Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 activity of ribonuclease P on precursor tRNA substrates from Escherichia coli can be abolished by pretreatment of this enzyme with micrococcal nuclease or pancreatic ribonuclease A, as well as by proteases and by thermal denaturation. Highly purified RNase P exhibits one prominent RNA and one prominent polypeptide component when examined in polyacrylamide gels containing sodium dodecyl sulfate. The buoyant density in CsCl of RNase P, 1.71 g/ml, is characteristic of a protein-RNA complex. The activity of RNase P is inhibited by various RNA molecules. The presence of a discrete RNA component in RNase P appears to be essential for enzymatic function. A model is described for enzyme-substrate recognition in which this RNA component plays an important role.
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PMID:Ribonuclease P: an enzyme with an essential RNA component. 35 97

Rat liver ribonuclease P was isolated from a cytosolic fraction and shown to have optimal activity in the presence of 1 mM MgCl2 and 150-200 mM KCl using Escherchia coli pre-tRNA(Tyr) as substrate. In cesium sulfate isopycnic density gradients, the enzyme had a buoyant density of 1.36 g/ml, indicating that it is a ribonucleoprotein complex. Analysis of the RNAs in the enzyme sample purified through two successive Cs2SO4 density gradient steps revealed the copurification of two major species of RNA (RRP1 and RRP2) along with several less abundant RNAs. Rat liver ribonuclease P activity was insensitive to micrococcal nuclease pretreatment. However, the nuclease-treated preparations contained several incompletely degraded RNA species that may have been sufficient to support the ribonuclease P activity. When RNase A was substituted for micrococcal nuclease, the ribonuclease P activity was diminished by greater than 90%, suggesting the requirement for an RNA subunit for activity.
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PMID:Characterization of ribonuclease P isolated from rat liver cytosol. 160 34

We have mapped a gene in the mitochondrial DNA of Candida (Torulopsis) glabrata and shown that it is required for 5' end maturation of mitochondrial tRNAs. It is located between the tRNAfMet and tRNAPro genes, the same tRNA genes that flank the mitochondrial RNase P RNA gene in the yeast Saccharomyces cerevisiae. The gene is extremely AT rich and codes for AU-rich RNAs that display some sequence homology with the mitochondrial RNase P RNA from S. cerevisiae, including two regions of striking sequence homology between the mitochondrial RNAs and the bacterial RNase P RNAs. RNase P activity that is sensitive to micrococcal nuclease has been detected in mitochondrial extracts of C. glabrata. An RNA of 227 nucleotides that is one of the RNAs encoded by the gene that we mapped cofractionated with this mitochondrial RNase P activity on glycerol gradients. The nuclease sensitivity of the activity, the cofractionation of the RNA with activity, and the homology of the RNA with known RNase P RNAs lead us to propose that the 227-nucleotide RNA is the RNA subunit of the C. glabrata mitochondrial RNase P enzyme.
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PMID:A gene required for RNase P activity in Candida (Torulopsis) glabrata mitochondria codes for a 227-nucleotide RNA with homology to bacterial RNase P RNA. 170 11

Ribonuclease P is the endonuclease that removes the leader fragments from the 5'-ends of precursor tRNAs. The enzyme isolated from eubacteria contains a catalytic RNA subunit. RNAs also copurify with eukaryotic RNase P, although catalysis by those RNAs has not been demonstrated. This paper reports the isolation and characterization of ribonuclease P from the thermoacidophilic archaebacterium Sulfolobus solfataricus. Archaebacteria are a primary evolutionary lineage, distinct from both eukaryotes and eubacteria. Ribonuclease P of S. solfataricus has reaction component requirements and a Km for substrate tRNA (2.5 X 10(-7) M) that are roughly similar to those reported for eubacterial and eukaryotic ribonuclease P. The temperature optimum for the reaction is 77 degrees C, reflecting the thermophilic character of the organism. The enzyme activity is not affected by treatment with micrococcal nuclease, suggesting that there is no RNA subunit or that it is protected from nuclease action. The density of the enzyme in cesium sulfate equilibrium density gradients is 1.27 g/ml, which is similar to that of protein. However, several RNAs between 200 and 400 nucleotides in size copurify with the enzyme activity on the density gradients, and one of them remains after micrococcal nuclease treatment. These properties of the S. solfataricus enzyme are compared with those of ribonuclease P from eukaryotes and eubacteria.
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PMID:Characterization of ribonuclease P from the archaebacterium Sulfolobus solfataricus. 211 85

A ribonuclease P-like activity was partially purified from HeLa cell mitochondria by DEAE-cellulose and octyl-Sepharose chromatography. RNase P-like activity can be quantitatively recovered from intact mitochondrial preparations treated with micrococcal nuclease, strongly suggesting that the enzyme is localized within the organelles. Mitochondrial RNase P (mtRNase P) cleaves the precursor to Escherichia coli suppressor tRNATyr at the same site as E. coli RNase P, producing the mature 5'-end of tRNATyr. The sensitivity of mtRNase P to pretreatment with nucleases or Pronase indicates that the enzyme has essential RNA and protein components. Although the ionic requirements of mtRNase P are similar to those of the RNase P activity isolated from the post-mitochondrial cytosol fraction, the chromatographic properties of mtRNase P are distinct. Mitochondrial RNase P is probably a part of the mitochondrial RNA processing machinery of mammalian mitochondria, being responsible for the endonucleolytic cleavage of the RNA transcripts at the 5'-side of the tRNA sequences.
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PMID:Characterization of an RNase P activity from HeLa cell mitochondria. Comparison with the cytosol RNase P activity. 258 45

