6I98

Structure of the ferrioxamine B transporter FoxA from Pseudomonas aeruginosa, apo state

• PDB DOI:  https://doi.org/10.2210/pdb6I98/pdb

• Classification: MEMBRANE PROTEIN
• Organism(s): Pseudomonas aeruginosa
• Expression System: Escherichia coli
• Mutation(s): No 
• Membrane Protein: Yes  PDBTMMemProtMD


• Deposited: 2018-11-22 Released: 2019-08-28 
• Deposition Author(s): Josts, I., Tidow, H.
• Funding Organization(s): German Research Foundation

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.80 Å
• R-Value Free: 0.260 
• R-Value Work: 0.213 
• R-Value Observed: 0.216 

Literature

Ternary structure of the outer membrane transporter FoxA with resolved signalling domain provides insights into TonB-mediated siderophore uptake.

Josts, I., Veith, K., Tidow, H.

(2019) Elife 8

• PubMed: 31385808 
• DOI: https://doi.org/10.7554/eLife.48528
• Primary Citation of Related Structures:  
  6I96, 6I97, 6I98


• PubMed Abstract: 
  

Many microbes and fungi acquire the essential ion Fe ³⁺ through the synthesis and secretion of high-affinity chelators termed siderophores. In Gram-negative bacteria, these ferric-siderophore complexes are actively taken up using highly specific TonB-dependent transporters (TBDTs) located in the outer bacterial membrane (OM). However, the detailed mechanism of how the inner-membrane protein TonB connects to the transporters in the OM as well as the interplay between siderophore- and TonB-binding to the transporter is still poorly understood. Here, we present three crystal structures of the TBDT FoxA from Pseudomonas aeruginosa (containing a signalling domain) in complex with the siderophore ferrioxamine B and TonB and combine them with a detailed analysis of binding constants. The structures show that both siderophore and TonB-binding is required to form a translocation-competent state of the FoxA transporter in a two-step TonB-binding mechanism. The complex structure also indicates how TonB-binding influences the orientation of the signalling domain.

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Organizational Affiliation: 

Department of Chemistry, Institute for Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany.

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 79.01 kDa 
• Atom Count: 5,532 
• Modelled Residue Count: 677 
• Deposited Residue Count: 677 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Ferric hydroxamate uptake	A	677	Pseudomonas aeruginosa	Mutation(s): 0  Gene Names: fhuA, fhuA_5, C0044_18480, CAZ10_13360, CCBH4851_00003, DZ940_30305, EGY23_22030, PAERUG_E15_London_28_01_14_03466 Membrane Entity: Yes
UniProt
Find proteins for Q9I116 (Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)) Explore Q9I116  Go to UniProtKB:  Q9I116

Small Molecules

Ligands 6 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
C8E	G [auth A], H [auth A], I [auth A], J [auth A]	(HYDROXYETHYLOXY)TRI(ETHYLOXY)OCTANE C16 H34 O5 FEOZZFHAVXYAMB-UHFFFAOYSA-N
FTT	K [auth A], L [auth A], M [auth A]	3-HYDROXY-TETRADECANOIC ACID C14 H28 O3 ATRNZOYKSNPPBF-CYBMUJFWSA-N
SO4	N [auth A], O [auth A], P [auth A], Q [auth A], R [auth A], S [auth A], T [auth A], U [auth A], V [auth A], W [auth A], X [auth A], Y [auth A]	SULFATE ION O4 S QAOWNCQODCNURD-UHFFFAOYSA-L
GOL	C [auth A], D [auth A], E [auth A], F [auth A]	GLYCEROL C3 H8 O3 PEDCQBHIVMGVHV-UHFFFAOYSA-N
NI	B [auth A]	NICKEL (II) ION Ni VEQPNABPJHWNSG-UHFFFAOYSA-N
NA	AA [auth A], Z [auth A]	SODIUM ION Na FKNQFGJONOIPTF-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.80 Å
• R-Value Free: 0.260 
• R-Value Work: 0.213 
• R-Value Observed: 0.216 
• Space Group: P 6₃ 2 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 174.554	α = 90
b = 174.554	β = 90
c = 180.245	γ = 120

Software Package:

Software Name	Purpose
REFMAC	refinement
XDS	data reduction
Aimless	data scaling
PHASER	phasing
PDB_EXTRACT	data extraction

Structure Validation

Entry History & Funding Information

Deposition Data

• Released Date: 2019-08-28 
Deposition Author(s): Josts, I., Tidow, H.

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Funding Organization	Location	Grant Number
German Research Foundation	Germany	--

Revision History  

• Version 1.0: 2019-08-28
  Type: Initial release