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:3.5.1.4 (deaminase)
5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. This manuscript describes two different strategies to progress from the clinical assessment of patients to the identification of disease-causing mutations. In the first disease, recognition of a metabolic abnormality allowed direct molecular analysis of the causal gene. In contrast, localization of the second disease gene by linkage analysis was critical to implicate a gene with a previously unsuspected disease role. 2. Two sisters with chronic respiratory disease and recurrent infections were identified as the first cases of adult onset immunodeficiency due to adenosine deaminase deficiency. Autosomal recessive inheritance of two mutations in the adenosine deaminase gene was demonstrated. Enzyme replacement therapy improved the patients' immunological and clinical status. 3. Individuals with pulmonary arteriovenous malformations were used to identify families with hereditary haemorrhagic telangiectasia (HHT, Rendu-Osler-Weber Syndrome). Linkage studies mapped the HHT disease gene in some families to chromosome 9, and demonstrated genetic heterogeneity. The chromosome 9 disease interval was refined, and several candidate genes were assessed. Following the first description of disease-segregating mutations, a complete analysis of the endoglin gene (which encodes an endothelial cell transforming growth factor-beta receptor) identified seven novel mutations. Two mutations did not produce mutant mRNA, and disease severity was comparable between families, indicating that HHT results from stoichiometric insufficiency of endoglin. 4. Each study has implications extending beyond the relatively rare disease analysed. The adenosine-deaminase-deficient patients highlight a treatable cause of HIV-negative CD4+ lymphopenia in adults, perhaps accounting for further cases of 'non-HIV AIDS'. The HHT studies have illuminated a novel area of vascular pathophysiology, with potential relevance to further disease states.
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PMID:Glaxo/MRS Young Investigator Medal. Molecular studies on adenosine deaminase deficiency and hereditary haemorrhagic telangiectasia. 961 53

The virus-associated VAI RNA of adenovirus is a small highly structured RNA that is required for the efficient translation of cellular and viral mRNAs at late times after infection. VAI RNA antagonizes the activation of the interferon-inducible RNA-dependent protein kinase, PKR, an important regulator of translation. The RNA-specific adenosine deaminase, ADAR, is an interferon-inducible RNA-editing enzyme that catalyzes the site-selective C-6 deamination of adenosine to inosine. ADAR possesses three copies of the highly conserved RNA-binding motif (dsRBM) that are similar to the two copies found in PKR, the enzyme in which the prototype dsRBM motif was discovered. We have examined the effect of VAI RNA on ADAR function. VAI RNA impairs the activity of ADAR deaminase. This inhibition can be observed in extracts prepared from interferon-treated human cells and from monkey COS cells in which wild-type recombinant ADAR was expressed. Analysis of wild-type and mutant forms of VA RNA suggests that the central domain is important in the antagonism of ADAR activity. These results suggest that VAI RNA may modulate viral and cellular gene expression by modulating RNA editing as well as mRNA translation.
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PMID:Adenovirus VAI RNA antagonizes the RNA-editing activity of the ADAR adenosine deaminase. 963 58

Purine nucleotides are formed de novo by a widespread biochemical route that may be of monophyletic origin, or are synthesized from preformed purine bases and nucleosides through different salvage pathways. Three monophyletic sets of purine salvage enzymes, each of which catalyzes mechanistically similar reactions, can be identified: (a) adenine-, xanthine-, hypoxanthine- and guanine-phosphoribosyltransferases, which are all homologous among themselves, as well as to nucleoside phosphorylases; (b) adenine deaminase, adenosine deaminase, and adenosine monophophate deaminase; and (c) guanine reductase and inosine monophosphate dehydrogenase. These homologies support the idea that substrate specificity is the outcome of gene duplication, and that the purine nucleotide salvage pathways were assembled by a patchwork process that probably took place before the divergence of the three cell domains (Bacteria, Archaea, and Eucarya). Based on the ability of adenine PRTase to catalyze the condensation of PRPP with 4-aminoimidazole-5-carboxamide (AICA), a simpler scheme of purine nucleotide biosynthesis is presented. This hypothetical route requires the prior evolution of PRPP biosynthesis. Since it has been argued that PRPP, nucleosides, and nucleotides are susceptible to hydrolysis, they are very unlikely prebiotic compounds. If this is the case, it implies that many purine salvage pathways appeared only after the evolution of phosphorylated sugar biosynthetic pathways made ribosides available.
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PMID:The role of gene duplication in the evolution of purine nucleotide salvage pathways. 974 28

