Department of Biochemistry, Hanover, New Hampshire 03755, USA.
Biochemistry. 2011 Aug 23;50(33):7111-6. doi: 10.1021/bi200786p. Epub 2011 Jul 21.
Infectious mouse prions can be produced from a mixture of bacterially expressed recombinant prion protein (recPrP), palmitoyloleoylphosphatidylglycerol (POPG), and RNA [Wang, F.; et al. (2010) Science 327, 1132]. In contrast, amyloid fibers produced from pure recPrP without POPG or RNA (recPrP fibers) fail to infect wild type mice [Colby, D.W.; et al. (2010) PLoS Pathog. 387, e1000736]. We compared the seeding specificity and ultrastructural features of infectious recombinant prions (recPrP(Sc)) with those of recPrP fibers. Our results indicate that PrP fibers are not able to induce the formation of PrP(Sc) molecules from wild type mouse brain homogenate substrate in serial protein misfolding cyclic amplification (sPMCA) reactions. Conversely, recPrP(Sc) molecules did not accelerate the formation of amyloid in vitro, under conditions that produce recPrP fibers spontaneously. Ultrastructurally, recombinant prions appear to be small spherical aggregates rather than elongated fibers, as determined by atomic force and electron microscopy. Taken together, our results show that recPrP(Sc) molecules and PrP fibers have different ultrastructural features and seeding specificities, suggesting that prion infectivity may be propagated by a specific and unique assembly pathway facilitated by cofactors.
传染性鼠朊病毒可由细菌表达的重组朊蛋白（recPrP）、十六烷酰基油酰基磷酸甘油（POPG）和 RNA 的混合物产生[Wang, F.; et al. (2010) Science 327, 1132]。相比之下，没有 POPG 或 RNA 的纯 recPrP 产生的淀粉样纤维（recPrP 纤维）不能感染野生型小鼠[Colby, D.W.; et al. (2010) PLoS Pathog. 387, e1000736]。我们比较了传染性重组朊病毒（recPrP(Sc)）与 recPrP 纤维的接种特异性和超微结构特征。我们的结果表明，在连续蛋白质错误折叠循环扩增（sPMCA）反应中，PrP 纤维不能从野生型鼠脑匀浆底物中诱导形成 PrP(Sc)分子。相反，在自发产生 recPrP 纤维的条件下，recPrP(Sc)分子也不会加速体外淀粉样形成。超微结构表明，重组朊病毒似乎是小的球形聚集体，而不是伸长的纤维，这是通过原子力和电子显微镜确定的。总之，我们的结果表明，recPrP(Sc)分子和 PrP 纤维具有不同的超微结构特征和接种特异性，表明朊病毒感染性可能通过辅助因子促进的特定和独特的组装途径传播。
