Staphylococcus aureus -Fibronectin Interactions with and without Fibronectin-Binding Proteins and Their Role in Adhesion and Desorption

Abstract

Adhesion and residence-time-dependent desorption of two Staphylococcus aureus strains with and without fibronectin (Fn) binding proteins (FnBPs) on Fn-coated glass were compared under flow conditions. To obtain a better understanding of the role of Fn-FnBP binding, the adsorption enthalpies of Fn with staphylococcal cell surfaces were determined using isothermal titration calorimetry (ITC). Interaction forces between staphylococci and Fn coatings were measured using atomic force microscopy (AFM). The strain with FnBPs adhered faster and initially stronger to an Fn coating than the strain without FnBPs, and its Fn adsorption enthalpies were higher. The initial desorption was high for both strains but decreased substantially within 2 s. These time scales of staphylococcal bond ageing were confirmed by AFM adhesion force measurement. After exposure of either Fn coating or staphylococcal cell surfaces to bovine serum albumin (BSA), the adhesion of both strains to Fn coatings was reduced, suggesting that BSA suppresses not only nonspecific but also specific Fn-FnBP interactions. Adhesion forces and adsorption enthalpies were only slightly affected by BSA adsorption. This implies that under the mild contact conditions of convective diffusion in a flow chamber, adsorbed BSA prevents specific interactions but does allow forced Fn-FnBP binding during AFM or stirring in ITC. The bond strength energies calculated from retraction force-distance curves from AFM were orders of magnitude higher than those calculated from desorption data, confirming that a penetrating Fn-coated AFM tip probes multiple adhesins in the outermost cell surface that remain hidden during mild landing of an organism on an Fn-coated substratum, like that during convective diffusional flow.Staphylococcus aureus is a versatile pathogen which can adhere to epithelial cells, endothelial cells, and fibroblasts, as well as to plasma-exposed biomaterial implant surfaces in the human body (12), causing potentially persistent infections. The best-described mechanism of S. aureus adhesion to eukaryotic cells and other fibronectin ( At constant temperature and pressure, bacterial adhesion to surfaces is accompanied by a decrease in the Gibbs energy (⌬G). ⌬G is composed of a change in enthalpy (⌬H) and a change in entropy (⌬S) according to the following equation:where T is the temperature (in Kelvin). The enthalpy tends to reach a minimum value, whereas the entropy strives for a maximum value. The change in enthalpy can be determined by determining the heat exchange between a system and its environment, while direct determination of the entropy is practically impossible. Many biological processes are characterized by strong enthalpy-entropy compensation (10); that is, they occur spontaneously by virtue of an increase in entropy that compensates for an unfavorable enthalpy effect or vice versa. The enthalpy of the interaction between bacterial cell surfaces and proteins can be assessed using isothermal titration calorimetry (ITC). Xu et al. (28) determined the adso...

Adhesive Bond Stiffness of Staphylococcus aureus with and without Proteins That Bind to an Adsorbed Fibronectin Film

“…As staphylococci subsequently adhered to the fibronectincoated surface, the frequency shift became more negative and the bandwidth further increased. S. aureus 8325-4, possessing FnBPs, yielded a negative frequency shift after 1 h of adhesion of around 8 Hz and a bandwidth increase of 18 Hz, whereas DU5883, without FnBPs, yielded a much more negative frequency shift of 30 Hz and a bandwidth increase of 25 Hz.…”

“…aureus can bind to plasma-exposed surfaces through the use of fibronectin binding proteins (FnBPs) (3,4,13,19,21,22). Xu et al (25) have determined the adhesion kinetics, desorption rates, and adhesion enthalpies, as well as the adhesion forces and energies, of S. aureus strains with and without FnBPs. Strain 8325-4, known to possess FnBPs, adhered to Fn-coated glass in higher numbers than strain DU5883, which lacks FnBPs.…”

Polymorphisms in fibronectin binding protein A of Staphylococcus aureus are associated with infection of cardiovascular devices

“…The binding forces that initiate a biofilm have been investigated for a handful of typestrains or laboratory-derived strains of S. aureus (e.g., refs. [16][17][18][19][20] and related species such as Staphylococcus epidermidis (e.g., ref. 21).…”

Influence of biomaterial nanotopography on the adhesive and elastic properties of Staphylococcus aureus cells

“…Altogether, these results suggest that both contact time and surface nanopatterning directly influence the early-adhesion of S. aureus to PC surfaces. In the literature, SCFS of S. aureus strain 8325-4 has been previously employed to measure its adhesion with Candida albicans hyphae and yeast cells and fibronectin-functionalised AFM cantilevers 35,36 . In both cases, reported adhesion forces were of higher magnitudes than the ones observed in the present study between S. aureus and PC.…”