Citti C, Maréchal-Drouard L, Saillard C, Weil J H, Bové J M
Laboratoire de Biologie Cellulaire et Moléculaire, Institut National de la Recherche Agronomique, Villenave d'Ornon, France.
J Bacteriol. 1992 Oct;174(20):6471-8. doi: 10.1128/jb.174.20.6471-6478.1992.
From the total tRNAs of Spiroplasma citri, we isolated and purified two tRNA(Trp) species by using chromatography on an RPC-5 column followed by denaturing polyacrylamide gel electrophoresis. The sequence of the two tRNAs, as well as the sequences of the corresponding genes, were determined. One of the two tRNA(Trp) species has a CCA anticodon and is able to pair with the universal UGG tryptophan codon, while the second has a UCA (U is a modified uridine) anticodon and is able to pair with UGA but also with UGG in accordance with the "U:N wobble" rule. Thus, in S. citri, UGA is not a stop codon but codes for tryptophan. The two tRNA(Trp) genes, together with a third tRNA gene, tRNA(Ser) (CGA), belong to a single transcription unit. The nucleotide sequences of the two tRNA(Trp) species show 82.9% similarity. The two spiroplasmal tRNA(Trp) species can be aminoacylated by using an aminoacyl-tRNA synthetase fraction from S. citri. In contrast, the enzyme fraction from Escherichia coli aminoacylates tRNA(Trp) (CCA) but not tRNA(Trp) (U*CA).
从柑橘螺原体的总tRNA中，我们通过RPC - 5柱层析，随后进行变性聚丙烯酰胺凝胶电泳，分离并纯化了两种tRNA（Trp）。测定了这两种tRNA以及相应基因的序列。两种tRNA（Trp）中的一种具有CCA反密码子，能够与通用的UGG色氨酸密码子配对，而另一种具有UCA（U是一种修饰的尿苷）反密码子，根据“U:N摆动”规则，它不仅能够与UGA配对，还能与UGG配对。因此，在柑橘螺原体中，UGA不是终止密码子，而是编码色氨酸。这两个tRNA（Trp）基因与第三个tRNA基因tRNA（Ser）（CGA）属于一个单一的转录单元。两种tRNA（Trp）的核苷酸序列相似度为82.9%。使用来自柑橘螺原体的氨酰 - tRNA合成酶组分可以使这两种螺原体tRNA（Trp）氨酰化。相反，来自大肠杆菌的酶组分能够使tRNA（Trp）（CCA）氨酰化，但不能使tRNA（Trp）（U*CA）氨酰化。
