3T5O

Crystal Structure of human Complement Component C6


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.869 Å
  • R-Value Free: 0.276 
  • R-Value Work: 0.222 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structure of Complement C6 Suggests a Mechanism for Initiation and Unidirectional, Sequential Assembly of Membrane Attack Complex (MAC).

Aleshin, A.E.Schraufstatter, I.U.Stec, B.Bankston, L.A.Liddington, R.C.Discipio, R.G.

(2012) J.Biol.Chem. 287: 10210-10222

  • DOI: 10.1074/jbc.M111.327809

  • PubMed Abstract: 
  • The complement membrane attack complex (MAC) is formed by the sequential assembly of C5b with four homologous proteins as follows: one copy each of C6, C7, and C8 and 12-14 copies of C9. Together these form a lytic pore in bacterial membranes. C6 thr ...

    The complement membrane attack complex (MAC) is formed by the sequential assembly of C5b with four homologous proteins as follows: one copy each of C6, C7, and C8 and 12-14 copies of C9. Together these form a lytic pore in bacterial membranes. C6 through C9 comprise a MAC-perforin domain flanked by 4-9 "auxiliary" domains. Here, we report the crystal structure of C6, the first and longest of the pore proteins to be recruited by C5b. Comparisons with the structures of the C8αβγ heterodimer and perforin show that the central domain of C6 adopts a "closed" (perforin-like) state that is distinct from the "open" conformations in C8. We further show that C6, C8α, and C8β contain three homologous subdomains ("upper," "lower," and "regulatory") related by rotations about two hinge points. In C6, the regulatory segment includes four auxiliary domains that stabilize the closed conformation, inhibiting release of membrane-inserting elements. In C8β, rotation of the regulatory segment is linked to an opening of the central β-sheet of its clockwise partner, C8α. Based on these observations, we propose a model for initiation and unidirectional propagation of the MAC in which the auxiliary domains play key roles: in the assembly of the C5b-8 initiation complex; in driving and regulating the opening of the β-sheet of the MAC-performin domain of each new recruit as it adds to the growing pore; and in stabilizing the final pore. Our model of the assembled pore resembles those of the cholesterol-dependent cytolysins but is distinct from that recently proposed for perforin.


    Organizational Affiliation

    Infectious and Inflammatory Disease Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Complement component C6
A
913Homo sapiensMutation(s): 0 
Gene Names: C6
Find proteins for P13671 (Homo sapiens)
Go to Gene View: C6
Go to UniProtKB:  P13671
Small Molecules
Ligands 6 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MAN
Query on MAN

Download SDF File 
Download CCD File 
A
ALPHA-D-MANNOSE
C6 H12 O6
WQZGKKKJIJFFOK-PQMKYFCFSA-N
 Ligand Interaction
BGC
Query on BGC

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Download CCD File 
A
BETA-D-GLUCOSE
C6 H12 O6
WQZGKKKJIJFFOK-VFUOTHLCSA-N
 Ligand Interaction
FUC
Query on FUC

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Download CCD File 
A
ALPHA-L-FUCOSE
C6 H12 O5
SHZGCJCMOBCMKK-SXUWKVJYSA-N
 Ligand Interaction
NAG
Query on NAG

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Download CCD File 
A
N-ACETYL-D-GLUCOSAMINE
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
FUL
Query on FUL

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Download CCD File 
A
BETA-L-FUCOSE
6-DEOXY-BETA-L-GALACTOSE
C6 H12 O5
SHZGCJCMOBCMKK-KGJVWPDLSA-N
 Ligand Interaction
CD
Query on CD

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Download CCD File 
A
CADMIUM ION
Cd
WLZRMCYVCSSEQC-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.869 Å
  • R-Value Free: 0.276 
  • R-Value Work: 0.222 
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 146.810α = 90.00
b = 180.150β = 90.00
c = 60.530γ = 90.00
Software Package:
Software NamePurpose
Blu-Icedata collection
SHARPphasing
PHENIXrefinement
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-02-01
    Type: Initial release
  • Version 1.1: 2012-02-08
    Type: Database references
  • Version 1.2: 2012-04-11
    Type: Database references