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RNA channelling by the eukaryotic exosome

Hélène Malet, Maya Topf, Daniel K Clare, Judith Ebert, Fabien Bonneau, Jerome Basquin, Karolina Drazkowska, Rafal Tomecki, Andrzej Dziembowski, Elena Conti, Helen R Saibil, Esben Lorentzen

Author Affiliations

  1. Hélène Malet1,
  2. Maya Topf1,
  3. Daniel K Clare1,
  4. Judith Ebert2,
  5. Fabien Bonneau2,
  6. Jerome Basquin2,
  7. Karolina Drazkowska3,4,
  8. Rafal Tomecki3,4,
  9. Andrzej Dziembowski3,4,
  10. Elena Conti2,
  11. Helen R Saibil1 and
  12. Esben Lorentzen (lorentze{at}biochem.mpg.de)*,1
  1. 1 Department of Biological Sciences, Institute of Structural and Molecular Biology, Crystallography, Birkbeck College, Malet Street, London, WC1E 7HX, UK
  2. 2 Department of Structural Cell Biology, Max‐Planck‐Institute of Biochemistry, Am Klopferspitz 18, Martinsried, D‐82152, Germany
  3. 3 Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, Warsaw, 02‐106, Poland
  4. 4 Department of Genetics & Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5a, Warsaw, 02‐106, Poland
  1. * Tel: +49 89 8578 3479; Fax: +49 89 8578 3605; E‐mail: lorentze{at}biochem.mpg.de

Abstract

The eukaryotic exosome is a key nuclease for the degradation, processing and quality control of a wide variety of RNAs. Here, we report electron microscopic reconstructions and pseudo‐atomic models of the ten‐subunit Saccharomyces cerevisiae exosome in the unbound and RNA‐bound states. In the RNA‐bound structures, extra density that is visible at the entry and exit sites of the exosome channel indicates that a substrate‐threading mechanism is used by the eukaryotic exosome. This channelling mechanism seems to be conserved in exosome‐like complexes from all domains of life, and might have been present in the most recent common ancestor.

  • Received July 14, 2010.
  • Revision received September 13, 2010.
  • Accepted September 16, 2010.