Article | Published:

The binding of Varp to VAMP7 traps VAMP7 in a closed, fusogenically inactive conformation

Nature Structural & Molecular Biology volume 19, pages 13001309 (2012) | Download Citation

Abstract

SNAREs provide energy and specificity to membrane fusion events. Fusogenic trans-SNARE complexes are assembled from glutamine-contributing SNAREs (Q-SNAREs) embedded in one membrane and an arginine-contributing SNARE (R-SNARE) embedded in the other. Regulation of membrane fusion events is crucial for intracellular trafficking. We identify the endosomal protein Varp as an R-SNARE–binding regulator of SNARE complex formation. Varp colocalizes with and binds to VAMP7, an R-SNARE that is involved in both endocytic and secretory pathways. We present the structure of the second ankyrin repeat domain of mammalian Varp in complex with the cytosolic portion of VAMP7. The VAMP7–SNARE motif is trapped between Varp and the VAMP7 longin domain, and hence Varp kinetically inhibits the ability of VAMP7 to form SNARE complexes. This inhibition will be increased when Varp can also bind to other proteins present on the same membrane as VAMP7, such as Rab32–GTP.

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Acknowledgements

We thank the beamline staff at IO3 (SLS Diamond plc), H. Kent and R. Suckling (Medical Research Council (MRC) Laboratory of Molecular Biology) and L. Jackson and A. Peden (Cambridge Institute for Medical Research, Cambridge) for assistance and useful discussions. MNT-1 cells were a kind gift of D. Cutler (Laboratory for Molecular Cell Biology, University College, London). D.J.O. is funded by a Wellcome Trust Principal Research Fellowship (PRF), J.P.L. is funded by an MRC programme grant (G0900113), I.B.S. and P.R.E. are supported by MRC grant U105178845, and G.G.H. is supported by a postdoctoral fellowship from the Canadian Institutes of Health Research. The Cambridge Institute for Medical Research is supported by a Wellcome Trust Strategic Award (079895).

Author information

Author notes

    • Ingmar B Schäfer
    •  & Paul R Pryor

    Present addresses: Max Planck Institute of Biochemistry, Department of Structural Cell Biology, Am Klopferspitz 18, Martinsried, Germany (I.B.S.); Department of Biology (Area 9), University of York, York, UK (P.R.P.).

    • J Paul Luzio
    •  & David J Owen

    These authors contributed equally to this work.

Affiliations

  1. Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.

    • Ingmar B Schäfer
    •  & Philip R Evans
  2. Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK.

    • Geoffrey G Hesketh
    • , Nicholas A Bright
    • , Sally R Gray
    • , Paul R Pryor
    • , J Paul Luzio
    •  & David J Owen

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Contributions

I.B.S. performed biochemistry. I.B.S. and P.R.E. determined structures. G.G.H. performed cell biology, and N.A.B. performed electron microscopy. S.R.G. and P.R.P. performed Y2H. D.J.O., I.B.S. and J.P.L. conceived and designed the study.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to J Paul Luzio or David J Owen.

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https://doi.org/10.1038/nsmb.2414

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