Streptavidin is widely used as an adaptor molecule in diagnostics, separati
ons, and laboratory assay applications. We have here engineered cell adhesi
ve peptides into the three-dimensional scaffolding of streptavidin to conve
rt streptavidin into a functional protein. The mutations did not alter refo
lding or tetramer assembly and the slow biotin dissociation rate of wild-ty
pe streptavidin was retained. The peptide targets were hexapeptide sequence
s derived from osteopontin and fibronectin that contain the RGD cell adhesi
on sequence. Cell binding assays directly demonstrated that I at aortic end
othelial cells and human melanoma cells adhered to surfaces coated with eit
her of the two RGD streptavidin mutants in a dose-dependent fashion. Wildty
pe streptavidin displayed no significant cell binding activity. Inhibition
studies with soluble RGD peptides confirmed that the cell adhesion was RGD
mediated. Further inhibition studies with antibodies directed against alpha
(v)beta(3) demonstrated that the RGD-streptavidin interaction was primarily
mediated by this integrin with melanoma cells. These results demonstrate t
hat peptide recognition sequences can be engineered into accessible surface
regions of streptavidin without disrupting biotin binding properties. This
approach to introducing secondary functional activities into streptavidin
may improve streptavidin's utility in existing applications or provide new
technology opportunities.