School of Biological and Biomedical Sciences, University of Durham Durham, UK.
Front Plant Sci. 2014 Apr 1;5:122. doi: 10.3389/fpls.2014.00122. eCollection 2014.
Ubiquitin is a peptide modifier able to form polymers of varying length and linkage as part of a powerful signaling system. Perhaps the best-known aspect of this protein's function is as the driver of targeted protein degradation through the Ubiquitin Proteasome System (UPS). Through the formation of lysine 48-linked polyubiquitin chains, it is able to direct the degradation of tagged proteins by the 26S proteasome, indirectly controlling many processes within the cell. However, recent research has indicated that ubiquitin performs a multitude of other roles within the cell beyond protein degradation. It is able to form 6 other "atypical" linkages though lysine residues at positions 6, 11, 27, 29, 33, and 63. These atypical chains perform a range of diverse functions, including the regulation of iron uptake in response to perceived deficiency, repair of double stranded breaks in the DNA, and regulation of the auxin response through the non-proteasomal degradation of auxin efflux carrier protein PIN1. This review explores the role ubiquitin chain topology plays in plant cellular function. We aim to highlight the importance of these varying functions and the future challenges to be encountered within this field.
泛素是一种能够形成不同长度和连接方式聚合物的肽修饰物，是一种强大的信号系统的一部分。这种蛋白质功能的最好的方面之一是作为通过泛素蛋白酶体系统 (UPS) 靶向蛋白质降解的驱动因素。通过形成赖氨酸 48 连接的多泛素链，它能够通过 26S 蛋白酶体直接引导标记蛋白的降解，间接控制细胞内的许多过程。然而，最近的研究表明，泛素在细胞内除了蛋白质降解之外还具有多种其他作用。它能够通过赖氨酸残基在位置 6、11、27、29、33 和 63 形成其他 6 种“非典型”连接。这些非典型链具有多种不同的功能，包括对感知到的缺乏的铁摄取的调节、DNA 双链断裂的修复，以及通过非蛋白酶体降解生长素流出载体蛋白 PIN1 来调节生长素反应。本综述探讨了泛素链拓扑结构在植物细胞功能中的作用。我们旨在强调这些不同功能的重要性以及该领域未来将面临的挑战。
