Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Structural insight into filament formation by mammalian septins

Nature volume 449, pages 311–315 (2007)Cite this article

Abstract

Septins are GTP-binding proteins that assemble into homo- and hetero-oligomers and filaments. Although they have key roles in various cellular processes, little is known concerning the structure of septin subunits or the organization and polarity of septin complexes. Here we present the structures of the human SEPT2 G domain and the heterotrimeric human SEPT2–SEPT6–SEPT7 complex. The structures reveal a universal bipolar polymer building block, composed of an extended G domain, which forms oligomers and filaments by conserved interactions between adjacent nucleotide-binding sites and/or the amino- and carboxy-terminal extensions. Unexpectedly, X-ray crystallography and electron microscopy showed that the predicted coiled coils are not involved in or required for complex and/or filament formation. The asymmetrical heterotrimers associate head-to-head to form a hexameric unit that is nonpolarized along the filament axis but is rotationally asymmetrical. The architecture of septin filaments differs fundamentally from that of other cytoskeletal structures.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on SpringerLink
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Structure and dimerization of SEPT2.
Figure 2: Structural analysis of the human septin complex.
Figure 3: Electron microscopic studies of septin complexes.
Figure 4: The septin filament.

Similar content being viewed by others

References

  1. Versele, M. & Thorner, J. Some assembly required: yeast septins provide the instruction manual. Trends Cell Biol. 15, 414–424 (2005)

    Article  CAS  Google Scholar 

  2. Kinoshita, M. The septins. Genome Biol. 4, 236 (2003)

    Article  MathSciNet  Google Scholar 

  3. Byers, B. & Goetsch, L. A highly ordered ring of membrane-associated filaments in budding yeast. J. Cell Biol. 69, 717–721 (1976)

    Article  CAS  Google Scholar 

  4. Haarer, B. K. & Pringle, J. R. Immunofluorescence localization of the Saccharomyces cerevisiae CDC12 gene product to the vicinity of the 10-nm filaments in the mother-bud neck. Mol. Cell. Biol. 7, 3678–3687 (1987)

    Article  CAS  Google Scholar 

  5. DeMarini, D. J. et al. A septin-based hierarchy of proteins required for localized deposition of chitin in the Saccharomyces cerevisiae cell wall. J. Cell Biol. 139, 75–93 (1997)

    Article  CAS  Google Scholar 

  6. Kozubowski, L. et al. A Bni4-Glc7 phosphatase complex that recruits chitin synthase to the site of bud emergence. Mol. Biol. Cell 14, 26–39 (2003)

    Article  CAS  Google Scholar 

  7. Kinoshita, M. Assembly of mammalian septins. J. Biochem. 134, 491–496 (2003)

    Article  CAS  Google Scholar 

  8. Macara, I. G. et al. Mammalian septins nomenclature. Mol. Biol. Cell 13, 4111–4113 (2002)

    Article  CAS  Google Scholar 

  9. Hall, P. A., Jung, K., Hillan, K. J. & Russell, S. E. H. Expression profiling the human septin gene family. J. Pathol. 206, 269–278 (2005)

    Article  CAS  Google Scholar 

  10. Kartmann, B. & Roth, D. Novel roles for mammalian septins: from vesicle trafficking to oncogenesis. J. Cell Sci. 114, 839–844 (2001)

    CAS  PubMed  Google Scholar 

  11. Hall, P. A. & Russell, S. E. H. The pathobiology of the septin gene family. J. Pathol. 204, 489–505 (2004)

    Article  CAS  Google Scholar 

  12. Kuhlenbaumer, G. et al. Mutations in SEPT9 cause hereditary neuralgic amyotrophy. Nature Genet. 37, 1044–1046 (2005)

    Article  Google Scholar 

  13. Mitchison, T. J. & Field, C. M. Cytoskeleton: What does GTP do for septins? Curr. Biol. 12, R788–R790 (2002)

    Article  CAS  Google Scholar 

  14. Kinoshita, M., Field, C. M., Coughlin, M. L., Straight, A. F. & Mitchison, T. J. Self- and actin-templated assembly of mammalian septins. Dev. Cell 3, 791–802 (2002)

    Article  CAS  Google Scholar 

  15. 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 

  16. Surka, M. C., Tsang, C. W. & Trimble, W. S. The mammalian septin MSF localizes with microtubules and is required for completion of cytokinesis. Mol. Biol. Cell 13, 3532–3545 (2002)

    Article  CAS  Google Scholar 

  17. Joberty, G. et al. Borg proteins control septin organization and are negatively regulated by Cdc42. Nature Cell Biol. 3, 861–866 (2001)

