Crystal structure of human filamin B actin binding domain at 1.9 Angstroms resolution

Experimental Data Snapshot

  • Resolution: 1.90 Å
  • R-Value Free: 0.216 
  • R-Value Work: 0.191 
  • R-Value Observed: 0.192 

Starting Model: experimental
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Disease-Associated Substitutions in the Filamin B Actin Binding Domain Confer Enhanced Actin Binding Affinity in the Absence of Major Structural Disturbance: Insights from the Crystal Structures of Filamin B Actin Binding Domains.

Sawyer, G.M.Clark, A.R.Robertson, S.P.Sutherland-Smith, A.J.

(2009) J Mol Biol 390: 1030

  • DOI: https://doi.org/10.1016/j.jmb.2009.06.009
  • Primary Citation of Related Structures:  
    2WA5, 2WA6, 2WA7

  • PubMed Abstract: 

    Missense mutations in filamin B (FLNB) are associated with the autosomal dominant atelosteogenesis (AO) and the Larsen group of skeletal malformation disorders. These mutations cluster in particular FLNB protein domains and act in a presumptive gain-of-function mechanism. In contrast the loss-of-function disorder, spondylocarpotarsal synostosis syndrome, is characterised by the complete absence of FLNB. One cluster of AO missense mutations is found within the second of two calponin homology (CH) domains that create a functional actin-binding domain (ABD). This N-terminal ABD is required for filamin F-actin crosslinking activity, a crucial aspect of filamin's role of integrating cell-signalling events with cellular scaffolding and mechanoprotection. This study characterises the wild type FLNB ABD and investigates the effects of two disease-associated mutations on the structure and function of the FLNB ABD that could explain a gain-of-function mechanism for the AO diseases. We have determined high-resolution X-ray crystal structures of the human filamin B wild type ABD, plus W148R and M202V mutants. All three structures display the classic compact monomeric conformation for the ABD with the CH1 and CH2 domains in close contact. The conservation of tertiary structure in the presence of these mutations shows that the compact ABD conformation is stable to the sequence substitutions. In solution the mutant ABDs display reduced melting temperatures (by 6-7 degrees C) as determined by differential scanning fluorimetry. Characterisation of the wild type and mutant ABD F-actin binding activities via co-sedimentation assays shows that the mutant FLNB ABDs have increased F-actin binding affinities, with dissociation constants of 2.0 microM (W148R) and 0.56 microM (M202V), compared to the wild type ABD K(d) of 7.0 microM. The increased F-actin binding affinity of the mutants presents a biochemical mechanism that differentiates the autosomal dominant gain-of-function FLNB disorders from those that arise through the complete loss of FLNB protein.

  • Organizational Affiliation

    Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
FILAMIN-B245Homo sapiensMutation(s): 0 
UniProt & NIH Common Fund Data Resources
Find proteins for O75369 (Homo sapiens)
Explore O75369 
Go to UniProtKB:  O75369
GTEx:  ENSG00000136068 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO75369
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.90 Å
  • R-Value Free: 0.216 
  • R-Value Work: 0.191 
  • R-Value Observed: 0.192 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 43.05α = 90
b = 71.183β = 90
c = 90.436γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-06-23
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Advisory, Version format compliance
  • Version 1.2: 2023-12-13
    Changes: Data collection, Database references, Derived calculations, Other, Refinement description