTermination of protein synthesis on the ribosome is catalyzed by release factors (RFs), which share a conserved glycine-glycine-glutamine (GGQ) motif. The glutamine residue is methylated in vivo, but a mechanistic understanding of its contribution to hydrolysis is lacking. Here, we show that the modification, apart from increasing the overall rate of termination on all dipeptides, substantially increases the rate of peptide release on a subset of amino acids. In the presence of unmethylated RFs, we measure rates of hydrolysis that are exceptionally slow on proline and glycine residues and approximately two orders of magnitude faster in the presence of the methylated factors. Structures of 70S ribosomes bound to methylated RF1 and RF2 reveal that the glutamine side-chain methylation packs against 23S rRNA nucleotide 2451, stabilizing the GGQ motif and placing the side-chain amide of the glutamine toward tRNA. These data provide a framework for understanding how release factor modifications impact termination. Uniformity of Peptide Release Is Maintained by Methylation of Release Factors.,Pierson WE, Hoffer ED, Keedy HE, Simms CL, Dunham CM, Zaher HS Cell Rep. 2016 Sep 27;17(1):11-8. doi: 10.1016/j.celrep.2016.08.085. PMID:27681416[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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