3RBH

Structure of alginate export protein AlgE from Pseudomonas aeruginosa


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.301 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.221 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Structural basis for alginate secretion across the bacterial outer membrane.

Whitney, J.C.Hay, I.D.Li, C.Eckford, P.D.Robinson, H.Amaya, M.F.Wood, L.F.Ohman, D.E.Bear, C.E.Rehm, B.H.Lynne Howell, P.

(2011) Proc.Natl.Acad.Sci.USA 108: 13083-13088

  • DOI: 10.1073/pnas.1104984108

  • PubMed Abstract: 
  • Pseudomonas aeruginosa is the predominant pathogen associated with chronic lung infection among cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopoly ...

    Pseudomonas aeruginosa is the predominant pathogen associated with chronic lung infection among cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopolysaccharide alginate. Secretion of newly synthesized alginate across the outer membrane is believed to occur through the outer membrane protein AlgE. Here we report the 2.3 Å crystal structure of AlgE, which reveals a monomeric 18-stranded β-barrel characterized by a highly electropositive pore constriction formed by an arginine-rich conduit that likely acts as a selectivity filter for the negatively charged alginate polymer. Interestingly, the pore constriction is occluded on either side by extracellular loop L2 and an unusually long periplasmic loop, T8. In halide efflux assays, deletion of loop T8 (ΔT8-AlgE) resulted in a threefold increase in anion flux compared to the wild-type or ΔL2-AlgE supporting the idea that AlgE forms a transport pathway through the membrane and suggesting that transport is regulated by T8. This model is further supported by in vivo experiments showing that complementation of an algE deletion mutant with ΔT8-AlgE impairs alginate production. Taken together, these studies support a mechanism for exopolysaccharide export across the outer membrane that is distinct from the Wza-mediated translocation observed in canonical capsular polysaccharide export systems.


    Organizational Affiliation

    Molecular Structure and Function, The Hospital for Sick Children, Toronto, ON, Canada M5G 1X8.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Alginate production protein AlgE
A, B, C, D
479Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)Mutation(s): 0 
Gene Names: algE (alg76)
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: BETA-BARREL
Sub Group: 
Beta-Barrel Membrane Proteins: Monomeric/Dimeric
Protein: 
AlgE alginate export protein
Find proteins for P18895 (Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1))
Go to UniProtKB:  P18895
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
C8E
Query on C8E

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

Download SDF File 
Download CCD File 
A, B, C, D
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
EDO
Query on EDO

Download SDF File 
Download CCD File 
A, B, C, D
1,2-ETHANEDIOL
ETHYLENE GLYCOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
MSE
Query on MSE
A, B, C, D
L-PEPTIDE LINKINGC5 H11 N O2 SeMET
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.301 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.221 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 162.018α = 90.00
b = 90.696β = 107.65
c = 160.279γ = 90.00
Software Package:
Software NamePurpose
PHENIXrefinement
HKL-2000data collection
HKL-2000data reduction
HKL-2000data scaling
SOLVEphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2011-07-27
    Type: Initial release
  • Version 1.1: 2011-08-24
    Type: Database references