Molecular characterization of the interaction of staphylococcal microbial surface components recognizing adhesive matrix molecules (MSCRAMM) ClfA and Fbl with fibrinogen

Research output: Contribution to journalArticle

Abstract

The ligand-binding domain of Fbl (the fibrinogen binding protein from Staphylococcus lugdunensis) shares 60% sequence identity with ClfA (clumping factor A) of Staphylococcus aureus. Recombinant Fbl corresponding to the minimum fibrinogen-binding region (subdomains N2N3) was compared with ClfA for binding to fibrinogen. Fbl and ClfA had very similar affinities for fibrinogen by surface plasmon resonance. The binding site for Fbl in fibrinogen was localized to the extreme C terminus of the fibrinogen gamma-chain at the same site recognized by ClfA. Isothermal titration calorimetry showed that Fbl and ClfA had very similar affinities for a peptide mimicking the C-terminal segment of the fibrinogen gamma-chain. The peptide also inhibited binding of Fbl and ClfA to fibrinogen. A series of substituted gamma-chain variant peptides behaved very similarly when used to inhibit ClfA and Fbl binding to immobilized fibrinogen. Both ClfA and Fbl bound to bovine fibrinogen with a lower affinity compared with human fibrinogen and did not bind detectably to ovine fibrinogen. The structure of the N2N3 subdomains of Fbl in complex with the fibrinogen gamma-chain peptide was modeled based on the crystal structure of the N2N3 subdomains of the ClfA-gamma-chain peptide complex. Residues in the putative binding trench likely to be involved in fibrinogen binding were identified. Fbl variant proteins with alanine substitutions in key residues had reduced affinities for fibrinogen. Thus Fbl and ClfA bind the same site in fibrinogen by similar mechanisms.

Details

Authors
  • Joan A Geoghegan
  • Vannakambadi K Ganesh
  • Emanuel Smeds
  • Xiaowen Liang
  • Magnus Höök
  • Timothy J Foster
External organisations
  • Trinity College Dublin
Research areas and keywords

Keywords

  • Adhesins, Bacterial/metabolism, Bacterial Adhesion, Binding Sites, Coagulase/metabolism, Fibrinogen/metabolism, Protein Binding, Staphylococcus/chemistry
Original languageEnglish
Pages (from-to)6208-16
JournalThe Journal of biological chemistry
Volume285
Issue number9
Publication statusPublished - 2010
Publication categoryResearch
Peer-reviewedYes
Externally publishedYes