During tRNA biosynthesis the 5'-leader sequences in precursor tRNAs are removed by the ribonucleoprotein RNase P, an enzyme whose RNA moiety is required for activity. To clarify some aspects of the enzyme mechanism, we examined substrate binding and product formation with mutant precursor tRNAs. Mutations G-1----A or U-2----C in the Schizosaccharomyces pombe sup3-e tRNASer, which cause mispairing at or near the top of the acceptor stem, prevent the removal of the 5'-leader sequences by Saccharomyces cerevisiae RNase P. Equilibrium binding studies involving specific gel retardation of RNase P-precursor tRNA complexes showed that complexes with wild-type and A-1 and C-2 mutant precursor tRNAs had very similar dissociation constants (average Kd for sup3 = 1.5 +/- 0.2 nM). Thus, the 5'-terminal nucleotides of mature tRNA, on the 3' proximal side of the RNase P cleavage site, affect the enzyme's catalytic function but not substrate binding. The catalytic integrity of the RNA component of RNase P is not essential for binding of tRNA precursors, as demonstrated by gel retardation of micrococcal nuclease-inactivated enzyme. This suggests a possible role for the protein component of the enzyme in substrate binding. Upon restoration of base pairing to the acceptor stem in the A-1 or C-2 mutants, we found that, in addition to a requirement for pairing at these positions, conservation of the wild-type first and second nucleotides of the tRNA was necessary to obtain maximal cleavage by RNase P. This indicates a distinct sequence preference of this enzyme.
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PMID:Yeast RNase P: catalytic activity and substrate binding are separate functions. 327 10

A requisite step in the biosynthesis of tRNA is the removal of 5' leader sequences from tRNA precursors. We have detected an RNase P activity in yeast mitochondrial extracts that can carry out this reaction on a homologous precursor tRNA. This mitochondrial RNase P was sensitive to both micrococcal nuclease and protease, demonstrating that it requires both a nucleic acid and protein for activity. The presence of RNase P activity in vitro directly correlated with the presence of a locus on yeast mitochondrial DNA previously shown by genetic and biochemical studies to be required for tRNA maturation. The product of the locus, the 9S RNA, and this newly described mitochondrial RNase P activity cofractionated, providing further evidence that the 9S RNA is the RNA component of yeast mitochondrial RNase P.
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PMID:RNase P activity in the mitochondria of Saccharomyces cerevisiae depends on both mitochondrion and nucleus-encoded components. 353 97

RNase P activity from Schizosaccharomyces pombe co-purifies with two RNA species. These RNAs are associated with enzyme activity as judged by titrated micrococcal nuclease inactivation experiments. The two RNAs, K1- and K2-RNA, are 285 and 270 nucleotides long, respectively. Both RNAs are transcribed from one gene, present in a single copy in the haploid genome. The primary and a secondary structure of K RNAs have been determined and compared with M1 RNA, their counterpart from Escherichia coli. Very limited sequence homology was observed, and this agrees with the finding that no cross-hybridization with M1 RNA can be detected in a Southern analysis with yeast genomic DNA. However, the secondary structures of K RNA and M1 RNA show the same basic organization and one conserved local motif, the sequence GUG--AGGPu in an exposed hairpin loop.
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PMID:Two RNA species co-purify with RNase P from the fission yeast Schizosaccharomyces pombe. 374 51

Ribonuclease P (RNase P) from Dictyostelium discoideum has been purified 470-fold. D. discoideum RNase P cleaves the precursor to Schizosaccharomyces pombe suppressor tRNA(Ser) at the same site as S. pombe RNase P, producing the mature 5' end of tRNA(Ser). pH and temperature optima for enzyme activity are 7.6 and 37 degrees C, respectively. The enzyme shows optimal activity in the presence of 5 mM MgCl2 and 10 mM NH4Cl or 5 mM KCl. The apparent Km for the S. pombe tRNA precursor derived from the supS1 tRNA(Ser) gene is 240 nM, and the apparent Vmax is 3.6 pmol/min. Inhibition of D. discoideum RNase P by proteinase K and micrococcal nuclease strongly indicates that the activity requires both protein and RNA components. In cesium sulfate density gradients, the enzyme has a buoyant density of 1.23 g/ml, indicating a low RNA/protein ratio for the holoenzyme.
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PMID:Partial purification and characterization of RNase P from Dictyostelium discoideum. 773 3

Two distinct RNase P-like activities which cleave leader sequences from pre-tRNA molecules to give mature 5' ends have been identified in carrot suspension-culture cells. An Escherichia coli pre-tRNA(Phe) and a tobacco pre-tRNA(Tyr) were transcribed in vitro then used as substrates for processing reactions in a cell-free extract. The pre-tRNA(Tyr) transcript was used to establish optimal salt and divalent cation requirements for processing. Kinetic experiments were then carried out on both substrates to determine if 5' and 3' processing were ordered. Primer extension analysis of processing intermediates and stable products verified that an ammonium sulfate fraction of the extract was indeed capable of accurately processing the 5' ends of both pre-tRNAs. Subsequent fractionation of the 5' end-processing activity by chromatography on phosphocellulose revealed two distinct activities, eluting at 0.1 and 0.5 M KCI, when assayed with the tobacco pre-tRNA(Tyr) substrate. When the same fractions were assayed with the E. coli pre-tRNA(Phe), only the 0.1 M KCI fraction exhibited activity. Both of the active fraction display sensitivity to micrococcal nuclease (MN) and proteinase K indicating each is a ribonucleoprotein, a result not seen with other plant RNase Ps. Subsequent FPLC fractionation of the two activities using Mono Q and Mono S columns demonstrated that the two activities could be further distinguished on the basis of their chromatographic behavior.
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PMID:Characterization and partial purification of two pre-tRNA 5'-processing activities from Daucus carrota (carrot) suspension cells. 774 55


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