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

Several modified nucleosides were introduced during in vitro RNA synthesis into a pre-tRNA(Ser). The pre-tRNAs were used as substrates for RNase P enzymes. No effects were observed with biotin-8-ATP or [alpha-S]-GPT, whereas with m7GTP, the cleavage reaction was completely inhibited. Analysis of pre-tRNAs which contained m7G at various positions has revealed a single base at the 5'-end of the acceptor stem where this modification absolutely prevents cleavage by catalytic M1 RNA, eukaryotic and prokaryotic RNase P holoenzymes. These results suggest that a critical contact must be made between pre-tRNA substrate and enzyme/ribozyme or that the approach of the potential cleaving agent (a positive magnesium ion) is made impossible by the positive charge at N-7 of the guanosine. In addition, we have shown that a pre-tRNA containing only m7G's can still form a complex with M1 RNA in a gel retardation assay.
 ...
PMID:The methylation of one specific guanosine in a pre-tRNA prevents cleavage by RNase P and by the catalytic M1 RNA. 217 70

All sequenced histidine tRNAs have one additional nucleotide at the 5' end when compared to other tRNA species. Sequence analysis of histidine tRNA genes from Drosophila melanogaster and Schizosaccharomyces pombe showed that the terminal guanylate residue of the mature tRNAs is not encoded by the genes. Analysis of the products from in vitro transcription of these genes in extracts from Drosophila Kc cells demonstrated that the 5'-terminal nucleotide present in the mature tRNA is added post-transcriptionally. The addition reaction requires ATP. A portion of the mature tRNAs are then modified at the 5'-terminal pG. Analysis of the RNA species formed during the in vitro maturation of the Drosophila histidine tRNA primary transcript uncovered the following maturation scheme: (i) the primary transcript is processed by RNase P at the 5' end to form an intermediate precursor; (ii) the 3'-flanking sequence is endonucleolytically removed, and a guanylate moiety is added to the 5' end to form mature-sized histidine tRNA; and (iii) a fraction of the 5'-terminal guanylate residues then undergoes modification. In contrast to the capping of eukaryotic mRNA, the guanylate addition to histidine tRNA results in the formation of a (3'-5')-phosphodiester bond. There are no precedents for the post-transcriptional addition of nucleotides (in phosphodiester linkage) to the 5' end of RNA precursors.
 ...
PMID:Post-transcriptional nucleotide addition is responsible for the formation of the 5' terminus of histidine tRNA. 629 3

For the first time mosaic nucleic acids composed of 50% RNA and 50% DNA can be obtained as transcripts with T7 RNA polymerase. Two NTPs could be replaced simultaneously in a transcription reaction. This means more than 40 deoxynucleotides were inserted in one transcript. Previously, a maximum of two deoxynucleotides could be incorporated and 2'-O-methyl-NTPs were not substrates at all. We obtained reasonable transcript yields with a maximal level of 99% 2'-O-methyl-NTPs, and the products contained up to 58% 2'-O-methylnucleotides at more than 20 positions. Sequence-specific nucleotide incorporation was monitored by sequence ladders (partial alkali or iodine cleavage). No base misincorporations were detected with 100% dGTP, dCTP and dTTP, and with partial incorporation of dATP alpha S, 2'-O-methyl-GTP alpha S and 2'-O-methyl-CTP alpha S, whereas they were found with dATP, 2'-O-methyl-ATP alpha S and 2'-O-methyl-UTP alpha S. Quantitative data allow predetermined modification levels of partially modified transcripts. Highly modified transcripts can be used for structural and functional studies, in modification interference approaches and for in vitro evolution procedures. Modification interference studies revealed a small number of important phosphate and ribose moieties in RNase P substrates. The conversion of T7 RNA polymerase to a DNA polymerase extends the observation that there is no absolute distinction between RNA and DNA polymerases. Accordingly, an adapted concept of a primordial RNA world is presented.
 ...
PMID:Enzymatic synthesis of 2'-modified nucleic acids: identification of important phosphate and ribose moieties in RNase P substrates. 754 Nov 30

