Nucleocytoplasmic transport: a target for cellular control

描述（由申请人提供）：核和细胞质室之间唯一的交换介质是核孔复合物（npc），由称为核孔蛋白或核孔蛋白的蛋白质组成。核细胞质运输是由可溶性运输因子驱动的（大多数属于一个相关的蛋白质家族，称为核细胞蛋白或Kaps），它们携带同源货物穿过鼻咽癌。这种运输在多个层面上受到调节，包括核细胞蛋白对货物的识别以及与NPC的相互作用。NPC还通过影响核结构和作为各种核过程的控制点，在基因表达中发挥关键的调节作用。主要的病理细胞过程与核细胞质运输的改变有关，许多病毒靶向核细胞质运输途径的成分来篡夺它。因此，核孔蛋白和转运因子是药物治疗的关键潜在靶点。我们将重点关注核胞质转运的两个关键调控领域，其中结构信息最有可能导致对这些调控过程的基本机制见解。首先，我们将调查Kaps如何识别他们的货物。Kaps的重叠特异性赋予细胞选择性控制数千种货物运输的能力，并为药物干预提供了丰富的潜在靶点来源。PSI生物公司将提供与货物结合的Kaps晶体结构，这将补充生化和生物信息学方法，以揭示货物识别的序列和结构要求。其次，我们将以高分辨率绘制NPC的篮子区域，这是一系列令人眼花缭乱的核过程的关键控制点。这些过程是由篮子蛋白之间的相互作用介导的；然而，将这些不同的功能分配到篮子蛋白的结构域已被证明是不成功的，主要是因为对其结构组织及其组成部分的相互依赖性知之甚少。因此，PSI生物公司的篮子成分及其相互作用物的原子结构将与我们选择的与NPC相关的亚复合物的补充生物物理、形态和蛋白质组学数据相结合，以获得NPC和核外围环境下核篮子的高分辨率地图。一旦建立，这张图将用于指导单个组件的解剖和扰动，以阐明篮子的结构组织与执行其各种功能的机制之间的关系。

DESCRIPTION (provided by applicant): The sole mediators of exchange between the nuclear and cytoplasmic compartments are nuclear pore complexes (NPCs), comprised of proteins termed nucleoporins or Nups. Nucleocytoplasmic transport is driven by soluble transport factors (most belonging to a related family of proteins termed karyopherins or Kaps) that carry their cognate cargos across the NPC. This transport is regulated at multiple levels, including cargo recognition by karyopherins and interactions with the NPC. The NPC also plays a key regulatory role in gene expression by influencing nuclear architecture and acting as a point of control for various nuclear processes. Major pathological cellular processes are associated with altered nucleocytoplasmic transport, and many viruses target components of the nucleocytoplasmic transport pathway to usurp it. Hence, nucleoporins and transport factors are key potential targets for drug therapy. We will focus on two of the key regulatory areas of nucleocytoplasmic transport, where structural information is most likely to lead to fundamental mechanistic insights into these regulatory processes. First, we will investigate how Kaps recognize their cargos. The overlapping specificity of Kaps endows cells with the ability to selectively control the transport of thousands of cargos and provides a rich source of potential targets for pharmacological intervention. PSI Biology will provide crystal structures of Kaps bound to their cargos, which will complement biochemical and bioinformatics approaches to reveal both the sequence and structure requirements for cargo recognition. Second, we will map at high resolution the basket region of the NPC, a critical point of control for a bewildering array of nuclear processes. These processes are mediated by the interplay of interactions among the basket proteins; however, assigning these varied functions to domains of the basket proteins has proven largely unsuccessful, primarily because little is known about its structural organization and the interdependence of its components. The atomic structures of basket components and their interactors from PSI Biology will therefore be integrated with our complementary biophysical, morphological, and proteomic data on selected subcomplexes associated with the NPC to obtain a high resolution map of the nuclear basket in the context of the NPC and nuclear periphery. Once established, this map will be used to guide the dissection and perturbation of individual components, to elucidate the relationship between the structural organization of the basket and the mechanisms by which it executes its various functions.