Ribosomal RNA evolution by fragmentation of the 23S progenitor: Maturation pathway parallels evolutionary emergence

Summary The eukaryotic 5.8S and the chloroplast 4.5S ribosomal RNAs were proposed to have arisen from the 5 and 3 ends respectively of prokaryotic 23S ribosomal RNA by the introduction of new processing sites during evolution. This hypothesis was supported by comparison of previously published primary sequences; in addition we can draw models of secondary structure in accord with this notion. Finally, we further noted that the sequence of processing cuts in the maturation pathway of ribosomal RNA reflects the probable order in which they arose during evolution.