Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A ribonuclease (ribonucleate 3-pyrimidine-oligonucleotidohydrolase, EC 3.1.4.22) was purified 8300-fold from soluble fraction of beef brain and its properties were investigated. The enzyme is an endonuclease capable of hydrolyzing tRNA, rRNA, poly(C), but shows no activity towards poly(U), poly(A), and poly(G). The preparation is free of deoxyribonuclease, non-specific phosphodiesterase and phosphomonoesterase activity. The enzyme has a pH optimum of 7.6, is not heat stable, has a molecular weight of 25 000, and has a K-m of 134 mu rRNA and K-m of 1600 mug poly(C) per ml.
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PMID:Purification of an alkaline ribonuclease from soluble fraction of beef brain. 23 61

Ribonucleases O and Q, the two putative nucleolytic activities which we detected previously in the crude extract from a thermosensitive ribonuclease P mutant (TS241) of Escherichia coli and which were shown to function in the processing of tRNA precursors in vitro, were partially purified from the 1000000 x g supernatant fraction of E. coli Q13. In the course of purification of these enzymes, the total RNAs synthesized in the thermosensitive mutant at the restrictive temperature were used as the substrates and the activities were identified from disappearance or alteration of specific tRNA precursor molecules in polyacrylamide gel electrophoresis. The purified ribonuclease O preparation cleaved specifically the multimeric tRNA precursors at the spacer regions. The purified ribonuclease Q preparation removed, in accordance with the definition of this enzyme, extra nucleotides from the 3'-terminal ends of monomeric tRNA precursors. Some properties of these two nucleases were investigated. In addition to these nucleases, another exonuclease (tentatively designated ribonuclease Y) and ribonuclease P, a well-characterized endonuclease, were also purified. The sequential mode of the processing of tRNA precursors, originally observed in the cleavage reactions with the crude extracts in vitro, was supported by studies with the purified enzyme preparations.
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PMID:Specific ribonucleases involved in processing of tRNA precursors of Escherichia coli. Partial purification and some properties. 35 May 82

Extracts of interferon-treated HeLa cells adsorbed to poly(I) . poly(C)-agarose have been used to synthesize 2'5'oligo(A). This oligonucleotide has been characterized by enzymatic digestion with alkaline phosphatase, snake venom phosphodiesterase, T2 ribonuclease and chromatography on DEAE, and PEI-cellulose. The oligonucleotide inhibits protein synthesis in vitro and activates an endonuclease present in extracts of control and interferon-treated cells. The metabolic stability of 2'5'oligo(A) has been investigated in these cell extracts. The oligonucleotide undergoes rapid degradation, particularly in the absence of ATP and of an energy regenerating system. Furthermore, the 2'5'oligo(A)-activated endonuclease reverts to an inactive state under these conditions, but can be reactivated upon further addition of 2'5'oligo(A). A possible role for the degradation of 2'5'oligo(A) in the mechanism of interferon action is discussed.
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PMID:Metabolic stability of 2' 5'oligo (A) and activity of 2' 5'oligo (A)-dependent endonuclease in extracts of interferon-treated and control HeLa cells. 42 14

Poly(A)-containing messenger RNA isolated from rabbit reticulocytes as estimated by periodate oxidation and condensation with [3H]isoniazid has two oxidizable end groups per molecule of mol. wt. 220000. When the mRNA is subjected to stepwise degradation by beta-elimination, only one oxidizable end-group is found. This indicates that one of the 2',3' hydroxyl end-groups is linked through the normal 3'--5' phosphodiester bond, but that the other is linked in such a way that after stepwise degradation no new 2',3 hydroxyl group is revealed. This structure could be a 5'-linked 5'-phospho di- or tri-ester. On digestion with ribonuclease the isoniazid-labelled RNA produced oligonucleotide hydrazones consistent with a poly(A) sequence at the 3' end plus fragments that are not found after stepwise degradation. These fragments have a charge of --6 and --8 from pancreatic ribonuclease or --7 from ribonuclease T1 digestion. These charges are changed to --3.4 and --4.1 after pancreatic ribonuclease, ribonuclease T2 and alkaline phosphatase digestion. methyl-3H-labelled-poly(A)-containing RNA isolated from late erythroid cells contain a methyl-labelled fragment resistant to endonuclease and phosphodiesterase II digestion. After digestion with phosphodiesterase I this fragment produces methyl-3 H-labelled nucleotides with the electrophoretic mobility of pm7G and pAm. It is concluded that globin mRNA has the 5' sequences m7G(5')ppp'AmpYpGp ... and m7G(5')pppAmpApGpYp.
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PMID:The nature of the 5'-linked 5' nucleotide sequence at the 5' end of rabbit globin messenger ribonucleic acid. 94 25

The Mg-2+-Sarkosyl crystals (M band) procedure was used to study the effect of ribonuclease (RNase) A on the association of Escherichia coli deoxyribonucleic acid (DNA) with membrane. Incubation of gently prepared cell extracts with RNase results in the release of DNA from membrane. This effect appears to result from the activation, by RNase, of endonuclease I and subsequent limited activity of this deoxyribonuclease. In support of this explanation, it is demonstrated (i) that the extent of the RNase-induced loss of DNA from membrane is directly correlated with the endogenous level of endonuclease I, and (ii) that endonucleolytic activity occurs when gently lysed cell preparations are incubated in the presence of RNase.
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PMID:Effect of ribonuclease on the association of deoxyribonucleic acid with the membrane in Escherichia coli. 109 60

