Effects of surface tethering on protein folding mechanisms
Effects of surface tethering on protein folding mechanisms
复制标题
DOI：
10.1073/pnas.0601210103
复制
发表时间：
2006-05-30
影响因子：
11.1
通讯作者：
Shea, Joan-Emma
中科院分区：
文献类型：
--
作者：
Friedel, Miriam;Baumketner, Andrij;Shea, Joan-Emma
蛋白质的折叠机制越来越多地通过单分子实验来探索，在单分子实验中，蛋白质被固定在表面上。然而，缺乏对表面如何影响折叠的清晰理解，以及它是否改变了其整体行为的折叠。在这项工作中，我们使用分子动力学模拟的模型β桶蛋白拴在一个表面，系统地研究如何影响表面折叠。在本体中，该蛋白质以三态方式通过紧密的中间态折叠，并且其过渡态（TS）具有良好形成的疏水核心。拴系后，我们发现，折叠速率和稳定性的影响不同的表面，依赖于系绳的长度和位置。对于不改变折叠温度的系链点，观察到折叠时间的显著变化。栓系还局部增强了邻近栓系点的残基的结构的形成。我们发现，无论是折叠机制，也没有TS的这种蛋白质被改变，如果系链是在一个完全结构化或完全非结构化的区域的TS。相比之下，在TS的部分结构化区域中的拴系导致显著的变化。对于一个这样的拴系点，消除了存在于本体折叠中的中间体，导致具有异质的高度非结构化的TS系综的双态折叠过程。这些结果对单分子实验的设计和拴系蛋白的生物技术应用都有影响。
The folding mechanisms of proteins are increasingly being probed through single-molecule experiments in which the protein is immobilized on a surface. Nevertheless, a clear understanding of how the surface might affect folding, and whether or not it changes folding from its bulk behavior, is lacking. In this work, we use molecular dynamics simulations of a model beta-barrel protein tethered to a surface to systematically investigate how the surface impacts folding. in the bulk, this protein folds in a three-state manner through a compact intermediate state, and its transition state (TS) has a well formed hydrophobic core. Upon tethering, we find that folding rates and stability are impacted differently by the surface, with dependencies on both the length and location of the tether. Significant changes in folding times are observed for tether points that do not alter the folding temperature. Tethering also locally enhances the formation of structure for residues proximal to the tether point. We find that neither the folding mechanism nor the TS of this protein are altered if the tether is in a fully structured or completely unstructured region of the TS. By contrast, tethering in a partially structured region of the TS leads to dramatic changes' For one such tether point, the intermediate present in bulk folding is eliminated, leading to a two-state folding process with a heterogeneous, highly unstructured TS ensemble. These results have implications for both the design of single-molecule experiments and biotechnological applications of tethered proteins.