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Structural basis of early translocation events on the ribosome

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 cycles(1). The cadence and fidelity of ribosome transit...

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Detalles Bibliográficos
Autores principales: Rundlet, Emily J., Holm, Mikael, Schacherl, Magdalena, Natchiar, S. Kundhavai, Altman, Roger B., Spahn, Christian M. T., Myasnikov, Alexander G., Blanchard, Scott C.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8318882/
https://www.ncbi.nlm.nih.gov/pubmed/34234344
http://dx.doi.org/10.1038/s41586-021-03713-x
Descripción
Sumario: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 cycles(1). 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.