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Structural basis for the Rho- and phosphoinositide-dependent localization of the exocyst subunit Sec3

Abstract

The exocyst complex is a hetero-octameric protein complex that functions during cell polarization by tethering the secretory vesicle to the target membrane. The yeast exocyst subunit Sec3 binds to phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) and the small GTPases Rho1 and Cdc42 via its N-terminal domain (Sec3-N), and these interactions target Sec3 to the plasma membrane. Here we report the crystal structure of the Sec3-N in complex with Rho1 at 2.6-Å resolution. Sec3-N adopts a pleckstrin homology (PH) fold, despite having no detectable sequence homology with other PH domains of known structure. Clusters of conserved basic residues constitute a positively charged cleft, which was identified as a binding site for PtdIns(4,5)P2. Residues Phe77, Ile115 and Leu131 of Sec3 bind to an extended hydrophobic surface formed around switch regions I and II of Rho1. To our knowledge, these are the first structural insights into how an exocyst subunit might interact with both protein and phospholipid factors on the target membrane.

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Figure 1: Overall structure of yeast Sec3-N in complex with the GppNHp-bound Rho1.
Figure 2: Interactions between Sec3-N and Rho1.
Figure 3: Interactions between Sec3-N and PtdIns(4,5)P2.
Figure 4: Conformational switch of Rho1.
Figure 5: In vivo localization of yeast Sec3 mutants.
Figure 6: The membrane attachment model between Sec3-N and the plasma membrane.

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References

  1. TerBush, D.R., Maurice, T., Roth, D. & Novick, P. The exocyst is a multiprotein complex required for exocytosis in Saccharomyces cerevisiae. EMBO J. 15, 6483–6494 (1996).

    Article  CAS  Google Scholar 

  2. Kee, Y. et al. Subunit structure of the mammalian exocyst complex. Proc. Natl. Acad. Sci. USA 94, 14438–14443 (1997).

    Article  CAS  Google Scholar 

  3. Grindstaff, K.K. et al. Sec6/8 complex is recruited to cell-cell contacts and specifies transport vesicle delivery to the basal-lateral membrane in epithelial cells. Cell 93, 731–740 (1998).

    Article  CAS  Google Scholar 

  4. Guo, W., Grant, A. & Novick, P. Exo84p is an exocyst protein essential for secretion. J. Biol. Chem. 274, 23558–23564 (1999).

    Article  CAS  Google Scholar 

  5. Hsu, S.C. et al. Subunit composition, protein interactions, and structures of the mammalian brain sec6/8 complex and septin filaments. Neuron 20, 1111–1122 (1998).

    Article  CAS  Google Scholar 

  6. Zhang, X. et al. Membrane association and functional regulation of Sec3 by phospholipids and Cdc42. J. Cell Biol. 180, 145–158 (2008).

    Article  CAS  Google Scholar 

  7. He, B., Xi, F., Zhang, X., Zhang, J. & Guo, W. Exo70 interacts with phospholipids and mediates the targeting of the exocyst to the plasma membrane. EMBO J. 26, 4053–4065 (2007).

    Article  CAS  Google Scholar 

  8. Liu, J., Zuo, X., Yue, P. & Guo, W. Phosphatidylinositol 4,5-bisphosphate mediates the targeting of the exocyst to the plasma membrane for exocytosis in mammalian cells. Mol. Biol. Cell 18, 4483–4492 (2007).

    Article  CAS  Google Scholar 

  9. Guo, W., Roth, D., Walch-Solimena, C. & Novick, P. The exocyst is an effector for Sec4p, targeting secretory vesicles to sites of exocytosis. EMBO J. 18, 1071–1080 (1999).

    Article  CAS  Google Scholar 

  10. Guo, W., Tamanoi, F. & Novick, P. Spatial regulation of the exocyst complex by Rho1 GTPase. Nat. Cell Biol. 3, 353–360 (2001).

    Article  CAS  Google Scholar 

  11. Zhang, X. et al. Cdc42 interacts with the exocyst and regulates polarized secretion. J. Biol. Chem. 276, 46745–46750 (2001).

    Article  CAS  Google Scholar 

  12. Zhang, X.M., Ellis, S., Sriratana, A., Mitchell, C.A. & Rowe, T. Sec15 is an effector for the Rab11 GTPase in mammalian cells. J. Biol. Chem. 279, 43027–43034 (2004).

    Article  CAS  Google Scholar 

  13. Moskalenko, S. et al. The exocyst is a Ral effector complex. Nat. Cell Biol. 4, 66–72 (2002).

    Article  CAS  Google Scholar 

  14. Sugihara, K. et al. The exocyst complex binds the small GTPase RalA to mediate filopodia formation. Nat. Cell Biol. 4, 73–78 (2002).

    Article  CAS  Google Scholar 

  15. Inoue, M., Chang, L., Hwang, J., Chiang, S.H. & Saltiel, A.R. The exocyst complex is required for targeting of Glut4 to the plasma membrane by insulin. Nature 422, 629–633 (2003).

