Oligomerization of the human prion protein proceeds via a molten globule intermediate
Oligomerization of the human prion protein proceeds via a molten globule intermediate
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DOI：
10.1074/jbc.m608926200
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发表时间：
2007-03-02
影响因子：
4.8
通讯作者：
James, William
中科院分区：
文献类型：
--
作者：
Gerber, Remo;Tahiri-Alaoui, Abdessamad;James, William
人类PrP蛋白从α-螺旋结构到β-折叠丰富结构的构象转变被认为是Prion发病机制中的关键事件。错误折叠的分子机制和中间态在这一转变中的作用仍然知之甚少。为了克服淀粉样蛋白纤维不溶的障碍，我们研究了一种富含β-折叠的蛋白亚型--6-寡聚体，它与淀粉样蛋白具有一些结构特性，包括对部分蛋白酶的抗性。我们在这里证明，β-齐聚物可以通过溶液状态的核磁共振波谱进行研究，并通过其瞬时单体前体获得对错误折叠机制的深入了解。人们通常认为，错误折叠成富含β-折叠的亚型是通过具有β-折叠亚单位结构的相容前体进行的。相反，我们在这里展示了几乎天然的富含α螺旋的单体前体状态的证据，具有熔融的球状特征，在体外转化为β-低聚物。我们提出了一种可能的形成β-齐聚物的机制，这种机制是由不断重排的结构之间的分子间接触触发的。结果表明，β-齐聚物的前驱体不是具有β-折叠结构的前体，而是部分展开的、可明显区分的α-螺旋状态。
The conformational transition of the human prion protein from an alpha-helical to a beta-sheet-rich structure is believed to be the critical event in prion pathogenesis. The molecular mechanism of misfolding and the role of intermediate states during this transition remain poorly understood. To overcome the obstacle of insolubility of amyloid fibrils, we have studied a beta-sheet-rich misfolded isoform of the prion protein, the 6-oligomer, which shares some structural properties with amyloid, including partial proteinase resistance. We demonstrate here that the beta-oligomer can be studied by solution-state NMR spectroscopy and obtain insights into the misfolding mechanism via its transient monomeric precursor. It is often assumed that misfolding into beta-sheet-rich isoforms proceeds via a compatible precursor with a beta-sheet subunit structure. We show here, on the contrary, evidence for an almost natively alpha-helix-rich monomeric precursor state with molten globule characteristics, converting in vitro into the beta-oligomer. We propose a possible mechanism for the formation of the beta-oligomer, triggered by intermolecular contacts between constantly rearranging structures. It is concluded that the beta-oligomer is not preceded by precursors with beta-sheet structure but by a partially unfolded clearly distinguishable alpha-helical state.