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)

This investigation was designed to characterize the immunoprotective antigen of ribosomal preparations from Haemophilus influenzae. The ribosomes that elicited 80 to 90% protection contained 25% protein and 75% ribonucleic acid but did not contain any detectable hexoses. The immunodiffusion and hemagglutination inhibition tests also failed to demonstrate that the capsular material (polyribose phosphate) was in ribosomal preparations. Treatment of ribosomes with ribonuclease degraded 78% ribonucleic acid but did not affect the immunogenicity of such preparations. The proteolytic enzymes reduced the immunogenicity of ribosomes corresponding to the amount of protein degraded. The protection elicited by ribosomal protein extracted with 2-chloroethanol was comparable to that induced by intact ribosomes. In contrast, the low levels of protection observed by immunization with phenol-extracted ribonucleic acid were dependent on the amounts of contaminating protein. Finally, immunogenicity of ribosomal ribonucleic acid and protein was abrogated by treatment with proteolytic enzymes. These results clearly indicate that the protein associated with Haemophilus ribosomes is the major immunoprotective antigen.
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PMID:Characterization of the immunoprotective antigen of ribosomal preparations from Haemophilus influenzae. 30 44

Ribonucleoproteins were prepared by ribonuclease digestion of a reconstitued complex of ribosomal protein L 1 and 23-S RNA from Escherichia coli. Three main ribonucleoproteins were identified. The largest was only obtained in an impure state at low ribonuclease concentration, whereas the two smaller ones, which were difficult to separate from one another electrophoretically, were stable over a range of enzyme concentrations. The two smaller ribonucleoproteins yielded a total of 13 RNA subfragments that were judged to be homogeneous electrophoretically. The latter were characterized for molecular weight and the subfragment composition of each of these ribonucleoproteins was established. Furthermore, the subfragments were shown to be maintained together in each ribonucleoprotein by RNA-RNA interactions. The primary and specific binding site of protein L1 was localized on one continuous RNA subfragment of about 110 nucleotides in length by two newly developed binding methods.
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PMID:The binding site of protein L1 on 23-S ribosomal RNA of Escherichia coli. 1. Isolation and characterization. 82 38

Ribonucleoproteins were obtained by T1 ribonuclease digestion of reconstitued complexes of ribosomal protein L1 AND 23-S RNA from Escherichia coli. The RNA region of the main ribonucleoprotein 2 was totally digested with T1 ribonuclease. The oligonucleotide products were characterised and they showed that this region comprises 148 nucleotides located between the 550th and 1000th necleotides from the 3' end of the 23-S RNA. Of the other two ribonucleoproteins, the largest ribonucleoprotein 1 contained an extra RNA sequence, of at least 15 nucleotides, that was located at the 5' end of the RNA region. The smallest ribonucleoprotein 3 lacked an RNA section towards the 3' end of the region. The order of the RNA subfragments and the enzymic cutting positions in the whole RNA region are given for the ribonucleoproteins. It is shown that protein L1 most strongly protects a continuous section of 115 nucleotides at the 5' end of the main RNA region. Finally, evidence is presented for a methylated base, and for two sequence heterogeneities, in this region of the 23-S RNA.
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PMID:The binding site of protein L1 ON 23-S ribosomal RNA of Escherichia coli. 2. Identification of the rna region contained in the L1 ribonucleoproteins and determination of the order of the RNA subfragments within this region. 82 39

A new transcription unit has been identified and characterized in the small single-copy region of tobacco chloroplast DNA. A primary transcript (1550 nucleotides) spanning the entire transcription unit contains no significant open reading frames (ORFs), other than ORF55, recently identified as the gene encoding the ribosomal protein CL32 (rpl32). The leader sequence extends 1101 nucleotides from the rpl32 initiation codon. Primer extension and in vitro capping experiments in combination with ribonuclease protection assays, revealed a promoter situated more than 322 bp inside the coding region of ndhF, which is divergently oriented with respect to rpl32. A canonical Pribnow-box is found just upstream of the transcription start site, but a typical -35 motif was not detected. This is the first internal divergent promoter to be characterized in the chloroplast genome.
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PMID:Active transcription from a promoter positioned within the coding region of a divergently oriented gene: the tobacco chloroplast rpl32 gene. 160 58

E. coli rnpA and rpmH genes encoding the protein portion of ribonuclease (RNase) P and L34 ribosomal protein were found to be homologous to the entire sequence of M1 RNA and virusoids. The resulting alignment strongly suggests that most primitive mRNAs must have emerged from virusoid-like ribo-organism.
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PMID:Possible evolutionary origin of primitive protein-encoding mRNAs as a virusoid-like ribo-organism. 171 69