    Article  CAS  Google Scholar 

  16. Robinson, N.G. et al. Rho3 of Saccharomyces cerevisiae, which regulates the actin cytoskeleton and exocytosis, is a GTPase which interacts with Myo2 and Exo70. Mol. Cell. Biol. 19, 3580–3587 (1999).

    Article  CAS  Google Scholar 

  17. Vetter, I.R. & Wittinghofer, A. The guanine nucleotide-binding switch in three dimensions. Science 294, 1299–1304 (2001).

    Article  CAS  Google Scholar 

  18. Wu, H., Rossi, G. & Brennwald, P. The ghost in the machine: small GTPases as spatial regulators of exocytosis. Trends Cell Biol. 18, 397–404 (2008).

    Article  CAS  Google Scholar 

  19. He, B. & Guo, W. The exocyst complex in polarized exocytosis. Curr. Opin. Cell Biol. 21, 537–542 (2009).

    Article  CAS  Google Scholar 

  20. Fukai, S., Matern, H.T., Jagath, J.R., Scheller, R.H. & Brunger, A.T. Structural basis of the interaction between RalA and Sec5, a subunit of the sec6/8 complex. EMBO J. 22, 3267–3278 (2003).

    Article  CAS  Google Scholar 

  21. Jin, R. et al. Exo84 and Sec5 are competitive regulatory Sec6/8 effectors to the RalA GTPase. EMBO J. 24, 2064–2074 (2005).

    Article  CAS  Google Scholar 

  22. Moskalenko, S. et al. Ral GTPases regulate exocyst assembly through dual subunit interactions. J. Biol. Chem. 278, 51743–51748 (2003).

    Article  CAS  Google Scholar 

  23. Fruman, D.A., Meyers, R.E. & Cantley, L.C. Phosphoinositide kinases. Annu. Rev. Biochem. 67, 481–507 (1998).

    Article  CAS  Google Scholar 

  24. Martin, T.F. PI(4,5)P2 regulation of surface membrane traffic. Curr. Opin. Cell Biol. 13, 493–499 (2001).

    Article  CAS  Google Scholar 

  25. Simonsen, A., Wurmser, A.E., Emr, S.D. & Stenmark, H. The role of phosphoinositides in membrane transport. Curr. Opin. Cell Biol. 13, 485–492 (2001).

    Article  CAS  Google Scholar 

  26. Dong, G., Hutagalung, A.H., Fu, C., Novick, P. & Reinisch, K.M. The structures of exocyst subunit Exo70p and the Exo84p C-terminal domains reveal a common motif. Nat. Struct. Mol. Biol. 12, 1094–1100 (2005).

    Article  CAS  Google Scholar 

  27. Hamburger, Z.A., Hamburger, A.E., West, A.P., Jr. & Weis, W.I. Crystal structure of the S. cerevisiae exocyst component Exo70p. J. Mol. Biol. 356, 9–21 (2006).

    Article  CAS  Google Scholar 

  28. Moore, B.A., Robinson, H.H. & Xu, Z. The crystal structure of mouse Exo70 reveals unique features of the mammalian exocyst. J. Mol. Biol. 371, 410–421 (2007).

    Article  CAS  Google Scholar 

  29. Christoforidis, S., McBride, H.M., Burgoyne, R.D. & Zerial, M. The Rab5 effector EEA1 is a core component of endosome docking. Nature 397, 621–625 (1999).

    Article  CAS  Google Scholar 

  30. Holm, L. & Sander, C. Dali: a network tool for protein structure comparison. Trends Biochem. Sci. 20, 478–480 (1995).

    Article  CAS  Google Scholar 

  31. Jezyk, M.R. et al. Crystal structure of Rac1 bound to its effector phospholipase C-β2. Nat. Struct. Mol. Biol. 13, 1135–1140 (2006).

    Article  CAS  Google Scholar 

  32. Bunney, T.D. et al. Structural insights into formation of an active signaling complex between Rac and phospholipase Cγ2. Mol. Cell 34, 223–233 (2009).

    Article  CAS  Google Scholar 

  33. Vetter, I.R., Nowak, C., Nishimoto, T., Kuhlmann, J. & Wittinghofer, A. Structure of a Ran-binding domain complexed with Ran bound to a GTP analogue: implications for nuclear transport. Nature 398, 39–46 (1999).

    Article  CAS  Google Scholar 

  34. Walliser, C. et al. rac regulates its effector phospholipase Cγ2 through interaction with a split pleckstrin homology domain. J. Biol. Chem. 283, 30351–30362 (2008).

    Article  CAS  Google Scholar 

  35. Cronin, T.C., DiNitto, J.P., Czech, M.P. & Lambright, D.G. Structural determinants of phosphoinositide selectivity in splice variants of Grp1 family PH domains. EMBO J. 23, 3711–3720 (2004).

    Article  CAS  Google Scholar 

  36. Hyvonen, M. et al. Structure of the binding site for inositol phosphates in a PH domain. EMBO J. 14, 4676–4685 (1995).

