Journal of Muscle Research and Cell Motility

, Volume 36, Issue 6, pp 525–533 | Cite as

Electrostatic interaction map reveals a new binding position for tropomyosin on F-actin

Original Paper

Abstract

Azimuthal movement of tropomyosin around the F-actin thin filament is responsible for muscle activation and relaxation. Recently a model of αα-tropomyosin, derived from molecular-mechanics and electron microscopy of different contractile states, showed that tropomyosin is rather stiff and pre-bent to present one specific face to F-actin during azimuthal transitions. However, a new model based on cryo-EM of troponin- and myosin-free filaments proposes that the interacting-face of tropomyosin can differ significantly from that in the original model. Because resolution was insufficient to assign tropomyosin side-chains, the interacting-face could not be unambiguously determined. Here, we use structural analysis and energy landscapes to further examine the proposed models. The observed bend in seven crystal structures of tropomyosin is much closer in direction and extent to the original model than to the new model. Additionally, we computed the interaction map for repositioning tropomyosin over the F-actin surface, but now extended over a much larger surface than previously (using the original interacting-face). This map shows two energy minima—one corresponding to the “blocked-state” as in the original model, and the other related by a simple 24 Å translation of tropomyosin parallel to the F-actin axis. The tropomyosin-actin complex defined by the second minimum fits perfectly into the recent cryo-EM density, without requiring any change in the interacting-face. Together, these data suggest that movement of tropomyosin between regulatory states does not require interacting-face rotation. Further, they imply that thin filament assembly may involve an interplay between initially seeded tropomyosin molecules growing from distinct binding-site regions on actin.

