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:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A temperature-sensitive mutant of Escherichia coli at the nonpermissive temperature fails to produce normal levels of 5 S rRNA. Instead, a number of larger RNA molecules are accumulated. One of these molecules, a 9 S RNA, contains 5 S rRNA sequences. When the strain is shifted from a nonpermissive to a permissive temperature, radioactive label is lost from the 9 S RNA and appears in 5 S rRNA. The identification of this 5 S rRNA-containing molecule indicates the participation of a new processing ribonuclease (RNase E) in the maturation of rRNA in E. coli. The 9 S RNA was not detected in a wild type strain, indicating that the processing step(s) involved in the formation of 5 S rRNA might be performed before the growing rRNA transcript is terminated.
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PMID:Identification of a novel RNA molecule in a new RNA processing mutant of Escherichia coli which contains 5 S rRNA sequences. 10 52

Temperature-sensitive mutants were isolated from an rnc (RNase III-) strain of Escherichia coli, and their rRNA metabolism was analyzed on 3% polyacrylamide gels. One of these mutants was unable to produce 23S and 5S rRNAs at the nonpermissive temperature. When an rnc+ allele was introduced to this strain, it remained temperature sensitive. At the nonpermissive temperature, this strain could then produce 23S rRNA but was unable to make normal levels of 5S rRNA. In matings and transduction experiments, the defect in rRNA metabolism and temperature sensitivity behaved as a syndrome caused by a single point mutation, which was mapped at min 23.5 on the E. coli chromosome. This mutation probably affects an enzyme, ribonuclease E (RNase E), which introduces a cut in the nascent rRNA transcript between the 23S and the 5S rRNA cistrons. The mutation rne is recessive with respect to temperature sensitivity and the pattern of rRNA. Revertants able to grow at 43 degrees and with normal metabolism of rRNA were isolated; genetic analysis showed that they do not contain the original rne mutation, suggesting that they were true revertants. By combining the rne mutation with an rnc mutation, double rnc rne strains were synthesized, which behaved very similarly to the original rnc strain from which the rne mutation was isolated. Such strains have RNA metabolism that is similar to that of rnc strains at permissive temperatures, but at the nonpermissive temperature they fail to synthesize p23, m23, and 5S rRNAs. Thus, the experiments reported here, together with previous studies, suggest the existence of a new processing ribonuclease activity in Escherichia coli, which is called ribonuclease E.
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PMID:Isolation, genetic mapping and some characterization of a mutation in Escherichia coli that affects the processing of ribonuleic acid. 36 43

In Rhodobacter capsulatus the puf operon encodes proteins of the photosynthetic apparatus. The polycistronic puf mRNA is comprised of segments that show differential stability. Here, we show that the rate of decay of the 2.7-kb pufBALMX mRNA species in Escherichia coli depends on the activity of ribonuclease E (RNase E), whereas the degradation of the 0.5-kb pufBA mRNA segment is not affected by a mutation in the rne gene. The RNase E-promoted decay of the pufLMX mRNA depends on the presence of a 1.4-kb pufLM mRNA segment, in which rate-limiting endonucleolytic cleavage was postulated to occur in R. capsulatus. The insertion of 185 bp of this 1.4-kb segment into pufB results in an RNase E-dependent decay of the modified pufBA mRNA segment in E. coli. Our findings suggest that in R. capsulatus an RNase E-like activity is responsible for the rate-limiting endonucleolytic cleavage occurring within the pufLM mRNA segment, whereas the 0.5-kb pufBA mRNA segment is degraded by a different RNase E-independent decay mechanism.
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PMID:The rate of decay of Rhodobacter capsulatus-specific puf mRNA segments is differentially affected by RNase E activity in Escherichia coli. 142 2

