Destabilization and recovery of a yeast prion after mild heat shock.
Destabilization and recovery of a yeast prion after mild heat shock.
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DOI：
10.1016/j.jmb.2011.02.034
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发表时间：
2011-05-06
影响因子：
5.6
通讯作者：
Chernoff YO
中科院分区：
文献类型：
--
作者：
Newnam GP;Birchmore JL;Chernoff YO
酵母朊病毒 [PSI+] 是翻译终止因子 Sup35 的自我永存淀粉样蛋白。尽管 [PSI+] 传播受到热休克蛋白 (Hsps) 的调节，但之前报道高温对 [PSI+] 影响很小或没有影响。我们的结果表明，指数生长的酵母培养物短期暴露于轻度热休克，然后立即恢复生长，会导致 [PSI+] 不稳定，有时在热休克后持续数次细胞分裂。热休克后第一次分裂中发生的朊病毒损失优先在子细胞中检测到，表明朊病毒分离受损，导致母细胞和芽之间的朊病毒分布不对称。热激后较长时间的热激或在缺乏营养物的情况下长时间孵育会导致 [PSI+] 恢复。热休克过程中朊病毒的不稳定和恢复都取决于蛋白质的合成。最大程度的朊病毒不稳定与 Hsp104 和其他 Hsp（例如 Hsp70-Ssa）之间的最大不平衡相一致。单个 SSA 基因的缺失会增加朊病毒的不稳定和/或阻碍恢复。不稳定和恢复过程中朊病毒聚集的动态与有效的朊病毒碎片和分离需要 Hsp104 和其他（例如 Hsp70-Ssa）分子伴侣之间的适当平衡的概念是一致的。与热休克相反，渗透应激源引起的[PSI+]不稳定并不总是依赖于细胞增殖和/或蛋白质合成，这表明不同的应激可能通过不同的机制影响朊病毒。我们的数据表明，热应激会导致细胞分裂中朊病毒分布不对称，并证实热休克蛋白对朊病毒的影响具有生理相关性。
Yeast prion [PSI+] is a self-perpetuating amyloid of the translational termination factor Sup35. Although [PSI+] propagation is modulated by heat shock proteins (Hsps), high temperature was previously reported to have little or no effect on [PSI+]. Our results show that short-term exposure of exponentially growing yeast culture to mild heat shock, followed by immediate resumption of growth, leads to [PSI+] destabilization, sometimes persisting for several cell divisions after heat shock. Prion loss occurring in the first division after heat shock is preferentially detected in a daughter cell, indicating the impairment of prion segregation that results in asymmetric prion distribution between a mother cell and a bud. Longer heat shock or prolonged incubation in the absence of nutrients after heat shock lead to [PSI+] recovery. Both prion destabilization and recovery during heat shock depend on protein synthesis. Maximal prion destabilization coincides with maximal imbalance between Hsp104 and other Hsps such as Hsp70-Ssa. Deletions of individual SSA genes increase prion destabilization and/or counteract recovery. Dynamics of prion aggregation during destabilization and recovery is consistent with the notion that efficient prion fragmentation and segregation require a proper balance between Hsp104 and other (e. g. Hsp70-Ssa) chaperones. In contrast to heat shock, [PSI+] destabilization by osmotic stressors does not always depend on cell proliferation and/or protein synthesis, indicating that different stresses may impact the prion via different mechanisms. Our data demonstrate that heat stress causes asymmetric prion distribution in a cell division, and confirm that effects of Hsps on prions are physiologically relevant.
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