High resolution structures define divergent and convergent mechanisms of archaeal proteasome activation.
High resolution structures define divergent and convergent mechanisms of archaeal proteasome activation.
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DOI：
10.1038/s42003-023-05123-3
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发表时间：
2023-07-15
影响因子：
5.9
通讯作者：
Smith, David M.
中科院分区：
文献类型：
--
作者：
Chuah, Janelle J. Y.;Rexroad, Matthew S.;Smith, David M.
考虑到神经退行性疾病和蛋白酶体功能受损之间的联系，以及动物模型中蛋白酶体活性增强的神经保护作用，理解蛋白酶体激活机制至关重要。蛋白酶体激活复合物C-末端的疏水性酪氨酸-任何残基（HbYX）基序独立地触发20 S核心颗粒的开门以进行蛋白质降解;然而，因果变构机制仍不清楚。我们的研究采用了结构上不可还原的二肽HbYX模拟物，研究古细菌蛋白酶体中的门开放的变构机制。高分辨率cryo-EM结构可精确定位与HbYX依赖性激活有关的蛋白酶体α亚基中的重要残基和构象变化。使用点突变，我们模拟HbYX结合状态，为我们的机制模型提供支持。我们发现了四个触发门打开的主要机制元件：1）邻近K66的回环重排，2）α亚基内和α亚基间的构象变化，3）疏水口袋的占据，以及4）20 S通道中高度保守的异亮氨酸-苏氨酸对稳定打开和关闭状态，称为“IT开关”。不同复合物的比较揭示了HbYX依赖性和非依赖性激活剂之间20 S门开放的会聚和发散机制。这项研究提供了HbYX依赖性20 S门开放的详细分子模型，使小分子蛋白酶体激活剂的开发有望治疗神经退行性疾病。用模拟HbYX基序的小分子激活剂对古细菌20 S蛋白酶体进行的冷冻电镜结构和诱变揭示了保守的门控开关机制的新细节以及HbYX依赖性和非依赖性门控打开之间的机制差异
Considering the link between neurodegenerative diseases and impaired proteasome function, and the neuro-protective impact of enhanced proteasome activity in animal models, it’s crucial to understand proteasome activation mechanisms. A hydrophobic-tyrosine-any residue (HbYX) motif on the C-termini of proteasome-activating complexes independently triggers gate-opening of the 20S core particle for protein degradation; however, the causal allosteric mechanism remains unclear. Our study employs a structurally irreducible dipeptide HbYX mimetic to investigate the allosteric mechanism of gate-opening in the archaeal proteasome. High-resolution cryo-EM structures pinpoint vital residues and conformational changes in the proteasome α-subunit implicated in HbYX-dependent activation. Using point mutations, we simulated the HbYX-bound state, providing support for our mechanistic model. We discerned four main mechanistic elements triggering gate-opening: 1) back-loop rearrangement adjacent to K66, 2) intra- and inter- α subunit conformational changes, 3) occupancy of the hydrophobic pocket, and 4) a highly conserved isoleucine-threonine pair in the 20S channel stabilizing the open and closed states, termed the "IT switch." Comparison of different complexes unveiled convergent and divergent mechanism of 20S gate-opening among HbYX-dependent and independent activators. This study delivers a detailed molecular model for HbYX-dependent 20S gate-opening, enabling the development of small molecule proteasome activators that hold promise to treat neurodegenerative diseases. Cryo-EM structures and mutagenesis of the archaeal 20S proteasome with a small molecular activator mimicking the HbYX motif reveal new details of a conserved gating switch mechanism and mechanistic differences between HbYX-dependent and -independent gate-opening
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影响因子：
16.6
作者：
Choi WH;de Poot SA;Lee JH;Kim JH;Han DH;Kim YK;Finley D;Lee MJ
通讯作者：
Lee MJ
影响因子：
16
作者：
Köhler, A;Cascio, P;Finley, D
通讯作者：
Finley, D
影响因子：
4.8
作者：
Chondrogianni, Niki;Georgila, Konstantina;Gonos, Efstathios S.
通讯作者：
Gonos, Efstathios S.
影响因子：
4.7
作者：
Keller, JN;Hanni, KB;Markesbery, WR
通讯作者：
Markesbery, WR
DOI：
10.1038/80992
发表时间：
2000-11-01
期刊：
NATURE STRUCTURAL BIOLOGY
影响因子：
--
作者：
Groll, M;Bajorek, M;Finley, D
通讯作者：
Finley, D