Effects of Q/N-rich, polyQ, and non-polyQ amyloids on the de novo formation of the [PSI+] prion in yeast and aggregation of Sup35 in vitro
Effects of Q/N-rich, polyQ, and non-polyQ amyloids on the de novo formation of the [PSI+] prion in yeast and aggregation of Sup35 in vitro
复制标题
DOI：
10.1073/pnas.0404968101
复制
发表时间：
2004-08-31
影响因子：
11.1
通讯作者：
Liebman, SW
中科院分区：
文献类型：
--
作者：
Derkatch, IL;Uptain, SM;Liebman, SW
朊病毒是感染性蛋白质构象，通常是有序的蛋白质聚集体。在没有朊病毒的情况下，这些相同蛋白质的新合成分子通常保持传统的可溶性构象。然而，即使没有同源的朊病毒模板，朊病毒偶尔也会出现。导致具有富含谷氨酰胺/精氨酸（Q/N）的朊病毒结构域的酵母朊病毒从头出现的构象转换（例如，[PSI+]），由具有相似结构域的异源朊病毒（例如，[RNQ(+）]，也称为[PIN+]），或通过过表达具有朊病毒样Q-、N-或Q/N-富集结构域的蛋白质。这一发现导致了一种假设，即异源蛋白质的聚集体提供了一个不完美的模板，新的朊病毒就接种在这个模板上。事实上，我们表明，新形成的Sup 35和预先存在的Rnq 1聚集体总是共定位时，[PSI+]的外观是由[RNQ（+）]朊病毒促进，Rnq 1纤维增强体外形成的纤维由朊病毒结构域Sup 35（NM）。然而，蛋白质不形成混合的、叉指状的聚集体。我们还表明，聚集的亨廷顿蛋白的polyQ-含有域的变体促进从头转换Sup 35到[PSI+]，而非聚集的亨廷顿蛋白和聚集体的非polyQ淀粉样蛋白，甲状腺素运载蛋白，α-突触核蛋白，synphilin不。此外，甲状腺素运载蛋白和α-突触核蛋白淀粉样蛋白在体外不促进NM聚集，即使在[PSI+]细胞中NM和甲状腺素运载蛋白聚集体也偶尔共定位。我们的数据，特别是在体外繁殖的高度特异性异源播种效应，提供了强有力的支持，交叉播种的假设，在自发启动朊病毒状态。
Prions are infectious protein conformations that are generally ordered protein aggregates. In the absence of prions, newly synthesized molecules of these same proteins usually maintain a conventional soluble conformation. However, prions occasionally arise even without a homologous prion template. The conformational switch that results in the de novo appearance of yeast prions with glutamine/aspargine (Q/N)-rich prion domains (e.g., [PSI+]), is promoted by heterologous prions with a similar domain (e.g., [RNQ(+)], also known as [PIN+]), or by overexpression of proteins with prion-like Q-, N-, or Q/N-rich domains. This finding led to the hypothesis that aggregates of heterologous proteins provide an imperfect template on which the new prion is seeded. Indeed, we show that newly forming Sup35 and preexisting Rnq1 aggregates always colocalize when [PSI+] appearance is facilitated by the [RNQ(+)] prion, and that Rnq1 fibers enhance the in vitro formation of fibers by the prion domain of Sup35 (NM). The proteins do not however form mixed, interdigitated aggregates. We also demonstrate that aggregating variants of the polyQ-containing domain of huntingtin promote the de novo conversion of Sup35 into [PSI+]; whereas nonaggregating variants of huntingtin and aggregates of non-polyQ amyloidogenic proteins, transthyretin, a-synuclein, and synphilin do not. Furthermore, transthyretin and a-synuclein amyloids do not facilitate NM aggregation in vitro, even though in [PSI+] cells NM and transthyretin aggregates also occasionally colocalize. Our data, especially the in vitro reproduction of the highly specific heterologous seeding effect, provide strong support for the hypothesis of cross-seeding in the spontaneous initiation of prion states.