Department of Biochemistry, Molecular Biology and Biotechnology, Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland.
Department of Biochemistry, Molecular Biology and Biotechnology, Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland.
Int J Biol Macromol. 2020 Nov 15;163:108-119. doi: 10.1016/j.ijbiomac.2020.06.255. Epub 2020 Jun 30.
The FKBP39 from Drosophila melanogaster is a multifunctional regulatory immunophilin. It contains two globular domains linked by a highly charged disordered region. The N-terminal domain shows homology to the nucleoplasmin core domain, and the C-terminal domain is characteristic for the family of the FKBP immunophilin ligand binding domain. The specific partially disordered structure of the protein inspired us to investigate whether FKBP39 can drive spontaneous liquid-liquid phase separation (LLPS). Preliminary analyses using CatGranule and Pi-Pi contact predictors suggested a propensity for LLPS. Microscopy observations revealed that FKBP39 can self-concentrate to form liquid condensates. We also found that FKBP39 can lead to LLPS in the presence of RNA and peptides containing Arg-rich linear motifs derived from selected nuclear and nucleolar proteins. These heterotypic interactions have a stronger propensity for driving LLPS when compared to the interactions mediated by self-associating FKBP39 molecules. To investigate whether FKBP39 can drive LLPS in the cellular environment, we analysed it in fusion with YFP in COS-7 cells. The specific distribution and diffusion kinetics of FKBP39 examined by FRAP experiments provided evidence that immunophilin is an important driver of phase separation. The ability of FKBP39 to go into heterotypic interaction may be fundamental for ribosome subunits assembly.
果蝇 FKBP39 是一种多功能调节免疫亲和素。它包含两个由高电荷无序区连接的球状结构域。N 端结构域与核质素核心结构域具有同源性，C 端结构域是 FKBP 免疫亲和素配体结合域家族的特征。该蛋白特殊的部分无序结构激发了我们研究 FKBP39 是否可以驱动自发液-液相分离（LLPS）。使用 CatGranule 和 Pi-Pi 接触预测器的初步分析表明，该蛋白具有 LLPS 的倾向。显微镜观察显示，FKBP39 可以自我浓缩形成液滴。我们还发现，FKBP39 可以在 RNA 存在下以及在含有来自选定核和核仁蛋白的富含精氨酸的线性基序的肽存在下导致 LLPS。与由自缔合 FKBP39 分子介导的相互作用相比，这些异质相互作用具有更强的驱动 LLPS 的倾向。为了研究 FKBP39 是否可以在细胞环境中驱动 LLPS，我们在 COS-7 细胞中与 YFP 融合进行了分析。通过 FRAP 实验检测到的 FKBP39 的特定分布和扩散动力学提供了证据表明，免疫亲和素是相分离的重要驱动因素。FKBP39 进行异质相互作用的能力对于核糖体亚基的组装可能是至关重要的。
