Hashimoto T, Sánchez L B, Shirakura T, Müller M, Hasegawa M
The Institute of Statistical Mathematics, 4-6-7 Minami-Azabu, Minato-ku, Tokyo 106, Japan.
Proc Natl Acad Sci U S A. 1998 Jun 9;95(12):6860-5. doi: 10.1073/pnas.95.12.6860.
Nuclear-coded valyl-tRNA synthetase (ValRS) of eukaryotes is regarded of mitochondrial origin. Complete ValRS sequences obtained by us from two amitochondriate protists, the diplomonad, Giardia lamblia and the parabasalid, Trichomonas vaginalis were of the eukaryotic type, strongly suggesting an identical history of ValRS in all eukaryotes studied so far. The findings indicate that diplomonads are secondarily amitochondriate and give further evidence for such conclusion reached recently concerning parabasalids. Together with similar findings on other amitochondriate groups (microsporidia and entamoebids), this work provides critical support for the emerging notion that no representatives of the premitochondrial stage of eukaryotic phylogenesis exist among the species living today.
真核生物的核编码缬氨酰 - tRNA合成酶(ValRS)被认为起源于线粒体。我们从两种无线粒体的原生生物——双滴虫贾第虫和副基体阴道毛滴虫中获得的完整ValRS序列属于真核类型,这强烈表明到目前为止在所有研究的真核生物中ValRS具有相同的演化历史。这些发现表明双滴虫是次生无线粒体的,并为最近关于副基体的这一结论提供了进一步的证据。连同在其他无线粒体类群(微孢子虫和内阿米巴)上的类似发现,这项工作为一个新出现的观点提供了关键支持,即现存物种中不存在真核生物系统发生线粒体前期阶段的代表。