TELOMERIC FUNCTION OF THE TRANSFER RNA-LIKE STRUCTURE OF BROME MOSAIC-VIRUS RNA
TELOMERIC FUNCTION OF THE TRANSFER RNA-LIKE STRUCTURE OF BROME MOSAIC-VIRUS RNA
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DOI：
10.1073/pnas.86.14.5335
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发表时间：
1989-07-01
影响因子：
11.1
通讯作者：
HALL, TC
中科院分区：
文献类型：
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作者：
RAO, ALN;DREHER, TW;HALL, TC
四个突变型雀麦花叶病毒（BMV）RNA 3转录本在tRNA样结构的3“-CCAOH末端带有单或双碱基变化，先前被表征为在体外缺乏氨酰化和复制活性，现在已经在体内测定了它们在大麦原生质体和植物中的复制能力（在野生型RNA 1和-2的转录本存在下）。在用原生质体进行的测试中，无论感染后的时间如何，所有四种突变体都是完全可行的，并且每个突变体的正链和负链复制的相对水平与野生型相似。用这些突变体接种大麦植株导致与野生型感染相似的表型症状和病毒产量。对每个突变体子代RNA 3的分析表明，3“末端的改变序列恢复到野生型的序列。这些观察结果表明，在体内存在BMV RNA的3“末端的快速更新和校正。这种校正与tRNA核苷酸转移酶的作用相当，但它不同于BMV RNA 3相对不常见的重组过程。这些结果支持病毒tRNA样结构的3“-CCAOH末端与染色体DNA的端粒功能相似的结论。
Four mutant brome mosaic virus (BMV) RNA3 transcripts, bearing single or double base changes in the 3''-CCAOH terminus of the tRNA-like structure, previously characterized as being deficient in vitro with respect to aminoacylation and replication activities, have now been assayed in vivo for their ability to replicate (in the presence of transcripts of wild-type RNA1 and -2) in barley protoplasts and plants. In tests conducted with protoplasts, irrespective of the time post-infection, all four mutants were fully viable, and the relative levels of both plus and minus strand replication for each mutant were similar to that of the wild type. Inoculation of barley plants with these mutants resulted in phenotypic symptoms and viral yields that were similar to those from wild-type infections. Analysis of each mutant progeny RNA3 indicated that the altered sequence at the 3'' terminus was restored to that of wild type. These observations indicate that there is a rapid turnover and correction of the 3'' termini of BMV RNAs in vivo. Such correction is commensurate with the action of tRNA nucleotidyltransferase, but it differs from recombination processes that appear to be relatively infrequent for BMV RNA3. These results support the conclusion that the 3''-CCAOH termini of viral tRNA-like structures function analogously to telomeres of chromosomal DNA.