5NUP

Structural basis for maintenance of bacterial outer membrane lipid asymmetry


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.90 Å
  • R-Value Free: 0.290 
  • R-Value Work: 0.241 
  • R-Value Observed: 0.243 

Starting Model: experimental
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Ligand Structure Quality Assessment 


This is version 1.3 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: https://doi.org/10.1038/s41564-017-0046-x
  • Primary Citation of Related Structures:  
    5NUO, 5NUP, 5NUQ, 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 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.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
OmpK36
A, B, C
344Klebsiella pneumoniaeMutation(s): 0 
Gene Names: ompK36
Membrane Entity: Yes 
UniProt
Find proteins for F2VN85 (Klebsiella pneumoniae)
Explore F2VN85 
Go to UniProtKB:  F2VN85
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupF2VN85
Sequence Annotations
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
ABC transporter permease
D, E, F
236Klebsiella pneumoniaeMutation(s): 0 
Gene Names: mlaAvacJAGG09_21815BB749_07690BCB67_11070BL143_09030BN49_3944PMK1_00224SAMEA3531778_01593SM57_02930
UniProt
Find proteins for A0A0W8AQT6 (Klebsiella pneumoniae)
Explore A0A0W8AQT6 
Go to UniProtKB:  A0A0W8AQT6
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA0A0W8AQT6
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
LMT
Query on LMT

Download Ideal Coordinates CCD File 
BA [auth F],
Q [auth B],
R [auth B]
DODECYL-BETA-D-MALTOSIDE
C24 H46 O11
NLEBIOOXCVAHBD-QKMCSOCLSA-N
C8E
Query on C8E

Download Ideal Coordinates CCD File 
AA [auth F]
G [auth A]
H [auth A]
I [auth A]
J [auth A]
AA [auth F],
G [auth A],
H [auth A],
I [auth A],
J [auth A],
K [auth A],
L [auth A],
M [auth B],
N [auth B],
O [auth B],
P [auth B],
S [auth C],
T [auth C],
U [auth C],
V [auth C],
W [auth D],
X [auth D],
Y [auth E],
Z [auth E]
(HYDROXYETHYLOXY)TRI(ETHYLOXY)OCTANE
C16 H34 O5
FEOZZFHAVXYAMB-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.90 Å
  • R-Value Free: 0.290 
  • R-Value Work: 0.241 
  • R-Value Observed: 0.243 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 92.377α = 90
b = 145.24β = 90
c = 232.535γ = 90
Software Package:
Software NamePurpose
DIALSdata reduction
Aimlessdata scaling
PHASERphasing
Cootmodel building
PHENIXrefinement

Structure Validation

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Ligand Structure Quality Assessment 


Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
European UnionUnited Kingdom115525

Revision History  (Full details and data files)

  • 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
  • Version 1.3: 2024-01-17
    Changes: Data collection, Database references, Refinement description