West Danella L, Loughlin Fionna E, Rivero-Rodríguez Francisco, Vankadari Naveen, Velázquez-Cruz Alejandro, Corrales-Guerrero Laura, Díaz-Moreno Irene, Wilce Jacqueline A
Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia.
Institute for Chemical Research, University of Seville-CSIC, Seville, Spain.
Front Mol Biosci. 2022 Jul 14;9:960806. doi: 10.3389/fmolb.2022.960806. eCollection 2022.
Stress granules are non-membrane bound RNA-protein granules essential for survival during acute cellular stress. TIA-1 is a key protein in the formation of stress granules that undergoes liquid-liquid phase separation by association with specific RNAs and protein-protein interactions. However, the fundamental properties of the TIA-1 protein that enable phase-separation also render TIA-1 susceptible to the formation of irreversible fibrillar aggregates. Despite this, within physiological stress granules, TIA-1 is not present as fibrils, pointing to additional factors within the cell that prevent TIA-1 aggregation. Here we show that heterotypic interactions with stress granule co-factors Zn and RGG-rich regions from FUS each act together with nucleic acid to induce the liquid-liquid phase separation of TIA-1. In contrast, these co-factors do not enhance nucleic acid induced fibril formation of TIA-1, but rather robustly inhibit the process. NMR titration experiments revealed specific interactions between Zn and H94 and H96 in RRM2 of TIA-1. Strikingly, this interaction promotes multimerization of TIA-1 independently of the prion-like domain. Thus, through different molecular mechanisms, these stress granule co-factors promote TIA-1 liquid-liquid phase separation and suppress fibrillar aggregates, potentially contributing to the dynamic nature of stress granules and the cellular protection that they provide.
应激颗粒是在急性细胞应激期间对生存至关重要的无膜结合RNA-蛋白质颗粒。TIA-1是应激颗粒形成中的关键蛋白，它通过与特定RNA的结合以及蛋白质-蛋白质相互作用经历液-液相分离。然而，使TIA-1能够进行相分离的基本特性也使TIA-1易于形成不可逆的纤维状聚集体。尽管如此，在生理应激颗粒中，TIA-1并非以纤维形式存在，这表明细胞内存在其他防止TIA-1聚集的因素。在此，我们表明与应激颗粒辅助因子锌以及FUS的富含RGG区域的异型相互作用各自与核酸共同作用，诱导TIA-1的液-液相分离。相反，这些辅助因子不会增强核酸诱导的TIA-1纤维形成，而是强烈抑制该过程。核磁共振滴定实验揭示了锌与TIA-1的RRM2中H94和H96之间的特异性相互作用。引人注目的是，这种相互作用独立于朊病毒样结构域促进TIA-1的多聚化。因此，通过不同的分子机制，这些应激颗粒辅助因子促进TIA-1的液-液相分离并抑制纤维状聚集体，这可能有助于应激颗粒的动态性质以及它们所提供的细胞保护。
