ABSTRACT
1. Microbial pathogenicity is in many instances associated with the ability to adhere to host surfaces or to extracellular matrix components. 2. Laminin is a major glycoprotein of basement membranes which can promote specific bacterial adhesion. Staphylococcus aureus is a pathogenic bacterium which presents a laminin receptor of about 50-kDa molecular mass (Lopes JD, Reis M per cent Brentani RR (1985). Science, 229: 275-277). 3. Adhesion inhibition assays of [125iodine]-labeled bacteria to laminin demonstrate that the receptor binding site is contained in the pepsin-derived (P1) laminin fragment. 4. Cell adhesion to laminin is unaffected by periodate oxidation of sugars on the surface of bacteria or by removal of divalent cations by ethylenediaminetetraacetic acid (EDTA). In contrast, bacterial adhesion is reduced when laminin is deglycosylated with N-glycosidase F or when bacteria are submitted to controlled trypsin digestion. 5. Laminin binding to the S. aureus 50-kDa band in immunoblotting assays has confirmed all of these results obtained in cell adhesion experiments