The conformation of Escherichia coli 5 S rRNA was investigated using chemical and enzymatic probes. The four bases were monitored at one of their Watson-Crick positions with dimethylsulfate (at C(N-3) and A(N-1], with a carbodiimide derivative (at G(N-1) and U(N-3] and with kethoxal (at G(N-1, N-2]. Position N-7 of purine was probed with diethylpyrocarbonate (at A(N-7] and dimethylsulfate (at G(N-7]. Double-stranded or stacked regions were tested with RNase V1 and unpaired guanine residues with RNase T1. We also used lead(II) that has a preferential affinity for interhelical and loop regions and a high sensitivity for flexible regions. Particular care was taken to use uniform conditions of salt, magnesium, pH and temperature for the different enzymatic chemical probes. Derived from these experimental data, a three dimensional model of the 5 S rRNA was built using computer modeling which integrates stereochemical constraints and phylogenetic data. The three domains of 5 S rRNA secondary structure fold into a Y-shaped structure that does not accommodate long-range tertiary interactions between domains. The three domains have distinct structural and dynamic features as revealed by the chemical reactivity and the lead(II)-induced hydrolysis: domain 2 (loop B/helix III/loop C) displays a rather weak structure and possesses dynamic properties while domain 3 (helix V/region E/helix IV/loop D) adopts a highly structured and overall helical conformation. Conserved nucleotides are not crucial for the tertiary folding but maintain an intrinsic structure in the loop regions, especially via non-canonical pairing (A.G, G.U, G.G, A.C, C.C), which can close the loops in a highly specific fashion. In particular, nucleotides in the large external loop C fold into an organized conformation leading to the formation of a five-membered loop motif. Finally, nucleotides at the hinge region of the Y-shape are involved in a precise array of hydrogen bonds based on a triple interaction between U14, G69 and G107 stabilizing the quasi-colinearity of helices II and V. The proposed tertiary model is consistent with the localization of the ribosomal protein binding sites and possesses strong analogy with the model proposed for Xenopus laevis 5 S rRNA, indicating that the Y-shape model can be generalized to all 5 S rRNAs.
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PMID:Three-dimensional model of Escherichia coli ribosomal 5 S RNA as deduced from structure probing in solution and computer modeling. 171 95

We have studied the effect of the binding of ribosomal protein S1 and initiation factor IF3 on the accessibility of nucleotide residues 584-1506 in the small subunit of the Escherichia coli ribosome. Protein S1 strongly decreases RNase V1 attack at G1164, in hairpin 40 of the 3' major domain, and weakly decreases DMS attack at C1302, in the central loop of the 3' major domain, and at A1503, in the 3' minor domain. It also weakly increases the DMS reactivity of A1004, in the 3' major domain, and of A901, in the central domain. Factor IF3 strongly decreases RNase V1 attack (but not dimethyl sulfate attack) at A1408, in the decoding site, and weakly protects A1500, in the 3' minor domain and near the colicin E3 cleavage site. Neomycin does not interfere with this effect of IF3, but IF3 interferes with the protective effect of neomycin against dimethyl sulfate attack at A1408.
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PMID:Interaction of ribosomal protein S1 and initiation factor IF3 with the 3' major domain and the decoding site of the 30S subunit of Escherichia coli. 174 80

A wheat germ protease is responsible for Mr 105,000 methionyl-tRNA synthetase hydrolysis, generating two fragments of Mr 82,000 (harbouring the catalytic domain) and 20,000, respectively. Specificity of the protease was sought for using different kinds of protein substrates. It turned out that charged peptides were preferentially cleaved and that no proteolysis occurred when proteins were replaced by small synthetic substrates, harbouring target sites similar to those cleaved in proteins. The protease could be a ribosomal protein, since it remained associated to ribosomal structure, even after treatment by deoxycholate, Triton X-100, 800 mM KC1 and puromycin. Nevertheless, it was still active after ribonuclease treatment of the ribosomes. An identical protease activity was found in rat liver, but not in E. coli.
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PMID:Evidence for a ribosome-associated thiol protease cleaving wheat germ methionyl-tRNA synthetase. 186 82

The synthesis of an endogenous ribosomal protein, L1, is selectively and efficiently inhibited by microinjection of antisense L1 RNAs into Xenopus oocytes. Repression of L1 synthesis is achieved within 12 hr and is maintained for 48 hr. RNase-protection assays reveal the formation of RNA X RNA duplexes in vivo between the endogenous L1 mRNA and injected antisense transcripts. Partial-length antisense RNAs, complementary to only the 3'-terminal region of L1 mRNA, repress translation as effectively as a full-length antisense RNA, indicating that complementarity to the 5' region of L1 mRNA is not required for efficient inhibition. The use of antisense RNA to repress synthesis of an endogenous ribosomal protein provides a functional basis for determining mechanisms that integrate ribosomal protein synthesis with ribosome assembly during oogenesis.
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PMID:Stable repression of ribosomal protein L1 synthesis in Xenopus oocytes by microinjection of antisense RNA. 243 Feb 96

Ribosomal preparations were obtained from Streptococcus mutans. Sucrose density gradient analyses showed the ribosomes to be 70S and dissociated subunits to be 56S and 34S. The ribosomal preparation contained 57.4% RNA and 42.6% protein and gave an absorption maximum at 260 nm and a minimum at 235 nm and ribosomal particles were approximately 150-180 X 190-220 A as determined by electron microscopy. Immunodiffusion analysis of pooled antiserum raised by injecting the ribosomal preparation into rabbits disclosed precipitin lines with glucosyltransferase and lipoteichoic acid preparations from S. mutans. Gas chromatography showed rhamnose and glucose to be present in the ribosomal preparation indicating the presence of nonribosomal carbohydrate materials. The ribosomes were able to synthesize precipitable polypeptides when exogenous mRNA and tRNA were added and anti-ribosomal antibodies reduced this activity. Protease treatment rendered the ribosomal preparation less immunogenic in rats and less antigenic when the ribosomal preparation was used to coat erythrocytes for passive haemagglutination assays, while RNase treatment of the ribosomal preparation had no effect, suggesting that a protein(s) is the principal immunogenic moiety of the ribosomal antigen. Polyacrylamide gel electrophoresis of the ribosomal preparation revealed 27 protein bands of which five were found to react with hyperimmune rabbit antisera to the S. mutans ribosomal preparation by Western blot analysis. Washing the ribosomal preparation with 1 M NH4Cl did not remove any of the five immunogenic ribosomal protein antigens indicating that these were innate ribosomal proteins.
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PMID:Streptococcus mutans ribosomal preparations: purification and properties. 309 29


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