The interferon-inducible RNA-specific adenosine deaminase (ADAR1) is an RNA editing enzyme implicated in the site-selective deamination of adenosine to inosine in cellular pre-mRNAs. The pre-mRNA for the rat serotonin-2C receptor (5-HT2CR) possesses four editing sites (A, B, C, and D), which undergo A-to-I nucleotide conversions that alter the signaling function of the encoded G-protein-coupled receptor. Measurements of 5-HT2CR pre-mRNA editing in vitro revealed site-specific deamination catalyzed by ADAR1. Three splice site variants, ADAR1-a, -b, and -c, all efficiently edited the A site of 5-HT2CR pre-mRNA, but the D site did not serve as an efficient substrate for any of the ADAR1 variants. Mutational analysis of the three double-stranded (ds) RNA binding motifs present in ADAR1 revealed a different relative importance of the individual dsRNA binding motifs for deamination of the A site of 5-HT2CR and synthetic dsRNA substrates. Quantitative reverse transcription-polymerase chain reaction analyses demonstrated that the 5-HT2CR pre-mRNA was most highly expressed in the choroid plexus of rat brain. However, ADAR1 and the related deaminase ADAR2 showed significant expression in all regions of the brain examined, including cortex, hippocampus, olfactory bulb, and striatum, where the 5-HT2CR pre-mRNA was extensively edited.
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PMID:Serotonin-2C receptor pre-mRNA editing in rat brain and in vitro by splice site variants of the interferon-inducible double-stranded RNA-specific adenosine deaminase ADAR1. 1037 39

Slices of rat hippocampus can be induces to generate spontaneous interictal-like bursts of action potentials when perfused with a with a medium containing no added magnesium and 4-aminopyridine (4AP). The frequency of these bursts is depressed by adenosine 5'triphosphate (ATP) and this effect can be prevented by cyclopentyltheophylline but not by adenosine deaminase. AMP (50 microM) had a similar action to reduce discharge rate. At 10 microM, adenosine, diadenosine tetraphosphate and diadenosine pentaphosphate all decreased the burst frequency. Adenosine deaminase (0.2 U ml-1) totally annulled the inhibition of epileptiform activity produced by 10 microM adenosine but reduced only the later components of the inhibition by 10 microM diadenosine tetraphosphate and diadenosine pentaphosphate. Cyclopentyltheophylline prevented the depression of burst discharges by diadenosine tetraphosphate. 5'-adenylic acid deaminase (AMPPase) did not significantly alter the discharge rate over the 10 min superfusion period used for drum application but did prevent the depressant effect of AMP and ATP. AMP deaminase did not prevent the inhibitory effects of diadenosine tetraphosphate. The results suggests that in the CA3 region of the hippocampus, diadenosine tertraphosphate and diadenosine pentaphosphate act partly by stimulating xanthine sensitive receptors directly and partly via metabolism to adenosine, and that AMP may be responsible for the inhibitory effects of ATP on epileptiform activity.
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PMID:Nucleotide and dinucleotide effects on rates of paroxysmal depolarising bursts in rat hippocampus. 1055 Oct 2

Pre-mRNA editing involving the conversion of adenosine to inosine is mediated by adenosine deaminases that act on RNA (ADAR1 and ADAR2). ADARs contain multiple double-stranded RNA(dsRNA)-binding domains in addition to an adenosine deaminase domain. An adenosine deaminase acting on tRNAs, scTad1p (also known as scADAT1), cloned from Saccharomyces cerevisiae has a deaminase domain related to the ADARs but lacks dsRNA-binding domains. We have identified a gene homologous to scADAT1 in the region of Drosophila melanogaster Adh chromosome II. Recombinant Drosophila ADAT1 (dADAT1) has been expressed in the yeast Pichia pastoris and purified. The enzyme has no activity on dsRNA substrates but is a tRNA deaminase with specificity for adenosine 37 of insect alanine tRNA. dADAT1 shows greater similarity to vertebrate ADARs than to yeast Tad1p, supporting the hypothesis of a common evolutionary origin for ADARs and ADATs. dAdat1 transcripts are maternally supplied in the egg. Zygotic expression is widespread initially and later concentrates in the central nervous system.
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PMID:The properties of a tRNA-specific adenosine deaminase from Drosophila melanogaster support an evolutionary link between pre-mRNA editing and tRNA modification. 1062 39