Processing of 9 S precursor RNA in Escherichia coli requires the endoribonuclease RNase E, which makes two cleavages to liberate p5, the immature form of 5 S rRNA. The contributions of primary and secondary structure to RNase E-mediated cleavage of 9 S RNA were investigated. The structure of the 5' domain of 9 S RNA was probed by partial ribonuclease digestion and chemical modification. Our structural analysis of 9 S RNA supports a model in which the 5' spacer domain folds into tandem hairpins so that the first processing cleavage site 5' to the 5 S moiety resides in a stretch of single-stranded residues. Site-directed mutagenesis of a cloned 9 S RNA sequence was performed and synthetic transcripts derived from a variety of such mutant templates were assayed as substrates for RNase E-dependent endonuclease activity in fractionated extracts. Partial or complete deletion of the 5 S sequence did not eliminate site-specific processing of 9 S RNA. Mutations affecting the 5' domain revealed that secondary structure upstream from the first cleavage site is important in maintaining efficient processing. However, secondary structure downstream from either cleavage site is dispensable. Our results suggest that RNase E specifically recognizes and cleaves single-stranded RNA sequences only when presented in a proper conformational context. Adjacent secondary structures appear to play a direct and critical role in the enzyme's recognition of its substrate. Additionally, it may serve to anchor single-stranded regions to ensure the availability of the RNase E cleavage sites.
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PMID:Structural requirements for the processing of Escherichia coli 5 S ribosomal RNA by RNase E in vitro. 147 79

The in vitro and in vivo analysis of the ribonuclease E-deficient (rne-) and the altered mRNA stability protein-deficient (ams-) strains of Escherichia coli has demonstrated that they carry mutations in the same structural gene. Strains encoding either thermolabile RNase E (rne-3071) or Ams protein (ams-1) are defective in both rRNA processing and mRNA turnover. Immediately after a shift to the nonpermissive temperature, the chemical decay rate of bulk mRNA is slowed 2- to 3-fold, and within 70 min, precursors to 5S rRNA begin to accumulate. In addition, all of the phenotypes associated with either the rne-3071 or the ams-1 alleles were complemented by a recombinant plasmid carrying ams+. When taken together with previous genetic studies, these results suggest that the role of ribonuclease E in mRNA turnover involves endonucleolytic cleavages at the proposed ACAG(A/U)AUUUG consensus sequence.
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PMID:The Ams (altered mRNA stability) protein and ribonuclease E are encoded by the same structural gene of Escherichia coli. 184 32

A precursor molecule for 10Sb (M1) RNA, the RNA moiety of the RNA processing enzyme ribonuclease P (EC 3.1.26.5), is accumulated transiently in an Escherichia coli strain containing a plasmid that carries the 10Sb RNA gene. The same RNA precursor molecule is accumulated, in relatively large quantities, in a temperature-sensitive RNase E- mutant at the nonpermissive temperature. The RNA precursor includes 10Sb RNA and an extra 3' fragment that contains a termination stem and loop. It can be processed in vitro to a molecule the size of 10Sb RNA. None of the four endoribonucleases of E. coli--RNase III, RNase E, RNase F, or RNase P--takes part in this cleavage reaction. Therefore, we suggest that the processing of the precursor-10Sb RNA to 10Sb RNA is carried out by a thus-far unidentified endoribonuclease. The accumulation of a RNA molecule in a RNase E- mutant that does not contain a cleavage site for RNase E has been encountered previously and can be explained by assuming the existence of a RNA processing complex in the E. coli cell.
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PMID:Identification of a precursor molecular for the RNA moiety of the processing enzyme RNase P. 619 33

A transducing bacteriophage lambda Ch25rne+, which codes for ribonuclease E of E. coli, has been isolated. To achieve this a random library of Escherichia coli HindIII fragments was cloned in the lambda Charon 25 vector (prepared in F.R. Blattner's laboratory), and lambda Ch25rne+ was selected by its ability upon lysogenization to enable a temperature-sensitive (ts) rne-3071 mutant to grow and to exhibit normal RNA processing at the nonpermissive temperature of 45 degrees C. The level of RNase E was doubled in an rne+ strain lysogenized with lambda Ch25rne+. lambda Ch25rne+ directs the synthesis of a polypeptide of 71 000 m.wt., which is the size of RNase E. Restriction analysis and electron micrography of heteroduplexes suggested that the size of the host DNA insert is about 1.9 kb.
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PMID:Cloning the gene for ribonuclease E, an RNA processing enzyme. 626 May 92

