Phylogeny and self-splicing ability of the plastid tRNA-Leu group I intron
2003 | journal article. A publication with affiliation to the University of Göttingen.
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Phylogeny and self-splicing ability of the plastid tRNA-Leu group I intron
Simon, D.; Fewer, D. P.; Friedl, T. & Bhattacharya, D. (2003)
Journal of Molecular Evolution, 57(6) pp. 710-720. DOI: https://doi.org/10.1007/s00239-003-2533-3
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- Authors
- Simon, Dawn; Fewer, David P.; Friedl, Thomas; Bhattacharya, Debashish
- Abstract
- Group I introns are mobile RNA enzymes (ribozymes) that encode conserved primary and secondary structures required for autocatalysis. The group I intron that interrupts the tRNA-Leu gene in cyanobacteria and plastids is remarkable because it is the oldest known intervening sequence and may have been present in the common ancestor of the cyanobacteria (i.e., 2.7-3.5 billion years old). This intron entered the eukaryotic domain through primary plastid endosymbiosis. We reconstructed the phylogeny of the tRNA-Leu intron and tested the in vitro self-splicing ability of a diverse collection of these ribozymes to address the relationship between intron stability and autocatalysis. Our results suggest that the present-day intron distribution in plastids is best explained by strict vertical transmission, with no intron losses in land plants or a subset of the Stramenopiles (xanthophyceae/phaeophyceae) and frequent loss among green algae, as well as in the red algae and their secondary plastid derivatives (except the xanthophyceae/phaeophyceae lineage). Interestingly, all tested land plant introns could not self-splice in vitro and presumably have become dependent on a host factor to facilitate in vivo excision. The host dependence likely evolved once in the common ancestor of land plants. In all other plastid lineages, these ribozymes could either self-splice or complete only the first step of autocatalysis.
- Issue Date
- 2003
- Journal
- Journal of Molecular Evolution
- ISSN
- 0022-2844
- Language
- English