DCL4 targets Cucumber mosaic virus satellite RNA at novel secondary structures
DCL4 targets Cucumber mosaic virus satellite RNA at novel secondary structures
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DCL4 靶向黄瓜花叶病毒卫星 RNA 的新型二级结构
DOI：
10.1128/jvi.02885-06
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发表时间：
2007-09-01
影响因子：
5.4
通讯作者：
Guo, Hui-Shan
中科院分区：
文献类型：
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作者：
Du, Quan-Sheng;Duan, Cheng-Guo;Guo, Hui-Shan
据报道，植物病毒衍生的小干扰RNA（vsiRNA）主要来源于在细胞质中复制的正单链RNA病毒的结构化单链病毒RNA和双链DNA（dsDNA）病毒的核茎环35 S前导RNA。越来越多的证据也表明，植物Dicer样（DCL）蛋白的分级作用是小RNA生物合成过程所必需的，DCL 4是vsiRNA的主要生产者。然而，可以被DCL识别的这种单链病毒RNA的结构仍然未知。为了确定这些结构，我们克隆了来自黄瓜花叶病毒卫星RNA（satRNA）（CMV-satRNA）的siRNA，并研究了satRNA衍生的siRNA（satsiRNA）与satRNA二级结构之间的关系。satsiRNA被证实来源于单链satRNA，并且长度主要为21（64.7%）或22（22%）个核苷酸（nt）。发现最常克隆的正链satsiRNA来源于新型发夹，其不同于已知DCL底物、miRNA和siRNA前体的结构，其是普遍的茎环形或dsRNA。DCL 4被证明是satsiRNA的主要生产者。在不存在DCL 4的情况下，仅检测到22-nt satsiRNA。我们的研究结果表明，DCL 4能够访问灵活结构的单链RNA底物（优选T形发夹），以产生satsiRNA。这一结果表明，不同结构的病毒RNA可以刺激植物细胞中的抗病毒DCL活性。
It has been reported that plant virus-derived small interfering RNAs (vsiRNAs) originated predominantly from structured single-stranded viral RNA of a positive single-stranded RNA virus replicating in the cytoplasm and from the nuclear stem-loop 35S leader RNA of a double-stranded DNA (dsDNA) virus. Increasing lines of evidence have also shown that hierarchical actions of plant Dicer-like (DCL) proteins are required in the biogenesis process of small RNAs, and DCL4 is the primary producer of vsiRNAs. However, the structures of such single-stranded viral RNA that can be recognized by DCLs remain unknown. In an attempt to determine these structures, we have cloned siRNAs derived from the satellite RNA (satRNA) of Cucumber mosaic virus (CMV-satRNA) and studied the relationship between satRNA-derived siRNAs (satsiRNAs) and satRNA secondary structure. satsiRNAs were confirmed to be derived from single-stranded satRNA and are primarily 21 (64.7%) or 22 (22%) nucleotides (nt) in length. The most frequently cloned positive-strand satsiRNAs were found to derive from novel hairpins that differ from the structure of known DCL substrates, miRNA and siRNA precursors, which are prevalent stem-loop-shaped or dsRNAs. DCL4 was shown to be the primary producer of satsiRNAs. In the absence of DCL4, only 22-nt satsiRNAs were detected. Our results suggest that DCL4 is capable of accessing flexibly structured single-stranded RNA substrates (preferably T-shaped hairpins) to produce satsiRNAs. This result reveals that viral RNA of diverse structures may stimulate antiviral DCL activities in plant cells.