Location: Children's Nutrition Research CenterTitle: Binding of Efb from Staphylococcus aureus to fibrinogen blocks neutrophil adherence) Author
Submitted to: Journal of Biological Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2011
Publication Date: 1/19/2011
Citation: Ko, Y., Liang, X., Smith, W.C., Degen, J.L., Hook, M. 2011. Binding of Efb from Staphylococcus aureus to fibrinogen blocks neutrophil adherence. Journal of Biological Chemistry. 286(11):9865-9874. Interpretive Summary: Inflammation plays a very important role in the body’s ability to resist infections, heal injured tissue and respond to cancer. We are interested in the influence of nutrition on inflammation and we study very basic mechanisms of inflammation. In this paper we analyze how one type bacterium called Staphylococcus is able to interfere with the ability of white blood cells to resist infection. The evidence presented in this paper shows that the bacteria produces a chemical that blocks the ability of white blood cells to adhere to tissue cells. This blocks the ability of the white blood cells to crawl toward the site of infection.
Technical Abstract: In addition to its pivotal role in hemostasis, fibrinogen (Fg) and provisional fibrin matrices play important roles in inflammation and regulate innate immune responses by interacting with leukocytes. Efb (the extracellular fibrinogen-binding protein) is a secreted Staphylococcus aureus protein that engages host Fg and complement C3. However, the molecular details underlying the Efb-Fg interaction and the biological relevance of this interaction have not been determined. In the present study, we characterize the interaction of Efb with Fg. We demonstrate that the Fg binding activity is located within the intrinsically disordered N-terminal half of Efb (Efb-N) and that the D fragment of Fg is the region that mediates Efb-N binding. More detailed studies of the Efb-N-Fg interactions using ELISA and surface plasmon resonance analyses revealed that Efb-N exhibits a much higher affinity for Fg than typically observed with Fg-binding MSCRAMMs (microbial surface components recognizing adhesive matrix molecules), and data obtained from ELISA analyses using truncated Efb-N constructs demonstrate that Efb-N contains two binding sites located within residues 30-67 and 68-98, respectively. Efb-N inhibits neutrophil adhesion to immobilized Fg by binding to Fg and blocking the interaction of the protein with the leukocyte integrin receptor, a (M)ß(2). A motif in the Fg ' chain previously shown to be central to the a (M)ß(2) interaction was shown to be functionally distinguishable from the Efb-N binding site, suggesting that the Fg-Efb interaction indirectly impedes Fg engagement by a (M)ß(2). Taken together, these studies provide insights into how Efb interacts with Fg and suggest that Efb may support bacterial virulence at least in part by impeding Fg-driven leukocyte adhesion events.