Keywords

Actin Coiled-coil Electron microscopy, Molecular Dynamics Tropomyosin 

References

  1. Behrmann E, Müller M, Penczek PA, Mannherz HG, Manstein DJ, Raunser S (2012) Structure of the rigor actin–tropomyosin–myosin complex. Cell 150:327–338PubMedCentralCrossRefPubMedGoogle Scholar
  2. Brooks BR, Brooks CL, MacKerell AD, Nilsson L, Petrella RJ, Roux B et al (2009) CHARMM: the biomolecular simulation program. J Comput Chem 30:1545–1614PubMedCentralCrossRefPubMedGoogle Scholar
  3. Brown JH, Kim KH, Jun G, Greenfield NJ, Dominguez R, Volkmann N, Hitchcock-DeGregori SE, Cohen C (2001) Deciphering the design of the tropomyosin molecule. Proc Natl Acad Sci USA 98:8496–8501PubMedCentralCrossRefPubMedGoogle Scholar
  4. Brown JH, Zhou Z, Reshetnikova L, Robinson H, Yammani RD, Tobacman LS, Cohen C (2005) Structure of the mid-region of tropomyosin: bending and binding sites for actin. Proc Natl Acad Sci USA 102:18878–18883PubMedCentralCrossRefPubMedGoogle Scholar
  5. Galińska-Rakoczy A, Engel P, Xu C, Jung H, Craig R, Tobacman LS, Lehman W (2008) Structural basis for the regulation of muscle contraction by troponin and tropomyosin. J Mol Biol 379:929–935PubMedCentralCrossRefPubMedGoogle Scholar
  6. Gordon AM, Homsher E, Regnier M (2000) Regulation of contraction in striated muscle. Physiol Rev 80:853–924PubMedGoogle Scholar
  7. Gunning PW, Hardeman EC, Lappalanien P, Mulvihill DP (2015) Tropomyosin—master regulator of actin filament function in the cytoskeleton. J Cell Sci (in press). doi:10.1242/jcs.172502
  8. Hitchcock-DeGregori SE (2008) Tropomyosin: function follows form. Tropomyosin and the steric mechanism of muscle regulation. Adv Exp Med Biol 644:60–67CrossRefPubMedGoogle Scholar
  9. Holmes KC, Lehman W (2008) Gestalt-binding of tropomyosin to actin filaments. J Muscle Res Cell Motil 29:213–219CrossRefPubMedGoogle Scholar
  10. Humphrey W, Dalke A, Schulten K (1996) VMD: visual molecular dynamics. J Mol Graph 14:33–38CrossRefPubMedGoogle Scholar
  11. Hsiao JY, Goins LM, Petek NA, Mullins RD (2015) Arp2/3 complex and cofilin modulate binding of tropomyosin to branched actin filaments. Curr Biol 25:1573–1582CrossRefPubMedGoogle Scholar
  12. Johnson M, East DA, Mulvihill DP (2014) Formins determine the functional properties of actin filaments in yeast. Curr Biol 24:1525–1530Google Scholar
  13. Lehman W, Craig R, Vibert P (1994) Ca2+-induced tropomyosin movement in Limulus thin filaments revealed by three- dimensional reconstruction. Nature 368:65–67CrossRefPubMedGoogle Scholar
  14. Lehman W, Galińska-Rakoczy A, Hatch V, Tobacman LS, Craig R (2009) Structural basis for the activation of muscle contraction by troponin and tropomyosin. J Mol Biol 388:673–681PubMedCentralCrossRefPubMedGoogle Scholar
  15. Lehman W, Hatch V, Korman V, Rosol M, Thomas L, Maytum R, Geeves MA, Van Eyk JE, Tobacman LS, Craig R (2000) Tropomyosin and actin isoforms modulate the localization of tropomyosin strands on actin filaments. J Mol Biol 302:593–606CrossRefPubMedGoogle Scholar
  16. Lehman W, Orzechowski M, Li XE, Fischer S, Raunser S (2013) Gestalt-binding of tropomyosin on actin during thin filament activation. J Muscle Res Cell Motil 34:155–163CrossRefPubMedGoogle Scholar
  17. Li XE, Holmes KC, Lehman W, Jung H-S, Fischer S (2010) The shape and flexibility of tropomyosin coiled-coils: implications for actin filament assembly and regulation. J Mol Biol 395:327–399Google Scholar
  18. Li XE, Tobacman LS, Mun JY, Craig R, Fischer S, Lehman W (2011) Tropomyosin position on F-actin revealed by EM reconstruction and computational chemistry. Biophys J 100:1005–1013Google Scholar
  19. Li XE, Orzechowski M, Lehman W, Fischer S (2014) Structure and flexibility of the tropomyosin overlap junction. Biochem Biophys Res Commun 446:304–308Google Scholar
  20. Li Y, Mui S, Brown JH, Strand J, Reshetnikova L, Tobacman LS, Cohen C (2002) The crystal structure of the C-terminal fragment of striated-muscle alpha-tropomyosin reveals a key troponin T recognition site. Proc Natl Acad Sci USA 99:7378–7383Google Scholar
