Disrupted tRNA Gene Diversity and Possible Evolutionary Scenarios
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The following unusual tRNAs have recently been discovered in the genomes of Archaea and primitive Eukaryota: multiple-intron-containing tRNAs, which have more than one intron; split tRNAs, which are produced from two pieces of RNA transcribed from separate genes; tri-split tRNAs, which are produced from three separate genes; and permuted tRNA, in which the 5′ and 3′ halves are encoded with permuted orientations within a single gene. All these disrupted tRNA genes can form mature contiguous tRNA, which is aminoacylated after processing by cis or trans splicing. The discovery of such tRNA disruptions has raised the question of when and why these complex tRNA processing pathways emerged during the evolution of life. Many previous reports have noted that tRNA genes contain a single intron in the anticodon loop region, a feature common throughout all three domains of life, suggesting an ancient trait of the last universal common ancestor. In this context, these unique tRNA disruptions recently found only in Archaea and primitive Eukaryota provide new insight into the origin and evolution of tRNA genes, encouraging further research in this field. In this paper, we summarize the phylogeny, structure, and processing machinery of all known types of disrupted tRNAs and discuss possible evolutionary scenarios for these tRNA genes.
KeywordstRNA Intron-containing tRNA Split tRNA Permuted tRNA Evolution Archaea Cyanidioschyzon merolae
Many of the ideas presented in this paper were inspired by discussions with members of the RNA Research Group at the Institute for Advanced Biosciences, Keio University. We thank Drs Todd Lowe and Massimo Di Giulio for their scientific encouragement. This research was supported in part by the Japan Society for the Promotion of Science; a grant from the Ministry of Education, Culture, Sports, Science and Technology of Japan; and research funds from Yamagata Prefecture and Tsuruoka City, Japan.
- Tanaka T, Kikuchi Y (2001) Origin of the cloverleaf shape of transfer RNA—the double-hairpin model: implication of the role of tRNA intron and the long extra loop. Viva Origino 29:134–142Google Scholar
- Yoshinari S, Shiba T, Inaoka DK, Itoh T, Kurisu G, Harada S, Kita K, Watanabe Y (2009) Functional importance of Crenarchaea-specific extra-loop revealed by an X-ray structure of a heterotetrameric crenarchaeal splicing endonuclease. Nucleic Acids Res 37(14):4787–4798. doi: 10.1093/nar/gkp506 CrossRefPubMedGoogle Scholar