Characterization of human mitochondrial RNase P: novel aspects in tRNA processing

Biochem Biophys Res Commun. 1998 Jun 18;247(2):234-41. doi: 10.1006/bbrc.1998.8766.


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.

Publication types

  • Comparative Study

MeSH terms

  • Biophysical Phenomena
  • Biophysics
  • Cell Nucleus / enzymology
  • DNA, Mitochondrial / genetics
  • Endoribonucleases / chemistry
  • Endoribonucleases / genetics
  • Endoribonucleases / metabolism*
  • Escherichia coli / enzymology
  • Escherichia coli Proteins*
  • HeLa Cells
  • Humans
  • Mitochondria / enzymology*
  • Nucleic Acid Conformation
  • RNA / chemistry
  • RNA / metabolism
  • RNA Processing, Post-Transcriptional*
  • RNA, Catalytic / chemistry
  • RNA, Catalytic / genetics
  • RNA, Catalytic / metabolism*
  • RNA, Transfer / metabolism*
  • Ribonuclease P
  • Ribonucleoproteins / chemistry
  • Ribonucleoproteins / genetics
  • Ribonucleoproteins / metabolism


  • DNA, Mitochondrial
  • Escherichia coli Proteins
  • RNA, Catalytic
  • Ribonucleoproteins
  • RNA
  • RNA, Transfer
  • Endoribonucleases
  • RPP14 protein, human
  • Ribonuclease P
  • ribonuclease P, E coli