Functional compartmentalization of Rad9 and Hus1 reveals diverse assembly of the 9-1-1 complex components during the DNA damage response in Leishmania.
Functional compartmentalization of Rad9 and Hus1 reveals diverse assembly of the 9-1-1 complex components during the DNA damage response in Leishmania.
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DOI：
10.1111/mmi.13441
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发表时间：
2016-09
影响因子：
3.6
通讯作者：
Tosi LR
中科院分区：
文献类型：
--
作者：
Damasceno JD;Obonaga R;Santos EV;Scott A;McCulloch R;Tosi LR
在真核细胞中，Rad9‐Rad1‐Hus1（9‐1‐1）复合物是协调DNA损伤感知、细胞周期进程和DNA修复途径的关键成分。这种与PCNA相关的三聚体被装载到RPA包被的单链DNA上，并与ATR激酶相互作用，介导有效的检查点信号传导，从而停止细胞周期并促进DNA修复。除了这些核心活动，越来越多的证据表明，9‐1‐1结构多样化可以提供更广泛的功能。原生动物寄生虫利什曼原虫是一种早期分支真核生物，具有显著的可塑性基因组，这暗示了特殊的基因组维持机制。在此，我们研究了L. major中9‐1‐1复合体亚基的同源性，发现LmRad9和LmRad1在复制胁迫下与染色质结合，并在体内与LmHus1形成复合体。与LmHus1类似，LmRad9参与端粒稳态，并参与对复制应激和双链断裂的响应。然而，LmRad9和LmHus1‐缺陷细胞表现出明显相反的表型，这表明它们的功能区隔化。我们发现一些LmRad9的细胞池形成了一个替代复合体，而一些LmHus1作为单体存在。我们认为利什曼原虫9‐1‐1亚基的多样化组装介导了功能区隔化，这对基因毒性应激的反应有直接影响。
The Rad9‐Rad1‐Hus1 (9‐1‐1) complex is a key component in the coordination of DNA damage sensing, cell cycle progression and DNA repair pathways in eukaryotic cells. This PCNA‐related trimer is loaded onto RPA‐coated single stranded DNA and interacts with ATR kinase to mediate effective checkpoint signaling to halt the cell cycle and to promote DNA repair. Beyond these core activities, mounting evidence suggests that a broader range of functions can be provided by 9‐1‐1 structural diversification. The protozoan parasite Leishmania is an early‐branching eukaryote with a remarkably plastic genome, which hints at peculiar genome maintenance mechanisms. Here, we investigated the existence of homologs of the 9‐1‐1 complex subunits in L. major and found that LmRad9 and LmRad1 associate with chromatin in response to replication stress and form a complex in vivo with LmHus1. Similar to LmHus1, LmRad9 participates in telomere homeostasis and in the response to both replication stress and double strand breaks. However, LmRad9 and LmHus1‐deficient cells present markedly opposite phenotypes, which suggest their functional compartmentalization. We show that some of the cellular pool of LmRad9 forms an alternative complex and that some of LmHus1 exists as a monomer. We propose that the diverse assembly of the Leishmania 9‐1‐1 subunits mediates functional compartmentalization, which has a direct impact on the response to genotoxic stress.