We have described an in vitro system in which active su+III tRNATyr is synthesized from a phi80psu++III DNA template. Using this system, we have identified four essential components that are required for synthesis of tRNA. The first of these is DNA-dependent RNA polymerase. It has been shown that a crude preparation of DNA-dependent RNA polymerase synthesizes su++III tRNATyr precursor similar to that which has been isolated in vivo, and that this preparation is capable of supporting high levels of tRNA synthesis. With purified DNA-dependent RNA polymerase, the su++III tRNATyr precursor was not observed as a transcription product and tRNA synthesis was below detetable levels. On this basis, a second essential component for tRNA synthesis was identified. This fraction, designated Fraction V, in combination with purified RNA polymerase, catalyzes the synthesis of precursor tRNA. The third component is a ribonuclease (RNase P III), which specifically catalyzes the removal of the extra nucleotides present at the 3' terminus of the tRNA precursor. In the absence of this fraction, the in vitro synthesized su++III tRNATyr is slightly larger than 4 S and contains additional nucleotides beyond the normal --CCAOH 3 terminus of the mature tRNA. The fourth essential component required is a fraction containing RNase P, a previously identified endonuclease which specifically catalyzes the removal of the 5' extra nucleotides present on tRNA precursors.
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PMID:In vitro synthesis of transfer RNA. I. Purification of required components. 109 89

We have shown that the synthesis of active su+III tRNATyr from a phi80psu+III DNA template requires the action of four distinct enzymatic activities. The first of these, DNA-dependent RNA polymerase, catalyzes the formation of a large molecular weight transcript, initiating synthesis at a specific site 41 nucleotides proximal to the 5' end of the su+III tRNATyr structural gene and continuing at least 100 nucleotides beyond the 3' terminus of the su+III tRNATyr sequence. The second required component, designated Fraction V, allows purified DNA-DEPENDENT RNA polymerase to function in tRNA synthesis. We have shown that this fraction contains an endonuclease that together with DNA-dependent RNA polymerase is responsible for the synthesis of su+III tRNATyr "precursor". Thus, su+III tRNATyr precursor is not itself the primary transcription product of the su+III tRNATyr gene, but rather, it arises as a result of post-transcriptional cleavage of a much larger transcript by the action of the nuclease present in Fraction V. The third enzymatic activity required for synthesis of active su+III tRNATyr is a ribonuclease (RNase P III) that specifically catalyzes the removal of the 3' extra nucleotides from the su+III tRNATyr precursor. The fourth activity required for synthesis of tRNA is a previously identified endonuclease, RNase P, that specifically catalyzes the removal of the 5' extra nucleotides from tRNA precursors. The properties of RNase P purified according to the procedure developed in this laboratory have been compared with those of the enzyme purified from ribosomes according to the procedure described by Robertson et al. (Robertson, H.D., Altman, S., and Smith, F.D. (1972) J.Biol. Chem. 247, 5243-5251.).
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PMID:In vitro synthesis of transfer RNA. II. Identification of required enzymatic activities. 109 90

A comparative study of ribonuclease activity of isolated rat liver nuclei, nuclear membranes with buoyant density rho 1,19 and rho 1,22 and pH 8 nuclear membrane extract showed high nuclear membranes activity with different affinity to RNA and synthetic polyribonucleotides. Chromatographic analysis of poly-U degradation products demonstrates that the nuclear membrane extract contains at least two ribonucleases: a 3'-endonuclease and a 5'-endonuclease.
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PMID:[Ribonucleases of rat liver nuclear membranes]. 120 59

A synthetic RNA transcript containing the entire sequence of one of the two natural mRNAs for Escherichia coli ribosomal protein S20 is a substrate for specific cleavage by an endonuclease which is or depends on ribonuclease E (Mackie, G. A. (1991) J. Bacteriol. 173, 2488-2497). Partial cleavage with ribonucleases T1 or CL3 and limited modification with dimethyl sulfate have been employed to identify residues that are likely to be single stranded in the S20 mRNA's native state. The data show that the 5' one-third of the mRNA is relatively unstructured whereas the 3' one-third is extensively folded. The latter property can account for the previously observed accumulation of a 147-residue product co-terminal with the 3' end of the S20 mRNA (Mackie, G. A. (1989) J. Bacteriol. 171, 4112-4120). Sites of cleavage by the ribonuclease E-dependent activity map to single-stranded regions of the RNA. In addition, denaturation of the RNA substrate results in loss of susceptibility to the ribonuclease E-dependent activity and simultaneous loss of the single-stranded character of the two most prominent cleavage sites. It is proposed that ribonuclease E is a single-strand-specific enzyme with few primary structural constraints but a preference for an AU dinucleotide 3' to the site of cleavage.
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PMID:Secondary structure of the mRNA for ribosomal protein S20. Implications for cleavage by ribonuclease E. 137 Apr 57

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


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