    Article  CAS  Google Scholar 

  18. Frazier, J. A. et al. Polymerization of purified yeast septins — evidence that organized filament arrays may not be required for septin function. J. Cell Biol. 143, 737–749 (1998)

    Article  CAS  Google Scholar 

  19. Oegema, K., Desai, A., Won, M. L., Mitchison, T. J. & Field, C. M. Purification and assay of a septin complex from Drosophila embryos. Methods Enzymol. 298, 279–295 (1998)

    Article  CAS  Google Scholar 

  20. Field, C. M. et al. A purified Drosophila septin complex forms filaments and exhibits GTPase activity. J. Cell Biol. 133, 605–616 (1996)

    Article  CAS  Google Scholar 

  21. Vrabioiu, A. M., Gerber, S. A., Gygi, S. P., Field, C. M. & Mitchison, T. J. The majority of the Saccharomyces cerevisiae septin complexes do not exchange guanine nucleotides. J. Biol. Chem. 279, 3111–3118 (2004)

    Article  CAS  Google Scholar 

  22. Farkasovsky, M., Herter, P., Voss, B. & Wittinghofer, A. Nucleotide binding and filament assembly of recombinant yeast septin complexes. Biol. Chem. 386, 643–656 (2005)

    Article  CAS  Google Scholar 

  23. Sheffield, P. J. et al. Borg/septin interactions and the assembly of mammalian septin heterodimers, trimers, and filaments. J. Biol. Chem. 278, 3483–3488 (2003)

    Article  CAS  Google Scholar 

  24. Nguyen, T. Q., Sawa, H., Okano, H. & White, J. G. The C. elegans septin genes, unc-59 and unc-61, are required for normal postembryonic cytokineses and morphogenesis but have no essential function in embryogenesis. J. Cell Sci. 113, 3825–3837 (2000)

    CAS  PubMed  Google Scholar 

  25. Mendoza, M., Hyman, A. A. & Glotzer, M. GTP binding induces filament assembly of a recombinant septin. Curr. Biol. 12, 1858–1863 (2002)

    Article  CAS  Google Scholar 

  26. Huang, Y. W., Surka, M. C., Reynaud, D., Pace-Asciak, C. & Trimble, W. S. GTP binding and hydrolysis kinetics of human septin 2. FEBS J. 273, 3248–3260 (2006)

    Article  CAS  Google Scholar 

  27. Leipe, D. D., Wolf, Y. I., Koonin, E. V. & Aravind, L. Classification and evolution of P-loop GTPases and related ATPases. J. Mol. Biol. 317, 41–72 (2002)

    Article  CAS  Google Scholar 

  28. Scrima, A. & Wittinghofer, A. Dimerisation-dependent GTPase reaction of MnmE: how potassium acts as GTPase-activating element. EMBO J. 25, 2940–2951 (2006)

    Article  CAS  Google Scholar 

  29. Gasper, R., Scrima, A. & Wittinghofer, A. Structural insights into HypB, a GTP-binding protein that regulates metal binding. J. Biol. Chem. 281, 27492–27502 (2006)

    Article  CAS  Google Scholar 

  30. Low, C. & Macara, I. G. Structural analysis of septin 2, 6, and 7 complexes. J. Biol. Chem. 281, 30697–30706 (2006)

    Article  CAS  Google Scholar 

  31. Boehringer, D. et al. Three-dimensional structure of a pre-catalytic human spliceosomal complex B. Nature Struct. Mol. Biol. 11, 463–468 (2004)

    Article  CAS  Google Scholar 

  32. van Heel, M. & Frank, J. Use of multivariate statistics in analysing the images of biological macromolecules. Ultramicroscopy 6, 187–194 (1981)

    CAS  PubMed  Google Scholar 

  33. Chant, J. Septin scaffolds and cleavage planes in Saccharomyces. Cell 84, 187–190 (1996)

    Article  CAS  Google Scholar 

  34. Vrabioiu, A. M. & Mitchison, T. J. Structural insights into yeast septin organization from polarized fluorescence microscopy. Nature 443, 466–469 (2006)

    Article  CAS  ADS  Google Scholar 

  35. Kabsch, W. Automatic processing of rotation diffraction data from crystals of initially unknown symmetry and cell constants. J. Appl. Cryst. 26, 795–800 (1993)

    Article  CAS  Google Scholar 

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

    Article  Google Scholar 

  37. Terwilliger, T. C. SOLVE and RESOLVE: automated structure solution and density modification. Methods Enzymol. 374, 22–37 (2003)

