The silencing suppressor P25 of Potato virus X interacts with Argonaute1 and mediates its degradation through the proteasome pathway
The silencing suppressor P25 of Potato virus X interacts with Argonaute1 and mediates its degradation through the proteasome pathway
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DOI：
10.1111/j.1364-3703.2010.00634.x
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发表时间：
2010-09-01
影响因子：
4.9
通讯作者：
Tsai, Ching-Hsiu
中科院分区：
文献类型：
--
作者：
Chiu, Meng-Hsuen;Chen, I-Hsuan;Tsai, Ching-Hsiu
先前的证据已经表明，由马铃薯X病毒（PVX）编码的P25蛋白抑制基于RNA沉默的抗病毒防御系统中的效应复合物的组装或功能（Bayne et al.，马铃薯X病毒的细胞间移动依赖于RNA沉默的抑制。Plant J. 44，471-482）。这一发现促使我们研究P25靶向RNA沉默的Argonaute（AGO）效应核酸酶的可能性。免疫共沉淀和Western blot分析表明，P25和拟南芥AGO 1蛋白在烟草中瞬时共表达时存在较强的相互作用。P25还与AGO 1、AGO 2、AGO 3和AGO 4相互作用，但不与AGO 5和AGO 9相互作用。作为一种有效的抑制剂，在P25的存在下积累的AGO 1的量显着低于与HcPro浸润，但恢复与蛋白酶体抑制剂MG 132处理时。这些发现与RNA沉默是一种抗病毒防御机制以及P25的反防御作用是通过蛋白酶体途径降解AGO蛋白的观点一致。进一步支持这一观点的是，观察到用MG 132处理的植物对PVX及其相关的竹花叶病毒不太敏感。
P>Previous evidence has indicated that the P25 protein encoded by Potato virus X (PVX) inhibits either the assembly or function of the effector complexes in the RNA silencing-based antiviral defence system (Bayne et al., Cell-to-cell movement of Potato Potexvirus X is dependent on suppression of RNA silencing. Plant J. 44, 471-482). This finding prompted us to investigate the possibility that P25 targets the Argonaute (AGO) effector nuclease of RNA silencing. Co-immunoprecipitation and Western blot analysis indicated that there is a strong interaction between P25 and AGO1 of Arabidopsis when these proteins are transiently co-expressed in Nicotiana benthamiana. P25 also interacts with AGO1, AGO2, AGO3 and AGO4, but not with AGO5 and AGO9. As an effective suppressor, the amount of AGO1 accumulated in the presence of P25 was dramatically lower than that infiltrated with HcPro, but was restored when treated with a proteasome inhibitor MG132. These findings are consistent with the idea that RNA silencing is an antiviral defence mechanism and that the counter-defence role of P25 is through the degradation of AGO proteins via the proteasome pathway. Further support for this idea is provided by the observation that plants treated with MG132 are less susceptible to PVX and its relative Bamboo mosaic virus.