The Evolution of RNase P and Its RNA
RNase P is generally comprised of a single RNA and one or more protein subunits. The RNA is the catalytic subunit, but the protein(s) are also required under physiological conditions for efficient activity. Although there is remarkable sequence and structural diversity of the RNase P RNA, they are all clearly homologous, and a consensus “core” structure can be identified. Type A RNase P RNAs are ancestral in both Bacteria and Archaea, implying that the last common ancestor also contained a type A RNA. However, in the case for the protein subunits of the enzyme, there is no clear homology in either sequence or structure between the single rnpA protein found universally in Bacteria and any of the archaeal or eukaryotic nuclear (eukaryal) proteins, including the four conserved RNase P proteins (Rpp21, Rpp29, Rpp30 and Pop5p) common to these two Domains. The simplest explanation for this difference in proteins is that the RNase P of last common ancestor was an RNA-only enzyme that acquired the rnpA protein in the case of Bacteria and the Rpp21/Rpp29/Rpp30/Pop5p proteins in the archaeal/eukaryal lineage, which was subsequently expanded in the case of the eukaryal enzyme. In this chapter, we will discuss the structural diversity of the RNase P RNA and their associated proteins in Bacteria, Archaea, and Eukaryotes. Special cases of evolutionary diversity within the domains and future directions will be given special attention.
KeywordsProtein Subunit Substrate Recognition Human RNase Pyrococcus Horikoshii Bacterial RNase
This research was supported in part by the Intramural Research Program of the NIH, National Institute of Environmental Health Sciences.
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