Mechanistic and Structural Insights into the Prion-Disaggregase Activity of Hsp104.
Mechanistic and Structural Insights into the Prion-Disaggregase Activity of Hsp104.
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DOI：
10.1016/j.jmb.2015.11.016
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发表时间：
2016-05-08
影响因子：
5.6
通讯作者：
Shorter J
中科院分区：
文献类型：
--
作者：
Sweeny EA;Shorter J
热休克蛋白104是一个动态的环转位酶和六聚体AAA+蛋白在酵母中发现，它耦合ATP水解蛋白质的拆卸和再活化中捕获的可溶性类淀粉样蛋白低聚物，无序的蛋白质聚集体，和稳定的淀粉样蛋白或朊病毒构象。在这里，我们强调了我们对Hsp 104的结构理解以及Hsp 104如何解构Sup 35朊病毒的进展。虽然Hsp 104六聚体的原子结构仍不确定，但通过小角X射线散射在ATPγS、ADP-AlFx（ATP水解过渡态模拟物）和ADP中对Hsp 104六聚体的体积重建揭示了ATP水解时的蠕动泵送运动。这种泵送运动可能驱动定向底物易位通过中心Hsp 104通道。Hsp 104最初与Sup 35朊病毒的C-末端直接接合到它们的交叉-β结构。然后，通过Hsp 104的定向拉动以逐步的方式解析N-末端交叉-β结构。首先，Hsp 104使朊病毒片段化。第二，Hsp 104展开交叉β结构。第三，Hsp 104释放可溶性Sup 35。Hsp 104 N-末端结构域（NTD）的缺失产生了具有改变的泵送机制的亚型解聚酶Hsp 104 ΔN。Hsp 104 ΔN片段化Sup 35朊病毒而不解折叠交叉β结构或释放可溶性Sup 35。此外，Hsp 104 ΔN活性不能通过增强解聚酶活性的中间结构域中的突变来增强。因此，NTD对于Hsp 104活性的全部库是至关重要的。
Hsp104 is a dynamic ring-translocase and hexameric AAA+ protein found in yeast, which couples ATP hydrolysis to disassembly and reactivation of proteins trapped in soluble preamyloid oligomers, disordered protein aggregates, and stable amyloid or prion conformers. Here, we highlight advances in our structural understanding of Hsp104 and how Hsp104 deconstructs Sup35 prions. Although the atomic structure of Hsp104 hexamers remains uncertain, volumetric reconstruction of Hsp104 hexamers in ATPγS, ADP-AlFx (ATP hydrolysis transition state mimic), and ADP via small-angle x-ray scattering has revealed a peristaltic pumping motion upon ATP hydrolysis. This pumping motion likely drives directional substrate translocation across the central Hsp104 channel. Hsp104 initially engages Sup35 prions immediately C-terminal to their cross-β structure. Directional pulling by Hsp104 then resolves N-terminal cross-β structure in a stepwise manner. First, Hsp104 fragments the prion. Second, Hsp104 unfolds cross-β structure. Third, Hsp104 releases soluble Sup35. Deletion of the Hsp104 N-terminal domain (NTD) yields a hypomorphic disaggregase, Hsp104ΔN, with an altered pumping mechanism. Hsp104ΔN fragments Sup35 prions without unfolding cross-β structure or releasing soluble Sup35. Moreover, Hsp104ΔN activity cannot be enhanced by mutations in the middle domain that potentiate disaggregase activity. Thus, the NTD is critical for the full repertoire of Hsp104 activities.