Protein aggregates arise naturally under normal physiological conditions, but their formation is accelerated by age or stress-induced protein misfolding. When the stressful event dissolves, these aggregates are removed by mechanisms such as aggrephagy, chaperone-mediated autophagy, refolding attempts, or the proteasome. It was recently shown that mitochondria in yeast cells may support these primarily cytosolic processes. Protein aggregates attach to mitochondria and misfolded proteins are transported into the matrix and degraded by mitochondria-specific proteases. Using a proximity labelling method and colocalization with an established stress granule marker, we were able to show that these mitochondria localized aggregates that harbor the "super aggregator" Ola1p are, in fact, stress granules (SGs). Our in vivo and in vitro studies have revealed that Ola1p can be transferred from mitochondria to lipid droplets (LDs). This "mitochondria to LD" aggregate transfer dampens proteotoxic effects. The LD-based protein aggregate removal system gains importance when other proteolytic systems fail. Furthermore, we were able to show that the distribution of SGs is drastically altered in LD-deficient yeast cells, demonstrating that LDs play a role in the SG life cycle.

中文翻译：

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Ola1p 运输表明在应激时线粒体、脂滴和应激颗粒之间存在相互作用网络。

蛋白质聚集体在正常生理条件下自然产生，但它们的形成会因年龄或压力诱导的蛋白质错误折叠而加速。当应激事件消失时，这些聚集物会通过聚合吞噬、分子伴侣介导的自噬、重折叠尝试或蛋白酶体等机制被清除。最近的研究表明，酵母细胞中的线粒体可能支持这些主要的胞质过程。蛋白质聚集物附着在线粒体上，错误折叠的蛋白质被转运到基质中并被线粒体特异性蛋白酶降解。使用邻近标记方法和与已建立的应激颗粒标记的共定位，我们能够证明这些含有“超级聚合器”Ola1p 的线粒体局部聚集体实际上是应激颗粒 (SG)。我们的体内和体外研究表明，Ola1p 可以从线粒体转移到脂滴 (LD)。这种“线粒体到LD”聚集体转移抑制了蛋白毒性作用。当其他蛋白水解系统失败时，基于 LD 的蛋白质聚集物去除系统就变得很重要。此外，我们还发现，在 LD 缺陷的酵母细胞中，SG 的分布发生了巨大变化，这表明 LD 在 SG 生命周期中发挥着作用。