Biological Assembly 1  

 3D View: Structure | 1D-3D View | Electron Density | Validation Report

Global Symmetry: Cyclic - C2  (3D View)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 22.60 kDa 
• Atom Count: 1723 
• Modelled Residue Count: 205 
• Deposited Residue Count: 208 
• Unique protein chains: 1

1IX2

Crystal Structure of Selenomethionine PcoC, a Copper Resistance Protein from Escherichia coli

• PDB DOI: 10.2210/pdb1IX2/pdb

• Classification: METAL BINDING PROTEIN
• Organism(s): Escherichia coli
• Expression System: Escherichia coli
• Mutation(s): Yes 


• Deposited: 2002-06-10 Released: 2002-11-27 
• Deposition Author(s): Wernimont, A.K., Huffman, D.L., Finney, L.A., Demeler, B., O'Halloran, T.V., Rosenzweig, A.C.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.55 Å
• R-Value Free: 0.228 
• R-Value Work: 0.207 
• R-Value Observed: 0.207 

Literature

Crystal structure and dimerization equilibria of PcoC, a methionine-rich copper resistance protein from Escherichia coli

Wernimont, A.K., Huffman, D.L., Finney, L.A., Demeler, B., O'Halloran, T.V., Rosenzweig, A.C.

(2003) J Biol Inorg Chem 8: 185-194

• PubMed: 12459914 
• DOI: 10.1007/s00775-002-0404-9
• Primary Citation of Related Structures:  
  1IX2, 1LYQ


• PubMed Abstract: 
  

PcoC is a soluble periplasmic protein encoded by the plasmid-born pco copper resistance operon of Escherichia coli. Like PcoA, a multicopper oxidase encoded in the same locus and its chromosomal homolog CueO, PcoC contains unusual methionine rich sequences. Although essential for copper resistance, the functions of PcoC, PcoA, and their conserved methionine-rich sequences are not known. Similar methionine motifs observed in eukaryotic copper transporters have been proposed to bind copper, but there are no precedents for such metal binding sites in structurally characterized proteins. The high-resolution structures of apo PcoC, determined for both the native and selenomethionine-containing proteins, reveal a seven-stranded beta barrel with the methionines unexpectedly housed on a solvent-exposed loop. Several potential metal-binding sites can be discerned by comparing the structures to spectroscopic data reported for copper-loaded PcoC. In the native structure, the methionine loop interacts with the same loop on a second molecule in the asymmetric unit. In the selenomethionine structure, the methionine loops are more exposed, forming hydrophobic patches on the protein surface. These two arrangements suggest that the methionine motifs might function in protein-protein interactions between PcoC molecules or with other methionine-rich proteins such as PcoA. Analytical ultracentrifugation data indicate that a weak monomer-dimer equilibrium exists in solution for the apo protein. Dimerization is significantly enhanced upon binding Cu(I) with a measured delta(deltaG degrees )

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Organizational Affiliation: 

Department of Biochemistry, Northwestern University, Evanston, IL 60208, USA.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
PcoC copper resistance protein	A, B	104	Escherichia coli	Mutation(s): 5  Gene Names: plasmid pRJ1004, pcoC
UniProt
Find proteins for Q47454 (Escherichia coli) Explore Q47454  Go to UniProtKB:  Q47454

Small Molecules

Modified Residues  1 Unique
ID	Chains	Type	Formula	2D Diagram	Parent
MSE	A, B	L-PEPTIDE LINKING	C5 H11 N O2 Se		MET

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.55 Å
• R-Value Free: 0.228 
• R-Value Work: 0.207 
• R-Value Observed: 0.207 
• Space Group: I 2 3

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 107.65	α = 90
b = 107.65	β = 90
c = 107.65	γ = 90

Software Package:

Software Name	Purpose
DENZO	data reduction
SCALEPACK	data scaling
SOLVE	phasing
CNS	refinement

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2002-06-10 
• Released Date: 2002-11-27 
Deposition Author(s): Wernimont, A.K., Huffman, D.L., Finney, L.A., Demeler, B., O'Halloran, T.V., Rosenzweig, A.C.

Revision History  

• Version 1.0: 2002-11-27
  Type: Initial release
  
• Version 1.1: 2008-04-27
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance