1ml5
Structure of the E. coli ribosomal termination complex with release factor 2
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OverviewOverview
Termination of protein synthesis occurs when the messenger RNA presents a, stop codon in the ribosomal aminoacyl (A) site. Class I release factor, proteins (RF1 or RF2) are believed to recognize stop codons via tripeptide, motifs, leading to release of the completed polypeptide chain from its, covalent attachment to transfer RNA in the ribosomal peptidyl (P) site., Class I RFs possess a conserved GGQ amino-acid motif that is thought to be, involved directly in protein-transfer-RNA bond hydrolysis. Crystal, structures of bacterial and eukaryotic class I RFs have been determined, but the mechanism of stop codon recognition and peptidyl-tRNA hydrolysis, remains unclear. Here we present the structure of the Escherichia coli, ribosome in a post-termination complex with RF2, obtained by, single-particle cryo-electron microscopy (cryo-EM). Fitting the known 70S, and RF2 structures into the electron density map reveals that RF2 adopts a, different conformation on the ribosome when compared with the crystal, structure of the isolated protein. The amino-terminal helical domain of, RF2 contacts the factor-binding site of the ribosome, the 'SPF' loop of, the protein is situated close to the mRNA, and the GGQ-containing domain, of RF2 interacts with the peptidyl-transferase centre (PTC). By connecting, the ribosomal decoding centre with the PTC, RF2 functionally mimics a tRNA, molecule in the A site. Translational termination in eukaryotes is likely, to be based on a similar mechanism.
About this StructureAbout this Structure
1ML5 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
Structure of the Escherichia coli ribosomal termination complex with release factor 2., Klaholz BP, Pape T, Zavialov AV, Myasnikov AG, Orlova EV, Vestergaard B, Ehrenberg M, van Heel M, Nature. 2003 Jan 2;421(6918):90-4. PMID:12511961
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