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

---

Query: EC:3.1.26.9 (ribonuclease)
6,589 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.
...
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.
...
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.
...
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.
...
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.
...
PMID:The Ams (altered mRNA stability) protein and ribonuclease E are encoded by the same structural gene of Escherichia coli. 184 32

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.
...
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.
...
PMID:Maturation of 5-S rRNA: ribonuclease E cleavages and their dependence on precursor sequences. 633 34

Ribonuclease II (RNase II), encoded by the rnb gene, is one of the two major Escherichia coli exonucleases involved in mRNA degradation. Some of the ribonucleases implicated in this process have recently been shown to be inter-regulated. In this paper we studied the effects of the endonucleases RNase E and RNase III in rnb expression. We have shown that RNase E cleaves the rnb message internally: when this ribonuclease is inactivated rnb mRNA accumulates with a concomitant increase in RNase II activity. RNase III also affects RNase II expression but in an indirect way. We discuss these implications for the regulation of mRNA degradation.
...
PMID:The role of endonucleases in the expression of ribonuclease II in Escherichia coli. 764 46

The rne gene of Escherichia coli encodes a 118 kDa protein that has ribonuclease E (RNase E) activity and binds RNA. A functional rne gene product is essential for cell viability and for the processing and/or decay of a variety of RNA species, including 9 S RNA, mRNA and RNAI, the antisense RNA regulator of ColE1-type plasmid replication. By testing the ability of different segments of the Rne protein to catalyze RNA cleavage and to bind RNA, we found that the N-terminal half (residues 1 to 498) of Rne contains a catalytic function sufficient for site-specific cleavage of oligoribonucleotides and complex RNAs. The C-terminal half of the protein, which contains both an arginine-rich region (residues 597 to 684) that we show binds RNA and a segment that is essential for cell viability (residues 844 to 1061), had no detectable endoribonucleolytic activity. Our results, which map the catalytic domain of RNase E, indicate the existence of discrete functional domains within the multifaceted Rne protein.
...
PMID:The N-terminal domain of the rne gene product has RNase E activity and is non-overlapping with the arginine-rich RNA-binding site. 856 79

Differential gene expression from operons encoding fimbrial adhesins in Escherichia coli involves processing and differential decay of polycistronic transcripts. Previous analyses of mRNA processing in vivo using ribonuclease mutants of E. coli have given different results with the different fimbrial gene systems tested. For the pap operon from uropathogenic E. coli, the results suggested that the mRNA processing is dependent on ribonuclease E (RNase E), whereas in other fimbrial operons with similar genetic organisation, the processing was concluded to be RNase E independent. We have developed an in vitro system allowing us to assess the cleavage of pap mRNA, to study the mRNA processing of a fimbrial operon in more detail, and to define the enzymatic activity and target. The results of this study establish that RNase E does indeed cleave the papBA intercistronic transcript. Analysis of the cleavage products reveals that in vitro RNase E can cleave the mRNA at other positions in addition to the site preferentially cleaved in vivo. The specificity of the cleavage pattern was assessed using transcripts derived from mutants with base substitutions near, or within, the major in vivo cleavage site. Such mutants have alternative cleavage sites. A common feature of the different cleavage sites is a high A/U nucleotide content, similar to other known RNase E cleavage sites. Features of the secondary structure of the papBA intercistronic mRNA were investigated using single-strand-specific and double-strand-specific nucleases. The secondary structure model derived from stability calculations and our results from the nuclease-probing experiments indicate that the positions subject to RNase E cleavage are mainly single stranded and flanked by more stable stem-loop structures. The results are consistent with the notion that an mRNA conformation exposing A/U-rich, non-paired regions constitutes the target, i.e. a flexible determinant, for processing by RNase E in the pap transcript. The findings are discussed in relation to the existence of a potential recognition site for RNase E and the analysis of RNase E cleavages in other RNA molecules.
...
PMID:In vitro analysis of mRNA processing by RNase E in the pap operon of Escherichia coli. 884 34


1 2 3 4 5 6 7 Next >>

---