The U-Box E3 Ligase SPL11/PUB13 Is a Convergence Point of Defense and Flowering Signaling in Plants
The U-Box E3 Ligase SPL11/PUB13 Is a Convergence Point of Defense and Flowering Signaling in Plants
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DOI：
10.1104/pp.112.199430
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发表时间：
2012-09-01
期刊：
影响因子：
7.4
通讯作者：
Wang, Guo-Liang
中科院分区：
文献类型：
--
作者：
Liu, Jinling;Li, Wei;Wang, Guo-Liang
泛素-蛋白酶体系统（UPS）参与真核生物细胞中蛋白质的选择性降解，由三种主要酶组成：泛素激活酶（E1）、泛素结合酶（E2）和泛素连接酶（E3）。在典型的泛素化反应中，E1、E2和E3酶参与将泛素单体转移到目标蛋白中赖氨酸残基的e-氨基。在反应的第一步，E1通过ATP催化泛素的活化，产生高能硫醇中间体。激活后，泛素被转移到E2，然后转移到E3连接酶，这是该过程的最后一步，这涉及在泛素的c端Gly和底物蛋白中的Lys残基之间建立异肽键（回顾，见Vierstra, 2009； Ye和Rape， 2009）。植物中的UPS对这三种酶具有层次结构：很少有e1，大约有50个e2，但有超过1000个e3。例如，水稻（Oryza sativa）基因组编码6个E1基因，49个E2和E2样基因，以及1300多个E3基因（Du et al., 2009）。UPS系统中丰富的E3蛋白允许植物靶向许多生物过程的底物，因为每个E3泛素连接酶仅对一种或几种靶蛋白的泛素化起作用。根据亚基组成和作用方式，E3连接酶可分为两种主要类型：单亚基型（与E6羧基末端[HECT]和RING/U-box同源）和多亚基型（Skp1 [s期激酶相关蛋白1]-CUL1 [Cullin1]-F-box [SCF]，后期促进复合物[APC]， CUL3-BTB [brick -a- brac, tramtrack broad complex]， CUL4-DDB[损伤特异性]）
The ubiquitin-proteasome system (UPS) is involved in the selective degradation of proteins in the cells of eukaryotic organisms and consists of three main enzymes: ubiquitin-activating enzymes (E1), ubiquitinconjugating enzymes (E2), and ubiquitin ligases (E3). In a typical ubiquitination reaction, E1, E2, and E3 enzymes participate in the transfer of the ubiquitin monomers to the e-amino group of a Lys residue in the target protein. In the first step of the reaction, E1 catalyzes the activation of ubiquitin via ATP, creating a high-energy thiol intermediate. After activation, ubiquitin is transferred to the E2 and then to the E3 ligase for the final step in the process, which involves the creation of an isopeptide bond between the C-terminal Gly of ubiquitin and a Lys residue in the substrate protein (for review, see Vierstra, 2009; Ye and Rape, 2009). The UPS in plants has a hierarchical structure for the three enzymes: there are few E1s, about 50 E2s, but over 1,000 E3s. For example, the rice (Oryza sativa) genome encodes six E1 genes, 49 E2 and E2-like genes, and over 1,300 E3 genes (Du et al., 2009). The abundance of the E3 proteins in the UPS system allows plants to target substrates for many biological processes, because each E3 ubiquitin ligase acts for the ubiquitination of only one or a few target proteins. Based on the subunit component and action modes, E3 ligases can be divided into two major types: the singlesubunit type (Homology to E6 carboxyl terminus [HECT] and RING/U-box) and the multisubunit type (Skp1 [for S-phase kinase-associated protein1]-CUL1 [for Cullin1]-F-box [SCF], Anaphase promoting complex [APC], CUL3-BTB [for Bric-a-Brac, tramtrack broad complex], CUL4-DDB [for damage-specific