3OJY

Crystal Structure of Human Complement Component C8


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.51 Å
  • R-Value Free: 0.337 
  • R-Value Work: 0.249 

wwPDB Validation 3D Report Full Report


This is version 1.4 of the entry. See complete history

Literature

Structure of human C8 protein provides mechanistic insight into membrane pore formation by complement.

Lovelace, L.L.Cooper, C.L.Sodetz, J.M.Lebioda, L.

(2011) J.Biol.Chem. 286: 17585-17592

  • DOI: 10.1074/jbc.M111.219766
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • C8 is one of five complement proteins that assemble on bacterial membranes to form the lethal pore-like "membrane attack complex" (MAC) of complement. The MAC consists of one C5b, C6, C7, and C8 and 12-18 molecules of C9. C8 is composed of three gene ...

    C8 is one of five complement proteins that assemble on bacterial membranes to form the lethal pore-like "membrane attack complex" (MAC) of complement. The MAC consists of one C5b, C6, C7, and C8 and 12-18 molecules of C9. C8 is composed of three genetically distinct subunits, C8α, C8β, and C8γ. The C6, C7, C8α, C8β, and C9 proteins are homologous and together comprise the MAC family of proteins. All contain N- and C-terminal modules and a central 40-kDa membrane attack complex perforin (MACPF) domain that has a key role in forming the MAC pore. Here, we report the 2.5 Å resolution crystal structure of human C8 purified from blood. This is the first structure of a MAC family member and of a human MACPF-containing protein. The structure shows the modules in C8α and C8β are located on the periphery of C8 and not likely to interact with the target membrane. The C8γ subunit, a member of the lipocalin family of proteins that bind and transport small lipophilic molecules, shows no occupancy of its putative ligand-binding site. C8α and C8β are related by a rotation of ∼22° with only a small translational component along the rotation axis. Evolutionary arguments suggest the geometry of binding between these two subunits is similar to the arrangement of C9 molecules within the MAC pore. This leads to a model of the MAC that explains how C8-C9 and C9-C9 interactions could facilitate refolding and insertion of putative MACPF transmembrane β-hairpins to form a circular pore.


    Organizational Affiliation

    Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Complement component C8 alpha chain
A
554Homo sapiensMutation(s): 0 
Gene Names: C8A
Find proteins for P07357 (Homo sapiens)
Go to Gene View: C8A
Go to UniProtKB:  P07357
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Complement component C8 beta chain
B
537Homo sapiensMutation(s): 0 
Gene Names: C8B
Find proteins for P07358 (Homo sapiens)
Go to Gene View: C8B
Go to UniProtKB:  P07358
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
Complement component C8 gamma chain
C
182Homo sapiensMutation(s): 0 
Gene Names: C8G
Find proteins for P07360 (Homo sapiens)
Go to Gene View: C8G
Go to UniProtKB:  P07360
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download SDF File 
Download CCD File 
A, B
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
BMA
Query on BMA

Download SDF File 
Download CCD File 
A, B
BETA-D-MANNOSE
C6 H12 O6
WQZGKKKJIJFFOK-RWOPYEJCSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
TPO
Query on TPO
B
L-PEPTIDE LINKINGC4 H10 N O6 PTHR
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.51 Å
  • R-Value Free: 0.337 
  • R-Value Work: 0.249 
  • Space Group: P 63
Unit Cell:
Length (Å)Angle (°)
a = 139.575α = 90.00
b = 139.575β = 90.00
c = 127.160γ = 120.00
Software Package:
Software NamePurpose
PHASERphasing
DENZOdata reduction
REFMACrefinement
PDB_EXTRACTdata extraction
SERGUIdata collection
SCALEPACKdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2011-04-13
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance
  • Version 1.2: 2011-10-26
    Type: Database references
  • Version 1.3: 2014-04-16
    Type: Other
  • Version 1.4: 2017-11-08
    Type: Refinement description