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SMG6 promotes endonucleolytic cleavage of nonsense mRNA in human cells

Nature Structural & Molecular Biology volume 16, pages 4955 (2009) | Download Citation

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Abstract

From yeast to humans, mRNAs harboring premature termination codons (PTCs) are recognized and degraded by nonsense-mediated mRNA decay (NMD). However, degradation mechanisms of NMD have been suggested to differ between species. In Drosophila melanogaster, NMD is initiated by endonucleolysis near the PTC, whereas in yeast and human cells the current view posits that NMD occurs by exonucleolysis from one or both RNA termini. Here we report that degradation of human nonsense mRNAs can be initiated by PTC-proximal endonucleolytic cleavage. We identify the metazoan-specific NMD factor SMG6 as the responsible endonuclease by demonstrating that mutation of conserved residues in its nuclease domain—the C-terminal PIN motif—abolishes endonucleolysis in vivo and in vitro. Our data lead to a revised mechanistic model for degradation of nonsense mRNA in human cells and suggest that endonucleolytic cleavage is a conserved feature in metazoan NMD.

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Acknowledgements

We thank J. Lykke-Andersen (University of Colorado, USA), G. Pruijn (Radboud University Nijmegen, The Netherlands), J. Lingner (Ecole Polytechnique Federale de Lausanne, Switzerland), M.-D. Ruepp and D. Schümperli (both University of Bern, Switzerland) for reagents; J. Lykke-Andersen and M. Rosbash for comments on the manuscript; and D. Riishøj and K. Jürgensen for excellent technical assistance. B. Seraphin and A. Dziembowski are acknowledged for communication of unpublished results. The work was supported by the Danish National Research Foundation and the Danish Natural Science Research Council (S.L.-A. and T.H.J.), and by the Swiss National Science Foundation, the Max Cloëtta Foundation and a Starting Grant of the European Research Council (A.B.E. and O.M.).

Author information

Author notes

    • Andrea B Eberle
    •  & Søren Lykke-Andersen

    These authors contributed equally to this work.

Affiliations

  1. Institute of Cell Biology, University of Bern, Baltzerstrasse 4, CH-3012 Bern, Switzerland.

    • Andrea B Eberle
    •  & Oliver Mühlemann
  2. Centre for mRNP Biogenesis and Metabolism, Department of Molecular Biology, Aarhus University, C.F. Møllers Alle, Building 1130, 8000 Aarhus, Denmark.

    • Søren Lykke-Andersen
    •  & Torben Heick Jensen

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Corresponding authors

Correspondence to Oliver Mühlemann or Torben Heick Jensen.

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DOI

https://doi.org/10.1038/nsmb.1530

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