Olsthoorn R C, Bol J F
Institute of Molecular Plant Sciences, Gorlaeus Laboratories, Leiden University, The Netherlands.
RNA. 2001 Oct;7(10):1370-7.
Sequences of 191 flavivirus RNAs belonging to four sero-groups were used to predict the secondary structure of the 3' noncoding region (3' NCR) directly upstream of the conserved terminal hairpin. In mosquito-borne flavivirus RNAs (n = 164) a characteristic structure element was identified that includes a phylogenetically well-supported pseudoknot. This element is repeated in the dengue and Japanese encephalitis RNAs and centers around the conserved sequences CS2 and RCS2. In yellow fever virus RNAs that contain one CS2 motif, only one copy of this pseudoknotted structure was found. The conserved pseudoknotted element is absent from the 3' NCR of tick-borne virus RNAs, which altogether adopt a secondary structure that is very different from that of mosquito-borne virus RNAs. The strong conservation of the pseudoknot in mosquito-borne flavivirus RNAs implies a stronger relationship between these viruses than concluded from previous secondary structure analyses. The role of the (tandem) pseudoknots in flavivirus replication is discussed.
利用属于四个血清群的191种黄病毒RNA序列,预测保守末端发夹结构上游3'非编码区(3'NCR)的二级结构。在蚊媒黄病毒RNA(n = 164)中,鉴定出一个特征性结构元件,其中包括一个系统发育上得到有力支持的假结。该元件在登革热和日本脑炎RNA中重复出现,并以保守序列CS2和RCS2为中心。在含有一个CS2基序的黄热病毒RNA中,仅发现该假结结构的一个拷贝。蜱传病毒RNA的3'NCR中不存在保守的假结元件,其整体二级结构与蚊媒病毒RNA的二级结构非常不同。蚊媒黄病毒RNA中假结的高度保守意味着这些病毒之间的关系比之前二级结构分析得出的结论更为密切。文中讨论了(串联)假结在黄病毒复制中的作用。