Sass Mikaila I, Mack Deirdre C, Nickles Riley A, Jones Caelen A, Brunsdale Rex L, Cottam Samuel L, Shen Peter S, Willardson Barry M
Department of Chemistry and Biochemistry, Brigham Young University, C100 BNSN, Provo, UT 84602, USA.
Department of Biochemistry, School of Medicine, University of Utah, 15 N. Medical Drive East, Salt Lake City, UT 84112, USA.
bioRxiv. 2025 May 30:2025.05.28.656654. doi: 10.1101/2025.05.28.656654.
The Chaperonin Containing Tailless polypeptide 1 (CCT or TRiC) is an essential cytosolic chaperone that folds multiple protein substrates, including many with β-propeller folds. One β-propeller substrate is the G protein β subunit (Gβ) of Regulator of G protein Signaling (RGS) complexes that determine the duration of G protein signals in neurons. In recent work, we used cryo-electron microscopy (cryo-EM) to visualize the complete CCT-mediated folding trajectory for Gβ, from an initiating electrostatic interaction of a single β-strand in Gβ with CCT5 to a completely folded β-propeller structure. Here, we used biochemistry and cryo-EM to determine how missense mutations in Gβ, including those that cause severe neurological diseases, alter the Gβ folding trajectory and lead to incompletely folded, trapped intermediates. These findings highlight how defects in chaperonin-mediated folding contribute to disease and suggest potential strategies for stabilizing misfolded proteins to restore function.
含无尾多肽1的伴侣蛋白（CCT或TRiC）是一种重要的胞质伴侣蛋白，可折叠多种蛋白质底物，包括许多具有β-螺旋桨折叠结构的底物。一种β-螺旋桨底物是G蛋白信号调节因子（RGS）复合物的G蛋白β亚基（Gβ），它决定神经元中G蛋白信号的持续时间。在最近的研究中，我们利用冷冻电子显微镜（cryo-EM）观察了CCT介导的Gβ完整折叠轨迹，从Gβ中一条β链与CCT5的起始静电相互作用到完全折叠的β-螺旋桨结构。在这里，我们利用生物化学和冷冻电子显微镜来确定Gβ中的错义突变，包括那些导致严重神经疾病的突变，如何改变Gβ折叠轨迹并导致折叠不完全、被困的中间体。这些发现突出了伴侣蛋白介导的折叠缺陷如何导致疾病，并提出了稳定错误折叠蛋白以恢复功能的潜在策略。
