Molecular characterization and expression of a gene encoding a Staphylococcus aureus collagen adhesin

Some strains of Staphylococcus aureus bind collagen with a high degree of specificity and affinity. This interaction can represent a mechanism of substrate adhesion and may be an important step in the pathogenesis of osteomyelitis and infectious arthritis. We now report on the cloning, sequencing, and expression of a gene named cna, encoding a S. aureus collagen adhesin. The cna gene was isolated from a λGT11 S. aureus genomic library and encodes an 1185 amino acid polypeptide. The deduced amino acid sequence reveals several structural characteristics similar to previously described Gram-positive bacterial cell surface proteins. Antibodies raised against the native collagen adhesin from S. aureus recognize the recombinant collagen adhesin. Collagen binding activity can be detected in a lysate obtained from Escherichia coli cells, which harbor the cloned cna gene on an expression plasmid. Collagen-binding proteins can be detected in the lysate when analyzed by a Western blot type assay in which the membrane-transferred proteins are probed with radioactively labeled collagen. Finally, the bacterial lysate containing the recombinant adhesin can effectively inhibit the binding of soluble collagen to cells of S. aureus.