  21. Lorenz M, Poole KJV, Popp D, Rosenbaum G, Holmes KC (1995) An atomic model of the unregulated thin filament obtained by X-ray fiber diffraction on oriented actin-tropomyosin gels. J Mol Biol 246:108–119CrossRefPubMedGoogle Scholar
  22. Maytum R, Hatch V, Konrad M, Lehman W, Geeves MA (2008) Ultra short yeast tropomyosins show novel myosin regulation. J Biol Chem 283:1902–1910CrossRefPubMedGoogle Scholar
  23. McKillop DFA, Geeves MA (1993) Regulation of the interaction between actin and myosin subfragment-1: evidence for three states of the thin filament. Biophys J 65:693–701PubMedCentralCrossRefPubMedGoogle Scholar
  24. Meshcheryakov VA, Krieger I, Kostyukova AS, Samatey FA (2011) Structure of a tropomyosin N-terminal fragment at 0.98 Å resolution. Acta Crystallogr D 67:822–825PubMedCentralCrossRefPubMedGoogle Scholar
  25. Monteiro PB, Lataro RC, Ferro JA, Reinach Fde C (1994) Functional alpha-tropomyosin produced in Escherichia coli. A dipeptide extension can substitute the amino-terminal acetyl group. J Biol Chem 269:10461–10466PubMedGoogle Scholar
  26. Nitanai Y, Minakata S, Maeda K, Oda N, Maéda Y (2007) Crystal structures of tropomyosin: flexible coiled-coil. Adv Exp Med Biol 592:137–151CrossRefPubMedGoogle Scholar
  27. Oda T, Iwasa M, Aihara T, Maéda Y, Narita A (2009) The nature of the globular- to fibrous-actin transition. Nature 457:441–445CrossRefPubMedGoogle Scholar
  28. Orzechowski M, Li XE, Fischer S, Lehman W (2014a) An atomic model of the tropomyosin cable on F-actin. Biophys J 107:694–699PubMedCentralCrossRefPubMedGoogle Scholar
  29. Orzechowski M, Moore JR, Fischer S, Lehman W (2014b) Tropomyosin movement on F-actin during muscle activation explained by energy landscapes. Arch Biochem Biophys 545:63–68PubMedCentralCrossRefPubMedGoogle Scholar
  30. Pettersen EF, Goddard TD, Huang CC, Couch GS, Greenblatt DM, Meng EC, Ferrin TE (2004) UCSF Chimera–a visualization system for exploratory research and analysis. J Comput Chem 25:1605–1612CrossRefPubMedGoogle Scholar
  31. Pirani A, Xu C, Hatch V, Craig R, Tobacman LS, Lehman W (2005) Single particle analysis of relaxed and activated muscle thin filaments. J Mol Biol 346:761–772CrossRefPubMedGoogle Scholar
  32. Poole KJ, Lorenz M, Evans G, Rosenbaum G, Pirani A, Tobacman LS, Lehman W, Holmes KC (2006) A comparison of muscle thin filament models obtained from electron microscopy reconstructions and low-angle X-ray fibre diagrams from non-overlap muscle. J Struct Biol 155:273–284CrossRefPubMedGoogle Scholar
  33. Potter JD, Gergely J (1974) Troponin, tropomyosin, and actin interactions in the Ca2+ regulation of muscle contraction. Biochemistry 13:2697–2703CrossRefPubMedGoogle Scholar
  34. Rao JN, Rivera-Santiago R, Li XE, Lehman W, Dominguez R (2012) Structural analysis of smooth muscle tropomyosin α and β isoforms. J Biol Chem 287:3165–3174PubMedCentralCrossRefPubMedGoogle Scholar
  35. Schmidt WM, Lehman W, Moore JR (2015) Direct observation of tropomyosin binding to actin filaments. Cytoskeleton 72:292–303. doi:10.1002/cm.21225 CrossRefPubMedGoogle Scholar
  36. Vibert P, Craig R, Lehman W (1997) Steric-model for activation of muscle thin filaments. J Mol Biol 266:8–14CrossRefPubMedGoogle Scholar
  37. von der Ecken J, Müller M, Lehman W, Manstein DJ, Penczek PA, Raunser S (2014) Structure of the F-actin-tropomyosin complex. Nature 519:114–117CrossRefPubMedGoogle Scholar
  38. Wegner A (1980) The interaction of alpha, alpha-and alpha, beta-tropomyosin with actin filaments. FEBS Lett 119:245–248CrossRefPubMedGoogle Scholar
  39. Whitby FG, Phillips GN Jr (2000) Crystal structure of tropomyosin at 7 Angstroms resolution. Proteins 38:49–59Google Scholar
  40. Yang S, Barbu-Tudoran L, Orzechowski M, Craig R, Trinick J, White H, Lehman W (2014) Three-dimensional organization of troponin on cardiac thin filaments in the relaxed state. Biophys J 106:855–864Google Scholar

Copyright information

© Springer International Publishing Switzerland 2015

Authors and Affiliations

  1. 1.Department of Physiology & BiophysicsBoston University School of MedicineBostonUSA
  2. 2.Computational Biochemistry Group, Interdisciplinary Center for Scientific Computing (IWR)University of HeidelbergHeidelbergGermany

Personalised recommendations