Effect of macromolecular crowding on protein folding dynamics at the secondary structure level.
Effect of macromolecular crowding on protein folding dynamics at the secondary structure level.
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DOI：
10.1016/j.jmb.2009.08.016
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发表时间：
2009-10-16
影响因子：
5.6
通讯作者：
Gai, Feng
中科院分区：
文献类型：
--
作者：
Mukherjee, Smita;Waegele, Matthias M.;Chowshury, Pramit;Guo, Lin;Gai, Feng
大分子拥挤是细胞环境的关键特征之一，因此与体内蛋白质折叠过程密切相关。虽然以前的研究已经为拥挤对蛋白质三级结构的稳定性和折叠速度的影响提供了宝贵的见解，但对于拥挤如何影响蛋白质二级结构水平的折叠动力学却知之甚少。在这里，我们研究了三个小的折叠基序，即34个残基的α-螺旋、34个残基的交联螺旋-转弯螺旋和16个残基的β发夹在两种常用的挤压剂葡聚糖70(200g/L)和菲科尔70(200g/L)的存在下的热稳定性和折叠-去折叠动力学。我们发现，这些聚合物不会导致两个螺旋肽的折叠动力学发生任何明显的变化，这有点令人惊讶，因为螺旋-螺旋转变动力学已经被证明依赖于粘度。同样令我们惊讶的是，与对较大蛋白质观察到的情况相反，我们发现拥挤导致最短的β-发夹多肽的折叠率显著下降，这表明在评估拥挤对蛋白质折叠动力学的净影响时，除了排除的体积效应外，还需要考虑其他因素。提出了一个同时考虑拥挤剂存在时的静态和动态影响的模型，以使这些结果更加合理。
Macromolecular crowding is one of the key characteristics of the cellular environment and therefore, is intimately coupled to the process of protein folding in vivo. While previous studies have provided invaluable insight into the effect of crowding on the stability and folding rate of protein tertiary structures, very little is known about how crowding affects protein folding dynamics at the secondary structure level. Herein, we examine the thermal stability and folding-unfolding kinetics of three small folding motifs, i.e., a 34-residue α-helix, a 34-residue cross-linked helix-turn-helix, and a 16-residue β hairpin, in the presence of two commonly used crowding agents, Dextran 70 (200 g/L) and Ficoll 70 (200 g/L). We find that these polymers do not induce any appreciable changes in the folding kinetics of the two helical peptides, which is somewhat surprising as the helix-coil transition kinetics have been shown to depend on viscosity. Also to our surprise and in contrast to what has been observed for larger proteins, we find that crowding leads to an appreciable decrease in the folding rate of the shortest β-hairpin peptide, indicating that besides the excluded volume effect, other factors also need to be considered when evaluating the net effect of crowding on protein folding kinetics. A model considering both the static and dynamic effects arising from the presence of the crowding agent is proposed to rationalize these results.
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发表时间：
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