Guanidine hydrochloride blocks a critical step in the propagation of the prion-like determinant [PSI+] of Saccharomyces cerevisiae
Guanidine hydrochloride blocks a critical step in the propagation of the prion-like determinant [PSI+] of Saccharomyces cerevisiae
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DOI：
10.1073/pnas.97.1.240
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发表时间：
2000-01-04
影响因子：
11.1
通讯作者：
Tuite, MF
中科院分区：
文献类型：
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作者：
Eaglestone, SS;Ruddock, LW;Tuite, MF
酿酒酵母的胞质可遗传决定簇[Psi+]反映了染色体编码蛋白Sup35p的类Pron特性。该蛋白是一种必需的真核生物多肽释放因子，即eRF3。在[PSL(+)]背景下，Sup35p的Prion构象形成大的寡聚体，导致细胞内功能释放因子的耗尽，从而导致翻译终止效率低下。我们研究了通过在蛋白质变性剂盐酸胍(GuHCl)存在下生长，有效地从菌株中消除[PSI+]决定簇的过程。菌株的[PSI+]可以通过毫摩尔浓度的盐酸铵“治愈”，远低于蛋白质变性通常所需的浓度。在这里，我们提供的证据表明，[PSI+]行列式的消除并不是由GuHCl直接溶解自我复制的[PSI+]种子所产生的。虽然GuHCl确实引起了适度的应激反应，但[PSI+]的清除并没有因应激而增强，而且还表现出对持续细胞分裂的绝对要求。我们提出了GuHCl抑制PrP构象繁殖的一个关键事件，并证明了GuHCl固化的动力学符合随机分离模型，即可遗传的[PSI+]元素从培养物中被稀释。用盐酸古胺完全抑制PrP复制后。
The cytoplasmic heritable determinant [PSI+] of the yeast Saccharomyces cerevisiae reflects the prion-like properties of the chromosome-encoded protein Sup35p. This protein is known to be an essential eukaryote polypeptide release factor, namely eRF3. In a [PSl(+)] background, the prion conformer of Sup35p forms large oligomers, which results in the intracellular depletion of functional release factor and hence inefficient translation termination. We have investigated the process by which the [PSI+] determinant can be efficiently eliminated from strains, by growth in the presence of the protein denaturant guanidine hydrochloride (GuHCl). Strains are "cured" of [PSI+] by millimolar concentrations of GuHCl, well below that normally required for protein denaturation. Here we provide evidence indicating that the elimination of the [PSI+] determinant is not derived from the direct dissolution of self-replicating [PSI+] seeds by GuHCl. Although GuHCl does elicit a moderate stress response, the elimination of [PSI+] is not enhanced by stress, and furthermore, exhibits an absolute requirement for continued cell division. We propose that GuHCl inhibits a critical event in the propagation of the prion conformer and demonstrate that the kinetics of curing by GuHCl fit a random segregation model whereby the heritable [PSI+] element is diluted from a culture. after the total inhibition of prion replication by GuHCl.