1KK7

SCALLOP MYOSIN IN THE NEAR RIGOR CONFORMATION


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.20 Å
  • R-Value Free: 0.313 
  • R-Value Work: 0.259 
  • R-Value Observed: 0.263 

Starting Model: experimental
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This is version 1.4 of the entry. See complete history


Literature

Crystallographic findings on the internally uncoupled and near-rigor states of myosin: further insights into the mechanics of the motor.

Himmel, D.M.Gourinath, S.Reshetnikova, L.Shen, Y.Szent-Gyorgyi, A.G.Cohen, C.

(2002) Proc Natl Acad Sci U S A 99: 12645-12650

  • DOI: https://doi.org/10.1073/pnas.202476799
  • Primary Citation of Related Structures:  
    1KK7, 1KK8, 1KQM, 1KWO, 1L2O

  • PubMed Abstract: 

    Here we report a 2.3-A crystal structure of scallop myosin S1 complexed with ADP.BeF(x), as well as three additional structures (at 2.8-3.8 A resolution) for this S1 complexed with ATP analogs, some of which are cross-linked by para-phenyl dimaleimide, a short intramolecular cross-linker. In all cases, the complexes are characterized by an unwound SH1 helix first seen in an unusual 2.5-A scallop myosin-MgADP structure and described as corresponding to a previously unrecognized actin-detached internally uncoupled state. The unwinding of the SH1 helix effectively uncouples the converter/lever arm module from the motor and allows cross-linking by para-phenyl dimaleimide, which has been shown to occur only in weak actin-binding states of the molecule. Mutations near the metastable SH1 helix that disable the motor can be accounted for by viewing this structural element as a clutch controlling the transmission of torque to the lever arm. We have also determined a 3.2-A nucleotide-free structure of scallop myosin S1, which suggests that in the near-rigor state there are two conformations in the switch I loop, depending on whether nucleotide is present. Analysis of the subdomain motions in the weak actin-binding states revealed by x-ray crystallography, together with recent electron microscopic results, clarify the mechanical roles of the parts of the motor in the course of the contractile cycle and suggest how strong binding to actin triggers both the power stroke and product release.


  • Organizational Affiliation

    Rosenstiel Basic Medical Sciences Research Center, Waltham, MA 02454-9110, USA.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
MYOSIN HEAVY CHAIN, STRIATED MUSCLE837Argopecten irradiansMutation(s): 0 
UniProt
Find proteins for P24733 (Argopecten irradians)
Explore P24733 
Go to UniProtKB:  P24733
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UniProt GroupP24733
Sequence Annotations
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  • Reference Sequence
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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
MYOSIN REGULATORY LIGHT CHAIN, STRIATED ADDUCTOR MUSCLEB [auth Y]156Argopecten irradiansMutation(s): 0 
UniProt
Find proteins for P13543 (Argopecten irradians)
Explore P13543 
Go to UniProtKB:  P13543
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UniProt GroupP13543
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  • Reference Sequence
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Entity ID: 3
MoleculeChains Sequence LengthOrganismDetailsImage
MYOSIN ESSENTIAL LIGHT CHAIN, STRIATED ADDUCTOR MUSCLEC [auth Z]156Argopecten irradiansMutation(s): 0 
UniProt
Find proteins for P07291 (Argopecten irradians)
Explore P07291 
Go to UniProtKB:  P07291
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UniProt GroupP07291
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.20 Å
  • R-Value Free: 0.313 
  • R-Value Work: 0.259 
  • R-Value Observed: 0.263 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 159.849α = 90
b = 51.227β = 99.48
c = 84.073γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
AMoREphasing
CNSrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2002-10-09
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-02-01
    Changes: Structure summary
  • Version 1.4: 2023-08-16
    Changes: Data collection, Database references, Derived calculations, Refinement description