3NMS

Staphylococcal Complement Inhibitor (SCIN) in complex with Human Complement C3c


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 4.1 Å
  • R-Value Free: 0.289 
  • R-Value Work: 0.271 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Molecular Basis for Complement Recognition and Inhibition Determined by Crystallographic Studies of the Staphylococcal Complement Inhibitor (SCIN) Bound to C3c and C3b.

Garcia, B.L.Ramyar, K.X.Tzekou, A.Ricklin, D.McWhorter, W.J.Lambris, J.D.Geisbrecht, B.V.

(2010) J.Mol.Biol. 402: 17-29

  • DOI: 10.1016/j.jmb.2010.07.029
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The human complement system plays an essential role in innate and adaptive immunity by marking and eliminating microbial intruders. Activation of complement on foreign surfaces results in proteolytic cleavage of complement component 3 (C3) into the p ...

    The human complement system plays an essential role in innate and adaptive immunity by marking and eliminating microbial intruders. Activation of complement on foreign surfaces results in proteolytic cleavage of complement component 3 (C3) into the potent opsonin C3b, which triggers a variety of immune responses and participates in a self-amplification loop mediated by a multi-protein assembly known as the C3 convertase. The human pathogen Staphylococcus aureus has evolved a sophisticated and potent complement evasion strategy, which is predicated upon an arsenal of potent inhibitory proteins. One of these, the staphylococcal complement inhibitor (SCIN), acts at the level of the C3 convertase (C3bBb) and impairs downstream complement function by trapping the convertase in a stable but inactive state. Previously, we have shown that SCIN binds C3b directly and competitively inhibits binding of human factor H and, to a lesser degree, that of factor B to C3b. Here, we report the co-crystal structures of SCIN bound to C3b and C3c at 7.5 and 3.5 A limiting resolution, respectively, and show that SCIN binds a critical functional area on C3b. Most significantly, the SCIN binding site sterically occludes the binding sites of both factor H and factor B. Our results give insight into SCIN binding to activated derivatives of C3, explain how SCIN can recognize C3b in the absence of other complement components, and provide a structural basis for the competitive C3b-binding properties of SCIN. In the future, this may suggest templates for the design of novel complement inhibitors based upon the SCIN structure.


    Organizational Affiliation

    Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, 5100 Rockhill Road, Kansas City, MO 64110, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Complement C3
A
645Homo 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
C
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: 3
MoleculeChainsSequence LengthOrganismDetails
Staphylococcal complement inhibitor
M
88Staphylococcus aureus (strain Mu50 / ATCC 700699)Mutation(s): 0 
Gene Names: scn
Find proteins for Q931M7 (Staphylococcus aureus (strain Mu50 / ATCC 700699))
Go to UniProtKB:  Q931M7
Entity ID: 4
MoleculeChainsSequence LengthOrganismDetails
Complement C3
B
206Homo sapiensMutation(s): 0 
Gene Names: C3 (CPAMD1)
Find proteins for P01024 (Homo sapiens)
Go to Gene View: C3
Go to UniProtKB:  P01024
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NAG
Query on NAG

Download SDF File 
Download CCD File 
A
N-ACETYL-D-GLUCOSAMINE
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 4.1 Å
  • R-Value Free: 0.289 
  • R-Value Work: 0.271 
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 214.067α = 90.00
b = 68.434β = 90.00
c = 114.928γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data scaling
HKL-2000data reduction
SCALEPACKdata scaling
PHASERphasing
HKL-2000data collection
PDB_EXTRACTdata extraction
DENZOdata reduction
PHENIXrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2010-08-04
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance
  • Version 1.2: 2017-11-08
    Type: Refinement description