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

Abstract

Medical implants, like cardiovascular devices, improve the quality of life for countless individuals but may become infected with bacteria like Staphylococcus aureus. Such infections take the form of a biofilm, a structured community of bacterial cells adherent to the surface of a solid substrate. Every biofilm begins with an attractive force or bond between bacterium and substratum. We used atomic force microscopy to probe experimentally forces between a fibronectin-coated surface (i.e., proxy for an implanted cardiac device) and fibronectin-binding receptors on the surface of individual living bacteria from each of 80 clinical isolates of S. aureus. These isolates originated from humans with infected cardiac devices (CDI; n = 26), uninfected cardiac devices (n = 20), and the anterior nares of asymptomatic subjects (n = 34). CDI isolates exhibited a distinct bindingforce signature and had specific single amino acid polymorphisms in fibronectin-binding protein A corresponding to E652D, H782Q, and K786N. In silico molecular dynamics simulations demonstrate that residues D652, Q782, and N786 in fibronectin-binding protein A form extra hydrogen bonds with fibronectin, complementing the higher binding force and energy measured by atomic force microscopy for the CDI isolates. This study is significant, because it links pathogenic bacteria biofilms from the length scale of bonds acting across a nanometer-scale space to the clinical presentation of disease at the human dimension.adhesion | binding strength | host-pathogen interaction | pacemaker | prosthesis

Staphylococcus aureus Infections: Epidemiology, Pathophysiology, Clinical Manifestations, and Management

“…This binding of S. aureus FnBPA to human fibronectin is thought to be a critical initial step in the pathogenesis of prosthetic device infections (577). Lower et al showed that specific single nucleotide polymorphisms in fnbA were associated with (i) greater in vitro binding to fibronectin, as assessed by atomic force microscopy; (ii) a higher number of hydrogen bonds between fibronectin and FnBPA in a simulated model system; and (iii) a higher risk of cardiac device infection (CDI) in patients with SAB (578).…”

Plasmonic imaging of protein interactions with single bacterial cells

“…The surfaces of bacteria act as the first line of defense against harmful external stimuli, including antibiotics (Delcour, 2009) and antimicrobial peptides, (Fantner et al, 2010;Sochacki et al, 2011) and also play crucial roles in interacting with other surfaces, including host tissues (Van Houdt and Michiels, 2005) and medical plastics, (Lower et al, 2011) to help bacterial cells attach and colonize. In order to survive in a changing environment, bacteria replicate and evolve quickly, (Carnes et al, 2010;van der Mei and Busscher, 2012) leading to diversity of different bacteria species, and variability within the same species.…”

“…The data generated with these bulk assays are averaged over many bacteria, which wash out important variability or heterogeneity of different bacterial cells. Various imaging techniques, such as fluorescence (Cywes--Bentley et al, 2013;Sochacki et al, 2011), AFM (Fantner et al, 2010;Lower et al, 2011) and transmission electron microscopy (TEM) (Cywes--Bentley et al, 2013), and non--imaging microfluidics techniques, such as flow cytometry (Tracy et al, 2010) and micro electrophoresis (van der Mei and Busscher, 2012), have been used to study bacterial surfaces. These techniques have contributed to the understanding of bacteria, but each has disadvantages.…”

“…(Fantner et al, 2010;Lower et al, 2011) The ex situ approaches include the study of reconstituted artificial membranes (Früh et al, 2011;Hirst et al, 2013), membrane protein embedded liposomes (Liu and Boyd, 2013), and extracted surface constituents (e.g., membrane proteins (Holden et al, 2006) and sugars (Grant et al, 2008) from bacteria. Given the complexity of the bacteria, in situ study of intact bacterial cells in their native environments are more attractive.…”

Molecular interactions and inhibition of the staphylococcal biofilm-forming protein SdrC

“…Among these new tools, atomic force microscopy (AFM) allows us to analyze the organization, biophysical properties, and interactions of cell-wall molecules directly in single cells (14,15). During the past years, there has been much progress in applying AFM techniques to explore the forces involved in cell adhesion and biofilm formation by staphylococci, down to molecular resolution (16)(17)(18)(19)(20)(21)(22)(23). Here, we used AFM to study the forces guiding the self-association of the S. aureus serine-aspartate repeat protein SdrC (Fig.…”