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Author Notes:

Correspondence to christine.m.dunham@emory.edu or yiorgo@stanford.edu

YZ, acquisition of data, analysis and interpretation of data, revising the article.

SH, analysis and interpretation of data, drafting and revising the article.

AR, acquisition of data.

GS, interpretation of data, revising the article.

CMD, conception and design, interpretation of data, drafting and revising the article.

We acknowledge P. Cornish for reagents, B. Calderon for technical assistance, and G. Conn, J. Dunkle, K. Fredrick, E. Hoffer and H. Zaher for critical reading of the manuscript.

The authors declare no competing interest.


Research Funding:

This work was supported in part by National Institutes of Health (NIH) GM093278 award and Emory University Department of Biochemistry funds (CMD).


  • Science & Technology
  • Life Sciences & Biomedicine
  • Biochemistry & Molecular Biology
  • Biophysics
  • Cell Biology
  • L1 STALK

Alternative Mode of E-Site tRNA Binding in the Presence of a Downstream mRNA Stem Loop at the Entrance Channel


Journal Title:



Volume 26, Number 3


, Pages 437-+

Type of Work:

Article | Post-print: After Peer Review


Structured mRNAs positioned downstream of the ribosomal decoding center alter gene expression by slowing protein synthesis. Here, we solved the cryo-EM structure of the bacterial ribosome bound to an mRNA containing a 3′ stem loop that regulates translation. Unexpectedly, the E-site tRNA adopts two distinct orientations. In the first structure, normal interactions with the 50S and 30S E site are observed. However, in the second structure, although the E-site tRNA makes normal interactions with the 50S E site, its anticodon stem loop moves ∼54 Å away from the 30S E site to interact with the 30S head domain and 50S uL5. This position of the E-site tRNA causes the uL1 stalk to adopt a more open conformation that likely represents an intermediate state during E-site tRNA dissociation. These results suggest that structured mRNAs at the entrance channel restrict 30S subunit movement required during translation to slow E-site tRNA dissociation. Zhang, Hong et al. solved cryo-EM structures of the 70S ribosome interacting with mRNA containing a stem loop at the mRNA entrance channel. The study provides insight into how the stem loop interacts with uS3 and into the conformation of the E-site tRNA, suggesting how structured mRNAs affect translation.

Copyright information:

© 2018 Elsevier Ltd

This is an Open Access work distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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