6I8X

As-p18, an extracellular fatty acid binding protein


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.220 
  • R-Value Work: 0.179 
  • R-Value Observed: 0.181 

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Ligand Structure Quality Assessment 


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Literature

As-p18, an extracellular fatty acid binding protein of nematodes, exhibits unusual structural features.

Ibanez-Shimabukuro, M.Rey-Burusco, M.F.Gabrielsen, M.Franchini, G.R.Riboldi-Tunnicliffe, A.Roe, A.J.Griffiths, K.Cooper, A.Corsico, B.Kennedy, M.W.Smith, B.O.

(2019) Biosci Rep 

  • DOI: 10.1042/BSR20191292
  • Primary Citation of Related Structures:  
    6I8X, 6I9F

  • PubMed Abstract: 
  • Intracellular lipid-binding proteins (iLBPs) of the fatty acid-binding protein (FABP) family of animals transport, mainly fatty acids or retinoids, are confined to the cytosol and have highly similar 3D structures. In contrast, nematodes possess fatty acid-binding proteins (nemFABPs) that are secreted into the perivitelline fluid surrounding their developing embryos ...

    Intracellular lipid-binding proteins (iLBPs) of the fatty acid-binding protein (FABP) family of animals transport, mainly fatty acids or retinoids, are confined to the cytosol and have highly similar 3D structures. In contrast, nematodes possess fatty acid-binding proteins (nemFABPs) that are secreted into the perivitelline fluid surrounding their developing embryos. We report structures of As-p18, a nemFABP of the large intestinal roundworm Ascaris suum , with ligand bound, determined using X-ray crystallography and nuclear magnetic resonance spectroscopy. In common with other FABPs, As-p18 comprises a ten β-strand barrel capped by two short α-helices, with the carboxylate head group of oleate tethered in the interior of the protein. However, As-p18 exhibits two distinctive longer loops amongst β-strands not previously seen in a FABP. One of these is adjacent to the presumed ligand entry portal, so it may help to target the protein for efficient loading or unloading of ligand. The second, larger loop is at the opposite end of the molecule and has no equivalent in any iLBP structure yet determined. As-p18 preferentially binds a single 18-carbon fatty acid ligand in its central cavity but in an orientation that differs from iLBPs. The unusual structural features of nemFABPs may relate to resourcing of developing embryos of nematodes.


    Related Citations: 
    • Useable diffraction data from a multiple microdomain-containing crystal of Ascaris suum As-p18 fatty-acid-binding protein using a microfocus beamline.
      Gabrielsen, M., Riboldi-Tunnicliffe, A., Ibanez-Shimabukuro, M., Griffiths, K., Roe, A.J., Cooper, A., Smith, B.O., Corsico, B., Kennedy, M.W.
      (2012) Acta Crystallogr Sect F Struct Biol Cryst Commun 68: 939

    Organizational Affiliation

    Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, UK Brian.Smith@glasgow.ac.uk Malcolm.Kennedy@glasgow.ac.uk.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Fatty acid-binding protein homologA, B149Ascaris suumMutation(s): 0 
Membrane Entity: Yes 
UniProt
Find proteins for P55776 (Ascaris suum)
Explore P55776 
Go to UniProtKB:  P55776
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP55776
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.220 
  • R-Value Work: 0.179 
  • R-Value Observed: 0.181 
  • Space Group: I 4
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 102.254α = 90
b = 102.254β = 90
c = 103.392γ = 90
Software Package:
Software NamePurpose
BUSTERrefinement
XDSdata reduction
XDSdata scaling
PHASERphasing

Structure Validation

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Ligand Structure Quality Assessment 



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Wellcome TrustUnited Kingdom083625
Biotechnology and Biological Sciences Research CouncilUnited KingdomBB/G011389/1

Revision History  (Full details and data files)

  • Version 1.0: 2019-07-17
    Type: Initial release