MULTIPLE BINDING-SITES IN THE INTERACTION BETWEEN AN EXTRACELLULAR FIBRINOGEN-BINDING PROTEIN FROM STAPHYLOCOCCUS-AUREUS AND FIBRINOGEN

Efb (previously Fib) is a fibrinogen-binding protein secreted by Staph ylococcus aureus. It has previously been shown that it plays a role in a wound infection model in the rat and that antibodies against Efb re duce the number of recovered bacteria from the mammary glands in a mou se mastitis model. Efb binds to the alpha-chain of fibrinogen and does not participate in bacterial adherence to fibrinogen. The binding of Efb to fibrinogen is divalent, with one binding site within the two re peat regions in Efb at the N terminus and one binding site at the C te rminus. The divalent binding nature leads to precipitation of Efb-fibr inogen complex when the proteins are added to each other at a 1:1 mola r ratio. The interaction between Efb and fibrinogen is strongly enhanc ed by Ca2+ or Zn2+ but not by Mg-2.