Tombusvirus Y-Shaped Translational Enhancer Forms a Complex with eIF4F and Can Be Functionally Replaced by Heterologous Translational Enhancers

作者：Nicholson Beth L; Zaslaver Olga; Mayberry Laura K; Browning Karen S; White K Andrew^*

来源：Journal of Virology, 2013, 87(3): 1872-1883.

DOI：10.1128/JVI.02711-12

Certain plus-strand RNA plant viruses that are uncapped and nonpolyadenylated rely on RNA elements in their 3%26apos; untranslated region, termed 3%26apos;-cap-independent translational enhancers (3%26apos;CITEs), for efficient translation of their proteins. Here, we have investigated the properties of the Y-shaped class of 3%26apos;CITE present in the tombusvirus Carnation Italian ringspot virus (CIRV). While some types of 3%26apos;CITE have been found to function through recruitment of translation initiation factors to the viral genome, no trans-acting translation-related factors have yet been identified for the Y-shaped 3%26apos;CITE. Our results indicate that the CIRV 3%26apos;CITE complexes with eIF4F and eIFiso4F, with the former mediating translation more efficiently than the latter. In nature, some classes of 3%26apos;CITE are present in several different viral genera, suggesting that these elements hold a high degree of modularity. Here, we test this concept by engineering chimeric viruses containing heterologous 3%26apos;CITEs and show that the Y-shaped class of 3%26apos;CITE in CIRV can be replaced by two alternative types of 3%26apos;CITE, i.e., a Panicum mosaic virus-like 3%26apos;CITE or an I-shaped 3%26apos;CITE, without any major loss in in vitro translation or replication efficiency in protoplasts. The heterologous 3%26apos;CITEs also mediated whole-plant infections of Nicotiana benthamiana, where distinct symptoms were observed for each of the alternative 3%26apos;CITEs and 3%26apos;CITE evolution occurred during serial passaging. Our results supply new information on Y-shaped 3%26apos;CITE function and provide insights into 3%26apos;CITE virus-host compatibilities.

• 出版日期2013-2