REPLICATION INVIVO OF MUTANT BROME MOSAIC-VIRUS RNAS DEFECTIVE IN AMINOACYLATION
REPLICATION INVIVO OF MUTANT BROME MOSAIC-VIRUS RNAS DEFECTIVE IN AMINOACYLATION
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DOI：
10.1016/0022-2836(89)90491-9
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发表时间：
1989-04-05
影响因子：
5.6
通讯作者：
HALL, TC
中科院分区：
文献类型：
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作者：
DREHER, TW;RAO, ALN;HALL, TC
为了了解雀麦花叶病毒基因组RNA的复制和氨酰化之间的关系，研究了四种突变体在原生质体和植物中的复制，这些突变体的RNA预计（基于它们在体外的性质）在体内不能有效地被酪氨酸酰化。测试接种物由野生型RNA 1和2的加帽转录物以及在3“tRNA样区域中具有确定突变的RNA 3变体组成。突变体5“PsK在负链启动子活性上有缺陷，并且在体外对于酪氨酰化和3”腺苷酸化都是不良底物，其在原生质体中复制至野生型的20%，即使仅约6%的子代分子具有允许酪氨酰化的正确3“末端。突变. psi. GG在体外3“腺苷酸化和负链启动子活性有缺陷，但以接近正常的速率接受酪氨酸，在原生质体中复制到野生型的40%，尽管只有15%的后代分子具有正确的3”末端。另外两种突变体（Δ 5“和5”阿加），其体外酪氨酰化速率比野生型RNA低20倍，在原生质体中复制到野生型水平的60 - 70%，并在植物的系统感染中产生与野生型相似的产量。所有突变体序列都保留在子代RNA中，表明同源3“末端之间没有发生重组。突变体Δ 5 ″在原生质体中观察到40%的复制减少，其唯一已知的功能性损伤是体外酪氨酸化抑制，这可能表明存在氨酰化的间接作用。然而，所获得的结果反对在体内RNA复制中酪氨酸基化的强制性作用。
In order to understand the relationship between replication and aminoacylation of the genomic RNAs of brome mosaic virus, the replication of four mutants, whose RNAs were expected (on the basis of their properties in vitro) to be inefficiently tyrosylated in vivo, was studied in barely protoplasts and plants. Test inocula consisted of capped transcripts of wild-type RNAs 1 and 2, and of RNA3 variants with defined mutations in the 3'' tRNA-like region. Mutant 5''PsK, which is defective in minus-strand promoter activity and a poor substrate in vitro for both tyrosylation and 3'' adenylation, replicated in protoplasts to 20% of wild-type even though only about 6% of the progeny molecules had correct 3'' termini that would permit tyrosylation. Mutant .psi. GG, which is defective in vitro for 3'' adenylation and minus-strand promoter activities but accepts tyrosine at near-normal rates, replicated to 40% of wild-type in protoplasts although only 15% of the progeny molecules had correct 3'' termini. Two other mutants (.DELTA.5'' and 5''AGA), with 20-fold lower rates of tyrosylation in vitro than wild-type RNA, replicated to 60 to 70% of wild-type levels in protoplasts and gave similar yields to wild-type in systemic infections of plants. All mutant sequences were preserved in progeny RNAs, indicating that no recombination between homologous 3'' ends occurred. The 40% reduction of replication in protoplasts seen for mutant .DELTA.5'', whose only known functional lesion is depressed tyrosylation in vitro, may indicate that an indirect role for aminoacylation exists. However, the results obtained argue against an obligatory role for tyrosylation in RNA replication in vivo.