为了抵消宿主抗病毒RNA沉默,植物病毒编码多种RNA沉默的病毒抑制剂(VSR)。P0蛋白已在许多多病毒中被鉴定为VSR。然而,它们的抑制功能尚未得到充分表征。这里,我们通过绿色荧光蛋白(GFP)共浸润试验,研究了豌豆轻度萎黄病病毒(PMCV)P0在抑制野生型和GFP转基因烟草(16c系)局部和系统性RNA沉默中的作用.氨基酸缺失分析表明,N端残基Asn2和Val3,而不是C端残基从230-270aa,是PMCVP0(P0PM)VSR活性所必需的。P0PM作为F-box蛋白,在F-box样基序处的三重LPP突变(62LPxx79P)消除了其VSR活性。此外,P0PM未能与S期激酶相关蛋白1(SKP1)相互作用,这与马铃薯卷叶病毒P0的先前发现一致。这些数据进一步支持P0的VSR活性独立于P0-SKP1相互作用的观点。此外,我们检查了P0PM对ARGONAUTE1(AGO1)蛋白稳定性的影响,共表达分析表明,P0PM引发AGO1降解。一起来看,我们的研究结果表明,P0PM促进AGO1的降解,从而抑制RNA沉默,而与SKP1相互作用无关。
To counteract host antiviral RNA silencing, plant viruses encode numerous viral suppressors of RNA silencing (VSRs). P0 proteins have been identified as VSRs in many poleroviruses. However, their suppressor function has not been fully characterized. Here, we investigated the function of P0 from pea mild chlorosis virus (
PMCV) in the suppression of local and systemic RNA silencing via green fluorescent protein (GFP) co-infiltration assays in wild-type and GFP-transgenic Nicotiana benthamiana (line 16c). Amino acid deletion analysis showed that N-terminal residues Asn 2 and Val 3, but not the C-terminus residues from 230-270 aa, were necessary for
PMCV P0 (P0PM) VSR activity. P0PM acted as an F-box protein, and triple LPP mutation (62LPxx79P) at the F-box-like motif abolished its VSR activity. In addition, P0PM failed to interact with S-phase kinase-associated protein 1 (SKP1), which was consistent with previous findings of P0 from potato leafroll virus. These data further support the notion that VSR activity of P0 is independent of P0-SKP1 interaction. Furthermore, we examined the effect of P0PM on ARGONAUTE1 (AGO1) protein stability, and co-expression analysis showed that P0PM triggered AGO1 degradation. Taken together, our findings suggest that P0PM promotes degradation of AGO1 to suppress RNA silencing independent of SKP1 interaction.