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Crystal structure of bet3 reveals a novel mechanism for Golgi localization of tethering factor TRAPP

Nature Structural & Molecular Biology volume 12, pages 3845 (2005) | Download Citation

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Abstract

Transport protein particle (TRAPP) is a large multiprotein complex involved in endoplasmic reticulum–to–Golgi and intra-Golgi traffic. TRAPP specifically and persistently resides on Golgi membranes. Neither the mechanism of the subcellular localization nor the function of any of the individual TRAPP components is known. Here, the crystal structure of mouse Bet3p (bet3), a conserved TRAPP component, reveals a dimeric structure with hydrophobic channels. The channel entrances are located on a putative membrane-interacting surface that is distinctively flat, wide and decorated with positively charged residues. Charge-inversion mutations on the flat surface of the highly conserved yeast Bet3p led to conditional lethality, incorrect localization and membrane trafficking defects. A channel-blocking mutation led to similar defects. These data delineate a molecular mechanism of Golgi-specific targeting and anchoring of Bet3p involving the charged surface and insertion of a Golgi-specific hydrophobic moiety into the channels. This essential subunit could then direct other TRAPP components to the Golgi.

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Acknowledgements

We are grateful to M. Cygler (Biotechnology Research Institute) for invaluable input and discussions on this work, J. Wagner for technical assistance, and T. Stevens (University of Oregon) and S. Ferro-Novick (Yale University) for providing strains and reagents. This study made use of beamline 6B at Pohang Accelerator Laboratory. This work was supported by Creative Research Initiatives of the Korean Ministry of Science & Technology and by the Réseau Protéomique de Montréal Proteomics Network. Y.-G.K. was supported by the Brain Korea 21 Project.

Author information

Affiliations

  1. Center for Biomolecular Recognition, Department of Life Science and Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, Kyungbuk, 790-784, Korea.

    • Yeon-Gil Kim
    •  & Byung-Ha Oh
  2. Center for Plant Intracellular Trafficking, Department of Life Science and Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, Kyungbuk, 790-784, Korea.

    • Eun Ju Sohn
    •  & Inhwan Hwang
  3. Center for Cell Signaling Research, Division of Molecular Life Sciences and College of Pharmacy, Ewha Womans University, Seoul, 120-750, Korea.

    • Jawon Seo
    •  & Kong-Joo Lee
  4. Pohang Accelerator Laboratory, Pohang, Kyungbuk, 790-784, Korea.

    • Heung-Soo Lee
  5. Biotechnology Research Institute, 6100 Royalmount Avenue, Montreal, Quebec, Canada H4P 2R2.

    • Malcolm Whiteway
  6. Montreal Proteomics Network, 6100 Royalmount Avenue, Montreal, Quebec, Canada H4P 2R2.

    • Michael Sacher

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The authors declare no competing financial interests.

Corresponding authors

Correspondence to Michael Sacher or Byung-Ha Oh.

Supplementary information

PDF files

  1. 1.

    Supplementary Fig. 1

    Enlargement of the electron density for myristoyl-Cys68.

  2. 2.

    Supplementary Fig. 2

    CD spectra of yeast Bet3p proteins.

  3. 3.

    Supplementary Fig. 3

    ESI mass spectrum of bet3(8–172) produced in E. coli.

  4. 4.

    Supplementary Methods

    Supplementary Methods

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DOI

https://doi.org/10.1038/nsmb871

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