tRNA processing is a central event in mammalian mitochondrial gene expression. We have identified key enzymatic activities (ribonuclease P, precursor tRNA 3'-endonuclease, and ATP(CTP)-tRNA-specific nucleotidyltransferase) that are involved in HeLa cell mitochondrial tRNA maturation. Different mitochondrial tRNA precursors are cleaved precisely at the tRNA 5'- and 3'-ends in a homologous mitochondrial in vitro processing system. The cleavage at the 5'-end precedes that at the 3'-end, and the tRNAs are substrates for the specific CCA addition in the same in vitro system. Using a comparative enzymatic approach as well as biochemical and immunological techniques, we furthermore demonstrate that human cells contain two distinct enzymes that remove 5'-extensions from tRNA precursors, the previously characterized nuclear and the newly identified mitochondrial ribonuclease P. These two cellular isoenzymes have different substrate specificities that seem to be well adapted to their structurally disparate mitochondrial and nuclear tRNA substrates. This kind of approach may also help to understand the structural diversities and commonalities of tRNAs.
 ...
PMID:Human mitochondrial tRNA processing. 775 47

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.
 ...
PMID:Characterization of human mitochondrial RNase P: novel aspects in tRNA processing. 964 9

DEAD-box proteins have been implicated in a wide array of cellular processes ranging from initiation of protein synthesis and ribosome biogenesis to mRNA splicing. Here, we report the isolation, biochemical characterization and crystallization of the first thermophilic DEAD box protein, Hera (heat-resistant RNA-dependent ATPase) from Thermus thermophilus HB8. The molecular mass of the deduced Hera protein sequence (510 amino acid residues) is 55.95 kDa. Hera possesses all of the conserved motifs found among the, DEAD-box RNA helicases. In addition, it also has a motif characteristic of the protein component of ribonuclease P at its C-terminal region (residues 372-386). Hera appears to be non-specific with respect to the RNA species that triggers ATPase activity. Nevertheless, at high temperature, ATPase activity is at a maximum when bacterial 16 S rRNA or 23 S rRNA are used as the substrates. Moreover, a deletion of the RNase P protein motif significantly reduces the ability of Hera to hydrolyze ATP in the presence of RNase P RNA. Hera has a specific ATPase activity of 480 units/microg and therefore, displays the highest ATPase specific activity reported for a protein of the RNA helicase family. We determined that Hera shows helix-destabilizing activity, and that the RNA-unwinding or helix-destabilizing activity of Hera is coupled to ATP hydrolysis. Since Hera is a stable thermophilic protein and we have obtained crystals of it diffracting beyond 2.6 A, the possibilities for structure determination of a full-length RNA-helicase are open.
 ...
PMID:Hera from Thermus thermophilus: the first thermostable DEAD-box helicase with an RNase P protein motif. 1061 Jul 97

All mitochondrial tRNAs in kinetoplastid protozoa are encoded in the nucleus and imported from the cytosol. Incubation of two in vitro-transcribed tRNAs, tRNA(Ile)(UAU) and tRNA(Gln)(CUG), with isolated mitochondria from Leishmania tarentolae, in the absence of any added cytosolic fraction, resulted in a protease-sensitive, ATP-dependent importation, as measured by nuclease protection. Evidence that nuclease protection represents importation was obtained by the finding that Bacillus subtilis pre-tRNA(Asp) was protected from nuclease digestion and was also cleaved by an intramitochondrial RNase P-like activity to produce the mature tRNA. The presence of a membrane potential is not required for in vitro importation. A variety of small synthetic RNAs were also found to be efficiently imported in vitro. The data suggest that there is a structural requirement for importation of RNAs greater than approximately 17 nt, and that smaller RNAs are apparently nonspecifically imported. The signals for importation of folded RNAs have not been determined, but the specificity of the process was illustrated by the higher saturation level of importation of the mainly mitochondria-localized tRNA(Ile) as compared to the level of importation of the mainly cytosol-localized tRNA(Gln). Furthermore, exchanging the D-arm between the tRNA(Ile) and the tRNA(Gln) resulted in a reversal of the in vitro importation behavior and this could also be interpreted in terms of tertiary structure specificity.
 ...
PMID:Selective importation of RNA into isolated mitochondria from Leishmania tarentolae. 1091 95

