Quantitative Analysis of the Effects of Photoswitchable Distance Constraints on the Structure of a Globular Protein
Quantitative Analysis of the Effects of Photoswitchable Distance Constraints on the Structure of a Globular Protein
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DOI：
10.1021/bi300685a
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发表时间：
2012-08-14
期刊：
影响因子：
2.9
通讯作者：
Woolley, G. Andrew
中科院分区：
文献类型：
--
作者：
Beharry, Andrew A.;Chen, Tao;Woolley, G. Andrew
以光致异构化学交联形式的光可转换距离约束为可逆光控蛋白质的设计提供了一种通用方法。然而，为了有效地应用这些，必须有选择交联剂结构和交联剂连接位点的指导方针。在这里，我们调查的影响，不同的交联剂结构的光控Fyn SH3结构域，一个很好的研究模型蛋白质的折叠。我们开发了一个理论框架的基础上的显式链模型的蛋白质折叠，修改，包括详细的模型连接器，允许预测给定的连接器上的蛋白质折叠的自由能的影响。使用这个框架，我们能够定量地解释实验结果，即较长的，但有点灵活的，交联剂是不稳定的折叠状态比较短的更刚性的交联剂。这些模型还表明，错误折叠状态可能是如何通过交联产生的，为这些蛋白质的核磁共振分析中看到的改变动力学提供了理论基础。该理论框架可以移植到任何已知折叠态结构的蛋白质中，因此可以用于指导光开关蛋白质的设计。
Photoswitchable distance constraints in the form of photoisomerizable chemical cross-links offer a general approach to the design of reversibly photocontrolled proteins. To apply these effectively, however, one must have guidelines for the choice of cross-linker structure and cross-linker attachment sites. Here we investigate the effects of varying cross-linker structure on the photocontrol of folding of the Fyn SH3 domain, a well-studied model protein. We develop a theoretical framework based on an explicit-chain model of protein folding, modified to include detailed model linkers, that allows prediction of the effect of a given linker on the free energy of folding of a protein. Using this framework, we were able to quantitatively explain the experimental result that a longer, but somewhat flexible, cross-linker is less destabilizing to the folded state than a shorter more rigid cross-linker. The models also suggest how misfolded states may be generated by cross-linking, providing a rationale for altered dynamics seen in nuclear magnetic resonance analyses of these proteins. The theoretical framework is readily portable to any protein of known folded state structure and thus can be used to guide the design of photoswitchable proteins generally.