Formation mechanism of proteasome granules

蛋白酶体是一种ATP依赖性蛋白酶复合物，负责真核细胞中靶向蛋白质的降解。为了确定影响蛋白酶体动力学的因素，我们筛选了酵母突变体库，发现蛋白酶体在几乎所有的线粒体突变体中形成了一个大的细胞质颗粒。我们发现，降低细胞ATP水平诱导颗粒形成的蛋白酶体，即使在野生型细胞。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ATP耗竭形成纤维状聚集结构。两者合计，这些结果表明，蛋白酶体本身的传感器细胞ATP水平和自主形成可逆的颗粒结构，在响应细胞环境。

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.