RNA '98 (the RNA Society), Madison, WI

The Catalytic Activity of Archaeal RNase P RNA

James Pannucci*, Elizabeth S. Haas and James W. Brown
Dept. of Microbiology, North Carolina State Univ. Raleigh, NC. 27695

RNase P is an endoribonuclease responsible for processing the 5' termini of precursor-tRNAs. In Bacteria, RNase P consists of two subunits, a catalytic RNA and a 14 kD protein. Physiological ionic conditions require the presence of both subunits for pre-tRNA processing, but under appropriate in vitro conditions (increased ionic strength), the RNA is catalytically active without the RNase P protein. In other words, increased concentrations of monovalent and divalent cations can largely substitute for the RNase P protein. RNase P RNAs have been isolated from several species of Archaea. The secondary structures of archaeal RNase P RNAs are similar to bacterial RNase P RNAs, and contain the same core helices thought to be necessary for catalytic activity. In previous attempts, in vitro RNA activity without the protein subunit has not been demonstrated by an archaeal RNase P RNA. Recently, we isolated genes for RNase P RNA from the genus Methanobacterium (both from pure culture and environmental PCR amplifications). Synthetic RNase P RNAs made by in vitro transcription and RNase P RNAs extracted from methanobacterial cultures were catalytically activity. In vitro activity was also found among the extremely halophilic Archaea.