Proteins often interconvert between different conformations in ways critical to their function. While manipulating such equilibria for biophysical study is often challenging, the application of pressure is a potential route to achieve such control by favoring the population of lower volume states. Here, we use this feature to study the interconversion of ARNT PAS-B Y456T, which undergoes a dramatic beta-strand slip as it switches between two stably-folded conformations. Coupling high pressure and biomolecular NMR, we obtained the first quantitative data testing two key hypotheses of this process: the slipped conformation is both smaller and less compressible than the wildtype equivalent, and the interconversion proceeds through a chiefly-unfolded intermediate state. Our work exemplifies how these approaches, which can be generally applied to protein conformational switches, can provide unique information that is not easily accessible through other techniques.

中文翻译：

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高压NMR显示两个稳定折叠的蛋白质构象之间的体积和可压缩性差异

蛋白质通常以对其功能至关重要的方式在不同构象之间相互转换。虽然为生物物理研究操纵这种平衡通常是有挑战性的，但施加压力是通过偏爱较小体积状态的种群来实现这种控制的潜在途径。在这里，我们使用此功能来研究ARNT PAS-B Y456T的相互转换，该结构在两个稳定折叠的构象之间切换时会经历剧烈的β链滑动。结合高压和生物分子NMR，我们获得了第一个定量数据，测试了此过程的两个关键假设：滑动构象比野生型等效物更小且可压缩性更低，并且相互转化通过主要展开的中间状态进行。我们的工作举例说明了这些方法，