9-S RNA is a processing intermediate that accumulates in an RNase E- strain of Escherichia coli. It spans from the RNase III cleavage site, after 23-S rRNA, to the 3' end of the transcript and is derived from rRNA genes which do not contain tRNAs distal to 5-S rRNA. Here, we have studied the processing of 9-S RNA with ribonuclease E. RNase E cleaves 9-S RNA in two sites: one of these is three nucleotides upstream from the 5' end of 5-S rRNA, the other downstream from its 3' end. Both cleavages are probably introduced by the same enzyme, since both cleavages are thermolabile when an extract of a temperature-sensitive RNase E mutant was used for processing in vitro. In order to asses the role of 5' and 3' end precursor-specific sequences in the RNase E reaction, we isolated the molecules lacking nucleotides at the 5' or 3' end. Molecules having the 5' end of 9-S RNA but missing nucleotides from the 3' end (called 8-S RNA) were as good a substrate for RNase E as 9-S, RNA itself. However, molecules having the 3' end of 9-S RNA but the 5' end of p5 (called 7-S RNA), were less efficient substrates for RNase E. Finally, the removal of as little as seven nucleotides from the 5' end of 8-S RNA rendered it almost completely unsuitable as a substrate for RNase E.
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PMID:Maturation of 5-S rRNA: ribonuclease E cleavages and their dependence on precursor sequences. 633 34

As part of our genetic analysis of mRNA decay in Escherichia coli K-12, we examined the effect of the pcnB gene [encoding poly(A) polymerase I] on message stability. Eliminating poly(A) polymerase I (delta pcnB) dramatically stabilized the lpp, ompA, and trxA transcripts. The half-lives of individual mRNAs were increased in both a delta pcnB single mutant and a delta pcnB pnp-7 rnb-500 rne-1 multiple mutant. We also found mRNA decay intermediates in delta pcnB mutants that were not detected in control strains. By end-labeling total E. coli RNA with [32P]pCp and T4 RNA ligase and then digesting the RNA with RNase A and T1, we showed that many RNAs in a wild-type strain contained poly(A) tails ranging from 10 nt to > 50 nt long. When polynucleotide phosphorylase, RNase II, and RNase E were absent, the length (> 100 nt) and number (10- to 20-fold) of the poly(A) tails increased. After transcription initiation was stopped with rifampicin, polyadenylylation apparently continued. Deleting the structural gene for poly(A) polymerase I (pcnB) reduced the amount of 3'-terminal poly(A) sequences by > 90%. We propose a model for the role of polyadenylylation in mRNA decay.
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PMID:Polyadenylylation helps regulate mRNA decay in Escherichia coli. 789 80

The maturation of 5S RNA in Escherichia coli is poorly understood. Although it is known that large precursors of 5S RNA accumulate in mutant cells lacking the endoribonuclease-RNase E, almost nothing is known about how the mature 5' and 3' termini of these molecules are generated. We have examined 5S RNA maturation in wild-type and single- or multiple-exoribonuclease-deficient cells by Northern blot and primer-extension analysis. Our results indicate that no mature 5S RNA is made in RNase T-deficient strains. Rather, 5S RNA precursors containing predominantly 2 extra nucleotides at the 3' end accumulate. Apparently, these 5S RNAs are functional inasmuch as mutant cells are viable, growing only slightly slower than wild type. Purified RNase T can remove the extra 3' residues, showing that it is directly involved in the trimming reaction. In contrast, mutations affecting other 3' exoribonucleases have no effect on 5S RNA maturation. Approximately 90% of the 5S RNAs in both wild-type and RNase T- cells contain mature 5' termini, indicating that 5' processing is independent of RNase T action. These data identify the enzyme responsible for generating the mature 3' terminus of 5S RNA molecules and also demonstrate that a completely processed 5S RNA molecule is not essential for cell survival.
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PMID:The tRNA processing enzyme RNase T is essential for maturation of 5S RNA. 754 80


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