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:3.1.26.9 (ribonuclease)
6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

RNA ligase has been highly purified in good yields from bacteriophage T4-infected Escherichia coli by a rapid and reproducible procedure. The enzyme is free of phosphomonoesterase and ribonuclease activities and is therefore suitable for the synthesis of oligoribonucleotides and for the labeling of the 3'-terminus of RNA. Greater than 90% of the protein in the enzyme preparation migrates as a single band on gradient polyacrylamide gels containing sodium dodecyl sulfate during electrophoresis. For use as a DNA synthesis reagent the enzyme may be reliably freed of deoxyribonuclease activity by an additional chromatographic procedure using a commercially avialable resin.
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PMID:The purification of nuclease-free T4-RNA ligase. 21 95

We identified a Mg2+ dependent 5' exo-ribonuclease and an RNA ligase in cell-free extracts of Trypanosome brucei. The exo-ribonuclease in S100 or nuclear extracts, removes about 20 nts from the 5' end of SP6 derived capped as well as uncapped RNA and then stops. In contrast to the activity of the exo-ribonuclease on capped SP6 mini-exon transcripts, the exonuclease cannot degrade trypanosome-derived mini-exon transcripts or the mini-exon located at hsp 70 mRNAs. We therefore assume that the four secondary base modifications adjacent to the mini-exon cap, generated in vivo, confer resistance to the exo-ribonuclease. After exonuclease shortening of SP6 transcripts, an RNA ligase catalizes intramolecular ligation, generating a 3'-5' phosphodiester bond in a Mg2+ and ATP dependent reaction.
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PMID:A 5' exo-ribonuclease and RNA ligase of T. brucei. 246 Aug 26

Behaviour of modified nucleosides, tRNA components, and their analogues has been studied in the internucleotide bond formation catalysed by ribonucleases of various substrate specificity, polynucleotide phosphorylases, and T4 RNA ligase and the results are summarised in this paper. Pseudouridine, dihydrouridine, ribothymidine, 5-methylcytidine, inosine, and 6-methyladenosine can participate in the reaction of internucleotide bond formation the presence of most ribonucleases used, viz. Pb2, Pcl2, Pb1, Pch1, C2, T1, pancreatic RNase. 3-Methylcytidine and 4-acetylcytidine form internucleotide bond (as phosphate acceptors) usually by means of guanyl-specific ribonucleases, whereas 1-methylandenosine is incorporated with ribonuclease Pel2. 7-Methylguanosine and 1-methylguynosine 2',3'-cyclophosphates can be used as phosphate donors in the presence of ribonuclease Pb2; in the similar enzymatic reaction 6-isopentenyladenosine is an uneffective acceptor.
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PMID:[Enzymatic incorporation into oligonucleotides of modified nucleosides]. 367 47

Phenylalanine-specific tRNA from yeast was hydrolysed with cobra venom ribonuclease in the double-stranded regions and the fragments isolated. The 'dissected' molecules with nicks in positions 28 and 41 were reconstructed from supplementary fragments and treated with T-4 RNA ligase. A phosphodiester bond between two fragments was formed when the fragment combination (1-28) + (29-76) was used. A strong discrimination in the ligation yield between different nick positions in the same helix is shown.
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PMID:Reconstruction of tRNAPhe molecules from the fragments by linkage with T-4 RNA ligase in double-stranded regions. 636 20

Globin mRNA from rabbit reticulocytes was labelled at the 3'-end with [5'-32P]pCp by T4 RNA ligase. The 3'-poly(A) tail was released by digestion of mRNA with T1 ribonuclease and its size distribution determined by gel electrophoresis and autoradiography. The length of the 3'-poly(A) tails varied from about 15-150 residues, but the size distribution exhibited peaks in the abundance of poly(A) species at intervals of approx. 25 residues. This periodicity appears to reflect the manner in which proteins bind to the 3'-poly(A) tail. The function of such regular interactions may be to control mRNA breakdown in the cytoplasm.
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PMID:Periodicity in the length of 3'-poly(A) tails from native globin mRNA of rabbit. 681 23

