RNA sequences involved in transcriptional termination of respiratory syncytial virus
RNA sequences involved in transcriptional termination of respiratory syncytial virus
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DOI：
10.1128/jvi.75.1.36-44.2001
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发表时间：
2001-01-01
影响因子：
5.4
通讯作者：
Wertz, GW
中科院分区：
文献类型：
--
作者：
Harmon, SB;Megaw, AG;Wertz, GW
呼吸道合胞病毒（RS）基因末端的RNA信号指导多聚腺苷酸化和病毒转录的终止。这些基因末端含有两个保守区域，一个五核苷酸和一段尿苷酸（U）残基，由保守性较差的富含A/U的中心区域隔开。U道被认为是病毒mRNA通过逆转录进行多聚腺苷酸化的模板。通过诱变双顺反子RNA复制子中的基质（M）基因末端（3 '-UCAAUUAU UUUU-5'）来研究终止的顺式作用要求。终止效率通过单顺反子mRNA和当终止未能发生时产生的双顺反子通读RNA的细胞内代谢标记来定量。基因末端的所有三个区域都是终止所必需的。M基因末端的前8个核苷酸中的每一个突变为所有其他核苷酸，表明核苷酸2至6对于终止和不耐受变化是重要的，而核苷酸1和7是耐受变化的。在第8位，A或U允许终止，但G或C不允许。U形管的长度和位置对终止都很重要。在位置9至12的U残基是必要的，而在位置8，特别是位置13的额外的U残基，提高终止效率。改变中心区域的长度废除了终止，这表明U道相对于3 '-UCAAU-5'序列的位置是至关重要的。RS病毒10个基因的终止效率各不相同。由于转录是强制性顺序的，并且每个基因的终止是下游下一个基因转录所必需的，因此这些差异可能有助于基因调控。与我们的数据一致，当在RNA复制子中分析类似突变时，RS病毒的天然存在的无效终止的基因末端具有与减少的终止相关的短U带或其他序列特征。
RNA signals at the ends of the genes of respiratory syncytial (RS) virus direct polyadenylation and termination of viral transcription. These gene ends contain two conserved regions, a pentanucleotide and a tract of uridylate (U) residues, separated by an A/U-rich central region that is less well conserved. The U tract is thought to be the template for polyadenylation of viral mRNAs by reiterative transcription. The cis-acting requirements for termination were investigated by mutagenesis of the matrix (M) gene end (3'-UCAAUUAU UUUUU-5') in a dicistronic RNA replicon. Termination efficiencies were quantitated by intracellular metabolic labeling of monocistronic mRNAs and the dicistronic readthrough RNAs that result when termination fails to occur. All three regions of the gene end were necessary for termination. Mutation of each of the first 8 nucleotides of the M gene end to all other nucleotides showed that nucleotides 2 to 6 were important for termination and intolerant of change, whereas nucleotides 1 and 7 were tolerant of change. At position 8, A or U allowed termination, but G or C did not. Both the length and the position of the U tract were important for termination. U residues at positions 9 to 12 were necessary, while additional U residues at position 8, and especially position 13, enhanced termination efficiency. Altering the length of the central region abolished termination, suggesting that the position of the U tract with respect to the 3'-UCAAU-5' sequence was critical. The termination efficiencies of each of the 10 genes of RS virus are different. Since transcription is obligatorily sequential and termination of each gene is required for transcription of the next gene downstream, these differences may contribute to gene regulation. In agreement with our data, the naturally occurring gene ends of RS virus that terminate inefficiently have short U tracts or other sequence features that correlated with decreased termination when similar mutations were analyzed in RNA replicons.