Identification of F-Box Proteins in Toxoplasma

E3泛素连接酶的SKP 1/Cullin/F-box（SCF）类是进化上的一种 一个保守的酶家族，调节包括细胞在内的关键细胞过程 循环、膜运输和信号传导。SCF-E3由四个核心组成 Rbx 1、Cullin 1、SKP 1和F-box蛋白。F-box蛋白是 亚基，其募集底物蛋白以被SCF-E3多聚泛素化，并且它们 也可以直接聚泛素化。SCF-E3依赖性多聚泛素作为一种 用于靶向26 S-蛋白酶体并被其降解的信号。每一个真核生物 表达一系列F-box蛋白，其中大多数具有不同的亲和力 不同的底物蛋白。因此，F-box蛋白是至关重要的，因为它们决定了 特异性蛋白质将被SCF-E3泛素化。此外，F-box蛋白可以 功能独立于SCF-E3。因此，识别和表征F盒 蛋白质是理解SCF-E3的功能和重建的核心。 蛋白质组作为细胞从事新的功能。这很重要，因为蛋白质降解 与基因转录一样重要。在这里，我们将识别 必需的SCF-E3依赖性F-box蛋白，确定它们为什么是必需的， 识别作为其泛素化底物的蛋白质。这些研究将揭示 泛素如何支持一种主要的人类寄生虫的生长和毒力。此外，本发明还提供了一种方法， 考虑到SCF的保守性，这些发现将与相关病原体相关- E3和许多F-box蛋白在弓形虫和其他顶复门寄生虫之间的差异。

The SKP1/Cullin/F-box (SCF) class of E3 Ubiquitin Ligases is an evolutionarily conserved family of enzymes that regulate key cellular processes including the cell cycle, membrane trafficking, and signaling. The SCF-E3 is composed of four core components - Rbx1, Cullin1, SKP1, and a F-box protein. F-box proteins are the subunits that recruit substrate proteins to be poly-ubiquitinated by the SCF-E3, and they can also be directly poly-ubiquitinated. SCF-E3 dependent polyubiquitin serves as a signal for targeting to and degradation by the 26S-proteasome. Every eukaryote expresses a repertoire of F-box proteins, the majority of which have different affinities for different substrate proteins. Thus, F-box proteins are critical since they dictate which specific proteins will be ubiquitinated by the SCF-E3. In addition, F-box proteins can function independently of the SCF-E3. Thus, identifying and characterizing F-box proteins is central to understanding the functions of the SCF-E3 and remodeling of the proteome as cells engage new functions. This is important because protein degradation is as important as gene transcription in defining a cell's proteome. Here, we will identify essential SCF-E3 dependent F-box proteins, determine why they are essential, and identify the proteins that are their ubiquitination substrates. These studies will reveal how ubiquitin supports growth and virulence of a major human parasite. In addition, these findings will be relevant to related pathogens given the conservation of the SCF- E3 and many F-box proteins between Toxoplasma and other apicomplexan parasites.