Kazlauskaite Jurate, Young Anna, Gardner Catherine E, Macpherson Julie V, Vénien-Bryan Catherine, Pinheiro Teresa J T
Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
Biochem Biophys Res Commun. 2005 Mar 4;328(1):292-305. doi: 10.1016/j.bbrc.2004.12.172.
A key molecular event in prion diseases is the conversion of the prion protein (PrP) from its normal cellular form (PrPC) to the disease-specific form (PrPSc). The transition from PrPC to PrPSc involves a major conformational change, resulting in amorphous protein aggregates and fibrillar amyloid deposits with increased beta-sheet structure. Using recombinant PrP refolded into a beta-sheet-rich form (beta-PrP) we have studied the fibrillization of beta-PrP both in solution and in association with raft membranes. In low ionic strength thick dense fibrils form large networks, which coexist with amorphous aggregates. High ionic strength results in less compact fibrils, that assemble in large sheets packed with globular PrP particles, resembling diffuse aggregates found in ex vivo preparations of PrPSc. Here we report on the finding of a beta-turn-rich conformation involved in prion fibrillization that is toxic to neuronal cells in culture. This is the first account of an intermediate in prion fibril formation that is toxic to neuronal cells. We propose that this unusual beta-turn-rich form of PrP may be a precursor of PrPSc and a candidate for the neurotoxic molecule in prion pathogenesis.
朊病毒疾病中的一个关键分子事件是朊病毒蛋白（PrP）从其正常细胞形式（PrPC）转变为疾病特异性形式（PrPSc）。从PrPC到PrPSc的转变涉及主要的构象变化，导致无定形蛋白质聚集体和具有增加的β-折叠结构的纤维状淀粉样沉积物。使用重折叠成富含β-折叠形式（β-PrP）的重组PrP，我们研究了β-PrP在溶液中和与筏膜结合时的纤维化过程。在低离子强度下，粗大密集的纤维形成大网络，与无定形聚集体共存。高离子强度导致纤维不那么紧密，它们组装成由球状PrP颗粒堆积而成的大片，类似于在PrPSc体外制剂中发现的弥漫性聚集体。在此，我们报告发现了一种参与朊病毒纤维化的富含β-转角的构象，这种构象对培养中的神经元细胞有毒性。这是首次报道在朊病毒纤维形成过程中对神经元细胞有毒性的中间体。我们提出，这种异常的富含β-转角形式的PrP可能是PrPSc的前体，也是朊病毒发病机制中神经毒性分子的候选物。
