2W4U

Isometrically contracting insect asynchronous flight muscle quick frozen after a length step


Experimental Data Snapshot

  • Method: ELECTRON MICROSCOPY
  • Aggregation State: FILAMENT 
  • Reconstruction Method: HELICAL 

wwPDB Validation   3D Report Full Report


This is version 1.4 of the entry. See complete history


Literature

Structural Changes in Isometrically Contracting Insect Flight Muscle Trapped Following a Mechanical Perturbation.

Wu, S.Liu, J.Reedy, M.C.Perz-Edwards, R.J.Tregear, R.T.Winkler, H.Franzini-Armstrong, C.Sasaki, H.Lucaveche, C.Goldman, Y.E.Reedy, M.K.Taylor, K.A.

(2012) PLoS One 7: 39422

  • DOI: 10.1371/journal.pone.0039422
  • Primary Citation of Related Structures:  
    2W4H, 2W4U, 2W4V, 2W4W

  • PubMed Abstract: 
  • The application of rapidly applied length steps to actively contracting muscle is a classic method for synchronizing the response of myosin cross-bridges so that the average response of the ensemble can be measured. Alternatively, electron tomography (ET) is a technique that can report the structure of the individual members of the ensemble ...

    The application of rapidly applied length steps to actively contracting muscle is a classic method for synchronizing the response of myosin cross-bridges so that the average response of the ensemble can be measured. Alternatively, electron tomography (ET) is a technique that can report the structure of the individual members of the ensemble. We probed the structure of active myosin motors (cross-bridges) by applying 0.5% changes in length (either a stretch or a release) within 2 ms to isometrically contracting insect flight muscle (IFM) fibers followed after 5-6 ms by rapid freezing against a liquid helium cooled copper mirror. ET of freeze-substituted fibers, embedded and thin-sectioned, provides 3-D cross-bridge images, sorted by multivariate data analysis into ~40 classes, distinct in average structure, population size and lattice distribution. Individual actin subunits are resolved facilitating quasi-atomic modeling of each class average to determine its binding strength (weak or strong) to actin. ~98% of strong-binding acto-myosin attachments present after a length perturbation are confined to "target zones" of only two actin subunits located exactly midway between successive troponin complexes along each long-pitch helical repeat of actin. Significant changes in the types, distribution and structure of actin-myosin attachments occurred in a manner consistent with the mechanical transients. Most dramatic is near disappearance, after either length perturbation, of a class of weak-binding cross-bridges, attached within the target zone, that are highly likely to be precursors of strong-binding cross-bridges. These weak-binding cross-bridges were originally observed in isometrically contracting IFM. Their disappearance following a quick stretch or release can be explained by a recent kinetic model for muscle contraction, as behaviour consistent with their identification as precursors of strong-binding cross-bridges. The results provide a detailed model for contraction in IFM that may be applicable to contraction in other types of muscle.


    Related Citations: 
    • Methods for Identifying and Averaging Variable Molecular Conformations in Tomograms of Actively Contracting Insect Flight Muscle.
      Wu, S., Liu, J., Reedy, M.C., Winkler, H., Reedy, M.K., Taylor, K.A.
      (2009) J Struct Biol 168: 485

    Organizational Affiliation

    Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, United States of America.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
TROPONIN C, SKELETAL MUSCLEA [auth 0],
D [auth 3],
G [auth 6],
J [auth 9]
159Gallus gallusMutation(s): 0 
Gene Names: TNNC2
UniProt
Find proteins for P02588 (Gallus gallus)
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UniProt GroupP02588
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Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
TROPONIN T, FAST SKELETAL MUSCLE ISOFORMSB [auth 1],
E [auth 4],
H [auth 7],
IA [auth Y]
90Gallus gallusMutation(s): 0 
Gene Names: TNNT3
UniProt
Find proteins for P12620 (Gallus gallus)
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Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
TROPONIN I, FAST SKELETAL MUSCLEC [auth 2],
F [auth 5],
I [auth 8],
JA [auth Z]
141Gallus gallusMutation(s): 0 
Gene Names: TNNI2
UniProt
Find proteins for P68246 (Gallus gallus)
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Entity ID: 4
MoleculeChainsSequence LengthOrganismDetailsImage
TROPOMYOSIN ALPHA-1 CHAIN277Oryctolagus cuniculusMutation(s): 0 
Gene Names: TPM1TPMA
UniProt
Find proteins for P58772 (Oryctolagus cuniculus)
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Entity ID: 5
MoleculeChainsSequence LengthOrganismDetailsImage
ACTIN, ALPHA SKELETAL MUSCLE372Oryctolagus cuniculusMutation(s): 0 
Gene Names: ACTA1ACTA
UniProt
Find proteins for P68135 (Oryctolagus cuniculus)
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UniProt GroupP68135
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Experimental Data & Validation

Experimental Data

  • Method: ELECTRON MICROSCOPY
  • Aggregation State: FILAMENT 
  • Reconstruction Method: HELICAL 

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-08-25
    Type: Initial release
  • Version 1.1: 2012-07-18
    Changes: Database references
  • Version 1.2: 2012-08-08
    Changes: Database references, Version format compliance
  • Version 1.3: 2017-04-19
    Changes: Other
  • Version 1.4: 2019-10-23
    Changes: Author supporting evidence, Data collection, Other