Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.5 (RNase P)
 1,348 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mitochondrion-associated RNase P activity (mtRNase P) was extensively purified from HeLa cells and shown to reside in particles with a sedimentation constant ( approximately 17S) very similar to that of the nuclear enzyme (nuRNase P). Furthermore, mtRNase P, like nuRNase P, was found to process a mitochondrial tRNA(Ser(UCN)) precursor [ptRNA(Ser(UCN))] at the correct site. Treatment with micrococcal nuclease of highly purified mtRNase P confirmed earlier observations indicating the presence of an essential RNA component. Furthermore, electrophoretic analysis of 3'-end-labeled nucleic acids extracted from the peak of glycerol gradient-fractionated mtRNase P revealed the presence of a 340-nucleotide RNA component, and the full-length cDNA of this RNA was found to be identical in sequence to the H1 RNA of nuRNase P. The proportions of the cellular H1 RNA recovered in the mitochondrial fractions from HeLa cells purified by different treatments were quantified by Northern blots, corrected on the basis of the yield in the same fractions of four mitochondrial nucleic acid markers, and shown to be 2 orders of magnitude higher than the proportions of contaminating nuclear U2 and U3 RNAs. In particular, these experiments revealed that a small fraction of the cell H1 RNA (of the order of 0.1 to 0.5%), calculated to correspond to approximately 33 to approximately 175 intact molecules per cell, is intrinsically associated with mitochondria and can be removed only by treatments which destroy the integrity of the organelles. In the same experiments, the use of a probe specific for the RNA component of RNase MRP showed the presence in mitochondria of 6 to 15 molecules of this RNA per cell. The available evidence indicates that the levels of mtRNase P detected in HeLa cells should be fully adequate to satisfy the mitochondrial tRNA synthesis requirements of these cells.
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PMID:The RNase P associated with HeLa cell mitochondria contains an essential RNA component identical in sequence to that of the nuclear RNase P. 1171 Mar 32

Eukaryotic tRNAs are transcribed as precursors. A 5'-end leader and 3'-end trailer are endonucleolytically removed by RNase P and 3'-tRNase before 3'-end CCA addition, aminoacylation, nuclear export and translation. 3'-End -CC can be a 3'-tRNase anti-determinant with the ability to prevent mature tRNA from recycling through 3'-tRNase. Twenty-two tRNAs punctuate the two rRNAs and 13 mRNAs in long, bidirectional mitochondrial transcripts. Accurate mitochondrial gene expression thus depends on endonucleolytic excision of tRNAs. Various mitochondrial diseases and syndromes could arise from defective tRNA end processing. The U7445C substitution in the human mitochondrial L-strand transcript (U74C directly following the discriminator base of tRNA(Ser(UCN))) causes non-syndromic deafness. The sequence of the precursor (G/UCU) becomes G/CCU, resembling a 3'-tRNase anti-determinant. We demonstrate that a tRNA(Ser(UCN)) precursor with the U7445C substitution cannot be processed in vitro by 3'-tRNase from human mitochondria. A 3'-end processing defect in this tRNA precursor could thus be responsible for mitochondrial disease.
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PMID:In vitro 3'-end endonucleolytic processing defect in a human mitochondrial tRNA(Ser(UCN)) precursor with the U7445C substitution, which causes non-syndromic deafness. 1169 20

The deafness-associated 7472insC mtDNA mutation was previously shown to decrease the steady-state level of tRNA(Ser(UCN)) post-transcriptionally. To identify the affected tRNA maturation step(s) we analysed the effects of the mutation on processing in vivo and in vitro. tRNA(Ser(UCN)) from cybrid cells homoplasmic for 7472insC contained a high frequency (>11%) of molecules misprocessed at one or both termini. In vitro assays using partially purified HeLa cell RNase P and mitochondrial tRNA 3' processing endonuclease (tRNase Z) confirmed that the efficiency of both 5' and 3' processing was impaired. A mutant precursor not already processed at the 5' end was poorly processed in vitro by tRNase Z. Misprocessing at the 3' end further impaired the efficiency and accuracy of 5' processing of the mutant substrate. The mutation thus appears to affect several distinct, but interdependent, RNA processing steps, with the predicted outcome dependent on the exact processing pathway operating in vivo.
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PMID:The 7472insC mtDNA mutation impairs 5' and 3' processing of tRNA(Ser(UCN)). 1533 35

tRNAs are transcribed as precursors with a 5' end leader and a 3' end trailer. The 5' end leader is processed by RNase P, and in most organisms in all three kingdoms, transfer ribonuclease (tRNase) Z can endonucleolytically remove the 3' end trailer. Long ((L)) and short ((S)) forms of the tRNase Z gene are present in the human genome. tRNase Z(L) processes a nuclear-encoded pre-tRNA approximately 1600-fold more efficiently than tRNase Z(S) and is predicted to have a strong mitochondrial transport signal. tRNase Z(L) could, thus, process both nuclear- and mitochondrially encoded pre-tRNAs. More than 150 pathogenesis-associated mutations have been found in the mitochondrial genome, most of them in the 22 mitochondrially encoded tRNAs. All the mutations investigated in human mitochondrial tRNA(Ser(UCN)) affect processing efficiency, and some affect the cleavage site and secondary structure. These changes could affect tRNase Z processing of mutant pre-tRNAs, perhaps contributing to mitochondrial disease.
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PMID:Naturally occurring mutations in human mitochondrial pre-tRNASer(UCN) can affect the transfer ribonuclease Z cleavage site, processing kinetics, and substrate secondary structure. 1636 Dec 54

In this report, we investigated the molecular mechanism underlying a deafness-associated m.7516delA mutation affecting the 5' end processing sites of mitochondrial tRNAAsp and tRNASer(UCN). An in vitro processing experiment demonstrated that m.7516delA mutation caused the aberrant 5' end processing of tRNASer(UCN) and tRNAAsp precursors, catalyzed by RNase P. Using cytoplasmic hybrids (cybrids) derived from one hearing-impaired Chinese family bearing the m.7516delA mutation and control, we demonstrated the asymmetrical effects of m.7516delA mutation on the processing of tRNAs in the heavy (H)-strand and light (L)-strand polycistronic transcripts. Specially, the m.7516delA mutation caused the decreased levels of tRNASer(UCN) and downstream five tRNAs, including tRNATyr from the L-strand transcripts and tRNAAsp from the H-strand transcripts. Strikingly, mutant cybrids exhibited the lower level of COX2 mRNA and accumulation of longer and uncleaved precursors of COX2 from the H-strand transcripts. Aberrant RNA metabolisms yielded variable reductions in the mitochondrial proteins, especially marked reductions in the levels of ND4, ND5, CO1, CO2 and CO3. The impairment of mitochondrial translation caused the proteostasis stress and respiratory deficiency, diminished ATP production and membrane potential, increased production of reactive oxygen species and promoted apoptosis. Our findings provide new insights into the pathophysiology of deafness arising from mitochondrial tRNA processing defects.
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PMID:Asymmetrical effects of deafness-associated mitochondrial DNA 7516delA mutation on the processing of RNAs in the H-strand and L-strand polycistronic transcripts. 3304 34