1. Structural Biology and Molecular Biophysics
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Ribosome•RelA structures reveal the mechanism of stringent response activation

  1. Anna B Loveland
  2. Eugene Bah
  3. Rohini Madireddy
  4. Ying Zhang
  5. Axel F Brilot
  6. Nikolaus Grigorieff  Is a corresponding author
  7. Andrei A Korostelev  Is a corresponding author
  1. University of Massachusetts Medical School, United States
  2. Mayo Medical School, United States
  3. Brandeis University, United States
Research Article
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Cite this article as: eLife 2016;5:e17029 doi: 10.7554/eLife.17029

Abstract

Stringent response is a conserved bacterial stress response underlying virulence and antibiotic resistance. RelA/SpoT-homolog proteins synthesize transcriptional modulators (p)ppGpp, allowing bacteria to adapt to stresses. RelA is activated during amino-acid starvation, when cognate deacyl-tRNA binds to the ribosomal A (aminoacyl-tRNA) site. We report four cryo-EM structures of E. coli RelA bound to the 70S ribosome, in the absence and presence of deacyl-tRNA accommodating in the 30S A site. The boomerang-shaped RelA with a wingspan of more than 100 Å wraps around the A/R (30S A-site/RelA-bound) tRNA. The CCA end of the A/R tRNA pins the central TGS domain against the 30S subunit, presenting the (p)ppGpp-synthetase domain near the 30S spur. The ribosome and A/R tRNA are captured in three conformations, revealing hitherto elusive states of tRNA engagement with the ribosomal decoding center. Decoding-center rearrangements are coupled with the step-wise 30S-subunit 'closure', providing insights into the dynamics of high-fidelity tRNA decoding.

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Article and author information

Author details

  1. Anna B Loveland

    RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, United States
    Competing interests
    No competing interests declared.
  2. Eugene Bah

    Mayo Medical School, Rochester, United States
    Competing interests
    No competing interests declared.
  3. Rohini Madireddy

    RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, United States
    Competing interests
    No competing interests declared.
  4. Ying Zhang

    RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, United States
    Competing interests
    No competing interests declared.
  5. Axel F Brilot

    Department of Biochemistry, Brandeis University, Waltham, United States
    Competing interests
    No competing interests declared.
  6. Nikolaus Grigorieff

    Department of Biochemistry, Brandeis University, Waltham, United States
    For correspondence
    niko@grigorieff.org
    Competing interests
    Nikolaus Grigorieff, Reviewing editor, eLife.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-1506-909X
  7. Andrei A Korostelev

    RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, United States
    For correspondence
    andrei.korostelev@umassmed.edu
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-1588-717X

Funding

Howard Hughes Medical Institute

  • Nikolaus Grigorieff

National Institutes of Health (RO1 GM106105)

  • Andrei A Korostelev

National Institutes of Health (PO1 GM62580)

  • Nikolaus Grigorieff

Helen Hay Whitney Foundation

  • Anna B Loveland

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Rachel Green, Johns Hopkins School of Medicine, United States

Publication history

  1. Received: April 18, 2016
  2. Accepted: July 18, 2016
  3. Accepted Manuscript published: July 19, 2016 (version 1)
  4. Version of Record published: August 4, 2016 (version 2)

Copyright

© 2016, Loveland et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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