Transformation of a plasmid encoding an adhesin of Staphylococcus aureus into a nonadherent staphylococcal strain

Plasmid DNA was isolated and purified from a strain of Staphylococcus aureus demonstrating adherence to human epithelial cells, as determined by an assay quantitating adherence of radiolabeled S. aureus to HeLa cells in tissue culture. Other phenotypic characteristics of the donor strain are resistance to ampicillin and absence of hemolysis. A 23.5-kb (kilobase) plasmid was transformed into a nonadherent, ampicillin-sensitive, beta-hemolytic recipient of S. aureus, rendering it both ampicillin-resistant and adherent to a degree approaching that of the donor strain. Plasmid analysis of the donor and transformant strains revealed three identical EcoRI fragments of 7.6 kb, 6.5 kb, and 2.2 kb, together with a 3.6-kb EcoRI fragment in the transformant that demonstrated homology with the last 7.2-kb fragment in the donor. We conclude that an adhesin of S. aureus is encoded by this 23.5-kb penicillinase-encoding plasmid and that techniques of molecular genetics may be utilized to clarify the mechanisms of adherence of S. aureus.