Format

Send to

Choose Destination
Eur J Immunol. 2003 Apr;33(4):962-9.

A common site within factor H SCR 7 responsible for binding heparin, C-reactive protein and streptococcal M protein.

Author information

1
Department of Microbiology and Infectious Diseases, Flinders Medical Centre, Adelaide, Australia.

Abstract

The complement inhibitor factor H (fH) interacts via its seventh short consensus repeat (SCR) domain with multiple ligands including heparin, streptococcal M protein and C-reactive protein (CRP). The aim of this study was to localize the residues in SCR 7 required for these interactions. We initially built a homology model of fH SCR 6-7 using the averaged NMR structures of fH SCR 15-16 and vaccinia control protein SCR 3-4 as templates. Electrostatic potentials of the model's surface demonstrated a co-localization of three clusters of positively charged residues on SCR 7, labeled site A (R369 and K370), site B (R386 and K387) and site C (K392). These residues, localized to the linker region preceding SCR 7 and to the end of a "hypervariable loop" in SCR 7, were systematically replaced with uncharged alanine residues in an fH construct containing SCR 1-7. The resulting proteins were expressed in the methylotrophic yeast, Pichia pastoris. By ELISA analysis we demonstrated: first, that substituting site A inhibited heparin and CRP binding; secondly, that substituting site B inhibited binding to heparin, CRP and M protein; and thirdly, that substituting site C clearly inhibited only heparin binding.

PMID:
12672062
DOI:
10.1002/eji.200323541
[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center