Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, 63110, USA.
Center for Science and Engineering Living Systems (CSELS), Washington University, St. Louis, MO, 63130, USA.
Cell Commun Signal. 2021 Jun 5;19(1):65. doi: 10.1186/s12964-021-00744-9.
Biomolecular condensates are non-stoichiometric assemblies that are characterized by their capacity to spatially concentrate biomolecules and play a key role in cellular organization. Proteins that drive the formation of biomolecular condensates frequently contain oligomerization domains and intrinsically disordered regions (IDRs), both of which can contribute multivalent interactions that drive higher-order assembly. Our understanding of the relative and temporal contribution of oligomerization domains and IDRs to the material properties of in vivo biomolecular condensates is limited. Similarly, the spatial and temporal dependence of protein oligomeric state inside condensates has been largely unexplored in vivo.
In this study, we combined quantitative microscopy with number and brightness analysis to investigate the aging, material properties, and protein oligomeric state of biomolecular condensates in vivo. Our work is focused on condensates formed by AUXIN RESPONSE FACTOR 19 (ARF19), a transcription factor integral to the auxin signaling pathway in plants. ARF19 contains a large central glutamine-rich IDR and a C-terminal Phox Bem1 (PB1) oligomerization domain and forms cytoplasmic condensates.
Our results reveal that the IDR amino acid composition can influence the morphology and material properties of ARF19 condensates. In contrast the distribution of oligomeric species within condensates appears insensitive to the IDR composition. In addition, we identified a relationship between the abundance of higher- and lower-order oligomers within individual condensates and their apparent fluidity.
IDR amino acid composition affects condensate morphology and material properties. In ARF condensates, altering the amino acid composition of the IDR did not greatly affect the oligomeric state of proteins within the condensate. Video Abstract.
生物分子凝聚物是非化学计量的组装体，其特征是能够空间浓缩生物分子，并在细胞组织中发挥关键作用。驱动生物分子凝聚物形成的蛋白质通常含有寡聚化结构域和内源性无序区域（IDR），这两者都可以提供多价相互作用，从而推动高级组装。我们对寡聚化结构域和 IDR 对体内生物分子凝聚物的物质性质的相对和时间贡献的理解是有限的。同样，蛋白质寡聚态在凝聚物内部的时空依赖性在体内也在很大程度上尚未得到探索。
在这项研究中，我们将定量显微镜与数字和亮度分析相结合，研究了体内生物分子凝聚物的老化、物质性质和蛋白质寡聚态。我们的工作集中在由 AUXIN RESPONSE FACTOR 19（ARF19）形成的凝聚物上，ARF19 是植物中生长素信号通路的一个组成部分。ARF19 包含一个大的中央富含谷氨酰胺的 IDR 和一个 C 末端 Phox Bem1（PB1）寡聚化结构域，并形成细胞质凝聚物。
我们的结果表明，IDR 的氨基酸组成可以影响 ARF19 凝聚物的形态和物质性质。相比之下，凝聚物内寡聚体的分布似乎对 IDR 组成不敏感。此外，我们在单个凝聚物内鉴定出高序和低序寡聚物的丰度与它们的表观流动性之间存在关系。
IDR 的氨基酸组成影响凝聚物的形态和物质性质。在 ARF 凝聚物中，改变 IDR 的氨基酸组成不会显著影响凝聚物内蛋白质的寡聚状态。视频摘要。
