The binding of Pseudomonas aeruginosa outer membrane ghosts to human buccal epithelial cells

The binding of outer membrane (OM) ghosts derived from Pseudomonas aeruginosa strain 492c to human buccal epithelial cells (BECs) was examined. Electron microscopic examination of the binding of OM ghosts to BECs revealed direct OM ghost-BEC interaction. Equilibrium analysis of the binding of OM ghosts to trypsinized BECs employing the Langmuir adsorption isotherm indicated the number of binding sites (N) to be 1.3 X 10(-4) micrograms protein per BEC with an apparent association constant (Ka) of 3.4 X 10(-2) mL/microgram protein. The Langmuir analysis of binding of OM ghosts to untrypsinized BECs was complex, suggesting two possible classes of receptors, a high affinity-low copy number class (Ka, 7.8 X 10(-2)mL/microgram protein; N, 8.6 X 10(-5) microgram protein per BEC) and a low affinity-high copy number class (Ka, 3.7 X 10(-3)mL/microgram protein; N, 9.2 X 10(-4)microgram protein per BEC). Sugar inhibition studies incorporating D-galactose enhanced binding to each BEC type. N-Acetylneuraminic acid and N-acetylglucosamine both enhanced binding of OM ghosts to untrypsinized BECs, while inhibiting binding to trypsinized BECs. D-Arabinose inhibited binding to both BEC types. Binding of OM ghosts to both BEC types was greatly inhibited by D-fucose, while L-fucose only greatly inhibited binding to untrypsinized BECs. These sugar inhibition data demonstrated a difference in the binding of OM ghosts to trypsinized and untrypsinized BECs and possibly reveal the nature of the receptor(s), free of possible bacterial metabolic effects.(ABSTRACT TRUNCATED AT 250 WORDS)