Abstract
We have identified a discrete collagen-binding site within the Staphylococcus aureus collagen adhesin that is located in a region between amino acids Asp209 and Tyr233. Polyclonal antibodies raised against a recombinant form of the collagen adhesin inhibited the binding of collagen type II to S. aureus. When overlapping synthetic peptides mimicking segments of the adhesin fragment were tested for their ability to neutralize the inhibitory activity of the antibody only one peptide, CBD4 was found to be active. CBD4 bound directly to collagen and at high concentrations inhibited the binding of collagen to S. aureus. A synthetic peptide derivative of CBD4 lacking 2 carboxyl-terminal residues (Asn232, Tyr233) had no inhibitory activity. The importance of these residues for collagen binding was confirmed by biospecific interaction analysis. Mutant adhesin proteins N232-->A and Y233-->A exhibited dramatic changes in collagen binding activity. The dominant dissociation rate for the binding of mutant adhesin protein N232-->A to immobilized collagen II decreased almost 10-fold, while the Y233-->A and the double mutant exhibited even more significant decreases in affinity and apparent binding ratio when compared to the wild type protein.
Highlights
We have identified a discrete collagen-binding site within the Staphylococcus aureus collagen adhesin that is located in a region between amino acids Asp209 and Tyi-233 Polyclonal antibodies raised against a recombinant form of the collagen adhesin inhibited the binding of collagen type II to S. aureus
Staphylococcal strains recovered from the joints of patients diagnosed with septic arthritis or osteomyelitis almost invariably express a collagenbinding MSCRAMM, whereas significantly fewer isolates obtained from wound infections express this adhesin [2]
Taken together these results demonstrate that the collagen-binding MSCRAMM plays an important role in the pathogenesis of septic arthritis induced by S. aureus
Summary
Vol 270, No 20, Issue of May 19, pp. 12005-12011, 1995 Printed in U.S.A. Critical Residues in the Ligand-binding Site of the Staphylococcus aureus Collagen-binding Adhesin (MSCRAMM)*. Greater than 70% of mice injected with CNA+ strains (i.e. a clinical isolate expressing the collagen-binding MSCRAMM or a negative strain into which the cna gene had been introduced) developed clinical signs of arthritis, whereas less than 27% of the animals showed symptoms of disease when injected with CNAstrains (i.e. a strain lacking the cna gene or a strain in which the cna gene had been inactivated through homologous recombination). Taken together these results demonstrate that the collagen-binding MSCRAMM plays an important role in the pathogenesis of septic arthritis induced by S. aureus.
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