Binding sites for streptococci and staphylococci in fibronectin.
Purified cathepsin G fragments of fibronectin were used to locate the binding sites for streptococci and staphylococci in the fibronectin molecule. The iodinated, NH2-terminal, 30-kilodalton (kd) fragment bound to group A and G streptococci and to Staphylococcus aureus. The 125I-labeled, COOH-terminal, 120- to 140-kd fragment bound weakly to group A streptococcus strain and to S. aureus when tested in a buffer of low ionic strength. The 30- and 120- to 140-kd fragments inhibited the binding of iodinated fragments to bacteria. The two fragments were, on a molar basis, equally effective, and they were more potent inhibitors than intact fibronectin. The gelatin-binding 40-kd fragment neither bound to any of the bacterial strains nor inhibited the binding of 125I-labeled 30-kd or 125I-labeled 120- to 140-kd fragments to bacteria. The results indicate that fibronectin has at least two separate binding sites for streptococci and staphylococci, one in the NH2-terminal region and another in the COOH-terminal region of the molecule, both capable of specific interaction with a complementary structure exposed on streptococcal and staphylococcal cell surfaces.
D001665:Binding Sites; D005353:Fibronectins / Q000378:metabolism*; D008970:Molecular Weight; D010446:Peptide Fragments / Q000378:metabolism; D013211:Staphylococcus aureus / Q000378:metabolism*; D013291:Streptococcus / Q000378:metabolism*; D013329:Structure-Activity Relationship
D005353:Fibronectins; D010446:Peptide Fragments