CNRS, Université de Paris, UPR 9080, Laboratoire de Biochimie Théorique, 13 rue Pierre et Marie Curie, F-75005, Paris, France.
Institut de Biologie Physico-Chimique-Fondation Edmond de Rothschild, PSL Research University, Paris, France.
J Phys Chem Lett. 2021 Feb 18;12(6):1741-1746. doi: 10.1021/acs.jpclett.0c03626. Epub 2021 Feb 11.
The effect of macromolecular crowding on the stability of proteins can change with temperature. This dependence might reveal a delicate balance between two factors: the entropic excluded volume and the stability-modulating quinary interactions. Here we computationally investigate the thermal stability of the native state of chymotrypsin inhibitor 2 (CI2), which was previously shown by experiments to be destabilized by protein crowders at room temperature. Mimicking experimental conditions, our enhanced-sampling atomistic simulations of CI2 surrounded by lysozyme and bovine serum albumin reproduce this destabilization but also provide evidence of a crossover temperature above which lysozyme is found to become stabilizing, as previously predicted by analysis of thermodynamic data. We relate this crossover to the different CI2-crowder interactions and the local packing experienced by CI2. In fact, we clearly show that the pronounced stabilization induced by lysozyme at high temperatures stems from the tight local packing created around CI2 by this smaller crowder.
大分子拥挤对蛋白质稳定性的影响会随温度而变化。这种依赖性可能揭示了两种因素之间的微妙平衡：熵排斥体积和稳定调节的五元相互作用。在这里，我们通过计算方法研究了糜蛋白酶抑制剂 2（CI2）的天然状态的热稳定性，实验表明该蛋白质在室温下会被蛋白质拥挤物破坏。通过模拟实验条件，我们对溶菌酶和牛血清白蛋白包围的 CI2 进行增强采样原子模拟，重现了这种破坏作用，但也提供了一个交叉温度的证据，高于该温度时溶菌酶被发现具有稳定作用，这如先前对热力学数据的分析所预测的那样。我们将这种交叉温度与不同的 CI2-拥挤物相互作用和 CI2 所经历的局部堆积联系起来。事实上，我们清楚地表明，在高温下溶菌酶引起的显著稳定作用源于较小的拥挤物在 CI2 周围产生的紧密局部堆积。
