Binding of human clusterin byStaphylococcus epidermidis

To hypothesise that Staphylococcus epidermidis may possess clusterin receptor(s), bacterial binding of human clusterin was determined. In a fluid phase, the binding was markedly influenced by culture medium and three out of 12 S. epidermidis strains grown on ISO-sensitest agar expressed clusterin-binding ability. S. epidermidis J9P, selected for further study, showed saturable binding of iodine-labelled clusterin, and the binding was only inhibited by unlabelled clusterin. The binding was sensitive to protease treatment. Scatchard plot indicated one single class of binding sites (K(d)=104.2 nM). None of the S. epidermidis strains bound immobilised clusterin. These data imply that ligand-receptor interaction exists between S. epidermidis and clusterin in fluid phase, but the domain(s) recognised by bacteria may have been occluded when clusterin was adsorbed on a surface.