5NUO

Structural basis for maintenance of bacterial outer membrane lipid asymmetry


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.20 Å
  • R-Value Free: 0.269 
  • R-Value Work: 0.223 
  • R-Value Observed: 0.225 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Structural basis for maintenance of bacterial outer membrane lipid asymmetry.

Abellon-Ruiz, J.Kaptan, S.S.Basle, A.Claudi, B.Bumann, D.Kleinekathofer, U.van den Berg, B.

(2017) Nat Microbiol 2: 1616-1623

  • DOI: 10.1038/s41564-017-0046-x
  • Primary Citation of Related Structures:  
    5NUO, 5NUQ, 5NUP, 5NUR

  • PubMed Abstract: 
  • The Gram-negative bacterial outer membrane (OM) is a unique bilayer that forms an efficient permeation barrier to protect the cell from noxious compounds 1 , 2 . The defining characteristic of the OM is lipid asym ...

    The Gram-negative bacterial outer membrane (OM) is a unique bilayer that forms an efficient permeation barrier to protect the cell from noxious compounds 1 , 2 . The defining characteristic of the OM is lipid asymmetry, with phospholipids comprising the inner leaflet and lipopolysaccharides comprising the outer leaflet 1-3 . This asymmetry is maintained by the Mla pathway, a six-component system that is widespread in Gram-negative bacteria and is thought to mediate retrograde transport of misplaced phospholipids from the outer leaflet of the OM to the cytoplasmic membrane 4 . The OM lipoprotein MlaA performs the first step in this process via an unknown mechanism that does not require external energy input. Here we show, using X-ray crystallography, molecular dynamics simulations and in vitro and in vivo functional assays, that MlaA is a monomeric α-helical OM protein that functions as a phospholipid translocation channel, forming a ~20-Å-thick doughnut embedded in the inner leaflet of the OM with a central, amphipathic pore. This architecture prevents access of inner leaflet phospholipids to the pore, but allows outer leaflet phospholipids to bind to a pronounced ridge surrounding the channel, followed by diffusion towards the periplasmic space. Enterobacterial MlaA proteins form stable complexes with OmpF/C 5,6 , but the porins do not appear to play an active role in phospholipid transport. MlaA represents a lipid transport protein that selectively removes outer leaflet phospholipids to help maintain the essential barrier function of the bacterial OM.


    Organizational Affiliation

    Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK. bert.van-den-berg@ncl.ac.uk.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Outer membrane protein FACE340Escherichia coli K-12Mutation(s): 0 
Gene Names: ompFcmlBcoacrytolFb0929JW0912
Membrane protein
Mpstruc
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Outer Membrane Proteins
Protein: 
MlaA lipid transport protein in complex with OmpF
Find proteins for P02931 (Escherichia coli (strain K12))
Explore P02931 
Go to UniProtKB:  P02931
Protein Feature View
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
ABC transporter permeaseBDF236Klebsiella pneumoniaeMutation(s): 0 
Gene Names: 
Find proteins for A0A0W8AQT6 (Klebsiella pneumoniae)
Explore A0A0W8AQT6 
Go to UniProtKB:  A0A0W8AQT6
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
C8E
Query on C8E

Download CCD File 
A, B, C, D, E, F
(HYDROXYETHYLOXY)TRI(ETHYLOXY)OCTANE
C16 H34 O5
FEOZZFHAVXYAMB-UHFFFAOYSA-N
 Ligand Interaction
SO4
Query on SO4

Download CCD File 
A, C, E
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.20 Å
  • R-Value Free: 0.269 
  • R-Value Work: 0.223 
  • R-Value Observed: 0.225 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 95.597α = 90
b = 146.461β = 90
c = 234.931γ = 90
Software Package:
Software NamePurpose
DIALSdata reduction
xia2data reduction
Aimlessdata scaling
PHASERphasing
PHENIXrefinement
RESOLVEmodel building
Cootmodel building

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
European UnionUnited Kingdom115525

Revision History 

  • Version 1.0: 2017-10-25
    Type: Initial release
  • Version 1.1: 2017-11-01
    Changes: Database references
  • Version 1.2: 2017-12-06
    Changes: Database references