Document Detail

Permuted tRNA genes of Cyanidioschyzon merolae, the origin of the tRNA molecule and the root of the Eukarya domain.
MedLine Citation:
PMID:  18513750     Owner:  NLM     Status:  MEDLINE    
An evolutionary analysis is conducted on the permuted tRNA genes of Cyanidioschyzon merolae, in which the 5' half of the tRNA molecule is codified at the 3' end of the gene and its 3' half is codified at the 5' end. This analysis has shown that permuted genes cannot be considered as derived traits but seem to possess characteristics that suggest they are ancestral traits, i.e. they originated when tRNA molecule genes originated for the first time. In particular, if the hypothesis that permuted genes are a derived trait were true, then we should not have been able to observe that the most frequent class of permuted genes is that of the anticodon loop type, for the simple reason that this class would derive by random permutation from a class of non-permuted tRNA genes, which instead is the rarest. This would not explain the high frequency with which permuted tRNA genes with perfectly separate 5' and 3' halves were observed. Clearly the mechanism that produced this class of permuted genes would envisage the existence, in an advanced stage of evolution, of minigenes codifying for the 5' and 3' halves of tRNAs which were assembled in a permuted way at the origin of the tRNA molecule, thus producing a high frequency of permuted genes of the class here referred. Therefore, this evidence supports the hypothesis that the genes of the tRNA molecule were assembled by minigenes codifying for hairpin-like RNA molecules, as suggested by one model for the origin of tRNA [Di Giulio, M., 1992. On the origin of the transfer RNA molecule. J. Theor. Biol. 159, 199-214; Di Giulio, M., 1999. The non-monophyletic origin of tRNA molecule. J. Theor. Biol. 197, 403-414]. Moreover, the late assembly of the permuted genes of C. merolae, as well as their ancestrality, strengthens the hypothesis of the polyphyletic origins of these genes. Finally, on the basis of the uniqueness and the ancestrality of these permuted genes, I suggest that the root of the Eukarya domain is in the super-ensemble of the Plantae and that the Rhodophyta to which C. merolae belongs are the first line of divergence.
Massimo Di Giulio
Publication Detail:
Type:  Journal Article     Date:  2008-04-29
Journal Detail:
Title:  Journal of theoretical biology     Volume:  253     ISSN:  1095-8541     ISO Abbreviation:  J. Theor. Biol.     Publication Date:  2008 Aug 
Date Detail:
Created Date:  2008-07-18     Completed Date:  2008-09-04     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0376342     Medline TA:  J Theor Biol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  587-92     Citation Subset:  IM    
Laboratory for Molecular Evolution, Institute of Genetics and Biophysics 'Adriano Buzzati Traverso', CNR, Via P. Castellino, 111, 80131 Naples, Napoli, Italy.
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MeSH Terms
Algae, Red / genetics*
Eukaryotic Cells
Evolution, Molecular
Quantitative Trait, Heritable
RNA, Algal / genetics*
RNA, Transfer*
Reg. No./Substance:
0/RNA, Algal; 9014-25-9/RNA, Transfer

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