Guanidine hydrochloride inhibits the generation of prion "seeds" but not prion protein aggregation in yeast
Guanidine hydrochloride inhibits the generation of prion "seeds" but not prion protein aggregation in yeast
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DOI：
10.1128/mcb.22.15.5593-5605.2002
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发表时间：
2002-08-01
影响因子：
5.3
通讯作者：
Tuite, MF
中科院分区：
文献类型：
--
作者：
Ness, F;Ferreira, P;Tuite, MF
[PSI+]酿酒酵母菌株复制并传递朊病毒形式的Sup 35 p蛋白，但当在毫摩尔浓度的盐酸胍（GdnHCl）中生长时，可以永久地消除这种性质。GdnHCl处理导致持续[PSI+]繁殖所必需的[PSI+]种子复制的抑制。在这里，我们证明了新合成的Sup 35 p掺入高分子量聚集体的速率，诊断[PSI+]菌株，与细胞中的种子数成正比，在盐酸钆存在下，种子数下降（可溶性Sup 35 p的水平增加）。GdnHCl不会导致[PSI+]细胞中预先存在的Sup 35 p聚集体的分解。将GdnHCl处理的细胞转移到无GdnHCl的培养基中逆转了GdnHCl对[PSI+]种子复制的抑制，并允许在没有进行中的蛋白质合成的情况下以指数方式产生新的朊病毒种子。在这样的释放之后，[PSI+]种子数量每20到22分钟翻一番。Ferreira，F. Ness，S. R.爱德华兹，B。S.考克斯和M. F. Tuite，Mol. Microbiol. 40：1357-1369，2001; G. Jung和D. C. Masison，Curr. Microbiol. 43：7-10，2001），连同这里提供的数据一起，表明GdnHCl治愈酵母朊病毒是GdnHCl抑制分子伴侣Hsp 104活性的结果，而Hsp 104又是[PSI+]繁殖所必需的。消除[PSI+]的动力学的共表达的显性，ATP酶阴性等位基因的HSP 104是类似的GdnHCl诱导消除所观察到的。基于这些和其他数据，我们提出了一个两个周期的模型Sup 35 p在[PSI+]细胞中的“朊病毒化”：周期A是GdnHCl敏感（Hsp 104依赖）的朊病毒种子的复制，而周期B是一个GdnHCl不敏感（Hsp 104独立）的过程，将这些种子转化为颗粒状的聚集体。
[PSI+] strains of the yeast Saccharomyces cerevisiae replicate and transmit the prion form of the Sup35p protein but can be permanently cured of this property when grown in millimolar concentrations of guanidine hydrochloride (GdnHCl). GdnHCl treatment leads to the inhibition of the replication of the [PSI+] seeds necessary for continued [PSI+] propagation. Here we demonstrate that the rate of incorporation of newly synthesized Sup35p into the high-molecular-weight aggregates, diagnostic of [PSI+] strains, is proportional to the number of seeds in the cell, with seed number declining (and the levels of soluble Sup35p increasing) in the presence of GdnHCl. GdnHCl does not cause breakdown of preexisting Sup35p aggregates in [PSI+] cells. Transfer of GdnHCl-treated cells to GdnHCl-free medium reverses GdnHCl inhibition of [PSI+] seed replication and allows new prion seeds to be generated exponentially in the absence of ongoing protein synthesis. Following such release the [PSI+] seed numbers double every 20 to 22 min. Recent evidence (P. C. Ferreira, F. Ness, S. R. Edwards, B. S. Cox, and M. F. Tuite, Mol. Microbiol. 40:1357-1369, 2001; G. Jung and D. C. Masison, Curr. Microbiol. 43:7-10, 2001), together with data presented here, suggests that curing yeast prions by GdnHCl is a consequence of GdnHCl inhibition of the activity of molecular chaperone Hsp104, which in turn is essential for [PSI+] propagation. The kinetics of elimination of [PSI+] by coexpression of a dominant, ATPase-negative allele of HSP104 were similar to those observed for GdnHCl-induced elimination. Based on these and other data, we propose a two-cycle model for "prionization" of Sup35p in [PSI+] cells: cycle A is the GdnHCl-sensitive (Hsp104-dependent) replication of the prion seeds, while cycle B is a GdnHCl-insensitive (Hsp104-independent) process that converts these seeds to pelletable aggregates.