Skip to main content

Thank you for visiting 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.

Open channel structure of MscL and the gating mechanism of mechanosensitive channels


Mechanosensitive channels act as membrane-embedded mechano-electrical switches, opening a large water-filled pore in response to lipid bilayer deformations. This process is critical to the response of living organisms to direct physical stimulation, such as in touch, hearing and osmoregulation. Here, we have determined the structural rearrangements that underlie these events in the large prokaryotic mechanosensitive channel (MscL) using electron paramagnetic resonance spectroscopy and site-directed spin labelling. MscL was trapped in both the open and in an intermediate closed state by modulating bilayer morphology. Transition to the intermediate state is characterized by small movements in the first transmembrane helix (TM1). Subsequent transitions to the open state are accompanied by massive rearrangements in both TM1 and TM2, as shown by large increases in probe dynamics, solvent accessibility and the elimination of all intersubunit spin–spin interactions. The open state is highly dynamic, supporting a water-filled pore of at least 25 Å, lined mostly by TM1. These structures suggest a plausible molecular mechanism of gating in mechanosensitive channels.

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

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Functional and structural correlates of MscL gating.
Figure 2: Structural rearrangements underlying the transition to the PC14 intermediate state.
Figure 3: Structural rearrangements underlying the transition to the open state.
Figure 4: Changes in the pattern of TM1 intersubunit proximities upon transition to the intermediate and open states.
Figure 5: Structure of MscL transmembrane segments in the intermediate closed state (PC14).
Figure 6: Structure of MscL TM segments in the open state.
Figure 7: A structural model of gating in MscL.


  1. Sukharev, S. I., Blount, P., Martinac, B. & Kung, C. Mechanosensitive channels of Escherichia coli: the MscL gene, protein, and activities. Annu. Rev. Physiol. 59, 633–657 (1997)

    CAS  Article  Google Scholar 

  2. Wood, J. M. Osmosensing by bacteria: signals and membrane-based sensors. Microbiol. Mol. Biol. Rev. 63, 230–262 (1999)

    CAS  PubMed  PubMed Central  Google Scholar 

  3. Hamill, O. P. & Martinac, B. Molecular basis of mechanotransduction in living cells. Physiol. Rev. 81, 685–740 (2001)

    CAS  Article  Google Scholar 

  4. Martinac, B., Adler, J. & Kung, C. Mechanosensitive ion channels of E. coli activated by amphipaths. Nature 348, 261–263 (1990)

    ADS  CAS  Article  Google Scholar 

  5. Sukharev, S. I., Blount, P., Martinac, B., Blattner, F. R. & Kung, C. A large-conductance mechanosensitive channel in E. coli encoded by mscL alone. Nature 368, 265–268 (1994)

    ADS  CAS  Article  Google Scholar 

  6. Patel, A. J. et al. A mammalian two pore domain mechano-gated S-like K + channel. EMBO J. 17, 4283–4290 (1998)

    CAS  Article  Google Scholar 

  7. Levina, N. et al. Protection of Escherichia coli cells against extreme turgor by activation of MscS and MscL mechanosensitive channels: identification of genes required for MscS ativity. EMBO J. 18, 1730–1737 (1999)

    CAS  Article  Google Scholar 

  8. Chang, G., Spencer, R. H., Lee, A. T., Barclay, M. T. & Rees, D. C. Structure of the MscL homolog from Mycobacterium tuberculosis: a gated mechanosensitive ion channel. Science 282, 2220–2226 (1998)

    ADS  CAS  Article  Google Scholar 

  9. Ou, X., Blount, P., Hoffman, R. J. & Kung, C. One face of a transmembrane helix is crucial in mechanosensitive channel gating. Proc. Natl Acad. Sci. USA 95, 11471–11475 (1998)

