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

细胞粘附在材料表面的蛋白质对许多生物医学和生物技术应用至关重要，包括生物材料、组织工程和体外细胞培养系统。细胞对细胞外蛋白的附着主要是由细胞表面受体的整合素家族介导的。整合素与细胞外基质成分中的特定氨基酸序列结合。例如，整合素a5b1结合到纤维连接蛋白（Fn）的PHSRN和RGD结构域。这种相互作用是由两个结构域的相对结构取向控制的，这两个结构域相距3-4 nm。每个结构域单独对结合的贡献很小，但在结合时，它们协同结合受体，产生显著的粘附性增加。此外，在表面吸附后，Fn发生了结构变化，改变了a5b1的结合，这表明这些结合域的相对方向发生了变化。这个项目的重点是模拟Fn （FnIII7-10）的一个特征片段（包含PHSRN和RGD结合位点）在自组装的烷硫醇单层上的吸附，这些单层具有明确的表面化学成分（CH3, NH2， COOH和OH）。具体来说，我们采用创新的实验和计算方法来模拟PHSRN和RGD结构域相对方向的变化，以及这些结构变化与整合素结合之间的关系。首先，利用单克隆抗体和分子模拟获得的结构和热力学信息来表征吸附的FnIII7-10的构象。然后分析整合素a5b1与吸附的FnIII7-10的功能结合，以粘附强度和相对结合亲和力为特征，并与结构参数相关联。通过整合实验和计算方法，该分析将提供蛋白质-表面相互作用的机制理解以及吸附诱导的蛋白质功能结构变化的作用。最后，提出的研究将提供一个适用于其他蛋白质/表面的分析框架

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