The ability of bacteria to bind fibronectin is thought to enable the colonisation of wound tissue and blood clots. The fibronectin binding repeat is found in bacterial fibronectin binding proteins and serum opacity factor. Bacterial fibronectin binding proteins are surface proteins that covalently link to the bacterial cell wall, mediate adherence of the bacteria to host cells and trigger the fibronectin/integrin-mediated uptake of bacteria by host cells. Each fibronectin binding repeat is an array of short motifs that bind to fibronectin type I domains. Fibronectin binding repeats are natively unfolded in the absence of fibronectin and are thought to adopt a well-defined conformation (tandem beta-zipper) upon binding.