Powell Michael L, Brown T David K, Brierley Ian
Division of Virology, Department of Pathology, University of Cambridge, Cambridge, UK.
Biochem Soc Trans. 2008 Aug;36(Pt 4):717-22. doi: 10.1042/BST0360717.
Viruses have evolved a number of translational control mechanisms to regulate the levels of expression of viral proteins on polycistronic mRNAs, including programmed ribosomal frameshifting and stop codon readthrough. More recently, another unusual mechanism has been described, that of termination-dependent re-initiation (also known as stop-start). Here, the AUG start codon of a 3' ORF (open reading frame) is proximal to the termination codon of a uORF (upstream ORF), and expression of the two ORFs is coupled. For example, segment 7 mRNA of influenza B is bicistronic, and the stop codon of the M1 ORF and the start codon of the BM2 ORF overlap in the pentanucleotide UAAUG (stop codon of M1 is shown in boldface and start codon of BM2 is underlined). This short review aims to provide some insights into how this translational coupling process is regulated within different viral systems and to highlight some of the differences in the mechanism of re-initiation on prokaryotic, eukaryotic and viral mRNAs.
病毒已经进化出多种翻译控制机制，以调节多顺反子mRNA上病毒蛋白的表达水平，包括程序性核糖体移码和终止密码子通读。最近，又描述了另一种不同寻常的机制，即终止依赖性重新起始（也称为停止-起始）。在这里，3' 开放阅读框（ORF）的AUG起始密码子靠近上游开放阅读框（uORF）的终止密码子，并且两个开放阅读框的表达是偶联的。例如，乙型流感病毒的第7节段mRNA是双顺反子，M1开放阅读框的终止密码子与BM2开放阅读框的起始密码子在五核苷酸UAAUG中重叠（M1的终止密码子用粗体显示，BM2的起始密码子加下划线）。这篇简短的综述旨在深入了解这种翻译偶联过程在不同病毒系统中是如何被调控的，并突出原核生物、真核生物和病毒mRNA重新起始机制的一些差异。
