Biomedical subjects

M K Bodén

Publications and source records attributed to M K Bodén.

3 recordsLinked to original sources

PubMed1994

Cloning and characterization of a gene for a 19 kDa fibrinogen-binding protein from Staphylococcus aureus.

Staphylococcus aureus has been shown to interact specifically with fibrinogen. Three different extracellular fibrinogen-binding proteins, two of which have coagulase activity, are produced by S. aureus strain Newman. The role of these fibrinogen-binding proteins during staphylococcal colonization and infection has not yet been fully elucidated. Here we describe the cloning, sequencing and expression of a gene for a 19 kDa fibrinogen-binding protein. This gene, called fib, encodes a 165-amino-acid polypeptide, including a 29-amino-acid signal sequence. The recombinant protein, which has an estimated molecular mass of 15.9 kDa, bound fibrinogen and was recognized by a polyclonal antiserum against the native Fib protein. Homologies between the Fib protein and the fibrinogen-binding domain of coagulase suggest that amino acids within this domain are involved in the binding to fibrinogen.

Amino Acid Sequence↗

PubMed1992

Evidence for three different fibrinogen-binding proteins with unique properties from Staphylococcus aureus strain Newman.

Binding of extracellular components of Staphylococcus aureus strain Newman to fibrinogen and prothrombin was investigated. Affinity-purified material from fibrinogen- and prothrombin-Sepharose was analysed on immunoblots, and two proteins with coagulase activity were identified. The two coagulases were produced in a sequential manner during staphylococcal growth. An 87 kDa fibrinogen-binding coagulase was produced mainly during the exponential growth phase and was replaced by a 60 kDa fibrinogen- and prothrombin-binding coagulase which was produced mainly during the post-exponential growth phase. In addition, a 19 kDa fibrinogen-binding protein was constitutively produced. Analyses of immunogenic properties and NH2-terminal sequences suggested that the 19, 60 and 87 kDa fibrinogen-binding proteins are not closely related. The NH2-terminal sequence of the 87 kDa protein is identical to a previously described coagulase from Staphylococcus aureus strain 8325-4. The 19 kDa fibrinogen-binding protein, which spontaneously aggregates into dimers and larger molecular weight complexes, had a unique NH2-terminal sequence.

Amino Acid Sequence↗

PubMed1989

Fibrinogen-binding protein/clumping factor from Staphylococcus aureus.

The binding of staphylococcal components to fibrinogen was studied. Fibrinogen-binding material from lysed staphylococcal cells or culture supernatants was affinity purified on fibrinogen-Sepharose and analyzed on Western (immuno-) blots by the use of fibrinogen and antifibrinogen antibodies. Two main bands of 87 and 19 kilodaltons (kDa) and a weaker band of 35 kDa bound specifically to fibrinogen. A monoclonal antibody bound to all three bands, indicating that these were of the same origin. The yield of these components was much higher in the culture supernatant than on washed cells, suggesting that these molecules are essentially extracellular products. In a plasma coagulase test, the 87-kDa band, but not the 19-kDa band, clotted rabbit plasma, demonstrating that the 87-kDa molecule is coagulase. This was further confirmed by the fact that the 87-kDa band binds specifically to prothrombin. It was shown that the 87- and the 19-kDa molecules were present on the cell surface by surface labeling the cells with 125I. In addition, the fact that killed and washed cells could induce plasma clotting demonstrates that staphylococci have coagulase exposed on the surface. It was concluded that cell-bound coagulase has affinity for fibrinogen also in the absence of prothrombin and thus is responsible for the clumping of staphylococci in fibrinogen.

Bacterial Proteins↗