Identification of Plasmodium falciparum DNA Repair Protein Mre11 with an Evolutionarily Conserved Nuclease Function
Identification of Plasmodium falciparum DNA Repair Protein Mre11 with an Evolutionarily Conserved Nuclease Function
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DOI：
10.1371/journal.pone.0125358
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发表时间：
2015-05-04
期刊：
影响因子：
3.7
通讯作者：
Bhattacharyya, Mrinal Kanti
中科院分区：
文献类型：
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作者：
Badugu, Sugith Babu;Nabi, Shaik Abdul;Bhattacharyya, Mrinal Kanti
真核细胞减数分裂重组蛋白11(Mre11)在DNA损伤反应(DDR)中起着关键作用。具体地说，Mre11负责DNA双链断裂(DSB)的感知和信号传递，并通过属于同源重组(HR)或非同源末端连接(NHEJ)修复机制的效应蛋白促进其修复。在人类疟疾寄生虫恶性疟原虫中，已鉴定出HR和Alternative-NHEJ；然而，对这种生物DDR所涉及的上游因素知之甚少。在这份报告中，我们确定了恶性疟原虫Mre11的一个推测的同源基因，它与人的Mre11有22%的序列相似性。同源模拟显示，预测的PfaMre11核酸酶结构域与酿酒酵母Mre11(ScMre11)的核酸酶结构域具有显著的结构相似性。互补分析揭示了PfaMre11核酸酶活性的功能保守，这体现在PfaMre11核酸酶结构域与ScMre11的C-末端结构域结合在一起，在功能上补充了Mre11缺失的酵母菌株。功能互补实际上被PfaMre11核酸酶结构域(D398N)上的氨基酸取代而取消。在恶性疟原虫有丝分裂活跃的滋养体和裂殖体阶段，PfaMre11大量表达，并在DNA损伤反应中上调，提示在DDR中发挥作用。PfaMre11与PFalRad50显示出物理相互作用。此外，酵母双杂交研究表明PfaMre11与ScRad50和ScXrs2相互作用，ScRad50和ScXrs2是Mre11-Rad50-Xrs2复合体的两个重要组成部分，参与酿酒酵母的DDR信号转导和修复，进一步支持PfaMre11在DDR中的作用。综上所述，这些发现提供了证据，表明PfaMre11是疟原虫DDR的一个进化保守的成分。
The eukaryotic Meiotic Recombination protein 11 (Mre11) plays pivotal roles in the DNA damage response (DDR). Specifically, Mre11 senses and signals DNA double strand breaks (DSB) and facilitates their repair through effector proteins belonging to either homologous recombination (HR) or non-homologous end joining (NHEJ) repair mechanisms. In the human malaria parasite Plasmodium falciparum, HR and alternative-NHEJ have been identified; however, little is known about the upstream factors involved in the DDR of this organism. In this report, we identify a putative ortholog of Mre11 in Plasmodium falciparum (PfalMre11) that shares 22% sequence similarity to human Mre11. Homology modeling reveals striking structural resemblance of the predicted PfalMre11 nuclease domain to the nuclease domain of Saccharomyces cerevisiae Mre11 (ScMre11). Complementation analyses reveal functional conservation of PfalMre11 nuclease activity as demonstrated by the ability of the PfalMre11 nuclease domain, in conjunction with the C-terminal domain of ScMre11, to functionally complement an mre11 deficient yeast strain. Functional complementation was virtually abrogated by an amino acid substitution in the PfalMre11 nuclease domain (D398N). PfalMre11 is abundant in the mitotically active trophozoite and schizont stages of Plasmodium falciparum and is up-regulated in response to DNA damage, suggesting a role in the DDR. PfalMre11 exhibits physical interaction with PfalRad50. In addition, yeast 2-hybrid studies show that PfalMre11 interacts with ScRad50 and ScXrs2, two important components of the well characterized Mre11-Rad50-Xrs2 complex which is involved in DDR signaling and repair in Saccharomyces cerevisiae, further supporting a role for PfalMre11 in the DDR. Taken together, these findings provide evidence that PfalMre11 is an evolutionarily conserved component of the DDR in Plasmodium.