2QKI

Human C3c in complex with the inhibitor compstatin


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.4 Å
  • R-Value Free: 0.281 
  • R-Value Work: 0.213 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Structure of compstatin in complex with complement component C3c reveals a new mechanism of complement inhibition.

Janssen, B.J.Halff, E.F.Lambris, J.D.Gros, P.

(2007) J.Biol.Chem. 282: 29241-29247

  • DOI: 10.1074/jbc.M704587200

  • PubMed Abstract: 
  • Undesired complement activation is a major cause of tissue injury in various pathological conditions and contributes to several immune complex diseases. Compstatin, a 13-residue peptide, is an effective inhibitor of the activation of complement compo ...

    Undesired complement activation is a major cause of tissue injury in various pathological conditions and contributes to several immune complex diseases. Compstatin, a 13-residue peptide, is an effective inhibitor of the activation of complement component C3 and thus blocks a central and crucial step in the complement cascade. The precise binding site on C3, the structure in the bound form, and the exact mode of action of compstatin are unknown. Here we present the crystal structure of compstatin in complex with C3c, a major proteolytic fragment of C3. The structure reveals that the compstatin-binding site is formed by the macroglobulin (MG) domains 4 and 5. This binding site is part of the structurally stable MG-ring formed by domains MG 1-6 and is far away from any other known binding site on C3. Compstatin does not alter the conformation of C3c, whereas compstatin itself undergoes a large conformational change upon binding. We propose a model in which compstatin sterically hinders the access of the substrate C3 to the convertase complexes, thus blocking complement activation and amplification. These insights are instrumental for further development of compstatin as a potential therapeutic.


    Organizational Affiliation

    Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Sciences, Utrecht University, 3584 CH Utrecht, The Netherlands.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Complement C3
A, D
643Homo sapiensMutation(s): 0 
Gene Names: C3 (CPAMD1)
Find proteins for P01024 (Homo sapiens)
Go to Gene View: C3
Go to UniProtKB:  P01024
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Complement C3
B, E
188Homo sapiensMutation(s): 0 
Gene Names: C3 (CPAMD1)
Find proteins for P01024 (Homo sapiens)
Go to Gene View: C3
Go to UniProtKB:  P01024
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
Complement C3
C, F
343Homo sapiensMutation(s): 0 
Gene Names: C3 (CPAMD1)
Find proteins for P01024 (Homo sapiens)
Go to Gene View: C3
Go to UniProtKB:  P01024
Entity ID: 4
MoleculeChainsSequence LengthOrganismDetails
compstatin
G, H
15N/AMutation(s): 0 
Protein Feature View is not available: No corresponding UniProt sequence found.
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
K
Query on K

Download SDF File 
Download CCD File 
A, C, D, F
POTASSIUM ION
K
NPYPAHLBTDXSSS-UHFFFAOYSA-N
 Ligand Interaction
GOL
Query on GOL

Download SDF File 
Download CCD File 
A, B, C, D, E, F, H
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
BR
Query on BR

Download SDF File 
Download CCD File 
A, B, C, D, E, F
BROMIDE ION
Br
CPELXLSAUQHCOX-UHFFFAOYSA-M
 Ligand Interaction
NAG
Query on NAG

Download SDF File 
Download CCD File 
A, D
N-ACETYL-D-GLUCOSAMINE
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
Modified Residues  2 Unique
IDChainsTypeFormula2D DiagramParent
NH2
Query on NH2
G, H
NON-POLYMERH2 N

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ACE
Query on ACE
G, H
NON-POLYMERC2 H4 O

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Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.4 Å
  • R-Value Free: 0.281 
  • R-Value Work: 0.213 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 85.809α = 90.00
b = 124.754β = 95.08
c = 127.367γ = 90.00
Software Package:
Software NamePurpose
MOSFLMdata reduction
REFMACrefinement
DNAdata collection
SCALAdata scaling
PHASERphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-08-14
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Atomic model, Database references, Derived calculations, Non-polymer description, Structure summary, Version format compliance