2Z5H

Crystal structure of the head-to-tail junction of tropomyosin complexed with a fragment of TnT

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.89 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.237 
  • R-Value Observed: 0.237 

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This is version 1.3 of the entry. See complete history. 


Literature

Structural basis for tropomyosin overlap in thin (actin) filaments and the generation of a molecular swivel by troponin-T

Murakami, K., Stewart, M., Nozawa, K., Tomii, K., Kudou, N., Igarashi, N., Shirakihara, Y., Wakatsuki, S., Yasunaga, T., Wakabayashi, T.

(2008) Proc Natl Acad Sci U S A 105: 7200-7205

  • DOI: 10.1073/pnas.0801950105
  • Primary Citation of Related Structures:  
    2Z5H, 2Z5I

  • PubMed Abstract: 

    • Head-to-tail polymerization of tropomyosin is crucial for its actin binding, function in actin filament assembly, and the regulation of actin-myosin contraction. Here, we describe the 2.1 A resolution structure of crystals containing overlapping tropomyosin N and C termini (TM-N and TM-C) and the 2 ...

    Head-to-tail polymerization of tropomyosin is crucial for its actin binding, function in actin filament assembly, and the regulation of actin-myosin contraction. Here, we describe the 2.1 A resolution structure of crystals containing overlapping tropomyosin N and C termini (TM-N and TM-C) and the 2.9 A resolution structure of crystals containing TM-N and TM-C together with a fragment of troponin-T (TnT). At each junction, the N-terminal helices of TM-N were splayed, with only one of them packing against TM-C. In the C-terminal region of TM-C, a crucial water in the coiled-coil core broke the local 2-fold symmetry and helps generate a kink on one helix. In the presence of a TnT fragment, the asymmetry in TM-C facilitates formation of a 4-helix bundle containing two TM-C chains and one chain each of TM-N and TnT. Mutating the residues that generate the asymmetry in TM-C caused a marked decrease in the affinity of troponin for actin-tropomyosin filaments. The highly conserved region of TnT, in which most cardiomyopathy mutations reside, is crucial for interacting with tropomyosin. The structure of the ternary complex also explains why the skeletal- and cardiac-muscle specific C-terminal region is required to bind TnT and why tropomyosin homodimers bind only a single TnT. On actin filaments, the head-to-tail junction can function as a molecular swivel to accommodate irregularities in the coiled-coil path between successive tropomyosins enabling each to interact equivalently with the actin helix.

    Organizational Affiliation: 

    Department of Biosciences, School of Science and Engineering, Teikyo University, Toyosatodai 1-1, Utsunomiya 320-8551, Japan.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
General control protein GCN4 and Tropomyosin alpha-1 chain
A, B, C, D, E, F, G, H
A, B, C, D, E, F, G, H
52Saccharomyces cerevisiae, Oryctolagus cuniculus
This entity is chimeric		Mutation(s): 0 
UniProt
Find proteins for P03069 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c))
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Go to UniProtKB:  P03069
Find proteins for P58772 (Oryctolagus cuniculus)
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Go to UniProtKB:  P58772
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupsP58772P03069
Protein Feature View
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  • Reference Sequence
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Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Tropomyosin alpha-1 chain and General control protein GCN4I40Oryctolagus cuniculus, Saccharomyces cerevisiae
This entity is chimeric		Mutation(s): 0 
Gene Names: TPM1
UniProt
Find proteins for P03069 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c))
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Go to UniProtKB:  P03069
Find proteins for P58772 (Oryctolagus cuniculus)
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Entity Groups  
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UniProt GroupsP58772P03069
Protein Feature View
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Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
Troponin T, fast skeletal muscle isoformsJ [auth T]55Gallus gallusMutation(s): 0 
Gene Names: TNNT3
UniProt
Find proteins for P12620 (Gallus gallus)
Explore P12620 
Go to UniProtKB:  P12620
Entity Groups  
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UniProt GroupP12620
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.89 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.237 
  • R-Value Observed: 0.237 
  • Space Group: I 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 86.809α = 90
b = 158.308β = 90
c = 163.57γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
HKL-2000data collection
DENZOdata reduction
SCALEPACKdata scaling
PHASESphasing
CNSrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2008-04-22
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2013-09-18
    Changes: Database references, Derived calculations
  • Version 1.3: 2017-08-16
    Changes: Advisory, Source and taxonomy