Evolution of compensatory substitutions through G.U intermediate state in Drosophila rRNA.
It has often been suggested that the frequently observed Watson-Crick base-pair compensatory substitutions in RNA helical structures occur mainly through a slightly deleterious G.U intermediate state. We have scored base substitutions in a set of 82 related Drosophila species for the D1 and D2 variable domains of the large rRNA subunit. In all locations where a G-C in equilibrium with A-U compensatory base change occurred, a G.U pair has been observed in one or several species. As this dominant process implies two transitions, their rate was far higher in paired regions (92%) than in unpaired regions (47%). The other types of compensation were rarer and no intermediate states were observed. Most of the G.U base pairs observed in a species are not slightly deleterious. The rate of evolution of compensatory substitution is close to that predicted by a simple model of compensatory substitution through slightly deleterious or slightly advantageous G.U pairs, although some exceptions are presented.
Rousset
F
F
Laboratoire de Biologie et Génétique Evolutives, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.
Pélandakis
M
M
Solignac
M
M
D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D005075:Biological Evolution; D004330:Drosophila / Q000235:genetics*; D006147:Guanine; D006860:Hydrogen Bonding; D008957:Models, Genetic; D008961:Models, Structural; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011336:Probability; D012335:RNA, Ribosomal / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D014498:Uracil
D012335:RNA, Ribosomal; D014498:Uracil; D006147:Guanine