    ADS  CAS  Article  Google Scholar 

  10. Yoshimura, K., Batiza, A., Schroeder, M., Blount, P. & Kung, C. Hydrophilicity of a single residue residue within MscL correlates with increased channel mechanosensitivity. Biophys. J. 77, 1960–1972 (1999)

    CAS  Article  Google Scholar 

  11. Yoshimura, K., Batiza, A. & Kung, C. Chemically charging the pore constriction opens the mechanosensitive channel MscL. Biophys. J. 80, 2198–2206 (2001)

    CAS  Article  Google Scholar 

  12. Cruickshank, C. C., Minchin, R. F., Le Dain, A. C. & Martinac, B. Estimation of the pore size of the large-conductance mechanosensitive ion channel of Escherichia coli. Biophys. J. 73, 1925–1931 (1997)

    CAS  Article  Google Scholar 

  13. Spencer, R. H., Chang, G. & Rees, D. C. ‘Feeling the pressure’: structural insights into a gated mechanosensitive channel. Curr. Opin. Struct. Biol. 9, 448–454 (1999); erratum 9, 650–651 (1999)

    CAS  Article  Google Scholar 

  14. Batiza, A. F., Rayment, I. & Kung, C. Channel gate: Tension, leak and disclosure. Struct. Fold. Design 7, R99–R103 (1999)

    CAS  Article  Google Scholar 

  15. Sukharev, S., Betanzos, M., Chiang, C.-S. & Guy, H. The gating mechanism of the large mechanosensitive channel MscL. Nature 409, 720–724 (2001)

    ADS  CAS  Article  Google Scholar 

  16. Sukharev, S., Durell, S. R. & Guy, H. R. Structural models of the MscL gating mechanism. Biophys. J. 81, 917–936 (2001)

    CAS  Article  Google Scholar 

  17. Perozo, E., Kloda, A., Cortes, D. M. & Martinac, B. Physical principles underlying the transduction of bilayer deformation forces during mechanosensitive channel gating. Nature Struct. Biol. 9, 696–703 (2002).

  18. Maingret, F., Patel, A. J., Lesage, F., Lazdunski, M. & Honoré, E. Lysophospholipids open the two-pore domain mechano-gated K+ channels TREK-1 and TRAAK. J. Biol. Chem. 275, 10128–10133 (2000)

    CAS  Article  Google Scholar 

  19. Hubbell, W. L., Gross, A., Langen, R. & Lietzow, M. A. Recent advances in site-directed spin labeling of proteins. Curr. Opin. Struct. Biol. 8, 649–656 (1998)

    CAS  Article  Google Scholar 

  20. Hubbell, W. L., Cafiso, D. S. & Altenbach, C. Identifying conformational changes with site-directed spin labeling. Nature Struct. Biol. 7, 735–739 (2000)

    CAS  Article  Google Scholar 

  21. Mchaourab, H. & Perozo, E. in Biological Magnetic Resonance Vol. 19 (eds Eaton, G. R., Eaton, S. S. & Berliner, L. J.) 155–218 (Kluwer-Plenum, New York, 2000)

    Google Scholar 

  22. Perozo, E., Kloda, A., Cortes, D. M. & Martinac, B. Site-directed spin-labeling analysis of reconstituted Mscl in the closed state. J. Gen. Physiol. 118, 193–206 (2001)

    CAS  Article  Google Scholar 

  23. Sompornpisut, P., Liu, Y. S. & Perozo, E. Calculation of rigid-body conformational changes using restraint-driven Cartesian transformations. Biophys. J. 81, 2530–2546 (2001)

    CAS  Article  Google Scholar 

  24. Liu, Y. S., Sompornpisut, P. & Perozo, E. Structure of the KcsA channel intracellular gate in the open state. Nature Struct. Biol. 8, 883–887 (2001)

    CAS  Article  Google Scholar 

  25. Lee, B. & Richards, F. M. The interpretation of protein structures: estimation of static accessibility. J. Mol. Biol. 55, 379–400 (1971)

