Functional characterization of the nuclear localization signal for a suppressor of posttranscriptional gene silencing
Functional characterization of the nuclear localization signal for a suppressor of posttranscriptional gene silencing
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DOI：
10.1128/jvi.77.12.7026-7033.2003
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发表时间：
2003-06-01
影响因子：
5.4
通讯作者：
Hong, YG
中科院分区：
文献类型：
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作者：
Dong, XL;van Wezel, R;Hong, YG
中国番茄黄卷叶病毒（TYLCV-C）的C2蛋白是转录后基因沉默（PTGS）的活性抑制因子。同样，TYLCV-C感染导致植物PTGS阻滞。C2蛋白在碱性氨基酸丰富区域KVQHRIAKKTTRRRR（31）内具有功能性的、富含精氨酸的核定位信号（17）。在马铃薯X病毒中表达时，被绿色荧光蛋白（GFP）标记的C2-RRRR(31)DVGG（其中四个连续的精氨酸残基28RRRR31被DVGG取代）不能将GFP转运到细胞核中，并且在诱导坏死和抑制PTGS方面功能失调。氨基酸取代突变体C2-K17D-GFP、c2 - hr21d - gfp和C2-KK25DI-GFP定位于细胞核并产生坏死，但只有C2-K17D-GFP抑制PTGS。与GFP融合的n端C2（1-31）和C2（17-31）能够将GFP靶向细胞核，但不引起坏死，也不影响PTGS。我们的数据表明，C2蛋白在C2介导的诱导坏死和抑制PTGS中发挥作用可能需要核定位，这可能遵循多种途径。讨论了C2蛋白参与这些生物学功能的可能机制。
The nucleus-localized C2 protein of Tomato yellow leaf curl virus-China (TYLCV-C) is an active suppressor of posttranscriptional gene silencing (PTGS). Consistently, infection with TYLCV-C resulted in PTGS arrest in plants. The C2 protein possesses a functional, arginine-rich nuclear localization signal within the basic amino acid-rich region (17)KVQHRIAKKTTRRRR(31). When expressed from potato virus X, C2-RRRR(31)DVGG (in which the four consecutive arginine residues 28RRRR31 were replaced with DVGG) that had been tagged with a green fluorescent protein (GFP) failed to transport GFP into nuclei and was dysfunctional in inducing necrosis and suppressing PTGS in plants. Amino acid substitution mutants C2-K17D-GFP, C2-HR21DV-GFP, and C2-KK25DI-GFP localized to nuclei and produced necrosis, but only C2-K17D-GFP suppressed PTGS. The N-terminal portions C2(1-31) and C2(17-31), fused in frame to GFP were capable of targeting GFP to nuclei, but neither caused necrosis nor affected PTGS. Our data establish that nuclear localization is likely required for C2 protein to function in C2-mediated induction of necrosis and suppression of PTGS, which may follow diverse pathways in plants. Possible mechanisms of how the C2 protein involves these biological functions are discussed.