Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, 5 Memorial Drive, Bethesda, MD 20892-0520, USA.
Chembiochem. 2021 Jun 2;22(11):1985-1991. doi: 10.1002/cbic.202100055. Epub 2021 Apr 7.
Huntington's disease arises from polyQ expansion within the exon-1 region of huntingtin (htt ), resulting in an aggregation-prone protein that accumulates in neuronal inclusion bodies. We investigate the interaction of various htt constructs with the bacterial analog (GroEL) of the human chaperonin Hsp60. Using fluorescence spectroscopy and electron and atomic force microscopy, we show that GroEL inhibits fibril formation. The binding kinetics of htt constructs with intact GroEL and a mini-chaperone comprising the apical domain is characterized by relaxation-based NMR measurements. The lifetimes of the complexes range from 100 to 400 μs with equilibrium dissociation constants (K ) of ∼1-2 mM. The binding interface is formed by the N-terminal amphiphilic region of htt (which adopts a partially helical conformation) and the H and I helices of the GroEL apical domain. Sequestration of monomeric htt by GroEL likely increases the critical concentration required for fibrillization.
亨廷顿病是由于亨廷顿蛋白（htt）外显子 1 区域内的 polyQ 扩展引起的，导致易于聚集的蛋白质在神经元包含体内积累。我们研究了各种 htt 构建体与人类伴侣蛋白 Hsp60 的细菌类似物（GroEL）的相互作用。使用荧光光谱法、电子和原子力显微镜，我们表明 GroEL 抑制原纤维形成。通过基于松弛的 NMR 测量来表征具有完整 GroEL 和包含顶端结构域的 mini-chaperone 的 htt 构建体的结合动力学。复合物的寿命范围为 100 到 400 μs，平衡解离常数（K ）约为 1-2 mM。结合界面由 htt 的 N 端两亲性区域（其采用部分螺旋构象）和 GroEL 顶端结构域的 H 和 I 螺旋形成。GroEL 对单体 htt 的隔离可能会增加原纤维形成所需的临界浓度。
