Sequence and secondary structure of Porphyra umbilicalis 5S rRNA. Relevance for the evolutionary origin of red algae.

This pattern can be explained by assuming that the ancestral, eukaryotic 5S rRNA shared the first two features with the archaebacterlal and eubacterial 5S rRNAs, and that these were altered in the eukaryotic branch of evolution only after the divergence of the red algae, the latter conserving these ancestral features until the present time. As such, the study of 5S rRNA secondary structure consolidates phylogenetic studies (4) based on 5S rRNA sequences and pointing to the red algae as the earliest diverging branch of the eukaryotes.