1. Biochemistry and Chemical Biology
  2. Cell Biology
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A RanGTP-independent mechanism allows ribosomal protein nuclear import for ribosome assembly

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Cite this article as: eLife 2014;3:e03473 doi: 10.7554/eLife.03473

Abstract

Within a single generation time a growing yeast cell imports ~14 million ribosomal proteins (r-proteins) into the nucleus for ribosome production. After import, it is unclear how these intrinsically unstable and aggregation-prone proteins are targeted to the ribosome assembly site in the nucleolus. Here, we report the discovery of a conserved nuclear carrier Tsr2 that coordinates transfer of the r-protein eS26 to the earliest assembling pre-ribosome, the 90S. In vitro studies revealed that Tsr2 efficiently dissociates importin:eS26 complexes via an atypical RanGTP-independent mechanism that terminates the import process. Subsequently, Tsr2 binds the released eS26, shields it from proteolysis, and ensures its safe delivery to the 90S pre-ribosome. We anticipate similar carriers - termed here escortins - to securely connect the nuclear import machinery with pathways that deposit r-proteins onto developing pre-ribosomal particles.

Article and author information

Author details

  1. Sabina Schütz

    ETH Zürich, Zürich, Switzerland
    Competing interests
    The authors declare that no competing interests exist.
  2. Ute Fischer

    ETH Zürich, Zürich, Switzerland
    Competing interests
    The authors declare that no competing interests exist.
  3. Martin Altvater

    ETH Zürich, Zürich, Switzerland
    Competing interests
    The authors declare that no competing interests exist.
  4. Purnima Nerkurkar

    ETH Zürich, Zürich, Switzerland
    Competing interests
    The authors declare that no competing interests exist.
  5. Cohue Peña

    ETH Zürich, Zürich, Switzerland
    Competing interests
    The authors declare that no competing interests exist.
  6. Michaela Gerber

    ETH Zürich, Zürich, Switzerland
    Competing interests
    The authors declare that no competing interests exist.
  7. Yiming Chang

    ETH Zürich, Zürich, Switzerland
    Competing interests
    The authors declare that no competing interests exist.
  8. Stefanie Caesar

    Universität des Saarlandes, Homburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
  9. Olga Tatjana Schubert

    ETH Zürich, Zürich, Switzerland
    Competing interests
    The authors declare that no competing interests exist.
  10. Gabriel Schlenstedt

    Universität des Saarlandes, Homburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
  11. Vikram G Panse

    ETH Zürich, Zürich, Switzerland
    For correspondence
    vikram.panse@bc.biol.ethz.ch
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Ramanujan S Hegde, MRC Laboratory of Molecular Biology, United Kingdom

Publication history

  1. Received: May 24, 2014
  2. Accepted: August 20, 2014
  3. Accepted Manuscript published: August 21, 2014 (version 1)
  4. Accepted Manuscript updated: August 27, 2014 (version 2)
  5. Version of Record published: September 12, 2014 (version 3)

Copyright

© 2014, Schütz 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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