The Molecular Basis of Cadherin Adhesion

描述（由申请方提供）：钙粘蛋白是在所有软组织中介导细胞-细胞粘附的必需细胞表面蛋白。它们通过指导组织特异性细胞分离和分选，在发育和形态发生中发挥关键作用。一个主要的，未解决的问题涉及钙粘蛋白粘附和结合选择性的分子基础。有几个试图阐明钙粘蛋白功能的晶体结构的结构基础，但尽管许多生化和结构的研究，功能的粘附结构域的身份和钙粘蛋白结合的机制仍然存在争议。 在这项工作中，我们建议直接解决这个问题的实验方法，直接探测这些蛋白质的粘附功能。分子力探针提供了实现这一目标的手段。无论是表面力装置（SFA）和单分子动态力光谱（DFS）提供了一个强大的，互补的一套工具，独特地确定钙粘蛋白的粘附和选择性的分子机制。通过直接测量的距离依赖性钙粘蛋白与SFA的相互作用潜力，我们将获得独特的信息，关于钙粘蛋白对接对齐，因此，介导结合的蛋白质区域。这些信息，这不能直接获得任何其他现有技术，将有助于识别的粘附胞外域段，从而直接测试几个关键的假设有关的身份的功能性钙粘蛋白结构域。另一方面，提出的DFS测量将揭示单个钙粘蛋白键的细微细节，这些细节可能从群体平均的SFA测量中不明显，但仍然可以控制钙粘蛋白识别。这些后者的测量将测试的假设，即在钙粘蛋白债券的特点决定钙粘蛋白特异性的差异。 我们将直接测试模型的钙粘蛋白的结合和识别建议这些力的测量，通过确定钙粘蛋白的结构变化的影响，蛋白间的潜力和钙粘蛋白的键强度。后者将提供钙粘蛋白结构和功能之间的直接联系。总之，这些拟议的调查将提供一个全面的分析，钙粘蛋白的功能，在一个前所未有的详细程度，揭示了潜在的粘合机制和它们的结构起源。

DESCRIPTION (provided by applicant): Cadherins are essential cell surface proteins that mediate cell-cell adhesion in all soft tissues. They play critical roles in development and morphogenesis, by directing tissue-specific cell segregation and sorting. A major, unresolved question concerns the molecular basis of cadherin adhesion and binding selectivity. There have been several attempts to elucidate the structural basis of cadherin function from crystal structures, but despite numerous biochemical and structural studies, the identities of the functional adhesive domains and the mechanisms of cadherin binding remain controversial. In this work, we propose to directly address this issue with experimental approaches that directly probe the adhesive function of these proteins. Molecular force probes provide the means to achieve this. Both the surface force apparatus (SFA) and single molecule dynamic force spectroscopy (DFS) provide a powerful, complementary set of tools for uniquely determining the molecular mechanisms of cadherin adhesion and selectivity. By directly measuring the distance-dependent cadherin interaction potentials with the SFA, we will obtain unique information regarding the cadherin docking alignments, and hence, the protein regions that mediate binding. This information, which can't be directly obtained by any other current techniques, will facilitate the identification of the adhesive ectodomain segments, and thereby directly test several key hypotheses concerning the identities of the functional cadherin domains. On the other hand, the proposed DFS measurements will reveal subtle details of single cadherin bonds that may not be evident from the population-averaged, SFA measurements, but may nevertheless control cadherin recognition. These latter measurements will test the hypothesis that differences in the characteristics of cadherin bonds determine cadherin specificity. We will directly test models for cadherin binding and recognition suggested by these force measurements, by determining the impact of cadherin structure variations on both the interprotein potentials and the cadherin bond strengths. The latter will provide a direct link between cadherin architecture and function. Together, these proposed investigations will provide a comprehensive analysis of cadherin function at an unprecedented level of detail, revealing both the underlying adhesive mechanisms and their structural origins.