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Publication Abstract from PubMed

When the ribosome encounters a stop codon, it recruits a release factor (RF) to hydrolyze the ester bond between the peptide chain and tRNA. RFs have structural motifs that recognize stop codons in the decoding center and a GGQ motif for induction of hydrolysis in the peptidyl transfer center 70 A away. Surprisingly, free RF2 is compact, with only 20 A between its codon-reading and GGQ motifs. Cryo-EM showed that ribosome-bound RFs have extended structures, suggesting that RFs are compact when entering the ribosome and then extend their structures upon stop codon recognition. Here we use time-resolved cryo-EM to visualize transient compact forms of RF1 and RF2 at 3.5 and 4 A resolution, respectively, in the codon-recognizing ribosome complex on the native pathway. About 25% of complexes have RFs in the compact state at 24 ms reaction time, and within 60 ms virtually all ribosome-bound RFs are transformed to their extended forms.

The structural basis for release-factor activation during translation termination revealed by time-resolved cryogenic electron microscopy.,Fu Z, Indrisiunaite G, Kaledhonkar S, Shah B, Sun M, Chen B, Grassucci RA, Ehrenberg M, Frank J Nat Commun. 2019 Jun 12;10(1):2579. doi: 10.1038/s41467-019-10608-z. PMID:31189921^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.