Like proteins, single-stranded RNA's (ssRNAs) undergo intramolecular folding into complex conformations which determine their metabolic function. We have compiled nucleotide composition data, expressed as G+A and G+U in addition to G+C content, from phylogenetically representative samples of seven functional classes of ssRNA and artificial ribozymes. Unlike G+C content, which is known to vary within and between organisms, G+A and G+U contents are remarkably constrained among ssRNAs unrelated by sequence similarity and function. An analysis of the base composition of secondary structural elements indicates that paired and unpaired nucleotides, known to have different evolutionary rates, also have significantly different compositional biases; stems are G+C- and G+U-rich while loops are G+C-poor and G+A-rich. These universal compositional biases observed among ssRNA sharing little or no sequence similarity suggest, contrary to current understanding, that base composition biases constitute a convergent adaptation among a wide variety of molecular functions.
Download Info
To our knowledge, this item is not available for
download. To find whether it is available, there are three
options:
1. Check below under "Related research" whether another version of this item is available online.
2. Check on the provider's web page
whether it is in fact available.
3. Perform a search for a similarly titled item that would be
available.
Publisher Info
Paper provided by Santa Fe Institute in its series Working Papers with number
96-12-091.