Park Jong-Won, Desvoyes Bénédicte, Scholthof Herman B
Department of Plant Pathology and Microbiology, Intercollegiate Faculty of Virology, Texas A&M University, College Station, TX 77843, USA.
J Virol. 2002 Dec;76(24):12747-57. doi: 10.1128/jvi.76.24.12747-12757.2002.
This study on Tomato bushy stunt virus identified and defined three previously unknown regulatory sequences involved in RNA accumulation that are located within the 3'-proximal nested movement protein genes p22 and p19. The first is a 16-nucleotide (nt) element termed III-A that is positioned at the very 3' end of p22 and is essential for RNA accumulation. Approximately 300 nt upstream of III-A resides an approximately 80-nt inhibitory element (IE) that is obstructive to replication only in the absence of a third regulatory element of approximately 30 nt (SUR-III) that is positioned immediately upstream of III-A. Inspection of the nucleotide sequences predicted that III-A and SUR-III can form looped hairpins. A comparison of different tombusviruses showed, in each case, conservation for potential base pairing between the two predicted hairpin-loops. Insertion of a spacer adjacent to the predicted hairpins had no or a minimal effect on RNA accumulation, whereas an insertion in the putative III-A loop abolished genomic RNA multiplication. We conclude that the sequences composing the predicted III-A and SUR-III hairpin-loops are crucial for optimal RNA accumulation and that the inhibitory effect of IE surfaces when the alleged interaction between SUR-III and III-A is disturbed.
这项针对番茄丛矮病毒的研究鉴定并确定了三个先前未知的参与RNA积累的调控序列，它们位于3'-近端嵌套移动蛋白基因p22和p19内。第一个是一个16个核苷酸（nt）的元件，称为III-A，它位于p22的3'末端，对RNA积累至关重要。在III-A上游约300 nt处存在一个约80 nt的抑制元件（IE），仅在不存在位于III-A紧上游的约30 nt的第三个调控元件（SUR-III）时，该抑制元件才会阻碍复制。对核苷酸序列的检查预测III-A和SUR-III可以形成环状发夹结构。对不同番茄病毒的比较表明，在每种情况下，两个预测的发夹环之间潜在碱基配对具有保守性。在预测的发夹结构附近插入间隔序列对RNA积累没有影响或影响最小，而在假定的III-A环中插入则会消除基因组RNA的增殖。我们得出结论，构成预测的III-A和SUR-III发夹环的序列对于最佳RNA积累至关重要，并且当SUR-III和III-A之间的所谓相互作用受到干扰时，IE的抑制作用就会显现出来。
