Compositional Properties and Thermal Adaptation of SRP-RNA in Bacteria and Archaea |
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Authors: | Francisco Miralles |
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Institution: | 1. Institut Jacques Monod, CNRS UMR7592, Université Paris Diderot-Paris 7, Bat. Buffon, 75205, Paris Cedex 13, France 2. Department of Genetics Development and Molecular Pathology, Institut Cochin, 24 rue du Faubourg Saint-Jacques, 75014, Paris, France
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Abstract: | Previous studies have reported a positive correlation between the GC content of the double-stranded regions of structural
RNAs and the optimal growth temperature (OGT) in prokaryotes. These observations led to the hypothesis that natural selection
favors an increase in GC content to ensure the correct folding and the structural stability of the molecule at high temperature.
To date these studies have focused mainly on ribosomal and transfer RNAs. Therefore, we addressed the question of the relationship
between GC content and OGT in a different and universally conserved structural RNA, the RNA component of the signal recognition
particle (SRP). To this end we generated the secondary structures of SRP-RNAs for mesophilic, thermophilic, and hyperthermophilic
bacterial and archaeal species. The analysis of the GC content in the stems and loops of the SRP-RNA of these organisms failed
to detect a relationship between the GC contents in the stems of this structural RNA and the growth temperature of bacteria.
By contrast, we found that in archaea the GC content in the stem regions of SRP-RNA is highest in hyperthermophiles, intermediate
in thermophiles, and lower in mesophiles. In these organisms, we demonstrated a clear positive correlation between the GC
content of the stem regions of their SRP-RNAs and their OGT. This correlation was confirmed by a phylogenetic nonindependence
analysis. Thus we conclude that in archaea the increase in GC content in the stem regions of SRP-RNA is an adaptation response
to environmental temperature. |
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