Yasser Bustanji, Carla Renata Arciola,
Matteo Conti, Enrico Mandello, Lucio Montanaro, Bruno Samorì.
the interaction between a Fibronectin molecule and a living bacterium under
Proc. Natl. Acad. Sci. USA. 2003, 100,13292.
Fibronectin (Fn) is an important mediator of bacterial invasions and of
persistent infections like that of Staphylococcus epidermdis. Similar to
many other types of cell–protein adhesion, the binding between Fn and S.
epidermidis takes place under physiological shear rates. We investigated the
dynamics of the interaction between individual living S. epidermidis
cells and single Fn molecules under mechanical force by using the scanning force
microscope. The mechanical strength of this interaction and the binding site in
the Fn molecule were determined. The energy landscape of the binding_unbinding
process was mapped, and the force spectrum and the association and dissociation
rate constants of the binding pair were measured. The interaction between S.
epidermidis cells and Fn molecules is compared with those of two other
protein_ligand pairs known to mediate different dynamic states of adhesion of
cells under a hydrodynamic flow: the firm adhesion mediated by biotin_avidin
interactions, and the rolling adhesion, mediated by L-selectin_P-selectin
glycoprotein ligand-1 interactions. The inner barrier in the energy landscape of
the Fn case characterizes a high-energy binding mode that can sustain larger
deformations and for significantly longer times than the correspondent
high-strength L-selectin_P-selectin glycoprotein ligand-1 binding mode. The
association kinetics of the former interaction is much slower to settle than the
latter. On this basis, the observations made at the macroscopic scale by other
authors of a strong lability of the bacterial adhesions mediated by Fn under
high turbulent flow are rationalized at the molecular level.