Probing the mechanism of inhibition of amyloid-β(1-42)-induced neurotoxicity by the chaperonin GroEL
Probing the mechanism of inhibition of amyloid-β(1-42)-induced neurotoxicity by the chaperonin GroEL
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DOI：
10.1073/pnas.1817477115
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发表时间：
2018-12-18
影响因子：
11.1
通讯作者：
Clore, G. Marius
中科院分区：
文献类型：
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作者：
Walti, Marielle A.;Steiner, Joseph;Clore, G. Marius
人伴侣蛋白Hsp 60被认为通过减轻细胞内β-淀粉样蛋白应激在阿尔茨海默病的进展中起作用。在这里，我们表明，细菌同源物GroEL（51%的序列同一性）降低了β淀粉样蛋白（1-42）（A β 42）对人类神经干细胞衍生的神经元培养物的神经毒性作用。为了理解GroEL介导的神经毒性消除的机制，我们使用各种生物物理技术研究了A β 42与GroEL的相互作用。β 42作为单体与GroEL结合，其寿命类似于1 ms，如从基于多个弛豫的NMR实验的全局分析所确定的。动态光散射表明，GroEL溶解了新鲜可溶性A β 42制剂中存在的少量高分子量多分散聚集体。GroEL结合的A β 42的残基特异性横向弛豫速率曲线揭示了位于疏水性GroEL共有结合序列内的三个锚定结合区（残基16-21、31-34和40-41）的存在。A β 42与GroEL结合的单分子FRET分析导致双标记的A β 42构建体的FRET效率没有显著变化，表明A β 42在与GroEL结合时采样无规卷曲系综。最后，GroEL大大减缓了NMR可见A β 42物质的消失和A β 42原纤维和原纤维的出现，如通过电子和原子力显微镜所监测的。后一观察结果与GroEL对A β 42诱导的神经毒性的时程的影响相关。这些数据为理解Hsp 60如何减缓阿尔茨海默病的进展提供了物理基础。
The human chaperonin Hsp60 is thought to play a role in the progression of Alzheimer's disease by mitigating against intracellular beta-amyloid stress. Here, we show that the bacterial homolog GroEL (51% sequence identity) reduces the neurotoxic effects of amyloid beta(1-42) (A beta 42) on human neural stem cell-derived neuronal cultures. To understand the mechanism of GroEL-mediated abrogation of neurotoxicity, we studied the interaction of A beta 42 with GroEL using a variety of biophysical techniques. A beta 42 binds to GroEL as a monomer with a lifetime of similar to 1 ms, as determined from global analysis of multiple relaxation-based NMR experiments. Dynamic light scattering demonstrates that GroEL dissolves small amounts of high-molecular-weight polydisperse aggregates present in fresh soluble A beta 42 preparations. The residue-specific transverse relaxation rate profile for GroEL-bound A beta 42 reveals the presence of three anchor-binding regions (residues 16-21, 31-34, and 40-41) located within the hydrophobic GroEL-consensus binding sequences. Single-molecule FRET analysis of A beta 42 binding to GroEL results in no significant change in the FRET efficiency of a doubly labeled A beta 42 construct, indicating that A beta 42 samples a random coil ensemble when bound to GroEL. Finally, GroEL substantially slows down the disappearance of NMR visible A beta 42 species and the appearance of A beta 42 protofibrils and fibrils as monitored by electron and atomic force microscopies. The latter observations correlate with the effect of GroEL on the time course of A beta 42-induced neurotoxicity. These data provide a physical basis for understanding how Hsp60 may serve to slow down the progression of Alzheimer's disease.