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Crystal structure of an intramolecular chaperone mediating triple–β-helix folding

Nature Structural & Molecular Biology volume 17, pages 210215 (2010) | Download Citation

Abstract

Protein folding is often mediated by molecular chaperones. Recently, a novel class of intramolecular chaperones has been identified in tailspike proteins of evolutionarily distant viruses, which require a C-terminal chaperone for correct folding. The highly homologous chaperone domains are interchangeable between pre-proteins and release themselves after protein folding. Here we report the crystal structures of two intramolecular chaperone domains in either the released or the pre-cleaved form, revealing the role of the chaperone domain in the formation of a triple–β-helix fold. Tentacle-like protrusions enclose the polypeptide chains of the pre-protein during the folding process. After the assembly, a sensory mechanism for correctly folded β-helices triggers a serine-lysine catalytic dyad to autoproteolytically release the mature protein. Sequence analysis shows a conservation of the intramolecular chaperones in functionally unrelated proteins sharing β-helices as a common structural motif.

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Acknowledgements

The authors would like to thank the beamline staff scientists of European Synchrotron Radiation Facility, Dr. P. Tucker from the European Molecular Biology Laboratory for outstanding support during data collection at the Deutsches Elektronen Synchrotron and D. Gloth and J. Warweg for technical assistance.

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Affiliations

  1. Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Göttingen, Germany.

    • Eike C Schulz
    • , Achim Dickmanns
    • , Andreas Schmitt
    •  & Ralf Ficner
  2. Bioanalytische Massenspektrometrie, Max Planck Institut für biophysikalische Chemie, Göttingen, Germany.

    • Henning Urlaub
  3. Institut für Zelluläre Chemie, Medizinische Hochschule Hannover, Hannover, Germany.

    • Martina Mühlenhoff
    • , Katharina Stummeyer
    • , David Schwarzer
    •  & Rita Gerardy-Schahn

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Contributions

E.-C.S. performed molecular cloning, protein purification and crystallization, data collection, integration and refinement, data analysis and writing of the manuscript; A.D., sequence comparison and alignments and writing of the manuscript; H.U., MS analysis; A.S., molecular cloning; M.M., K.S., D.S., feedback on the manuscript; R.G.-S., initiator of the project; R.F., data analysis, writing of the manuscript and acted as project leader.

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The authors declare no competing financial interests.

Corresponding author

Correspondence to Ralf Ficner.

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https://doi.org/10.1038/nsmb.1746

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