Department of Experimental Oncology, European Institute of Oncology, Milan 20141, Italy.
Mol Cell. 2010 Jan 29;37(2):282-93. doi: 10.1016/j.molcel.2009.12.035.
The RAG1 and RAG2 proteins are the only lymphoid-specific factors required to perform the first step of V(D)J recombination, DNA cleavage. While the catalytic domain of RAG1, the core region, has been well characterized, the role of the noncore region in modulating chromosomal V(D)J recombination efficiency remains ill defined. Recent studies have highlighted the role of chromatin structure in regulation of V(D)J recombination. Here we show that RAG1 itself, through a RING domain within its N-terminal noncore region, preferentially interacts directly with and promotes monoubiquitylation of histone H3. Mutations affecting the RAG1 RING domain reduce histone H3 monoubiquitylation activity, decrease V(D)J recombination activity in vivo, reduce formation of both signal-joint and coding-joint products on episomal substrates, and decrease efficiency of V(D)J recombination at the endogenous IgH locus in lymphoid cells. The results reveal that RAG1-mediated histone monoubiquitylation activity plays a role in regulating the joining phase of chromosomal V(D)J recombination.
RAG1 和 RAG2 蛋白是执行 V(D)J 重组第一步 DNA 切割所必需的唯一淋巴细胞特异性因子。虽然 RAG1 的催化结构域（核心区域）已经得到了很好的描述，但非核心区域在调节染色体 V(D)J 重组效率方面的作用仍未明确。最近的研究强调了染色质结构在 V(D)J 重组调控中的作用。在这里，我们表明 RAG1 本身通过其 N 端非核心区域内的一个 RING 结构域，优先直接与组蛋白 H3 相互作用，并促进其单泛素化。影响 RAG1 RING 结构域的突变会降低组蛋白 H3 的单泛素化活性，降低体内 V(D)J 重组活性，减少游离载体上信号连接和编码连接产物的形成，并降低淋巴细胞中内源性 IgH 基因座上 V(D)J 重组的效率。这些结果表明，RAG1 介导的组蛋白单泛素化活性在调节染色体 V(D)J 重组的连接阶段中发挥作用。
