Abstract
In a previous study we demonstrated that cells of Staphylococcus aureus strain Cowan bind 125I-collagen in a receptor-ligand type of interaction (Speziale, P., Raucci, G., Visai, L., Switalski, L.M., Timpl, R., and Höök, M. (1986) J. Bacteriol. 167, 77-81). In the present communication we report on the isolation and preliminary characterization of a putative collagen receptor from a lysate of S. aureus strain Cowan. Antibodies raised against a collagen receptor positive strain inhibit the binding of 125I-collagen to bacterial cells, whereas antibodies raised against a collagen receptor negative strain were without effect. Solubilized cell surface components did not exhibit any measurable affinity for collagen-Sepharose. However, the inhibitory effect of the antibodies against bacterial cells was neutralized by the lysate from a receptor-positive but not receptor-negative strain. A collagen receptor assay was designed based on this observation and used to develop a receptor purification protocol involving anion exchange chromatography, ammonium sulfate precipitation, and gel chromatography. Using this procedure a protein with an apparent Mr of 135,000 was purified. This protein which was present on a collagen receptor-positive strain but not on a receptor-negative strain could completely neutralize the inhibitory activity of the antibodies raised against S. aureus strain Cowan. Furthermore, antibodies raised against the 135-kDa protein inhibited the binding of collagen to bacteria, and this protein is tentatively identified as a collagen receptor.
Highlights
A bacterial cell may simultaneously express receptors forseveral matrixproteins
Residual binding by enzyme-treated cells was quantified and compared with that of untreated bacteria (Fig. 1).Bacterial cells digested with proteolytic enzymes, trypsin, thermolysin, and papain, lost essentially all collagen binding activity as did bacteria treated withpeptidoglycan degrading enzyme, lysostaphin
Material released from bacteria during enzymedigestion was tested for its ability to inhibit '251-co11agenbinding to intact cells
Summary
A bacterial cell may simultaneously express receptors (adhesins) forseveral matrixproteins. Many potentially pathogenic microorganismsbind to extracellular matrix proteins such as fibrinogen, fibronectin, and gen were found suggesting that to inhibit the bindinogf staphylococci recognize collagen to bacteria, repetitive structures laminin. Itis believed that these interactions represenmtech- in the collagen molecule (Speziale et al, 1986). Bacterial cells possess spe- A collagen receptor from bacteria has previously not been cific receptor’ molecules on their surface which bind to dis- identified In this communication we report on the isolation tinct sites in the matrix proteinosf the host
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