Dissociation of Infectivity from Seeding Ability in Prions with Alternate Docking Mechanism
Dissociation of Infectivity from Seeding Ability in Prions with Alternate Docking Mechanism
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DOI：
10.1371/journal.ppat.1002128
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发表时间：
2011-07-01
期刊：
影响因子：
6.7
通讯作者：
Supattapone, Surachai
中科院分区：
文献类型：
--
作者：
Miller, Michael B.;Geoghegan, James C.;Supattapone, Surachai
先前的研究发现了两个哺乳动物朊病毒蛋白（PrP）多碱基结构域，它们与疾病相关的构象异构体PrPSc结合，表明细胞朊病毒蛋白（PrPC）的这些结构域在朊病毒繁殖过程中充当PrPSc的对接位点。为了研究多碱性结构域在全长 PrPC 中的作用，我们使用中国仓鼠卵巢 (CHO) 细胞表达的缺乏一个或两个多碱性结构域的朊病毒蛋白作为连续蛋白质错误折叠循环扩增 (sPMCA) 反应的底物。与 5 轮 sPMCA 类似后，形成了缺乏中心多元结构域 (Delta C) 的 PrPSc 分子。令人惊讶的是，与野生型朊病毒相比，Delta C-PrPSc 朊病毒可以结合并诱导所有多碱性域突变底物定量转化为 PrPSc 分子。值得注意的是，尽管 Delta C-PrPSc 和其他多碱域 PrPSc 分子能够引发正常小鼠脑匀浆的 sPMCA 反应，但相对于野生型 PrPSc，它们的生物感染性却减弱或缺失。因此，Delta C-PrPSc 朊病毒通过一种新颖的相互作用机制与 PrPC 分子相互作用，产生扩大的底物范围和高效的 PrPSc 传播。此外，多碱基结构域缺陷的 PrPSc 分子提供了正常脑匀浆 sPMCA 播种能力与生物朊病毒感染性之间分离的第一个例子。这些结果表明，PrPSc 分子的传播可能不依赖于单一的刻板机制，但可能需要通过多碱基结构域进行正常的 PrPC/PrPSc 相互作用才能产生朊病毒感染性。
Previous studies identified two mammalian prion protein (PrP) polybasic domains that bind the disease-associated conformer PrPSc, suggesting that these domains of cellular prion protein (PrPC) serve as docking sites for PrPSc during prion propagation. To examine the role of polybasic domains in the context of full-length PrPC, we used prion proteins lacking one or both polybasic domains expressed from Chinese hamster ovary (CHO) cells as substrates in serial protein misfolding cyclic amplification (sPMCA) reactions. After similar to 5 rounds of sPMCA, PrPSc molecules lacking the central polybasic domain (Delta C) were formed. Surprisingly, in contrast to wild-type prions, Delta C-PrPSc prions could bind to and induce quantitative conversion of all the polybasic domain mutant substrates into PrPSc molecules. Remarkably, Delta C-PrPSc and other polybasic domain PrPSc molecules displayed diminished or absent biological infectivity relative to wild-type PrPSc, despite their ability to seed sPMCA reactions of normal mouse brain homogenate. Thus, Delta C-PrPSc prions interact with PrPC molecules through a novel interaction mechanism, yielding an expanded substrate range and highly efficient PrPSc propagation. Furthermore, polybasic domain deficient PrPSc molecules provide the first example of dissociation between normal brain homogenate sPMCA seeding ability from biological prion infectivity. These results suggest that the propagation of PrPSc molecules may not depend on a single stereotypic mechanism, but that normal PrPC/PrPSc interaction through polybasic domains may be required to generate prion infectivity.