An extra tRNAGly(U*CU) found in ascidian mitochondria responsible for decoding non-universal codons AGA AGG as glycine
An extra tRNAGly(U*CU) found in ascidian mitochondria responsible for decoding non-universal codons AGA AGG as glycine
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DOI：
10.1093/nar/27.12.2554
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发表时间：
1999-06-15
影响因子：
14.9
通讯作者：
Watanabe, K
中科院分区：
文献类型：
--
作者：
Kondow, A;Suzuki, T;Watanabe, K
众所周知，在动物物种之间，已知后生动物密码子AGA/AGA的氨基酸分配是不同的。 Cnidaria中的精氨酸，无脊椎动物中的丝氨酸，并停在脊椎动物中。我们最近发现，在海藻卤素thia roretzi的线粒体中，这些密码子异常用于甘氨酸，并假设它们可能被tRNA（UCU）解码，以确定这个概念，以确定我们的完整RNA序列线粒体tRNA（UCU）被认为是解码海鞘中的密码子Aga/agg线粒体，发现它在反密码子的第一位置具有未鉴定的U衍生物。然后，我们在体内鉴定了连接到tRNA（u*cu）的氨基酸以及常规的tRNA（gly）（gly）（ucc）。结果清楚地表明，甘氨酸均连接到两个TRNA上，因为在线粒体基因组中还没有发现其他能够解码密码子AGA/AGG的tRNA，因此最有可能的tRNA（u*cu）实际上会翻译密码子Aga/agg aga/agg作为体内甘氨酸。 tRNA（ser）（gcu）的测序被认为只识别agu/agc的密码子，表明它在第34位的鸟苷存在未修饰的鸟嘌呤，脊椎动物线粒体tRNA（ser）（gcu）的情况也是如此。 agg。因此得出的结论是，在海藻中，密码子Agu/agc被tRNA（ser）（gcu）读取为丝氨酸，而aga/agg被添加的aga/agg读为甘氨酸（gly）（gly）（u*cu）。讨论了这种非正统遗传密码的可能起源。
Amino acid assignments of metazoan mitochondrial codons AGA/AGG are known to vary among animal species; arginine in Cnidaria, serine in invertebrates and stop in vertebrates. We recently found that in the mitochondria of the ascidian Halocynthia roretzi these codons are exceptionally used for glycine, and postulated that they are probably decoded by a tRNA(UCU), In order to verify this notion unambiguously, we determined the complete RNA sequence of the mitochondrial tRNA(UCU) presumed to decode codons AGA/AGG in the ascidian mitochondria, and found it to have an unidentified U derivative at the anticodon first position. We then identified the amino acids attached to the tRNA(U*CU), as well as to the conventional tRNA(Gly)(UCC) with an unmodified U34, in vivo. The results clearly demonstrated that glycine was attached to both tRNAs, Since no other tRNA capable of decoding codons AGA/AGG has been found in the mitochondrial genome, it is most probable that this tRNA(U*CU) does actually translate codons AGA/AGG as glycine in vivo. Sequencing of tRNA(Ser)(GCU), which is thought to recognize only codons AGU/AGC, revealed that it has an unmodified guanosine at position 34, as is the case with vertebrate mitochondrial tRNA(Ser)(GCU) for codons AGA/ AGG. It was thus concluded that in the ascidian, codons AGU/AGC are read as serine by tRNA(Ser)(GCU), whereas AGA/AGG are read as glycine by an extra tRNA(Gly)(U*CU). The possible origin of this unorthodox genetic code is discussed.