FORCE-MODULATED BINDING AFFINITY: COMPUTATIONAL STUDY OF FAT-PAXILLIN INTERACTI

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 机械信号已被证明可以调节多种生理行为，包括细胞生长、分化、凋亡、运动和基因表达。机械信号导致生化和细胞变化或机械转导的过程细节在很大程度上是未知的。一种提出的机制是，力驱动的构象变化导致结合亲和力改变，本质上将机械信号转换为浓度变化。我们将通过对蛋白质拉动模拟的详细结构和能量分析，表征力诱导结合变化的特性。在方法上，使用了多维副本交换协议，通过更好的采样来加速收敛，并使用加权直方图分析方法(WHAM)来计算机械扰动引起的自由能变化。我们正致力于粘着斑靶向(FAT)区域的粘着斑激酶与巴西林多肽的结合。焦点粘连是细胞与细胞外环境的锚定点，是一种动态的蛋白质复合体，可以作为机械感觉装置，其中机械力可以调节位置的组装并触发信号。虽然对力作出反应的蛋白质的确切身份尚不清楚，但脂肪和巴西林之间的相互作用在局部粘连的形成中起着重要作用，并被认为是机械传感机制的一部分。初步模拟表明，力可以通过激活新的接触来诱导脂肪-帕西林结合作用的加强。我们计划研究不同拉力方向上的不同影响，以深入了解这种反应在生物学背景下的稳健性，并对承载力量的残基进行突变研究。对机械转导分子机制的详细了解可以促进治疗学和组织工程学的进步，使培养条件的设计能够模拟细胞的自然化学和机械环境。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Mechanical signals have been shown to regulate various physiological behaviors, including cell growth, differentiation, apoptosis, motility and gene expression. The details of the processes by which mechanical cues result in biochemical and cellular change, or mechanotransduction, are largely unknown. One proposed mechanism is that a force-driven conformational change results in altered binding affinity, essentially converting a mechanical signal into a concentration change. We will characterize properties of force-induced binding changes, through detailed structural and energetic analysis of protein pulling simulations. Methodologically the work uses a multi-dimensional replica exchange protocol, which speeds up convergence through better sampling, and the Weighted Histogram Analysis Method (WHAM) to compute free energy changes induced by mechanical perturbation. We are focusing our efforts on the focal adhesion targeting (FAT) domain of focal adhesion kinase binding to a paxillin peptide. Focal adhesions, the cell anchor points to the extracellular environment, are dynamical protein complexes known to act as mechanosensory devices, where mechanical forces can regulate the assembly of the site and trigger signaling. While the precise identity of proteins responsive to force is not elucidated, interactions between FAT and paxillin play an important role in focal adhesion formation and are thought to be part of the mechanosensing machinery. Preliminary simulations have shown that force can induce strengthening of FAT-paxillin binding interactions through activation of new contacts. We plan to investigate variable effects along different pulling directions to gain insight into the robustness of this response in a biological context, as well as to carry out mutational studies of force-bearing residues. Detailed understanding of the molecular mechanisms of mechanotransduction could lead to advances in therapeutics and tissue engineering, with design of culture conditions mimicking the cells natural chemical and mechanical environment.