RAG1自身泛素化在V(D)J重组中的作用。
Role of RAG1 autoubiquitination in V(D)J recombination.
作者信息
Singh Samarendra K, Gellert Martin
机构信息
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892.
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892
出版信息
Proc Natl Acad Sci U S A. 2015 Jul 14;112(28):8579-83. doi: 10.1073/pnas.1510464112. Epub 2015 Jun 29.
The variable domains of Ig and T-cell receptor genes in vertebrates are assembled from gene fragments by the V(D)J recombination process. The RAG1-RAG2 recombinase (RAG1/2) initiates this recombination by cutting DNA at the borders of recombination signal sequences (RSS) and their neighboring gene segments. The RAG1 protein is also known to contain a ubiquitin E3 ligase activity, located in an N-terminal region that is not strictly required for the basic recombination reaction but helps to regulate recombination. The isolated E3 ligase domain was earlier shown to ubiquitinate one site in a neighboring RAG1 sequence. Here we show that autoubiquitination of full-length RAG1 at this specific residue (K233) results in a large increase of DNA cleavage by RAG1/2. A mutational block of the ubiquitination site abolishes this effect and inhibits recombination of a test substrate in mouse cells. Thus, ubiquitination of RAG1, which can be promoted by RAG1's own ubiquitin ligase activity, plays a significant role in governing the level of V(D)J recombination activity.
脊椎动物中免疫球蛋白（Ig）和T细胞受体基因的可变结构域是通过V（D）J重组过程由基因片段组装而成的。重组激活基因1-重组激活基因2重组酶（RAG1-RAG2，简称RAG1/2）通过在重组信号序列（RSS）及其相邻基因片段的边界切割DNA来启动这种重组。已知RAG1蛋白还具有泛素E3连接酶活性，位于N端区域，该区域对于基本重组反应并非严格必需，但有助于调节重组。早期研究表明，分离出的E3连接酶结构域可使相邻RAG1序列中的一个位点泛素化。在此我们表明，全长RAG1在这个特定残基（K233）处的自身泛素化会导致RAG1/2的DNA切割大幅增加。泛素化位点的突变阻断消除了这种效应，并抑制了小鼠细胞中测试底物的重组。因此，RAG1的泛素化（可由RAG1自身的泛素连接酶活性促进）在控制V（D）J重组活性水平方面发挥着重要作用。
Zotero 插件