SNAP annotations: PDB entry 7n2v

PDB-id

7n2v; DSSR-derived features in text and JSON formats; DNAproDB

Class

ribosome

Method

cryo-EM (2.54 Å)

Summary

Elongating 70s ribosome complex in a spectinomycin-stalled intermediate state of translocation bound to ef-g in an active, gtp conformation (int1)

Reference

Rundlet EJ, Holm M, Schacherl M, Natchiar SK, Altman RB, Spahn CMT, Myasnikov AG, Blanchard SC (2021): "Structural basis of early translocation events on the ribosome." Nature, 595, 741-745. doi: 10.1038/s41586-021-03713-x.

Abstract

Peptide-chain elongation during protein synthesis entails sequential aminoacyl-tRNA selection and translocation reactions that proceed rapidly (2-20 per second) and with a low error rate (around 10_-3 to 10_-5 at each step) over thousands of cycles₁. The cadence and fidelity of ribosome transit through mRNA templates in discrete codon increments is a paradigm for movement in biological systems that must hold for diverse mRNA and tRNA substrates across domains of life. Here we use single-molecule fluorescence methods to guide the capture of structures of early translocation events on the bacterial ribosome. Our findings reveal that the bacterial GTPase elongation factor G specifically engages spontaneously achieved ribosome conformations while in an active, GTP-bound conformation to unlock and initiate peptidyl-tRNA translocation. These findings suggest that processes intrinsic to the pre-translocation ribosome complex can regulate the rate of protein synthesis, and that energy expenditure is used later in the translocation mechanism than previously proposed.