Formation mechanism of proteasome granules

蛋白酶体是一种依赖于三磷酸腺苷的蛋白复合体，负责真核细胞中蛋白质的靶向性降解。为了确定影响蛋白酶体动态的因素，我们对酵母突变体库进行了筛选，发现在几乎所有的线粒体突变体中，蛋白酶体都形成了一个大的细胞质颗粒。我们发现，即使在野生型细胞中，细胞内ATP水平的降低也会诱导蛋白酶体颗粒的形成。重要的是，蛋白酶体的颗粒形成在酵母和人类中是保守的。此外，纯化的蛋白酶体通过耗尽ATP形成纤维状聚集结构。综上所述，这些结果表明，蛋白酶体本身感知细胞的ATP水平，并在响应细胞环境时自主形成可逆的颗粒结构。

The proteasome is an ATP-dependent protease complex responsible for targeted protein degradation in eukaryotic cells. To identify factors that affect the proteasome dynamics, we screened a yeast mutant library and found that the proteasome formed a large cytoplasmic granule in almost all the mitochondrial mutants. We found that lowered cellular ATP levels induce the granule formation of the proteasome even in the wild-type cells. Importantly, the granule formation of the proteasome is conserved in yeast and humans. Furthermore, the purified proteasomes formed fibrous aggregated structures by ATP depletion. Taken together, these results suggest that the proteasome itself senses cellular ATP levels and autonomously forms reversible granule structure in responding to cellular environments.