Mechanical unfolding of a knotted protein unveils the kinetic and thermodynamic consequences of threading a polypeptide chain
Mechanical unfolding of a knotted protein unveils the kinetic and thermodynamic consequences of threading a polypeptide chain
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DOI：
10.1038/s41598-020-66258-5
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发表时间：
2020-06
影响因子：
4.6
通讯作者：
M. Rivera;Yuxin Hao;Rodrigo A. Maillard;M. Báez
中科院分区：
文献类型：
--
作者：
M. Rivera;Yuxin Hao;Rodrigo A. Maillard;M. Báez
纽结是自然界中一种重要的拓扑结构。蛋白质晶体结构中结的存在激发了大量的研究，以确定穿链多肽链的动力学和热力学后果。通过机械操作MJ0366，一个小的单域蛋白窝藏浅三叶结，我们允许蛋白质从打结或未打结的变性状态重新折叠，以表征与两个折叠途径相关的自由能分布。通过比较天然状态与打结和未打结的变性状态的稳定性，我们发现打结MJ0366的多肽链增加折叠能垒的幅度接近于在变性状态下随机形成结的能量成本。这些结果支持蛋白质结可以在折叠的单个合作步骤期间形成，但是以自由能势垒的大增量为代价而发生。
Knots are remarkable topological features in nature. The presence of knots in crystallographic structures of proteins have stimulated considerable research to determine the kinetic and thermodynamic consequences of threading a polypeptide chain. By mechanically manipulating MJ0366, a small single domain protein harboring a shallow trefoil knot, we allow the protein to refold from either the knotted or the unknotted denatured state to characterize the free energy profile associated to both folding pathways. By comparing the stability of the native state with reference to the knotted and unknotted denatured state we find that knotting the polypeptide chain of MJ0366 increase the folding energy barrier in a magnitude close to the energy cost of forming a knot randomly in the denatured state. These results support that a protein knot can be formed during a single cooperative step of folding but occurs at the expenses of a large increment on the free energy barrier.