Fibronectin binding by Propionibacterium acnes

Strains of Propionibacterium acnes, isolated from different kinds of orthopaedic and biomaterial-associated infections and from skin flora were shown to express binding of soluble as well as immobilized fibronectin. Among these 7 strains isolated from orthopaedic infections, 2 from breast prostheses, and 9 skin isolates, 2, 2, and 5 strains respectively bound immobilized fibronectin. The fibronectin binding was sensitive to protease and heat treatment, and was inhibited by a cell surface extract from one of the binding strains. In SDS-PAGE and autoradiography of cell surface extracts, a band corresponding to a MW of about 80 kD reacted with fibronectin and the 150 kD fragment of fibronectin. Binding to fibronectin and the 150 kD fragment of fibronectin could be inhibited with heparin. We thus present a first Fn binding protein of P. acnes, a surface exposed protein of 80 kD. None of the strains bound soluble collagen, and only one strain expressed weak binding of vitronectin and bone sialoprotein II.