NANOSCALE: Structural Changes in Fibronectin Binding Domains upon Adsorption to Well-Defined Surface Chemistries

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

Cell adhesion to proteins adsorbed onto material surfaces is critical to numerous biomedical and biotechnological applications, including biomaterials, tissue engineering, and in vitro cell culture systems. Cell attachment to extracellular proteins is primarily mediated by the integrin family of cell surface receptors. Integrins bind to specific amino acid sequences in extracellular matrix components. For example, integrin a5b1 binds to the PHSRN and RGD domains in fibronectin (Fn). This interaction is controlled by the relative structural orientation of these two domains, which are 3-4 nm apart. Each domain independently contributes little to binding, but in combination, they synergistically bind to the receptor to produce significant increases in adhesion. Moreover, upon adsorption to surfaces, Fn undergoes structural changes that modify a5b1 binding, suggesting changes in the relative orientation of these binding domains. This project focuses on modeling the adsorption of a well-characterized fragment of Fn (FnIII7-10), which contains the PHSRN and RGD binding sites, onto self-assembled monolayers of alkanethiols presenting well-defined surface chemistries (CH3, NH2, COOH, and OH). Specifically, innovative experimental and computational approaches are integrated to model changes in the relative orientation of the PHSRN and RGD domains and the relationship between these structural changes and integrin binding. First, the conformation of adsorbed FnIII7-10 will be characterized using monoclonal antibodies and structural and thermodynamic information obtained from molecular simulations. The functional binding of integrin a5b1 to adsorbed FnIII7-10, characterized by adhesion strength and relative binding affinity, will then be analyzed and correlated to the structural parameters. By integrating experimental and computational approaches, this analysis will provide a mechanistic understanding of protein-surface interactions and the role of adsorption-induced structural changes in protein function. Finally, the proposed research will provide an analytical framework that is applicable to other protein/surface