We report here the complete sequence of the mitochondrial (mt) genome of the pathogenic yeast Candida glabrata. This 20 kb mt genome is the smallest among sequenced hemiascomycetous yeasts. Despite its compaction, the mt genome contains the genes encoding the apocytochrome b (COB), three subunits of ATP synthetase (ATP6, 8 and 9), three subunits of cytochrome oxidase (COX1, 2 and 3), the ribosomal protein VAR1, 23 tRNAs, small and large ribosomal RNAs and the RNA subunit of RNase P. Three group I introns each with an intronic open reading frame are present in the COX1 gene. This sequence is available under accession number AJ511533.
 ...
PMID:The complete mitochondrial genome sequence of the pathogenic yeast Candida (Torulopsis) glabrata. 1252 59

All tRNAHis molecules are unusual in having an extra 5' GMP residue (G(-1)) that, in eukaryotes, is added after transcription and RNase P cleavage. Incorporation of this G(-1) residue is a rare example of nucleotide addition occurring at an RNA 5' end in a normal phosphodiester linkage. We show here that the essential Saccharomyces cerevisiae ORF YGR024c (THG1) is responsible for this guanylyltransferase reaction. Thg1p was identified by survey of a genomic collection of yeast GST-ORF fusion proteins for addition of [alpha-32P]GTP to tRNAHis. End analysis confirms the presence of G(-1). Thg1p is required for tRNAHis guanylylation in vivo, because cells depleted of Thg1p lack G(-1) in their tRNAHis. His6-Thg1p purified from Escherichia coli catalyzes the guanylyltransferase step of G(-1) addition using a ppp-tRNAHis substrate, and appears to catalyze the activation step using p-tRNAHis and ATP. Thg1p is highlye conserved in eukaryotes, where G(-1) addition is necessary, and is not found in eubacteria, where G(-1) is genome-encoded. Thus, Thg1p is the first member of a new family of enzymes that can catalyze phosphodiester bond formation at the 5' end of RNAs, formally in a 3'-5' direction. Surprisingly, despite its varied activities, Thg1p contains no recognizable catalytic or functional domains.
 ...
PMID:tRNAHis maturation: an essential yeast protein catalyzes addition of a guanine nucleotide to the 5' end of tRNAHis. 1463 74

Ribonuclease P (RNase P) is a ribonucleoprotein complex that catalyzes the cleavage of the 5' end of precursor tRNA. To characterize the interface between the Bacillus subtilis RNA (PRNA) and protein (P protein) components, the intraholoenzyme KD is determined as a function of ionic strength using a magnetocapture-based assay. Three distinct phases are evident. At low ionic strength, the affinity of PRNA for P protein is enhanced as the ionic strength increases mainly due to stabilization of the PRNA structure by cations. Lithium substitution in lieu of potassium enhances the affinity at low ionic strength, whereas the addition of ATP, known to stabilize the structure of P protein, does not affect the affinity. At high ionic strength, the observed affinity decreases as the ionic strength increases, consistent with disruption of ionic interactions. These data indicate that three to four ions are released on formation of holoenzyme, reflecting the number of ion pairs that occur between the P protein and PRNA. At moderate ionic strength, the two effects balance so that the apparent KD is not dependent on the ionic strength. The KD between the catalytic domain (C domain) and P protein has a similar triphasic dependence on ionic strength. Furthermore, the intraholoenzyme KD is identical to or tighter than that of full-length PRNA, demonstrating that the P protein binds solely to the C domain. Finally, pre-tRNAasp (but not tRNAasp) stabilizes the PRNA*P protein complex, as predicted by the direct interaction between the P protein and pre-tRNA leader.
 ...
PMID:Ionic interactions between PRNA and P protein in Bacillus subtilis RNase P characterized using a magnetocapture-based assay. 1533 47


1 2 Next >>