Coupled translation of the second open reading frame of M2 mRNA is sequence dependent and differs significantly within the subfamily Pneumovirinae
Coupled translation of the second open reading frame of M2 mRNA is sequence dependent and differs significantly within the subfamily Pneumovirinae
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DOI：
10.1128/jvi.00457-07
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发表时间：
2007-08-01
影响因子：
5.4
通讯作者：
Easton, Andrew John
中科院分区：
文献类型：
--
作者：
Gould, Phillip Spencer;Easton, Andrew John
偶联翻译，首先在呼吸道合胞病毒（RSV）的M2基因中描述，是翻译起始的另一种机制，其中翻译第一个（M2-1）开放阅读框（ORF）的核糖体在终止后向上游移动一小段距离，并从第二个（M2-2）重叠的ORF重新启动翻译。禽肺炎病毒（APV）和小鼠肺炎病毒（PVM），尽管具有显著不同的效率。为了鉴定RSV和APV之间偶联表达效率变化的原因，我们使用了含有来自每种病毒的不同长度的M2-1 ORF的嵌合M2-1基因。允许嵌合体中偶联表达的基本组分是来自RSV M2-1编码区的含有高度二级结构的区段。当存在具有高水平二级结构的区域时，RSV M2-1 ORF 5'端的额外序列也促进偶联翻译。这些数据表明，至少两个遥远的部分的mRNA转录本，连同一个合适的重叠区域，参与耦合过程。用等同的APV序列替换RSV M2-1 ORF的最后102个核苷酸显示出相同水平的偶联翻译。因此，重叠区域可以将核糖体引导回到第二ORF的起始密码子上，而M2-1 ORF的上游编码序列决定偶联表达的水平。
Coupled translation, first described in the M2 gene of pneumovirus respiratory syncytial virus (RSV), is an alternative mechanism of translational initiation in which the ribosomes which translate the first (M2-1) open reading frame (ORF) move a short distance upstream after termination and reinitiate translation from a second (M2-2) overlapping ORE Here, we show that the same mechanism occurs in two closely related viruses, avian pneumovirus (APV) and pneumonia virus of mice (PVM), although with markedly different efficiencies. To identify the reasons for the variation in efficiency of coupled expression between RSV and APV, we used chimeric M2-1 genes containing different lengths of the M2-1 ORF from each virus. An essential component allowing coupled expression in the chimeras was a segment from the RSV M2-1 coding region containing a high degree of secondary structure. Additional sequences at the 5' end of the RSV M2-1 ORF also promoted coupled translation when the region with high levels of secondary structure was present. These data indicate that at least two distant parts of the mRNA transcript, together with a suitable overlapping region, are involved in the coupling process. Replacement of the last 102 nucleotides of the RSV M2-1 ORF with the equivalent APV sequence showed identical levels of coupled translation. Thus, the overlapping region can direct the ribosome back onto the start codon of the second ORF while the upstream coding sequence of the M2-1 ORF determines the levels of coupled expression.