2QY0

Active dimeric structure of the catalytic domain of C1r reveals enzyme-product like contacts

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.60 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.211 
  • R-Value Observed: 0.213 

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This is version 1.1 of the entry. See complete history. 


Literature

Revisiting the mechanism of the autoactivation of the complement protease C1r in the C1 complex: Structure of the active catalytic region of C1r.

Kardos, J., Harmat, V., Pallo, A., Barabas, O., Szilagyi, K., Graf, L., Naray-Szabo, G., Goto, Y., Zavodszky, P., Gal, P.

(2008) Mol Immunol 45: 1752-1760

  • DOI: 10.1016/j.molimm.2007.09.031
  • Primary Citation of Related Structures:  
    2QY0

  • PubMed Abstract: 

    • C1r is a modular serine protease which is the autoactivating component of the C1 complex of the classical pathway of the complement system. We have determined the first crystal structure of the entire active catalytic region of human C1r. This fragment c ...

    C1r is a modular serine protease which is the autoactivating component of the C1 complex of the classical pathway of the complement system. We have determined the first crystal structure of the entire active catalytic region of human C1r. This fragment contains the C-terminal serine protease (SP) domain and the preceding two complement control protein (CCP) modules. The activated CCP1-CCP2-SP fragment makes up a dimer in a head-to-tail fashion similarly to the previously characterized zymogen. The present structure shows an increased number of stabilizing interactions. Moreover, in the crystal lattice there is an enzyme-product relationship between the C1r molecules of neighboring dimers. This enzyme-product complex exhibits the crucial S1-P1 salt bridge between Asp631 and Arg446 residues, and intermolecular interaction between the CCP2 module and the SP domain. Based on these novel structural information we propose a new split-and-reassembly model for the autoactivation of the C1r. This model is consistent with experimental results that have not been explained adequately by previous models. It allows autoactivation of C1r without large-scale, directed movement of C1q arms. The model is concordant with the stability of the C1 complex during activation of the next complement components.

    Organizational Affiliation: 

    Department of Biochemistry, Institute of Biology, Eötvös Loránd University, Pázmány sétány 1/C, Budapest H-1117, Hungary.



Macromolecules
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(by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Complement C1r subcomponent A, C159Homo sapiensMutation(s): 0 
Gene Names: C1R
EC: 3.4.21.41
Find proteins for P00736 (Homo sapiens)
Explore P00736 
Go to UniProtKB:  P00736
NIH Common Fund Data Resources
PHAROS:  P00736
Protein Feature View
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  • Reference Sequence
Find similar proteins by: 
(by identity cutoff)  |  Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Complement C1r subcomponent B, D242Homo sapiensMutation(s): 0 
Gene Names: C1R
EC: 3.4.21.41
Find proteins for P00736 (Homo sapiens)
Explore P00736 
Go to UniProtKB:  P00736
NIH Common Fund Data Resources
PHAROS:  P00736
Protein Feature View
Expand
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.60 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.211 
  • R-Value Observed: 0.213 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 74.541α = 90
b = 92.416β = 90
c = 162.848γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
ADSCdata collection
MOSFLMdata reduction
SCALAdata scaling
BEASTphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2008-02-05
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Advisory, Version format compliance