Biological Assembly 1  

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

Global Symmetry: Cyclic - C2  (3D View)
Global Stoichiometry: Hetero 4-mer - A2B2 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 26.66 kDa 
• Atom Count: 1384 
• Modelled Residue Count: 159 
• Deposited Residue Count: 232 
• Unique protein chains: 2

5I0Q

Structure of human C4b-binding protein alpha chain CCP domains 1 and 2 in complex with the hypervariable region of mutant group A Streptococcus M2 (K65A, N66A) protein

• PDB DOI: 10.2210/pdb5I0Q/pdb

• Classification: IMMUNE SYSTEM
• Organism(s): Streptococcus pyogenes, Homo sapiens
• Expression System: Escherichia coli
• Mutation(s): Yes 


• Deposited: 2016-02-04 Released: 2016-07-20 
• Deposition Author(s): Buffalo, C.Z., Bahn-Suh, A.J., Ghosh, P.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.29 Å
• R-Value Free: 0.224 
• R-Value Work: 0.203 
• R-Value Observed: 0.205 

Literature

Conserved patterns hidden within group A Streptococcus M protein hypervariability recognize human C4b-binding protein.

Buffalo, C.Z., Bahn-Suh, A.J., Hirakis, S.P., Biswas, T., Amaro, R.E., Nizet, V., Ghosh, P.

(2016) Nat Microbiol 1: 16155-16155

• PubMed: 27595425 
• DOI: 10.1038/nmicrobiol.2016.155
• Primary Citation of Related Structures:  
  5HYP, 5HYT, 5HYU, 5HZP, 5I0Q


• PubMed Abstract: 
  

No vaccine exists against group A Streptococcus (GAS), a leading cause of worldwide morbidity and mortality. A severe hurdle is the hypervariability of its major antigen, the M protein, with >200 different M types known. Neutralizing antibodies typically recognize M protein hypervariable regions (HVRs) and confer narrow protection. In stark contrast, human C4b-binding protein (C4BP), which is recruited to the GAS surface to block phagocytic killing, interacts with a remarkably large number of M protein HVRs (apparently ∼90%). Such broad recognition is rare, and we discovered a unique mechanism for this through the structure determination of four sequence-diverse M proteins in complexes with C4BP. The structures revealed a uniform and tolerant 'reading head' in C4BP, which detected conserved sequence patterns hidden within hypervariability. Our results open up possibilities for rational therapies that target the M-C4BP interaction, and also inform a path towards vaccine design.

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Organizational Affiliation: 

Department of Chemistry &Biochemistry, University of California, San Diego, La Jolla, California 92093, USA.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
M protein, serotype 2.1	A	104	Streptococcus pyogenes	Mutation(s): 2  Gene Names: emmL2.1
UniProt
Find proteins for P50468 (Streptococcus pyogenes) Explore P50468  Go to UniProtKB:  P50468

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
C4b-binding protein alpha chain	B	128	Homo sapiens	Mutation(s): 0  Gene Names: C4BPA, C4BP
UniProt & NIH Common Fund Data Resources
Find proteins for P04003 (Homo sapiens) Explore P04003  Go to UniProtKB:  P04003
PHAROS:  P04003

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.29 Å
• R-Value Free: 0.224 
• R-Value Work: 0.203 
• R-Value Observed: 0.205 
• Space Group: P 4₃ 3 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 148.598	α = 90
b = 148.598	β = 90
c = 148.598	γ = 90

Software Package:

Software Name	Purpose
PHENIX	refinement
HKL-2000	data reduction
HKL-2000	data scaling
PHENIX	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2016-02-04 
• Released Date: 2016-07-20 
Deposition Author(s): Buffalo, C.Z., Bahn-Suh, A.J., Ghosh, P.

Revision History  

• Version 1.0: 2016-07-20
  Type: Initial release
  
• Version 1.1: 2016-10-26
  Changes: Database references