Biological Assembly 1  

 3D View: Structure | Electron Density | Ligand Interaction

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

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

Macromolecule Content

• Total Structure Weight: 17.82 kDa 
• Atom Count: 1458 
• Residue Count: 152 
• Unique protein chains: 1

1K9U

Crystal Structure of the Calcium-Binding Pollen Allergen Phl p 7 (Polcalcin) at 1.75 Angstroem

• DOI: 10.2210/pdb1K9U/pdb

• Classification: ALLERGEN
• Organism(s): Phleum pratense
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): No 


• Deposited: 2001-10-30 Released: 2003-04-30 
• Deposition Author(s): Verdino, P., Westritschnig, K., Valenta, R., Keller, W.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.75 Å
• R-Value Free: 0.223 
• R-Value Work: 0.192 

Literature

The cross-reactive calcium-binding pollen allergen, Phl p 7, reveals a novel dimer assembly

Verdino, P., Westritschnig, K., Valenta, R., Keller, W.

(2002) EMBO J 21: 5007-5016

• PubMed: 12356717 
• DOI: 10.1093/emboj/cdf526
• Primary Citation of Related Structures:  
  1K9U


• PubMed Abstract: 
  

The timothy grass pollen allergen Phl p 7 assembles most of the IgE epitopes of a novel family of 2 EF-hand calcium-binding proteins and therefore represents a diagnostic marker allergen and vaccine candidate for immunotherapy. Here we report the first three-dimensional structure of a representative of the 2 EF-hand allergen family, Phl p 7, in the calcium-bound form. The protein occurs as a novel dimer assembly with unique features: in contrast to well known EF-hand proteins such as calmodulin, parvalbumin or the S100 proteins, Phl p 7 adopts an extended conformation. Two protein monomers assemble in a head-to-tail arrangement with domain-swapped EF-hand pairing. The intertwined dimer adopts a barrel-like structure with an extended hydrophobic cavity providing a ligand-binding site. Calcium binding acts as a conformational switch between an open and a closed dimeric form of Phl p 7. These findings are interesting in the context of lipid- and calcium-dependent pollen tube growth. Furthermore, the structure of Phl p 7 allows for the rational development of vaccine strategies for treatment of sensitized allergic patients.

---

Organizational Affiliation: 

Institute of Chemistry, Structural Biology Group, Karl-Franzens-University Graz, Heinrichstrasse 28, A-8010 Graz, Austria.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Polcalcin Phl p 7	A, B	78	Phleum pratense	Mutation(s): 0  Gene Names: Phlpr, P7
Find proteins for O82040 (Phleum pratense) Explore O82040  Go to UniProtKB:  O82040

Small Molecules

Ligands 2 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
SO4	A, B	SULFATE ION O4 S QAOWNCQODCNURD-UHFFFAOYSA-L
CA	A, B	CALCIUM ION Ca BHPQYMZQTOCNFJ-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.75 Å
• R-Value Free: 0.223 
• R-Value Work: 0.192 
• Space Group: P 1 2₁ 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 31.084	α = 90
b = 56.205	β = 90.23
c = 37.238	γ = 90

Software Package:

Software Name	Purpose
MAR	data collection
SCALEPACK	data scaling
SOLVE	phasing
CNS	refinement
MAR	data reduction

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2001-10-30 
• Released Date: 2003-04-30 
Deposition Author(s): Verdino, P., Westritschnig, K., Valenta, R., Keller, W.

Revision History 

• Version 1.0: 2003-04-30
  Type: Initial release
  
• Version 1.1: 2008-04-27
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance