Developing strategies to interfere with allosteric interactions in proteins not only promises to deepen our understanding of vital cellular processes but also allows their regulation using external triggers. Light is particularly attractive as a trigger being spatiotemporally selective and compatible with the physiological environment. Here, we engineered a hybrid protein in which irradiation with light opens a new allosteric communication route that is not inherent to the natural system. We select human serum albumin, a promiscuous protein responsible for transporting a variety of ligands in plasma, and show that by covalently incorporating a synthetic photoswitch to subdomain IA we achieve optical control of the ligand binding in subdomain IB. Molecular dynamics simulations confirm the allosteric nature of the interactions between IA and IB in the engineered protein. Specifically, upon illumination, photoconversion of the switch is found to correlate with a less-coordinated motion of the two subdomains and an increased flexibility of the binding pocket in subdomain IB, whose fluctuations are cooperatively enhanced by the presence of ligands, ultimately facilitating their release. Our combined experimental and computational work demonstrates how harnessing artificial molecular switches enables photoprogramming the allosteric regulation of binding activities in such a prominent protein.

中文翻译：

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人血清白蛋白中的光编程变构。

制定策略来干扰蛋白质中的变构相互作用，不仅有望加深我们对重要细胞过程的理解，还可以使用外部触发因素对其进行调节。光是诱人的，因为它是时空选择性的并且与生理环境兼容。在这里，我们设计了一种杂合蛋白，其中光的照射打开了一条新的变构通讯途径，这不是天然系统固有的。我们选择人血清白蛋白，一种负责在血浆中运输各种配体的混杂蛋白，并显示通过将合成的光开关共价结合到亚结构域IA中，我们实现了对亚结构域IB中配体结合的光学控制。分子动力学模拟证实了工程蛋白中IA和IB之间相互作用的变构性质。具体而言，在照明时，发现开关的光转化与两个亚结构域的协调性较弱的运动以及亚结构域IB中结合口袋的柔性增加相关，其波动由于配体的存在而协同增强，最终促进了它们的释放。我们结合实验和计算工作，证明了利用人工分子开关如何使这种突出蛋白质中结合活性的变构调节成为可能。发现开关的光转化与两个亚结构域的较少协调的运动和亚结构域1B中结合口袋的增加的柔性相关，其结合由于配体的存在而协同增强，最终促进了它们的释放。我们结合实验和计算工作，证明了利用人工分子开关如何使这种突出蛋白质中结合活性的变构调节成为可能。发现开关的光转化与两个亚结构域的较少协调的运动和亚结构域1B中结合口袋的增加的柔性相关，其结合由于配体的存在而协同增强，最终促进了它们的释放。我们结合实验和计算工作，证明了利用人工分子开关如何使这种突出蛋白质中结合活性的变构调节成为可能。