The prr locus was originally described as coding a ribonuclease that is activated after phage T4 infection to cut within the anticodon of a specific tRNA, inactivating protein synthesis and thus blocking phage development. Wild-type T4 phage has two genes coding the enzymes polynucleotide kinase and RNA ligase, whose only function seems to be to repair the damage done by the anticodon nuclease. As the only apparent function of the prr ribonuclease is to combat phage infection, it can be considered as an RNA-based restriction enzyme. In non-infected cells, the prr enzyme is kept inactive in a complex with three other proteins which were predicted on the basis of DNA homologies to be the subunits of a type IC DNA restriction and modification system. Unlike other type IC systems so far characterized, prr is chromosomally rather than plasmid coded. However, sequences upstream from prr also have homology with sequences from the plasmid R124 and the prophage P1. We have now investigated the prr system and shown that it is indeed a bona fide type IC system which we call EcoprrI, and which is active both in vivo and in vitro. The system is fully functional even in the absence of the anticodon nuclease and seems to be a typical type I enzyme. EcoprrI recognizes the sequence CCA(N7)RTGC. One peculiarity is that, with low efficiency, EcoprrI will recognize and methylate variants of its recognition sequence such as CCT(N7)ATGC, which is methylated in one strand of the DNA only.
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PMID:The Escherichia coli prr region encodes a functional type IC DNA restriction system closely integrated with an anticodon nuclease gene. 814 41

The hammerhead ribozyme is a more efficient ribonuclease than an RNA ligase. Under typical reaction conditions, the rate of RNA chain cleavage is approximately 100-fold faster than the rate of the reverse ligation reaction such that virtually all of the hammerhead is in its cleaved form at equilibrium. Here we show that the introduction of a crosslink away from the catalytic core of the hammerhead has little effect on the cleavage rate but dramatically increases the ligation rate, thereby making the hammerhead an efficient RNA ligase. This experiment emphasizes the role of molecular flexibility in defining the properties of a macromolecular catalyst and suggests why other small ribozymes are more efficient ligases than ribonucleases.
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PMID:A covalent crosslink converts the hammerhead ribozyme from a ribonuclease to an RNA ligase. 1157 91

Many studies have been undertaken to investigate the mechanisms of skin differentiation. In particular, growth factors and hormones are believed to play important roles in skin proliferation, differentiation and survival. Insulin-like growth factor-1 (IGF-1) has been identified as a survival factor in many tissues including the skin, but the molecular mechanism of IGF-1 in epidermal differentiation is not completely understood. Neonatal mouse skin is useful for studying changes in gene expression, as the mitotic activity of skin cells changes shortly after birth. Using RNA differential display (DD), a 357-nt message that is specifically expressed in the epidermal keratinocytes of IGF-1-injected newborn mice but not in controls, has been identified. Confirmation of expression of this gene by ribonuclease protection assay (RPA) showed that its mRNA expression in the epidermal keratinocytes is induced by IGF-1. Using RNA ligase-mediated rapid amplification of 5' cDNA ends (RLM-5'-RACE), we have successfully isolated a 3473-bp full-length gene, c98, that has 97% sequence homology to a bcl-2-like gene, bcl-w. The latter has been identified as a proto-oncogene in several murine myeloid cell lines. Amino acid sequence analysis of the c98 showed that it has 97% sequence identity to the bcl-w protein and possesses bcl-2 homology domains (BH) 1, 2 and 3. Immunoblotting data revealed similar increases of c98 protein expression to its mRNA expression in the keratinocytes of IGF-1-injected animals. Weak expression of other bcl-2 family member proteins, bax, bcl-2 and bcl-xL, were also found in the immunoblots. Additionally, IGF-1 was found to be able to protect epidermal keratinocytes from dexamethasone (DEX)-induced apoptosis, based on the findings that after the cells were treated with DEX, DNA laddering was present in the control mice but not in those injected with IGF-1. Further, using a photometric enzyme-linked immunoassay to quantitate keratinocyte death, we found that after addition of DEX, the amounts of cytoplasmic histone-associated DNA fragments were not significantly (P>0.05) different in IGF-1-treated cells compared with untreated control cells during the high mitotic stage of skin epidermis. To assess the role of c98 in these anti-apoptotic processes, we have generated a recombinant plasmid that contains an expression vector and c98 and transfected this plasmid into the keratinocytes from mice without IGF-1-treatment. Expression of the c98 protein was found to completely (P>0.05) block DEX-induced apoptosis after cell transfection. Taken together, our current data demonstrated that IGF-1 plays an anti-apoptotic role in the DEX-induced apoptosis in epidermal keratinocytes and this, at least in part, may be mediated through expression of c98.
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PMID:Mouse keratinocytes express c98, a novel gene homologous to bcl-2, that is stimulated by insulin-like growth factor 1 and prevents dexamethasone-induced apoptosis. 1474 7

