Structural basis for engagement by complement factor H of C3b on a self surface

Nat Struct Mol Biol. 2011 Apr;18(4):463-70. doi: 10.1038/nsmb.2018. Epub 2011 Feb 13.


Complement factor H (FH) attenuates C3b molecules tethered by their thioester domains to self surfaces and thereby protects host tissues. Factor H is a cofactor for initial C3b proteolysis that ultimately yields a surface-attached fragment (C3d) corresponding to the thioester domain. We used NMR and X-ray crystallography to study the C3d-FH19-20 complex in atomic detail and identify glycosaminoglycan-binding residues in factor H module 20 of the C3d-FH19-20 complex. Mutagenesis justified the merging of the C3d-FH19-20 structure with an existing C3b-FH1-4 crystal structure. We concatenated the merged structure with the available FH6-8 crystal structure and new SAXS-derived FH1-4, FH8-15 and FH15-19 envelopes. The combined data are consistent with a bent-back factor H molecule that binds through its termini to two sites on one C3b molecule and simultaneously to adjacent polyanionic host-surface markers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Complement C3b / chemistry*
  • Complement C3b / genetics
  • Complement C3b / metabolism
  • Complement Factor H / chemistry*
  • Complement Factor H / genetics
  • Complement Factor H / metabolism
  • Crystallography, X-Ray
  • Models, Molecular
  • Mutagenesis
  • Nuclear Magnetic Resonance, Biomolecular
  • Protein Conformation


  • Complement C3b
  • Complement Factor H

Associated data

  • PDB/3OXU