Didemnin B and ternatin-4 inhibit conformational changes in eEF1A required for aminoacyl-tRNA accommodation into mammalian ribosomes

Juette, M. F.; Carelli, J. D.; Rundlet, E. J.; Brown, A.; Shao, S.; Ferguson, A.; Wasserman, M. R.; Holm, M.; Taunton, J.; Blanchard, S. C.

doi:10.1101/2022.08.01.502281

bioRxiv · 10.1101/2022.08.01.502281

Didemnin B and ternatin-4 inhibit conformational changes in eEF1A required for aminoacyl-tRNA accommodation into mammalian ribosomes

Juette, M. F.·Carelli, J. D.·Rundlet, E. J.·Brown, A.·Shao, S.·Ferguson, A.·Wasserman, M. R.·Holm, M.·Taunton, J.·Blanchard, S. C.

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Abstract

Rapid and accurate mRNA translation requires efficient codon-dependent delivery of the correct aminoacyl-tRNA (aa-tRNA) to the ribosomal A site. In mammals, this fidelity-determining reaction is facilitated by the GTPase elongation factor-1 alpha (eEF1A), which escorts aa-tRNA as an eEF1A(GTP)-aa-tRNA ternary complex into the ribosome. Two structurally unrelated cyclic peptides didemnin B and ternatin-4 bind to the eEF1A(GTP)-aa-tRNA ternary complex and inhibit translation. Here, we employ single-molecule fluorescence imaging and cryogenic electron microscopy to determine how these natural products inhibit translational elongation on mammalian ribosomes. By binding to a common allosteric site on eEF1A, didemnin B and ternatin-4 trap eEF1A in its GTPase-activated conformation, preventing aa-tRNA accommodation on the ribosome. We also show that didemnin B and ternatin-4 exhibit distinct effects on aa-tRNA selection that inform on observed disparities in their inhibition efficacies and physiological impacts. These integrated findings highlight the potential of single-molecule methods to reveal how distinct natural products differentially impact the human translation mechanism.

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Juette, M. F., Carelli, J. D., Rundlet, E. J., Brown, A., Shao, S., Ferguson, A., Wasserman, M. R., Holm, M., Taunton, J., Blanchard, S. C.. 2022-08-01. Didemnin B and ternatin-4 inhibit conformational changes in eEF1A required for aminoacyl-tRNA accommodation into mammalian ribosomes. https://doi.org/10.1101/2022.08.01.502281

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