中文摘要：黄瓜花叶病毒2b蛋白几乎在病毒周期的各个环节中都起着重要作用，包括细胞到细胞间的运动、症状的诱导和抗病毒RNA沉默的抑制。以前有研究表明，2b蛋白在细胞核和细胞质中也存在。2b蛋白磷酸化位点在所有CMV分离株中都是保守的，包括提议的酪蛋白激酶II和细胞周期蛋白依赖性激酶2的构成图谱。问了辨别2b蛋白磷酸化的影响，作者创设了8个不同突变体模拟蛋白非磷酸化（丝氨酸到丙氨酸）和磷酸化阶段（丝氨酸到天冬氨酸），从症状诱导、基因沉默抑制子活性和细胞定位等方面比较了这些突变体与野生型（Rs-CMV）病毒的差异。研究证实了2b蛋白在活体内的磷酸化作用；在磷酸化位点上含有天冬氨酸的突变体仅在细胞质中有积累，这表明磷酸化的2b蛋白不能进入细胞核。本研究确定了CMV2b蛋白中有一个保守的磷酸化双重开关，可保持2b蛋白在细胞核与细胞质之间来回运动的平衡，并可调控2b蛋白抑制子的活性。
外文摘要：The 2b protein of Cucumber mosaic virus has a role in nearly all steps of the viral cycle including cell-to-cell movement, symptom induction and suppression of antiviral RNA silencing. Previous studies demonstrated the presence of 2b protein in the nucleus and in cytoplasm as well. Phosphorylation site of 2b protein is conserved in all CMV isolates, including proposed constitute motifs for casein kinase II and cyclin-dependent kinase 2. To discern the impact of 2b protein phosphorylation, we created eight different mutants to mimic the non-phosporylated (serine to alanine) as well as the phosphorylated state (serine to aspartic acid) of the protein. We compared these mutants to the wild-type (Rs-CMV) virus in terms of symptom induction, gene silencing suppressor activity as well as in cellular localization. Here, in this study we confirmed the phosphorylation of 2b protein in vivo, both in infected N. benthamiana and in infiltrated patches. Mutants containing aspartic acid in the phosphorylation site accumulated only in the cytoplasm indicating that phosphorylated 2b protein could not enter the nucleus. We identified a conserved dual phosphorylation switch in CMV 2b protein, which equilibrates the shuttling of the 2b protein between the nucleus and the cytoplasm, and regulates the suppressor activity of the 2b protein.
作者：Nemes, Katalin; Gellert, Akos; Almasi, Aszteria; 等
作者单位：匈牙利科学院
期刊名称：SCIENTIFIC REPORTS
期刊影响因子：4.259
出版年份：2017
出版刊次：10
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