Cyclin A degradation by primate cytomegalovirus protein pUL21a counters its innate restriction of virus replication.
Cyclin A degradation by primate cytomegalovirus protein pUL21a counters its innate restriction of virus replication.
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DOI：
10.1371/journal.ppat.1003825
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发表时间：
2013
期刊：
影响因子：
6.7
通讯作者：
Yu D
中科院分区：
文献类型：
--
作者：
Caffarelli N;Fehr AR;Yu D
细胞周期蛋白A对细胞DNA合成和细胞周期的S期进展至关重要。人巨细胞病毒（HCMV）可降低细胞周期蛋白A（cyclin A）水平并阻断细胞DNA合成，而cyclin A过表达可抑制HCMV复制。这种相互作用以前仅在HCMV中观察到，因为鼠CMV不下调细胞周期蛋白A，并且尚未鉴定出负责的病毒因子。我们以前报道过HCMV蛋白pUL 21 a破坏了后期促进复合物（APC），但消除这种活性的点突变体没有表现出UL 21 a缺陷病毒，这表明pUL 21 a具有额外的功能。在这里，我们确定了一个保守的丙氨酸-x-亮氨酸（RxL）的细胞周期蛋白结合结构域的pUL 21 a，这使得pUL 21 a与细胞周期蛋白A相互作用，并靶向它的蛋白酶体降解。来自黑猩猩和恒河猴CMV的同源重组pUL 21 a蛋白也含有RxL结构域和类似的降解细胞周期蛋白A，表明这种功能在灵长类CMV中是保守的。RxL点突变使病毒阻断细胞DNA合成的能力丧失，并导致类似于pUL 21 a缺陷型病毒的生长缺陷。重要的是，敲低细胞周期蛋白A拯救了UL 21 a缺陷型病毒的生长。总之，这些数据表明，在进化过程中，灵长类CMV的pUL 21 a家族蛋白已经获得了一个细胞周期蛋白结合结构域，该结构域靶向细胞周期蛋白A进行降解，从而中和了其对病毒复制的限制。最后，pUL 21 a及其细胞靶标的组合蛋白酶体依赖性降解表明，pUL 21 a可能作为一种新型自杀蛋白，靶向其蛋白质货物进行破坏。细胞周期蛋白是进化上保守的蛋白质，其与细胞周期蛋白依赖性激酶（CDK）相关联以调节多种底物的磷酸化从而促进细胞周期进程。许多病毒操纵细胞周期，以创造一个适合复制的环境;然而，只有少数例子存在病毒调节细胞周期蛋白的活性。在这里，我们确定了人巨细胞病毒（HCMV）蛋白pUL 21 a内的细胞周期蛋白结合域，赋予其与细胞周期蛋白A相互作用的能力，并靶向其进行蛋白酶体降解。细胞周期蛋白A促进细胞DNA复制，这消耗了病毒复制所需的重要酶和代谢物，使得像HCMV这样的大型病毒阻断这种蛋白质的活性非常重要。与此雅阁，pUL 21 a降解细胞周期蛋白A的能力是病毒阻断细胞DNA复制和促进病毒复制所必需的。重要的是，切除细胞周期蛋白A的表达恢复了复制的病毒缺乏pUL 21 a，表明细胞周期蛋白A具有内在的能力，限制病毒复制，但特异性地抵消了pUL 21 a。结合我们先前的工作表明pUL 21 a还调节后期促进复合物，另一种主要的细胞周期调节因子，我们的研究现在已经揭示了HCMV在一种蛋白质中优雅地进化出双重功能，靶向病毒复制的细胞周期机制。
Cyclin A is critical for cellular DNA synthesis and S phase progression of the cell cycle. Human cytomegalovirus (HCMV) can reduce cyclin A levels and block cellular DNA synthesis, and cyclin A overexpression can repress HCMV replication. This interaction has only been previously observed in HCMV as murine CMV does not downregulate cyclin A, and the responsible viral factor has not been identified. We previously reported that the HCMV protein pUL21a disrupted the anaphase-promoting complex (APC), but a point mutant abrogating this activity did not phenocopy a UL21a-deficient virus, suggesting that pUL21a has an additional function. Here we identified a conserved arginine-x-leucine (RxL) cyclin-binding domain within pUL21a, which allowed pUL21a to interact with cyclin A and target it for proteasome degradation. Homologous pUL21a proteins from both chimpanzee and rhesus CMVs also contained the RxL domain and similarly degraded cyclin A, indicating that this function is conserved in primate CMVs. The RxL point mutation disabled the virus' ability to block cellular DNA synthesis and resulted in a growth defect similar to pUL21a-deficient virus. Importantly, knockdown of cyclin A rescued growth of UL21a-deficient virus. Together, these data show that during evolution, the pUL21a family proteins of primate CMVs have acquired a cyclin-binding domain that targets cyclin A for degradation, thus neutralizing its restriction on virus replication. Finally, the combined proteasome-dependent degradation of pUL21a and its cellular targets suggests that pUL21a may act as a novel suicide protein, targeting its protein cargos for destruction. Cyclins are evolutionarily conserved proteins that associate with cyclin-dependent kinases (CDKs) to regulate phosphorylation of multiple substrates to promote cell-cycle progression. Many viruses manipulate the cell cycle in order to create an environment suitable for replication; however, only few examples exist where viruses modulate cyclin activity. Here, we identified a cyclin-binding domain within the human cytomegalovirus (HCMV) protein pUL21a that confers its ability to interact with cyclin A and target it for proteasome degradation. Cyclin A promotes cellular DNA replication, which consumes important enzymes and metabolites needed for viral replication, making it important for large viruses like HCMV to block this protein's activity. In accord, the ability of pUL21a to degrade cyclin A was necessary for the virus to block cellular DNA replication and promote viral replication. Importantly, ablating cyclin A expression restored replication to a virus lacking pUL21a, demonstrating that cyclin A has the intrinsic ability to restrict viral replication, but is specifically countered by pUL21a. Together with our previous work showing that pUL21a also regulates the anaphase-promoting complex, another master cell cycle regulator, our studies have now revealed that HCMV has elegantly evolved dual functions within one protein targeting the cell cycle machinery for viral replication.
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影响因子：
15.9
作者：
Baumler, AJ
通讯作者：
Baumler, AJ
鼠伤寒沙门氏菌通过穿透和破坏佩耶斑块的专门上皮细胞来引起鼠的感染。
影响因子：
15.3
作者：
Jones, Bradley D.;Ghori, Nafisa;Falkow, Stanley
通讯作者：
Falkow, Stanley
DOI：
10.1084/jem.139.5.1189
发表时间：
1974-05-01
期刊：
The Journal of experimental medicine
影响因子：
--
作者：
Carter PB;Collins FM
通讯作者：
Collins FM
影响因子：
3.7
作者：
Audoly G;Vincentelli R;Edouard S;Georgiades K;Mediannikov O;Gimenez G;Socolovschi C;Mège JL;Cambillau C;Raoult D
通讯作者：
Raoult D
DOI：
10.1073/pnas.0808832106
发表时间：
2009-01-20
影响因子：
11.1
作者：
Fineran, Peter C.;Blower, Tim R.;Salmond, George P. C.
通讯作者：
Salmond, George P. C.