Open-gate mutants of the mammalian proteasome show enhanced ubiquitin-conjugate degradation.
Open-gate mutants of the mammalian proteasome show enhanced ubiquitin-conjugate degradation.
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DOI：
10.1038/ncomms10963
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发表时间：
2016-03-09
影响因子：
16.6
通讯作者：
Lee MJ
中科院分区：
文献类型：
--
作者：
Choi WH;de Poot SA;Lee JH;Kim JH;Han DH;Kim YK;Finley D;Lee MJ
当处于闭合形式时，蛋白酶体核心颗粒（CP）的底物转运通道被α-亚基的会聚N末端阻断。为了探索通道门控在哺乳动物蛋白酶体中的作用，我们删除了α3的N-末端尾;得到的α3ΔN蛋白酶体是完整的，但在荧光肽底物的水解和多聚泛素化蛋白的降解中过度活跃。表达高活性蛋白酶体的细胞显示出许多已建立的蛋白酶体底物的显著升高的降解和对氧化应激的抗性。多重定量蛋白质组学显示，突变细胞中有200种蛋白质水平降低。潜在毒性蛋白质如tau表现出减少的积累和聚集体形成。这些数据表明，CP门是哺乳动物中蛋白酶体功能的关键负调节因子，并且打开CP门可能是增加蛋白酶体活性和降低细胞中毒性蛋白水平的有效策略。 蛋白酶体通过介导泛素化底物的降解在蛋白质稳定中起关键作用。在这里，作者表明，蛋白酶体的开门突变体对底物的子集是过度活跃的，并且可以有效地延迟有毒蛋白质聚集体的积累。
When in the closed form, the substrate translocation channel of the proteasome core particle (CP) is blocked by the convergent N termini of α-subunits. To probe the role of channel gating in mammalian proteasomes, we deleted the N-terminal tail of α3; the resulting α3ΔN proteasomes are intact but hyperactive in the hydrolysis of fluorogenic peptide substrates and the degradation of polyubiquitinated proteins. Cells expressing the hyperactive proteasomes show markedly elevated degradation of many established proteasome substrates and resistance to oxidative stress. Multiplexed quantitative proteomics revealed ∼200 proteins with reduced levels in the mutant cells. Potentially toxic proteins such as tau exhibit reduced accumulation and aggregate formation. These data demonstrate that the CP gate is a key negative regulator of proteasome function in mammals, and that opening the CP gate may be an effective strategy to increase proteasome activity and reduce levels of toxic proteins in cells. The proteasome plays a key role in proteostasis by mediating the degradation of ubiquitinated substrates. Here the authors show that an open-gate mutant of the proteasome is hyperactive towards a subset of substrates and can effectively delay the accumulation of toxic protein aggregates.