DIFFRACTION IMAGING OF THE MYOSINSUPERLATTICE OF VERTEBRATE MUSCLERick Millane, David Wojtas, Chunhong Yoon* and John Squi...
Outline•   Myosin lattice of vertebrate muscle•   Electron microscopy and x-ray fibre diffraction•   Image analysis•   Dis...
Imaging and diffraction imagingMicroscopy  lightelectrons              specimen     FT lens         imageDiffraction Imagi...
Myosin latticeMuscle fibremyofibrilsarcomere                                4
Myosin latticeSimple lattice                 Superlattice                            Rotational disorder                  ...
Electron microscopy and image analysis                                         Close upCross-section of sarcomere         ...
Classification of orientations                                 7
Distribution of orientations                               8
Geometrically frustrated systemsA spin system, for example, for which as, a result of lattice topology,the energy of each ...
TIA correlationsDifferenttemperaturesPartitioned intotwo sublattices                                      10
Spatial correlations – myosin lattice and TIA           Observed – myosin lattice           TIA by Monte Carlo simulation ...
Myosin lattice disorder – measured and simulated             Myosin lattice   TIA                                         ...
X-ray fibre diffraction patterns from muscle                                               13
Fibre diffraction pattern from relaxed frog muscle         Iwamoto et al., Biophys. J., 85, 2492-2506 (2003).             ...
Measured diffraction data – layer line amplitudes                                                    15
Simulation of x-ray diffraction from the myosin array   Develop methods to simulate x-ray   diffraction from models of the...
Calculated diffraction – ordered crystalline specimen                                                    17
Calculated diffraction – completely disordered                                                 18
Calculated diffraction – TIA disorder                                        19
Summary• The superlattice disorder observed in the myosin  lattice of higher verebrate muscle is a manifestation of  a fru...
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14.04 o14 r millane

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14.04 o14 r millane

  1. 1. DIFFRACTION IMAGING OF THE MYOSINSUPERLATTICE OF VERTEBRATE MUSCLERick Millane, David Wojtas, Chunhong Yoon* and John Squire+ Department of Electrical and Computer Engineering University of Canterbury *Department of Physics, University of Wisconsin - Milwaukee, USA +Department of Physiology and Pharmacology University of Bristol, Bristol, UK New Zealand Institute of Physics Conference Wellington, 17-19 October 2011 Supported in part by the Marsden Fund 1
  2. 2. Outline• Myosin lattice of vertebrate muscle• Electron microscopy and x-ray fibre diffraction• Image analysis• Disordered systems – frustration – statistical physics• X-ray diffraction• Conclusions 2
  3. 3. Imaging and diffraction imagingMicroscopy lightelectrons specimen FT lens imageDiffraction Imaging x-rays computerelectrons image specimen diffraction pattern 3
  4. 4. Myosin latticeMuscle fibremyofibrilsarcomere 4
  5. 5. Myosin latticeSimple lattice Superlattice Rotational disorder 5
  6. 6. Electron microscopy and image analysis Close upCross-section of sarcomere Template Template for for rotations locations 6
  7. 7. Classification of orientations 7
  8. 8. Distribution of orientations 8
  9. 9. Geometrically frustrated systemsA spin system, for example, for which as, a result of lattice topology,the energy of each spin pair cannot be simultaneously minimised.A very simple classical example is a triangular lattice withantiferromagnetic interactions.I.e. “unlike’ spins, or states, are energetically preferred.It is not possible to satisfy the constraints on each elementaryplaquette of the lattice.Leads to a large number of ground states. ?This is the triangular Ising antiferromagnet – TIA.Characterised using spin-pair correlations. 9
  10. 10. TIA correlationsDifferenttemperaturesPartitioned intotwo sublattices 10
  11. 11. Spatial correlations – myosin lattice and TIA Observed – myosin lattice TIA by Monte Carlo simulation 11
  12. 12. Myosin lattice disorder – measured and simulated Myosin lattice TIA 12
  13. 13. X-ray fibre diffraction patterns from muscle 13
  14. 14. Fibre diffraction pattern from relaxed frog muscle Iwamoto et al., Biophys. J., 85, 2492-2506 (2003). 14
  15. 15. Measured diffraction data – layer line amplitudes 15
  16. 16. Simulation of x-ray diffraction from the myosin array Develop methods to simulate x-ray diffraction from models of the myosin filament. Need to incorporate: The molecular structure and helical symmetry. The TIA disorder. Cylindrical averaging. 16
  17. 17. Calculated diffraction – ordered crystalline specimen 17
  18. 18. Calculated diffraction – completely disordered 18
  19. 19. Calculated diffraction – TIA disorder 19
  20. 20. Summary• The superlattice disorder observed in the myosin lattice of higher verebrate muscle is a manifestation of a frustrated system.• The frustration is due to incompatible preferred interactions between the myosin filaments.• This may have evolutionary significance for muscle function.• Direct (electron microscopy) and diffraction (x-ray diffraction) imaging complement each other.• Effects of disorder can be incorporated into diffraction calculations to allow rigorous analysis of diffraction data.• Engineers and biophysicists can work productively together and have lots of fun! 20

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