Interactions of a Polypeptide with a Protein Nanopore Under Crowding Conditions
Interactions of a Polypeptide with a Protein Nanopore Under Crowding Conditions
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DOI：
10.1021/acsnano.9b00008
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发表时间：
2019-04-01
期刊：
影响因子：
17.1
通讯作者：
Movileanu, Liviu
中科院分区：
文献类型：
--
作者：
Larimi, Motahareh Ghahari;Mayse, Lauren Ashley;Movileanu, Liviu
分子拥挤是细胞环境中普遍存在的特征，对生物聚合物相互作用的动力学和平衡具有重要影响。在这项研究中，单个带电多肽暴露于将其推入跨膜蛋白孔的竞争力与将其拉出跨膜蛋白孔的力。利用单分子电生理学，我们提供了令人信服的实验证据，证明多肽孔相互作用的动力学细节很大程度上受到高浓度的低渗透性聚乙二醇（PEG）的影响。当聚合物浓度高于临界值时，这些中性大分子拥挤剂的存在增加了缔合速率常数，但降低了解离速率常数，从而导致更强的多肽-孔相互作用。此外，与较小分子量的PEG对应的那些值相比，较大分子量的PEG表现出较低的缔合速率常数但较高的解离速率常数。这些结果与在拥挤和限制条件下多肽的较低扩散常数和多肽与跨膜蛋白孔之间较高的耗尽吸引力相一致。
Molecular crowding, a ubiquitous feature of the cellular environment, has significant implications in the kinetics and equilibrium of biopolymer interactions. In this study, a single charged polypeptide is exposed to competing forces that drive it into a transmembrane protein pore versus forces that pull it outside. Using single-molecule electrophysiology, we provide compelling experimental evidence that the kinetic details of the polypeptide pore interactions are substantially affected by high concentrations of less-penetrating polyethylene glycols (PEGs). At a polymer concentration above a critical value, the presence of these neutral macromolecular crowders increases the rate constant of association but decreases the rate constant of dissociation, resulting in a stronger polypeptide-pore interaction. Moreover, a larger-molecular weight PEG exhibits a lower rate constant of association but a higher rate constant of dissociation than those values corresponding to a smaller-molecular weight PEG. These outcomes are in accord with a lower diffusion constant of the polypeptide and higher depletion-attraction forces between the polypeptide and transmembrane protein pore under crowding and confinement conditions.