Neonatal mouse skin is useful for studying changes in gene expression during development of hair follicles, as the mitotic activity of skin cells changes shortly after birth. Using ribonucleic acid (RNA) differential display, a 261-nt message has been identified in the skin, specifically on d 3-5 but not on d 2 after birth. Confirmation of its expression by ribonuclease protection assay showed that stronger expression is seen on d 3-5 compared with d 1-2. Using RNA ligase-mediated rapid amplification of 5' complementary deoxyribonucleic acid ends, we have successfully isolated a 3046-bp gene, which has 93% sequence homology to a mouse teashirt1 gene. Amino acid analysis showed that it has 74% identity to the mouse teashirt1 protein and possesses zinc-finger motifs 1, 2, and 3. In situ hybridization data revealed that it is mainly expressed in the follicle bulb, including dermal papilla and matrix cells. As the proliferation of bulb cells is important to follicle development during this period, the finding of its strong expression on d 3-5 suggests that the identified gene is a potential candidate for follicle growth.
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PMID:A novel gene homologous to teashirt is differentially expressed in neonatal mouse skin during development of hair follicles. 1545 59

The giant freshwater prawn Macrobrachium rosenbergii is commercially cultured throughout the world including Taiwan. From 1992 to 1995, Taiwanese production decreased by approximately 50% due to disease. The yeast Metschnikowia bicuspidata is considered to be one of the major causes of white muscle disease, but the molecular mechanism of its pathogenesis is not known. Using RNA differential display (DD) with muscle and hepatopancreatic tissue, we identified a 324 nucleotide (nt) message specifically expressed by M. rosenbergii infected with M. bicuspidata but not in the controls. A ribonuclease protection assay (RPA) confirmed expression in both tissues. RPA data also revealed an additional 230 bp mRNA message that was not identified by DD. Using RNA ligase-mediated rapid amplification of 5' cDNA ends (5'-RACE), we successfully isolated a 1357 bp full-length gene (c57) that showed 92 and 87% sequence identity to the actin gene of the Kuruma shrimp Marsupenaeus japonicus (also called Penaeus japonicus) (GenBank accession number AB055975) and the beta-actin gene of the white shrimp Litopenaeus vannamei (also called Penaeus vannamei) (GenBank accession number AF300705), respectively. The deduced amino acid sequence of c57 showed 83 % sequence similarity to M. japonicus and L. vannamei actin proteins. Based on this high homology, we suggest that upregulation of actin expression in the muscle and hepatopancreas is part of the shrimp response to M. bicuspidata infection. Increased expression may be related to repair of tissues damaged by yeast infection.
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PMID:Upregulation of actin-like gene expression in giant freshwater prawns Macrobrachium rosenbergii infected with Metschnikowia bicuspidata. 1623 45


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