A bipartite sequence motif induces translation reinitiation in feline calicivirus RNA
A bipartite sequence motif induces translation reinitiation in feline calicivirus RNA
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DOI：
10.1074/jbc.m608948200
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发表时间：
2007-03-09
影响因子：
4.8
通讯作者：
Meyers, Gregor
中科院分区：
文献类型：
--
作者：
Luttermann, Christine;Meyers, Gregor
真核生物中蛋白质合成终止后重新开始翻译的机制尚未得到详细解决。一个悬而未决的问题涉及终止后核糖体与mRNA的结合方式，以允许必要的起始因子的结合。在杯状病毒（一种正链RNA病毒家族）中，衣壳蛋白VP 2通过终止/再起始过程翻译。猫杯状病毒的VP 2在3 '-末端开放阅读框3（ORF 3）中编码，其与前面的ORF 2重叠4个核苷酸。在瞬时表达研究中，VP 2的表达效率比ORF 2蛋白低20倍。ORF 2终止信号和ORF 3 AUG密码子的紧密邻近是至关重要的，而AUG可以被替代密码子取代。缺失图谱显示ORF 2的3 '端69个核苷酸对VP 2的表达至关重要。该序列包含两个基本序列基序。第一个基序在杯状病毒中是保守的，并与18 S rRNA的一部分互补。总之，VP 2在翻译终止/再起始过程中表达，这是特殊的，因为它需要一个序列元件，可以通过与18 S rRNA杂交防止终止后核糖体的解离。
The mechanism leading to reinitiation of translation after termination of protein synthesis in eukaryotes has not yet been resolved in detail. One open question concerns the way the post-termination ribosome is tethered to the mRNA to allow binding of the necessary initiation factors. In caliciviruses, a family of positive strand RNA viruses, the capsid protein VP2 is translated via a termination/reinitiation process. VP2 of the feline calicivirus is encoded in the 3'-terminal open reading frame 3 (ORF3) that overlaps with the preceding ORF2 by four nucleotides. In transient expression studies, the efficiency of VP2 expression was 20 times lower than that of the ORF2 proteins. The close vicinity of the ORF2 termination signal and the ORF3 AUG codon was crucial, whereas the AUG could be replaced by alternative codons. Deletion mapping revealed that the 3'-terminal 69 nucleotides of ORF2 are crucial for VP2 expression. This sequence contains two essential sequence motifs. The first motif is conserved among caliciviruses and complementary to part of the 18 S rRNA. In conclusion, VP2 is expressed in a translation termination/reinitiation process that is special because it requires a sequence element that could prevent dissociation of post-termination ribosomes via hybridization with 18 S rRNA.