Non-sequence-specific interactions can account for the compaction of proteins unfolded under "native" conditions.
Non-sequence-specific interactions can account for the compaction of proteins unfolded under "native" conditions.
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非序列特异性相互作用可以解释在“天然”条件下展开的蛋白质的压缩。
DOI：
10.1016/j.jmb.2009.09.005
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发表时间：
2009
影响因子：
5.6
通讯作者：
Plaxco,KevinW
中科院分区：
文献类型：
--
作者：
Kohn,JonathanE;Gillespie,Blake;Plaxco,KevinW
通过高浓度化学变性剂展开的蛋白质采用扩展的，大部分无结构的构象集合，很接近于随机线圈。相比之下，在变性程度较低的条件下展开的球状蛋白质（通过突变，或在快速跳到自然条件后短暂展开）和熔融球状蛋白质（由于突变或共溶剂产生）通常是致密的。在这里，我们使用57个残基FynSH3结构域的截断平衡-未展开变体来探索这种压实的起源。通过远紫外圆二色性、核磁共振光谱和氢交换动力学监测，CΔ4 （FynSH3的4个残基羧基末端缺失变体）即使在没有变性剂的情况下也大部分展开。然而，CΔ4在这些条件下非常致密，其流体动力半径仅略大于天然蛋白质。为了了解这种熔融球状压实的起源，我们对CΔ4具有相同氨基酸组成的随机序列多肽进行了表征。值得注意的是，我们发现这种随机序列多肽的水动力半径也接近天然蛋白的水动力半径。因此，虽然原生相互作用可能有助于致密“未展开”状态的形成，但似乎非序列特异性单体-单体相互作用也可以解释熔融球和“生理”未展开状态所观察到的剧烈压实。
Proteins unfolded by high concentrations of chemical denaturants adopt expanded, largely structure-free ensembles of conformations that are well approximated as random coils. In contrast, globular proteins unfolded under less denaturing conditions (via mutations, or transiently unfolded after a rapid jump to native conditions) and molten globules (arising due to mutations or cosolvents) are often compact. Here we explore the origins of this compaction using a truncated equilibrium-unfolded variant of the 57-residue FynSH3 domain. As monitored by far-UV circular dichroism, NMR spectroscopy, and hydrogen-exchange kinetics, CΔ4 (a 4-residue carboxy-terminal deletion variant of FynSH3) appears to be largely unfolded even in the absence of denaturant. Nevertheless, CΔ4 is quite compact under these conditions, with a hydrodynamic radius only slightly larger than that of the native protein. In order to understand the origins of this molten-globule-like compaction, we have characterized a random sequence polypeptide of identical amino acid composition to CΔ4. Notably, we find that the hydrodynamic radius of this random sequence polypeptide also approaches that of the native protein. Thus, while native-like interactions may contribute to the formation of compact “unfolded” states, it appears that non-sequence-specific monomer–monomer interactions can also account for the dramatic compaction observed for molten globules and the “physiological” unfolded state.