Characterization of human mitochondrial RNase P: novel aspects in tRNA processing.
Human mitochondrial RNase P does not distinguish itself from other RNase P enzymes by most of its basic properties. 5' phosphates on tRNA products, strict dependence on a divalent cation, independence of ATP or other cofactors, and sensitivity to puromycin are generally characteristic for RNase P. Slow sedimentation of human mitochondrial RNase P in glycerol gradients suggests a molecular weight considerably lower than that of bacterial or nuclear RNase P. In contrast to fungi, all putative components of mammalian mitochondrial RNase P are encoded by the nucleus. Intriguingly, no indication of the involvement of a trans-acting RNA was found in mammalian mitochondrial tRNA processing. Mitochondrial RNase P is resistant to rigorous treatments with nucleases and exhibits a protein-like density in Cs2SO4 gradients. Moreover, an analysis of copurifying RNAs revealed no putative RNase P RNA candidates. These data suggest that mammalian mitochondrial RNase P, unlike its nuclear counterpart or its bacterial relatives, is not a ribonucleoprotein but a protein enzyme.
Rossmanith
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Institut für Tumorbiologie-Krebsforschung der Universität Wien, Borschkegasse 8a, Vienna, A-1090, Austria. walter.rossmanith@univie.ac.at
Karwan
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RM
D055592:Biophysical Phenomena; D001703:Biophysics; D002467:Cell Nucleus / Q000201:enzymology; D004272:DNA, Mitochondrial / Q000235:genetics; D004722:Endoribonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000201:enzymology*; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D016337:RNA, Catalytic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012343:RNA, Transfer / Q000378:metabolism*; D043262:Ribonuclease P; D012261:Ribonucleoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D004272:DNA, Mitochondrial; D029968:Escherichia coli Proteins; D016337:RNA, Catalytic; D012261:Ribonucleoproteins; D012313:RNA; D012343:RNA, Transfer; D004722:Endoribonucleases; C468368:RPP14 protein, human; D043262:Ribonuclease P; C470865:ribonuclease P, E coli