Structure-function properties in liquid organelles

项目摘要 生物分子凝聚物在各种疾病中正逐渐成为细胞功能的中心。 短信。这些凝析油通常具有液体性质，并由多价类聚合物组装而成 分子。总之，这些观察表明，一个无序的相互作用网络稳定了 凝析油。液体系统本质上是无序的，这似乎排除了有序性的水平 结构-功能特性出现所必需的。然而，初步结果显示， 隐藏在液体无序中的是赋予uid结构的分子组装的层次结构。 此外，稳定液体的触点内的这种结构赋予了关键的功能特征 凝析油。这意味着，为了了解这些凝析油是如何发挥作用的， 识别无序系统中的结构所必需的。这对结构的老化提出了挑战。 生物学，因为这种层级结构不能用像X射线、核磁共振、 和冷冻-EM。拟议的研究将建立识别和表征内部结构的方法 液体冷凝物。这些方法基于使用迭代单元的理论建模 类似于用核磁共振确定结构的过程。这将在两个系统中完成，每个系统 在一个特定的目标上有特色。RST系统是一种用于相分离的模型系统，它去除了 识别和量化交互站点的应用。在确定微观结构时 这种粘合剂和间隔物的结合系统，这被认为是液体冷凝物中的一个常见主题- 这一目标将确立分子结构如何决定空间组织的基本原则 从招募分子客户到细胞器分离/共定位的长度范围。 第二个目标是发展核仁的结构建模技术。这个核细胞器 是核糖体的组装场所。拟议的研究将使用体外相分离数据。 要了解颗粒成分(GC)中的主要分子相互作用，其中rRNAs 和蛋白质组装成核糖体亚基。GC中的相互作用主要是静电作用， 这与目标1关注的贴纸和间隔基序不同。接下来，这些相互作用 将用于构建核糖体亚基组装的动力学理论。这个模型将建立如何 GC组分的分子结构有助于核糖体的组装。在这两者中生成的理论 目标将是分析性的，这意味着它们将允许彻底探索参数空间和 可以很容易地应用于其他系统。

Project Abstract Biomolecular condensates are emerging as central to cellular functions in a wide variety of con- texts. These condensates often have liquid properties and are assembled from multivalent, polymer-like molecules. Together, these observations suggest a disordered network of interactions stabilizing the condensate. Liquid systems are inherently disordered, which would seem to preclude the level of order necessary for structure-function properties to emerge. However, preliminary results have shown that, hidden within the liquid disorder, is a hierarchy of molecular assemblies that give structure to the uid. Furthermore, this structure within the contacts stabilizing the liquid confers crucial functional features to the condensates. This means that in order to understand how these condensates function, it is necessary to identify structure in disordered systems. This poses a challenge to the eld of structural biology because this hierarchical structure cannot be resolved by workhorse techniques like X-ray, NMR, and cryo-EM. The proposed research will establish methods to identify and characterize structure within liquid condensates. These methods are based on theoretical modeling using an iterative re nement procedure analogous to structure determination by NMR. This will be done in two systems that are each featured in a speci c aim. The rst system is a model system for phase separation that removes com- plications with identifying and quantifying interaction sites. In determining the microscopic structure of this \sticker and spacer" binding system, which is thought to be a common motif in liquid conden- sates, this aim will establish basic principles of how molecular structure can dictate spatial organization on lengthscales ranging from the recruitment molecular clients to organelle segregation/colocalization. The second aim will develop the structural modeling techniques on the nucleolus. This nuclear organelle serves as the assembly site for ribosomes. The proposed research will use in vitro phase separation data to understand the primary molecular interactions within the granular component (GC) where rRNAs and protein assemble into ribosomal subunits. The interactions in the GC are primarily electrostatic, which is di erent than the sticker and spacer motif that is the focus of Aim 1. Next, these interactions will be used to build a kinetic theory of ribosome subunit assembly. This model will establish how the molecular structure of GC components facilitates ribosome assembly. The theories for generated in both aims will be analytic, meaning that they will allow for a thorough exploration of parameter space and can be readily applied to other systems.