The Structure and Function of Serum Opacity Factor: A Unique Streptococcal Virulence Determinant That Targets High-Density Lipoproteins

Figure 9

Model of quaternary complex between gelatin, fibronectin, fibulin-1, and SOF. Although SOF can bind to fibulin-1 independently of fibronectin, mixed binding experiments indicated that SOF binds much better to a complex of fibulin-1, fibronectin, and gelatin. Such complexes are possible because fibronectin contains independent binding sites for gelatin (collagen), fibulin-1, and SOF. Also SOF can react with fibulin-1 and fibronectin via independent binding domains. It is postulated that interactions between gelatin and fibronectin induces a conformational change in fibronectin that facilitates interactions with other ligands and SOF and enhances adhesion of streptococci to host surfaces. Reproduced from [49] with permission.