Miyagi Tamami, Ueda Koji, Sugimoto Masahiro, Yagi Takuya, Ito Daisuke, Yamazaki Rio, Narumi Satoshi, Hayamizu Yuhei, Uji-I Hiroshi, Kuroda Masahiko, Kanekura Kohsuke
Department of Molecular Pathology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160-8402, Japan.
Department of Pharmacology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160-8402, Japan.
iScience. 2023 May 25;26(6):106957. doi: 10.1016/j.isci.2023.106957. eCollection 2023 Jun 16.
Arginine-rich dipeptide repeat proteins (R-DPRs), poly(PR) and poly(GR), translated from the hexanucleotide repeat expansion in the amyotrophic lateral sclerosis (ALS)-causative gene, contribute significantly to pathogenesis of ALS. Although both R-DPRs share many similarities, there are critical differences in their subcellular localization, phase separation, and toxicity mechanisms. We analyzed localization, protein-protein interactions, and phase separation of R-DPR variants and found that sufficient segregation of arginine charges is necessary for nucleolar distribution. Proline not only efficiently separated the charges, but also allowed for weak, but highly multivalent binding. In contrast, because of its high flexibility, glycine cannot fully separate the charges, and poly(GR) behaves similarly to the contiguous arginines, being trapped in the cytoplasm. We conclude that the amino acid that spaces the arginine charges determines the strength and multivalency of the binding, leading to differences in localization and toxicity mechanisms.
富含精氨酸的二肽重复蛋白（R-DPRs），即多聚（PR）和多聚（GR），由肌萎缩侧索硬化症（ALS）致病基因中的六核苷酸重复扩增翻译而来，对ALS的发病机制有显著影响。尽管这两种R-DPRs有许多相似之处，但它们在亚细胞定位、相分离和毒性机制方面存在关键差异。我们分析了R-DPR变体的定位、蛋白质-蛋白质相互作用和相分离，发现精氨酸电荷的充分分隔对于核仁分布是必要的。脯氨酸不仅能有效分隔电荷，还能实现弱但高度多价的结合。相比之下，由于甘氨酸具有高度灵活性，它不能完全分隔电荷，多聚（GR）的行为类似于连续的精氨酸，被困在细胞质中。我们得出结论，分隔精氨酸电荷的氨基酸决定了结合的强度和多价性，导致定位和毒性机制的差异。