    Article  CAS  Google Scholar 

  38. CCP4. The CCP4 (Collaborative Computational Project Number 4) suite: programs for protein crystallography. Acta Crystallogr. D 50, 760–763 (1994)

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

    Article  Google Scholar 

  40. Murshudov, G. N., Vagin, A. A. & Dodson, E. J. Refinement of macromolecular structures by the maximum-likelihood method. Acta Crystallogr. D 53, 240–255 (1997)

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  42. DeLano, W. L. The PyMOL Molecular Graphics System 〈http://www.pymol.org 〉 (2006)

    Google Scholar 

  43. Dube, P., Tavares, P., Lurz, R. & van Heel, M. The portal protein of bacteriophage SPP1: a DNA pump with 13-fold symmetry. EMBO J. 12, 1303–1309 (1993)

    Article  CAS  Google Scholar 

  44. van Heel, M. & Frank, J. Use of multivariate statistics in analysing the images of biological macromolecules. Ultramicroscopy 6, 187–194 (1981)

    CAS  PubMed  Google Scholar 

  45. van Heel, M. Classification of very large electron microscopical image data sets. Opik 82, 114–126 (1989)

    Google Scholar 

  46. Sander, B., Golas, M. M. & Stark, H. Corrim-based alignment for improved speed in single-particle image processing. J. Struct. Biol. 143, 219–228 (2003)

    Article  CAS  Google Scholar 

  47. van Heel, M., Harauz, G., Orlova, E. V., Schmidt, R. & Schatz, M. A new generation of the IMAGIC image processing system. J. Struct. Biol. 116, 17–24 (1996)

    Article  CAS  Google Scholar 

Download references

Acknowledgements

Data collection was done at the Swiss Light Source, beam line X10SA, Paul Scherrer Institute, Villigen, Switzerland, and we thank the beam line staff for assistance. We would like to thank I. Vetter, I. Schlichting, T. Meinhart, W. Blankenfeldt, N. Schrader, E. Hofmann, K. Kühnel, A. Scrima, R. Gasper and R. Rose for data collection and crystallographic advice. M.S. and F.H. thank the International Max Planck Research School for financial support. This work was supported by the 3D Repertoire project, within the EU Sixth Framework Program, and the Fondation Louis-Jeantet.

Author Contributions M.S. purified and crystallized SEPT2-315 and the human septin complex and solved the structures. M.F. made the human septin complex constructs, developed the purification procedure and purified the yeast septin complex used in the electron microscopy. F.H. and H.S. did the electron microscopy analysis. D.K. made SEPT2-315 mutants. M.W. assisted M.S. throughout data collection and structure determination. I.G.M. provided the clones for human septins, and valuable hints. A.W. supervised the project and wrote the paper. All authors discussed the results and commented on the manuscript.

The atomic coordinates of SEPT2-315 and the human septin complex are deposited in the Protein Data Bank with accession numbers 2QA5 and 2QAG, respectively.

Author information

Author notes

  1. Marian Farkasovsky

    Present address: Present address: Institute of Molecular Biology SAS, Dubravska cesta 21, 845 51 Bratislava, Slovak Republic.,

Authors and Affiliations

  1. Abteilung Strukturelle Biologie, Max-Planck-Institut für molekulare Physiologie, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany,

    Minhajuddin Sirajuddin, Marian Farkasovsky, Dorothee Kühlmann, Michael Weyand & Alfred Wittinghofer

  2. Max-Planck-Institut für Biophysikaische Chemie, Am Fassberg 11, 37077 Goettingen, Germany,

    Florian Hauer & Holger Stark

  3. Department of Microbiology, Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, Virginia 22908-0577, USA,

    Ian G. Macara

Authors
  1. Minhajuddin Sirajuddin
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Marian Farkasovsky
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Florian Hauer
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Dorothee Kühlmann
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Ian G. Macara
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Michael Weyand
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Holger Stark
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Alfred Wittinghofer
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Alfred Wittinghofer.

Ethics declarations

Competing interests

Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Tables 1-4 describing the data collection, phasing, and refinement statistics and EM particle statistics, Supplementary Figures 1-3 with Legends showing sequence alignment of Sept2, 6 and 7 with secondary structural elements; details of Sept2 interface and raw electron density pictures of HSC. (PDF 569 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Sirajuddin, M., Farkasovsky, M., Hauer, F. et al. Structural insight into filament formation by mammalian septins. Nature 449, 311–315 (2007). https://doi.org/10.1038/nature06052

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature06052

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing