Ciliates use both variant and universal genetic codes: Evidence of omnipotent eRF1s in the class Litostomatea
Ciliates use both variant and universal genetic codes: Evidence of omnipotent eRF1s in the class Litostomatea
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DOI：
10.1016/j.gene.2008.03.018
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发表时间：
2008-07-01
期刊：
影响因子：
3.5
通讯作者：
Harumoto, Terue
中科院分区：
文献类型：
--
作者：
Kim, Oanh Thi Phuong;Sakurai, Aki;Harumoto, Terue
终止密码子重排在纤毛虫中发生频率很高。在一些纤毛虫物种中，通用终止密码子UAA和UAG被翻译成谷氨酰胺，而在一些其他物种中，通用终止密码子UGA似乎被翻译成半胱氨酸或色氨酸。Litostomatea类被假设为唯一使用通用遗传密码的纤毛虫。然而，这一假设是基于对相当小的序列数据集的统计分析，这不足以阐明这类高度偏离的门中的密码子使用。在这项研究中，连同更新的数据库序列分析的类，我们接近的问题，终止密码子的使用，通过检查翻译终止因子eRF1识别终止密码子的能力。使用在芽殖酵母体内测定系统，我们估计eRF 1的活性从两个litostome物种Didinium nasutum和Dileptus margaritifer。结果清楚地表明，Didinium和Dileptus eRF1有效地识别所有三个终止密码子。这是第一个实验证据，有力地支持这一假设，即litostome纤毛虫使用通用的遗传密码。（（c））2008 Elsevier B.V.保留所有权利。
Stop codon reassignments have occurred very frequently in ciliates. In some ciliate species, the universal stop codons UAA and UAG are translated into glutamine, while in some other species, the universal stop codon UGA appears to be translated into cysteine or tryptophan. The class Litostomatea has been hypothesized to be the only group of ciliates using the universal genetic code. However, the hypothesis was based on a statistical analysis of quite small sequence dataset which was insufficient to elucidate the codon usage of the class among such highly deviated phylum. In this study, together with the updated database sequence analysis for the class, we approached the problem of stop codon usage by examining the capacity of the translation termination factor eRF1 for recognizing stop codons. Using in vivo assay systems in budding yeast, we estimated the activity of eRF1 from two litostome species Didinium nasutum and Dileptus margaritifer. The results clearly showed that Didinium and Dileptus eRF1s efficiently recognize all three stop codons. This is the first experimental evidence that strongly supports the hypothesis that litostome ciliates use universal genetic code. ((c))2008 Elsevier B.V. All rights reserved.