4FXG

Complement C4 in complex with MASP-2

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.75 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.174 
  • R-Value Observed: 0.176 

wwPDB Validation   3D Report Full Report


Re-refinement Note

A newer entry is available that reflects an alternative modeling of the original data: 5JPM


Literature

Structural basis for activation of the complement system by component C4 cleavage.

Kidmose, R.T., Laursen, N.S., Dobo, J., Kjaer, T.R., Sirotkina, S., Yatime, L., Sottrup-Jensen, L., Thiel, S., Gal, P., Andersen, G.R.

(2012) Proc Natl Acad Sci U S A 109: 15425-15430

  • DOI: 10.1073/pnas.1208031109
  • Primary Citation of Related Structures:  
    4FXG, 4FXK

  • PubMed Abstract: 

    • An essential aspect of innate immunity is recognition of molecular patterns on the surface of pathogens or altered self through the lectin and classical pathways, two of the three well-established activation pathways of the complement system. This recogn ...

    An essential aspect of innate immunity is recognition of molecular patterns on the surface of pathogens or altered self through the lectin and classical pathways, two of the three well-established activation pathways of the complement system. This recognition causes activation of the MASP-2 or the C1s serine proteases followed by cleavage of the protein C4. Here we present the crystal structures of the 203-kDa human C4 and the 245-kDa C4·MASP-2 substrate·enzyme complex. When C4 binds to MASP-2, substantial conformational changes in C4 are induced, and its scissile bond region becomes ordered and inserted into the protease catalytic site in a manner canonical to serine proteases. In MASP-2, an exosite located within the CCP domains recognizes the C4 C345C domain 60 Å from the scissile bond. Mutations in C4 and MASP-2 residues at the C345C-CCP interface inhibit the intermolecular interaction and C4 cleavage. The possible assembly of the huge in vivo enzyme-substrate complex consisting of glycan-bound mannan-binding lectin, MASP-2, and C4 is discussed. Our own and prior functional data suggest that C1s in the classical pathway of complement activated by, e.g., antigen-antibody complexes, also recognizes the C4 C345C domain through a CCP exosite. Our results provide a unified structural framework for understanding the early and essential step of C4 cleavage in the elimination of pathogens and altered self through two major pathways of complement activation.

    Organizational Affiliation: 

    Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Complement C4 beta chain A, D656Homo sapiensMutation(s): 0 
Gene Names: C4A, CO4, CPAMD2
Find proteins for P0C0L4 (Homo sapiens)
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Go to UniProtKB:  P0C0L4
NIH Common Fund Data Resources
PHAROS:  P0C0L4
GTEx:  ENSG00000244731
Protein Feature View
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  • Reference Sequence
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Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Complement C4-A alpha chain B, E767Homo sapiensMutation(s): 0 
Gene Names: C4A, CO4, CPAMD2
Find proteins for P0C0L4 (Homo sapiens)
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Go to UniProtKB:  P0C0L4
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PHAROS:  P0C0L4
GTEx:  ENSG00000244731
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  • Reference Sequence
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Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
Complement C4 gamma chain C, F291Homo sapiensMutation(s): 0 
Gene Names: C4A, CO4, CPAMD2
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Go to UniProtKB:  P0C0L4
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PHAROS:  P0C0L4
GTEx:  ENSG00000244731
Protein Feature View
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  • Reference Sequence
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Entity ID: 4
MoleculeChainsSequence LengthOrganismDetailsImage
Mannan-binding lectin serine protease 2 A chain G, I154Homo sapiensMutation(s): 0 
Gene Names: MASP2
EC: 3.4.21.104
Find proteins for O00187 (Homo sapiens)
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PHAROS:  O00187
GTEx:  ENSG00000009724
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Entity ID: 5
MoleculeChainsSequence LengthOrganismDetailsImage
Mannan-binding lectin serine protease 2 B chain H, J242Homo sapiensMutation(s): 1 
Gene Names: MASP2
EC: 3.4.21.104
Find proteins for O00187 (Homo sapiens)
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PHAROS:  O00187
GTEx:  ENSG00000009724
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  • Reference Sequence
Oligosaccharides

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Entity ID: 6
MoleculeChainsChain Length2D Diagram Glycosylation3D Interactions
beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose
K, L, M, N, O, P
3 N-Glycosylation Oligosaccharides Interaction
Small Molecules
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
TYS
Query on TYS		B,EL-PEPTIDE LINKINGC9 H11 N O6 STYR
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.75 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.174 
  • R-Value Observed: 0.176 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 99.01α = 90
b = 215.01β = 110.11
c = 142.86γ = 90
Software Package:
Software NamePurpose
XDSdata scaling
PHASERphasing
PHENIXrefinement
XDSdata reduction
XSCALEdata scaling

Structure Validation

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View more in-depth experimental data

Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-08-22
    Type: Initial release
  • Version 1.1: 2012-09-19
    Changes: Database references
  • Version 1.2: 2012-10-03
    Changes: Database references
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Atomic model, Data collection, Database references, Derived calculations, Structure summary