A Dual Interaction between the DNA Damage Response Protein MDC1 and the RAG1 Subunit of the V(D)J Recombinase
A Dual Interaction between the DNA Damage Response Protein MDC1 and the RAG1 Subunit of the V(D)J Recombinase
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DOI：
10.1074/jbc.m112.402487
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发表时间：
2012-10-19
影响因子：
4.8
通讯作者：
Goldberg, Michal
中科院分区：
文献类型：
--
作者：
Coster, Gideon;Gold, Ayala;Goldberg, Michal
V（D）J重组的第一步是由RAG 1和RAG 2蛋白形成特异性DNA双链断裂（DSB），其形成RAG重组酶。DSB激活一个复杂的蛋白质网络，称为DNA损伤反应（DDR）。DDR中的一个关键早期事件是DSB周围组蛋白H2 AX的磷酸化，其形成MDC 1的串联BRCA 1 C末端（tBRCT）结构域的结合位点。该事件是后续信号放大和将额外的DDR蛋白募集到断裂位点所必需的。RAG 1在其C末端（R1 Ct）具有组蛋白H2 AX样基序，使其成为推定的MDC 1结合蛋白。在这项工作中，我们表明MDC 1的tBRCT结构域与RAG 1的R1 Ct基序结合。令人惊讶的是，我们还观察到两种蛋白质之间的第二个结合界面，涉及MDC 1的富含脯氨酸-丝氨酸-苏氨酸（PST）重复序列和RAG 1的N-末端非核心区（R1 Nt）。重复序列-R1 Nt相互作用是组成性的，而tBRCT-R1 Ct相互作用可能需要RAG 1的R1 Ct基序的磷酸化。由于RAG 1的C末端与RAG活性的抑制有关，我们提出了一种模型，其中RAG 1的R1 Ct基序的磷酸化作为自启动的调节信号发挥作用。
The first step in V(D)J recombination is the formation of specific DNA double-strand breaks (DSBs) by the RAG1 and RAG2 proteins, which form the RAG recombinase. DSBs activate a complex network of proteins termed the DNA damage response (DDR). A key early event in the DDR is the phosphorylation of histone H2AX around DSBs, which forms a binding site for the tandem BRCA1 C-terminal (tBRCT) domain of MDC1. This event is required for subsequent signal amplification and recruitment of additional DDR proteins to the break site. RAG1 bears a histone H2AX-like motif at its C terminus (R1Ct), making it a putative MDC1-binding protein. In this work we show that the tBRCT domain of MDC1 binds the R1Ct motif of RAG1. Surprisingly, we also observed a second binding interface between the two proteins that involves the Proline-Serine-Threonine rich (PST) repeats of MDC1 and the N-terminal non-core region of RAG1 (R1Nt). The repeats-R1Nt interaction is constitutive, whereas the tBRCT-R1Ct interaction likely requires phosphorylation of the R1Ct motif of RAG1. As the C terminus of RAG1 has been implicated in inhibition of RAG activity, we propose a model in which phosphorylation of the R1Ct motif of RAG1 functions as a self-initiated regulatory signal.