Archaeal RNase P has multiple protein subunits homologous to eukaryotic nuclear RNase P proteins

THOMAS A.  HALL  a1 p1 and JAMES W.  BROWN  a1 c1
a1 Department of Microbiology, North Carolina State University, Raleigh, North Carolina 27695-7615, USA


Although archaeal RNase P RNAs are similar in both sequence and structure to those of Bacteria rather than eukaryotes, and heterologous reconstitution between the Bacillus subtilis RNase P protein and some archaeal RNase P RNAs has been demonstrated, no archaeal protein sequences with similarity to any known bacterial RNase P protein subunit have been identified, and the density of Methanothermobacter thermoautotrophicus RNase P in Cs2SO4 (1.42 g/mL) is inconsistent with a single small bacterial-like protein subunit. Four hypothetical open reading frames (MTH11, MTH687, MTH688, and MTH1618) were identified in the genome of M. thermoautotrophicus that have sequence similarity to four of the nine Saccharomyces cerevisiae RNase P protein subunits: Pop4p, Pop5p, Rpp1p, and Rpr2p, respectively. Polyclonal antisera generated to recombinant Mth11p, Mth687p, Mth688p, and Mth1618p each recognized a protein of the predicted molecular weight in western blots of partially purified M. thermoautotrophicus RNase P, and immunoprecipitated RNase P activity from the same partially purified preparation. RNase P in Archaea is therefore composed of an RNA subunit similar to bacterial RNase P RNA and multiple protein subunits similar to those in the eukaryotic nucleus.

(Received November 15 2001)
(Revised December 10 2001)
(Accepted December 18 2001)

Key Words: archaebacteria; Methanobacterium thermoautotrophicum strain [Delta]H; Methanothermobacter thermoautotrophicus; ribonuclease P.

c1 Reprint requests to: James W. Brown, Department of Microbiology, 110 Derieux Place, North Carolina State University, Raleigh, North Carolina 27695-7615, USA; e-mail: james_brown@ncsu.edu.
p1 Present address: Ibis Therapeutics, 2292 Faraday Avenue, Carlsbad, California 92008, USA.