    CAS  Article  Google Scholar 

  26. Martinac, B., Buechner, M., Delcour, A. H., Adler, J. & Kung, C. Pressure-sensitive ion channel in Escherichia coli. Proc. Natl Acad. Sci. USA 84, 2297–2301 (1987)

    ADS  CAS  Article  Google Scholar 

  27. Martinac, B. Mechanosensitive channels in prokaryotes. Cell Physiol. Biochem. 11, 61–76 (2001)

    CAS  Article  Google Scholar 

  28. Gullingsrud, J., Kosztin, D. & Schulten, K. Structural determinants of MscL gating studied by molecular dynamics simulations. Biophys. J. 80, 2074–2081 (2001)

    CAS  Article  Google Scholar 

  29. Smart, O. S., Neduvelil, J. G., Wang, X., Wallace, B. A. & Sansom, M. S. HOLE: a program for the analysis of the pore dimensions of ion channel structural models. J. Mol. Graph. 14, 354–360 (1996)

    CAS  Article  Google Scholar 

  30. Sukharev, S. I., Sigurdson, W. J., Kung, C. & Sachs, F. Energetic and spatial parameters for gating of the bacterial large conductance mechanosensitive channel, MscL. J. Gen. Physiol. 113, 525–540 (1999)

    CAS  Article  Google Scholar 

  31. Perozo, E., Cortes, D. M. & Cuello, L. G. Three-dimensional architecture and gating mechanism of a K+ channel studied by EPR spectroscopy. Nature Struct. Biol. 5, 459–469 (1998)

    CAS  Article  Google Scholar 

  32. Cortes, D. M., Cuello, L. G. & Perozo, E. Molecular architecture of full-length KcsA: role of cytoplasmic domains in ion permeation and activation gating. J. Gen. Physiol. 117, 165–180 (2001)

    CAS  Article  Google Scholar 

  33. Altenbach, C., Marti, T., Khorana, H. G. & Hubbell, W. L. Transmembrane protein structure: spin labeling of bacteriorhodopsin mutants. Science 248, 1088–1092 (1990)

    ADS  CAS  Article  Google Scholar 

  34. Abragam, A. Principles of Nuclear Magnetism (Oxford Univ. Press, Oxford, 1961)

    Google Scholar 

  35. Sompornpisut, P., Mchaourab, H. & Perozo, E. Spectroscopically-determined solvent accessibilities as constraints for global fold discrimination in proteins. Biophys. J. 82, 474a (2002)

    Article  Google Scholar 

  36. Case, D. A. et al. AMBER 6 (Univ. California, San Francisco, 1999)

  37. Laskowski, R. A., Rullmannn, J. A., MacArthur, M. W., Kaptein, R. & Thornton, J. M. AQUA and PROCHECK-NMR: programs for checking the quality of protein structures solved by NMR. J. Biomol. NMR 8, 477–486 (1996)

    CAS  Article  Google Scholar 

  38. Nicholls, A., Sharp, K. A. & Honig, B. Protein folding and association: insights from the interfacial and thermodynamic properties of hydrocarbons. Proteins 11, 281–296 (1991)

    CAS  Article  Google Scholar 

Download references


We thank R. Nakamoto and M. Wiener for thoughtful discussions, C. Ptak for reading the manuscript, and S. Mochel for encouragement. This work was supported in part by the NIH (E.P.) and the McKnight endowment fund for neuroscience (E.P.), the Australian Research Council grants (B.M.) and the Australian Academy of Science (Scientific Visit Award to B.M). Transmembrane segment coordinates in the three conformations have been deposited in the Protein Data Bank (accession codes 1KYK, 1KYL and 1KYM).

Author information

Authors and Affiliations


Corresponding author

Correspondence to Eduardo Perozo.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Supplementary information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Perozo, E., Cortes, D., Sompornpisut, P. et al. Open channel structure of MscL and the gating mechanism of mechanosensitive channels. Nature 418, 942–948 (2002).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


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