The long noncoding region of the human parainfluenza virus type 1 F gene contributes to the read-through transcription at the M-F gene junction
The long noncoding region of the human parainfluenza virus type 1 F gene contributes to the read-through transcription at the M-F gene junction
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DOI：
10.1128/jvi.76.16.8244-8251.2002
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发表时间：
2002-08-01
影响因子：
5.4
通讯作者：
Takimoto, T
中科院分区：
文献类型：
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作者：
Bousse, T;Matrosovich, T;Takimoto, T
仙台病毒（SV）和人副流感病毒1型（hPIV 1）的基因组由非节段的负义RNA组成，其中6个基因被高度保守的基因间（IG）序列以及转录起始（S）和终止信号分开。在hPIV 1感染的细胞中，M-F基因连接处的转录终止是无效的;产生大量的M-F通读转录物（T. Bousse，T. Takimoto，K. G. Murti和A. Portner，Virology 232：44-52，1997）。相反，在SV感染的细胞中检测到很少的M-F通读转录本。序列分析表明，hPIV 1在M-F连接处的IG和S序列与SV不同。此外，hPIV 1 F基因含有异常长的非编码序列。为了鉴定阻止M-F连接处转录终止的顺式作用元件，我们拯救了重组SV（rSVhMFjCG），其中其M-F基因连接被bPtV 1的连接所取代。用rSVhMFjCG感染的细胞产生丰富的M-F通读转录物;该结果表明hPIV 1 M-F连接是无效终止的原因。当rSVhMFjCG中的IG和S位点中的一个或两个被SV的那些取代时，转录终止的效率增加，但未达到在野生型SV感染的细胞中观察到的水平。除了IG和S信号突变外，rSVhMFjCG中hPIV 1 F基因的大部分长非编码区的缺失导致有效终止，其与野生型病毒感染细胞中观察到的水平相当。因此，hPIV 1 F基因的长非编码序列含有影响转录终止的顺式作用元件。我们评估了无效的转录终止对培养物中病毒复制的影响，结果表明，感染rSVhMFjCG的细胞产生的F蛋白比感染野生型SV的细胞少，并且培养物中重组SV的组装效率较低。这些表型似乎是感染rSVhMFjCG的小鼠延长存活的原因。
Sendai virus (SV) and human parainfluenza virus type 1 (hPIV1) have genomes consisting of nonsegmented negative-sense RNA in which the six genes are separated by well-conserved intergenic (IG) sequences and transcriptional start (S) and end signals. In hPIV1-infected cells, transcriptional termination at the M-F gene junction is ineffective; a large number of M-F read-through transcripts are produced (T. Bousse, T. Takimoto, K. G. Murti, and A. Portner, Virology 232:44-52, 1997). In contrast, few M-F read-through transcripts are detected in SV-infected cells. Sequence analysis indicated that the hPIV1 IG and S sequences in the M-F junction differ from those of SV. Furthermore, the hPIV1 F gene contains an unusually long noncoding sequence. To identify the cis-acting elements that prevent transcriptional termination at the M-F junction, we rescued recombinant SV (rSVhMFjCG) in which its M-F gene junction was replaced by that of bPtV1. Cells infected with rSVhMFjCG produced an abundance of M-F read-through transcripts; this result indicated that the hPIV1 M-F junction is responsible for inefficient termination. When one or both of the IG and S sites in rSVhMFjCG were replaced by those of SV, the efficiency of transcriptional termination increased but not to the level observed in wild-type SV-infected cells. Deletion of most of the long noncoding region of the hPIV1 F gene in rSVhMFjCG in addition to the mutations in IG and S signals resulted in efficient termination that was equivalent to the level observed in wild-type virus-infected cells. Therefore, the long noncoding sequence of the hPIV1 F gene contains cis-acting element(s) that affects transcriptional termination. Our evaluation of the effect of inefficient transcriptional termination on viral replication in culture revealed that cells infected with rSVhMFjCG produced less F protein than cells infected with wild-type SV and that assembly of the recombinant SV in culture was less efficient. These phenotypes seem to be responsible for the extended survival of mice infected with rSVhMFjCG.