Crystal structure of the long-chain fatty acid transporter FadL mutant delta S3 kink

Experimental Data Snapshot

  • Resolution: 2.60 Å
  • R-Value Free: 0.294 
  • R-Value Work: 0.262 
  • R-Value Observed: 0.262 

Starting Model: experimental
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Transmembrane passage of hydrophobic compounds through a protein channel wall

Hearn, E.M.Patel, D.R.Lepore, B.W.Indic, M.van den Berg, B.

(2009) Nature 458: 367-370

  • DOI: https://doi.org/10.1038/nature07678
  • Primary Citation of Related Structures:  
    2R4L, 2R4N, 2R4O, 2R4P, 2R88, 3DWN, 3DWO

  • PubMed Abstract: 

    Membrane proteins that transport hydrophobic compounds have important roles in multi-drug resistance and can cause a number of diseases, underscoring the importance of protein-mediated transport of hydrophobic compounds. Hydrophobic compounds readily partition into regular membrane lipid bilayers, and their transport through an aqueous protein channel is energetically unfavourable. Alternative transport models involving acquisition from the lipid bilayer by lateral diffusion have been proposed for hydrophobic substrates. So far, all transport proteins for which a lateral diffusion mechanism has been proposed function as efflux pumps. Here we present the first example of a lateral diffusion mechanism for the uptake of hydrophobic substrates by the Escherichia coli outer membrane long-chain fatty acid transporter FadL. A FadL mutant in which a lateral opening in the barrel wall is constricted, but which is otherwise structurally identical to wild-type FadL, does not transport substrates. A crystal structure of FadL from Pseudomonas aeruginosa shows that the opening in the wall of the beta-barrel is conserved and delineates a long, hydrophobic tunnel that could mediate substrate passage from the extracellular environment, through the polar lipopolysaccharide layer and, by means of the lateral opening in the barrel wall, into the lipid bilayer from where the substrate can diffuse into the periplasm. Because FadL homologues are found in pathogenic and biodegrading bacteria, our results have implications for combating bacterial infections and bioremediating xenobiotics in the environment.

  • Organizational Affiliation

    Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Long-chain fatty acid transport protein
A, B
426Escherichia coliMutation(s): 0 
Gene Names: fadLttr
Membrane Entity: Yes 
Find proteins for P10384 (Escherichia coli (strain K12))
Explore P10384 
Go to UniProtKB:  P10384
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP10384
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.60 Å
  • R-Value Free: 0.294 
  • R-Value Work: 0.262 
  • R-Value Observed: 0.262 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 91.327α = 90
b = 91.37β = 90
c = 267.317γ = 90
Software Package:
Software NamePurpose
HKL-2000data reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2008-09-23
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2023-08-30
    Changes: Data collection, Database references, Refinement description