Dreher T W, Tsai C H, Skuzeski J M
Department of Agricultural Chemistry, Oregon State University, Corvallis 97331-7301, USA.
Proc Natl Acad Sci U S A. 1996 Oct 29;93(22):12212-6. doi: 10.1073/pnas.93.22.12212.
The turnip yellow mosaic virus genomic RNA terminates at its 3' end in a tRNA-like structure that is capable of specific valylation. By directed mutation, the aminoacylation specificity has been switched from valine to methionine, a novel specificity for viral tRNA-like structures. The switch to methionine specificity, assayed in vitro under physiological buffer conditions with wheat germ methionyl-tRNA synthetase, required mutation of the anticodon loop and the acceptor stem pseudoknot. The resultant methionylatable genomes are infectious and stable in plants, but genomes that lack strong methionine acceptance (as previously shown with regard to valine acceptance) replicate poorly. The results indicate that amplification of turnip yellow mosaic virus RNA requires aminoacylation, but that neither the natural (valine) specificity nor interaction specifically with valyl-tRNA synthetase is crucial.
芜菁黄花叶病毒基因组RNA在其3'端以一种能够进行特异性缬氨酰化的类似tRNA的结构终止。通过定向突变，氨酰化特异性已从缬氨酸转换为甲硫氨酸，这是病毒类似tRNA结构的一种新特异性。在生理缓冲条件下，用小麦胚甲硫氨酰-tRNA合成酶进行体外测定，向甲硫氨酸特异性的转换需要反密码子环和受体茎假结发生突变。产生的可被甲硫氨酰化的基因组在植物中具有感染性且稳定，但缺乏强甲硫氨酸接受性的基因组（如先前关于缬氨酸接受性所显示的）复制较差。结果表明，芜菁黄花叶病毒RNA的扩增需要氨酰化，但天然的（缬氨酸）特异性以及与缬氨酰-tRNA合成酶的特异性相互作用都不是关键的。
