Burgyán J, García-Arenal F
Agricultural Biotechnology Center, Plant Science Institute, 2101 Gödöllö, Hungary.
J Virol. 1998 Jun;72(6):5061-6. doi: 10.1128/JVI.72.6.5061-5066.1998.
RNA viruses which do not have a poly(A) tail or a tRNA-like structure for the protection of their vulnerable 3' termini may have developed a different strategy to maintain their genome integrity. We provide evidence that deletions of up to 7 nucleotides from the 3' terminus of cucumber mosaic cucumovirus (CMV) satellite RNA (satRNA) were repaired in planta in the presence of the helper virus (HV) CMV. Sequence comparison of 3'-end-repaired satRNA progenies, and of satRNA and HV RNA, suggested that the repair was not dependent on a viral template. The 3' end of CMV satRNA lacking the last three cytosines was not repaired in planta in the presence of tomato aspermy cucumovirus (TAV), although TAV is an efficient helper for the replication of CMV satRNA. With use of pseudorecombinants constructed by the interchange of RNAs 1 and 2 of TAV and CMV, evidence was provided that the 3'-end repair was controlled by RNAs 1 and 2 of CMV, which encode subunits of the viral RNA replicase. These results, and the observation of short repeated sequences close to the 3' terminus of repaired molecules, suggest that the HV replicase maintains the integrity of the satRNA genome, playing a role analogous to that of cellular telomerases.
没有多聚（A）尾或类似tRNA结构来保护其易受损伤的3'末端的RNA病毒，可能已经形成了一种不同的策略来维持其基因组的完整性。我们提供的证据表明，在辅助病毒（HV）黄瓜花叶病毒（CMV）存在的情况下，黄瓜花叶黄瓜病毒（CMV）卫星RNA（satRNA）3'末端多达7个核苷酸的缺失在植物体内得到了修复。对3'末端修复的satRNA子代以及satRNA和HV RNA进行序列比较，结果表明这种修复不依赖于病毒模板。在番茄不孕黄瓜病毒（TAV）存在的情况下，缺少最后三个胞嘧啶的CMV satRNA的3'末端在植物体内没有得到修复，尽管TAV是CMV satRNA复制的有效辅助病毒。通过交换TAV和CMV的RNA 1和RNA 2构建假重组体，结果表明3'末端修复受CMV的RNA 1和RNA 2控制，它们编码病毒RNA复制酶的亚基。这些结果，以及在修复分子的3'末端附近观察到短的重复序列，表明HV复制酶维持了satRNA基因组的完整性，其作用类似于细胞端粒酶。
