Regulation of Plasmodium falciparum Origin Recognition Complex subunit 1 (PfORC1) function through phosphorylation mediated by CDK-like kinase PK5
Regulation of Plasmodium falciparum Origin Recognition Complex subunit 1 (PfORC1) function through phosphorylation mediated by CDK-like kinase PK5
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DOI：
10.1111/mmi.13099
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发表时间：
2015-10-01
影响因子：
3.6
通讯作者：
Dhar, Suman Kumar
中科院分区：
文献类型：
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作者：
Deshmukh, Abhijit S.;Agarwal, Meetu;Dhar, Suman Kumar
恶性疟原虫起源识别复合物亚基1（PfORC 1）参与DNA复制和var基因调控。虽然C-末端参与DNA复制，但N-末端以Sir 2依赖的方式在var基因调控中具有特定作用。PfORC 1定位于核周边，在寄生虫发育的早期阶段，染色体末端的聚集可能是调节亚端粒var基因表达的关键。在寄生虫发育的后期，当端粒簇解体时，ORC 1分布在细胞核和寄生虫细胞质中，在那里它可能需要其他细胞功能，包括DNA复制。ORC 1的表达水平在早期阶段急剧下降。介导PfORC 1功能调节的机制在很大程度上是未知的。在这里，我们表明，通过使用重组蛋白和表达野生型或突变形式的ORC 1的转基因寄生虫，即磷酸化的PfORC 1-N末端结构域的细胞周期蛋白依赖性激酶（CDK）PfPK 5废除DNA结合活性，并导致亚细胞定位和蛋白酶体介导的降解的蛋白质的变化，在寄生虫。这些结果表明，PfORC 1磷酸化的CDK是中央的重要生物功能，如DNA复制和var基因沉默的调节。
Plasmodium falciparum Origin Recognition Complex subunit 1 (PfORC1) has been implicated in DNA replication and var gene regulation. While the C-terminus is involved in DNA replication, the specific role of N-terminus has been suggested in var gene regulation in a Sir2-dependent manner. PfORC1 is localized at the nuclear periphery, where the clustering of chromosomal ends at the early stage of parasite development may be crucial for the regulation of subtelomeric var gene expression. Upon disassembly of telomeric clusters at later stages of parasite development, ORC1 is distributed in the nucleus and parasite cytoplasm where it may be required for its other cellular functions including DNA replication. The level of ORC1 decreases dramatically at the late schizont stage. The mechanisms that mediate regulation of PfORC1 function are largely unknown. Here we show, by the use of recombinant proteins and of transgenic parasites expressing wild type or mutant forms of ORC1, that phosphorylation of the PfORC1-N terminal domain by the cyclin-dependent kinase (CDK) PfPK5 abolishes DNA-binding activity and leads to changes in subcellular localization and proteasome-mediated degradation of the protein in schizonts. These results reveal that PfORC1 phosphorylation by a CDK is central to the regulation of important biological functions like DNA replication and var gene silencing.