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Science Forum Index » Bio Evolution Forum » Paper: Evolutionary Patterns in the Sequence and...
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| Robert Karl Stonjek... |
 Posted: Fri Aug 01, 2008 7:22 am |
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Evolutionary Patterns in the Sequence and Structure of Transfer RNA: A
Window into Early Translation and the Genetic Code
Feng-Jie Sun, Gustavo Caetano-Anollés
Department of Crop Sciences, University of Illinois at Urbana-Champaign,
Urbana, Illinois, United States of America
Abstract
Transfer RNA (tRNA) molecules play vital roles during protein synthesis.
Their acceptor arms are aminoacylated with specific amino acid residues
while their anticodons delimit codon specificity. The history of these two
functions has been generally linked in evolutionary studies of the genetic
code. However, these functions could have been differentially recruited as
evolutionary signatures were left embedded in tRNA molecules. Here we built
phylogenies derived from the sequence and structure of tRNA, we forced taxa
into monophyletic groups using constraint analyses, tested competing
evolutionary hypotheses, and generated timelines of amino acid charging and
codon discovery. Charging of Sec, Tyr, Ser and Leu appeared ancient, while
specificities related to Asn, Met, and Arg were derived. The timelines also
uncovered an early role of the second and then first codon bases, identified
codons for Ala and Pro as the most ancient, and revealed important
evolutionary take-overs related to the loss of the long variable arm in
tRNA. The lack of correlation between ancestries of amino acid charging and
encoding indicated that the separate discoveries of these functions
reflected independent histories of recruitment. These histories were
probably curbed by co-options and important take-overs during early
diversification of the living world.
Source: PLoS One [Open Access]
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0002797
Posted by
Robert Karl Stonjek |
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