    Article  CAS  Google Scholar 

  37. Ihara, K. et al. Crystal structure of human RhoA in a dominantly active form complexed with a GTP analogue. J. Biol. Chem. 273, 9656–9666 (1998).

    Article  CAS  Google Scholar 

  38. Wei, Y. et al. Crystal structure of RhoA-GDP and its functional implications. Nat. Struct. Biol. 4, 699–703 (1997).

    Article  CAS  Google Scholar 

  39. Garrard, S.M. et al. Structure of Cdc42 in a complex with the GTPase-binding domain of the cell polarity protein, Par6. EMBO J. 22, 1125–1133 (2003).

    Article  CAS  Google Scholar 

  40. Matern, H.T., Yeaman, C., Nelson, W.J. & Scheller, R.H. The Sec6/8 complex in mammalian cells: characterization of mammalian Sec3, subunit interactions, and expression of subunits in polarized cells. Proc. Natl. Acad. Sci. USA 98, 9648–9653 (2001).

    Article  CAS  Google Scholar 

  41. Bryson, K. et al. Protein structure prediction servers at University College London. Nucleic Acids Res. 33, W36–W38 (2005).

    Article  CAS  Google Scholar 

  42. Scales, S.J., Hesser, B.A., Masuda, E.S. & Scheller, R.H. Amisyn, a novel syntaxin-binding protein that may regulate SNARE complex assembly. J. Biol. Chem. 277, 28271–28279 (2002).

    Article  CAS  Google Scholar 

  43. Rose, R., Wittinghofer, A. & Weyand, M. The purification and crystallization of mDia1 in complex with RhoC. Acta Crystallogr. Sect. F Struct. Biol. Cryst. Commun. 61, 225–227 (2005).

    Article  CAS  Google Scholar 

  44. Otwinowski, Z. & Minor, W. Processing of X-ray diffraction data collected in oscillation mode. Methods Enzymol. 276, 307–326 (1997).

    Article  CAS  Google Scholar 

  45. Collaborative Computational Project. The CCP4 suite: programs for protein crystallography. Acta Crystallogr. D Biol. Crystallogr. 50, 760–763 (1994).

  46. Schneider, T.R. & Sheldrick, G.M. Substructure solution with SHELXD. Acta Crystallogr. D Biol. Crystallogr. 58, 1772–1779 (2002).

    Article  Google Scholar 

  47. de la Fortelle, E. & Bricogne, G. Maximum-likelihood heavy-atom parameter refinement for multiple isomorphous replacement and multiwavelength anomalous diffraction methods. Methods Enzymol. 276, 472–494 (1997).

    Article  CAS  Google Scholar 

  48. Abrahams, J.P. & Leslie, A.G.W. Methods used in the structure determination of bovine mitochondrial F1 ATPase. Acta Crystallogr. D Biol. Crystallogr. 52, 429–439 (1996).

    Article  Google Scholar 

  49. Cowtan, K.D. & Main, P. Improvement of macromolecular electron-density maps by the simultaneous application of real and reciprocal space constraints. Acta Crystallogr. D Biol. Crystallogr. 49, 148–157 (1993).

    Article  CAS  Google Scholar 

  50. Vonrhein, C., Blanc, E., Roversi, P. & Bricogne, G. Automated structure solution with autoSHARP. Methods Mol. Biol. 364, 215–230 (2007).

    CAS  Google Scholar 

  51. Emsley, P. & Cowtan, K. Coot: model-building tools for molecular graphics. Acta Crystallogr. D Biol. Crystallogr. 60, 2126–2132 (2004).

    Article  Google Scholar 

  52. Brunger, A.T. et al. Crystallography & NMR system: A new software suite for macromolecular structure determination. Acta Crystallogr. D Biol. Crystallogr. 54, 905–921 (1998).

    Article  CAS  Google Scholar 

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Acknowledgements

We thank C. Toyoshima for support of this research, S. Kaiser for critical reading and improvement of this manuscript, and the beamline staffs at PFAR-NW12A and BL-5A of PF (Tsukuba, Japan) and BL41XU of SPring8 (Hyogo, Japan) for technical help during data collection. This work was supported by grants from the Japanese Ministry of Education, Culture, Sports, Science and Technology to S.F., A.Yamagata and H.M. Y.S. and M.Y. are supported by Japan Society for the Promotion of Science research fellowships for young scientists.

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M.Y. carried out sample preparation, crystallization, structure determination and in vitro binding assays; Y.S., A.Yoshikawa, H.M., A.Yamagata and S.F. assisted with these experiments; K.K. carried out in vivo localization experiments using yeast transformants prepared by M.Y.; M.Y. and S.F. wrote the paper; S.F. designed the research with advice from K.S. and A.N.; all authors discussed the results and commented on the manuscript; S.F. supervised the work.

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Correspondence to Shuya Fukai.

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Yamashita, M., Kurokawa, K., Sato, Y. et al. Structural basis for the Rho- and phosphoinositide-dependent localization of the exocyst subunit Sec3. Nat Struct Mol Biol 17, 180–186 (2010). https://doi.org/10.1038/nsmb.1722

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