RNase P RNAs from some Archaea are catalytically active

The RNA subunits of RNase Ps of Archaea and eukaryotes have been thought to depend fundamentally on protein for activity, unlike those of Bacteria tha t are capable of efficient catalysis in the absence of protein. Although th e eukaryotic RNase P RNAs are quite different than those of Bacteria in bot h sequence and structure, the archaeal RNAs generally contain the sequences and structures of the bacterial, phylogenetically conserved catalytic core . A spectrum of archaeal RNase P RNAs were therefore tested for activity in a wide range of conditions. Many remain inactive in ionically extreme cond itions, but catalytic activity could be detected from those of the methanob acteria, thermococci, and halobacteria. Chimeric holoenzymes, reconstituted from the Methanobacterium RNase P RNA and the Bacillus subtilis RNase P pr otein subunits, were functional at low ionic strength. The properties of th e archaeal RNase P RNAs (high ionic-strength requirement, low affinity for substrate, and catalytic reconstitution by bacterial RNase P protein) are s imilar to synthetic RNase P RNAs that contain all of the catalytic core of the bacterial RNA but lack phylogenetically variable, stabilizing elements.