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X-ray diffraction evidence for myosin-troponin connections and tropomyosin movement during stretch activation of insect flight muscle

Academic Article
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Overview

related to degree

  • Ward, Andrew, Ph.D. in Biology, Scripps Research 2003 - 2008

authors

  • Perz-Edwards, R. J.
  • Irving, T. C.
  • Baumann, B. A. J.
  • Gore, D.
  • Hutchinson, D. C.
  • Krzic, U.
  • Porter, R. L.
  • Ward, Andrew
  • Reedy, M. K.

publication date

  • January 2011

journal

  • Proceedings of the National Academy of Sciences of the United States of America  Journal

abstract

  • Stretch activation is important in the mechanical properties of vertebrate cardiac muscle and essential to the flight muscles of most insects. Despite decades of investigation, the underlying molecular mechanism of stretch activation is unknown. We investigated the role of recently observed connections between myosin and troponin, called "troponin bridges," by analyzing real-time X-ray diffraction "movies" from sinusoidally stretch-activated Lethocerus muscles. Observed changes in X-ray reflections arising from myosin heads, actin filaments, troponin, and tropomyosin were consistent with the hypothesis that troponin bridges are the key agent of mechanical signal transduction. The time-resolved sequence of molecular changes suggests a mechanism for stretch activation, in which troponin bridges mechanically tug tropomyosin aside to relieve tropomyosin's steric blocking of myosin-actin binding. This enables subsequent force production, with cross-bridge targeting further enhanced by stretch-induced lattice compression and thick-filament twisting. Similar linkages may operate in other muscle systems, such as mammalian cardiac muscle, where stretch activation is thought to aid in cardiac ejection.

subject areas

  • Actins
  • Animals
  • Biomechanical Phenomena
  • Calcium
  • Flight, Animal
  • Heteroptera
  • Models, Biological
  • Models, Molecular
  • Muscles
  • Signal Transduction
  • Tropomyosin
  • X-Ray Diffraction
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Identity

PubMed Central ID

  • PMC3017141

International Standard Serial Number (ISSN)

  • 0027-8424

Digital Object Identifier (DOI)

  • 10.1073/pnas.1014599107

PubMed ID

  • 21148419
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Additional Document Info

start page

  • 120

end page

  • 125

volume

  • 108

issue

  • 1

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