The 3'-C-branched-adenosine and 2'-deoxyadenosine analogues 1-7 were tested as substrate of adenosine deaminase. The 9-(3'-C-ethynyl-beta-D-ribo-pentofuranosyl)adenine 1 and its 2'-deoxy analogue 7 were deaminated by the enzyme while the vinyl and ethyl derivatives 2 and 3 were not. The 9-(3'-C-branched-beta-D-xylo-pentofuranosyl)adenines 4-6 were deaminated by the deaminase.
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PMID:3'-Beta-ethynyl and 2'-deoxy-3'-beta-ethynyl adenosines: first 3'-beta-branched-adenosines substrates of adenosine deaminase. 1067 97

A series of N3-substituted coformycin aglycon analogues are described that inhibit adenosine 5'-monophosphate deaminase (AMPDA) or adenosine deaminase (ADA). The key steps involved in the preparation of these compounds are (1) treating the sodium salt of 6, 7-dihydroimidazo[4,5-d][1,3]diazepin-8(3H)-one (4) with an alkyl bromide or an alkyl mesylate to generate the N3-alkylated compound 5 and (2) reducing 5 with NaBH(4). Selective inhibition of AMPDA was realized when the N3-substituent contained a carboxylic acid moiety. For example, compound 7b which has a hexanoic acid side chain inhibited AMPDA with a K(i) = 4.2 microM and ADA with a K(i) = 280 microM. Substitution of large lipophilic groups alpha to the carboxylate provided a moderate potency increase with maintained selectivity as exemplified by the alpha-benzyl analogue 7j (AMPDA K(i) = 0.41 microM and ADA K(i) > 1000 microM). These compounds, as well as others described in this series of papers, are the first compounds suitable for testing whether selective inhibition of AMPDA can protect tissue from ischemic damage by increasing local adenosine concentrations at the site of injury and/or by minimizing adenylate loss.
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PMID:AMP deaminase inhibitors. 2. Initial discovery of a non-nucleotide transition-state inhibitor series. 1078 Sep 6

Adenosine A(1) receptors (A(1)Rs) have been characterized in primary cultures of neurons from cerebral cortex. The specific adenosine A(1) antagonist 8-cyclopentyl-1,3-[(3)H]dipropylxanthine bound to both membranes and intact cells. When saturation experiments were performed in membranes, a K(D) value of 0.76 nM and a B(max) of 57 fmol/mg of protein were obtained. Competition assays revealed a pharmacological profile characteristic of A(1)Rs. The presence of this receptor was further confirmed by RT-PCR analysis. The expression of the receptor showed no significant changes during the period of culture studied, up to 12 days in vitro. A(1)R agonist inhibited forskolin-stimulated adenylyl cyclase, showing the functional coupling of these receptors with the effector. alphaG(i1, 2) protein level, detected by immunoblot, presented an increase during the period of culture. This increase correlated with an increase in the mRNA level of alphaG(i1) but not alphaG(i2). By immunochemical assays, it is shown that these receptors are expressed in both the neuronal cell body and the proximal dendrites. Colocalization of A(1)Rs with microtubule-associated protein 2 and cell surface adenosine deaminase was shown by confocal microscopy. The high degree of colocalization observed between A(1)Rs and ectoadenosine deaminase in neurons could suggest an important role of the enzyme in adenosine-mediated neuromodulation.
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PMID:Adenosine A(1) receptor in cultured neurons from rat cerebral cortex: colocalization with adenosine deaminase. 1089 40

We have previously identified a Trypanosoma cruzi cDNA encoding a protein named Tc52 sharing structural and functional properties with the thioredoxin and glutaredoxin protein family involved in thiol-disulphide redox reactions. Furthermore, we reported that Tc52 also plays a role in T. cruzi-associated immunosuppression observed during Chagas' disease. Moreover, Tc52 gene targeting deletion strategy allowed us to demonstrate that monoallelic disruption of Tc52 resulted in the alteration of the metacyclogenesis process and the production of less virulent parasites. Sequence analysis of a 7358 bp genomic fragment containing the Tc52 encoding gene revealed two additional open reading frames (ORF-A and C). The ORFs are likely to have protein coding function by a number of criteria, including reverse transcriptase polymerase chain reaction (RT-PCR), Western blot and immunofluorescence analyses. The deduced amino-acid (aa) sequence of the ORF-A localized upstream of the Tc52 gene revealed that it contains within its N-terminus (aa 1 to 170) four RGG boxes known to act as RNA binding motifs in some proteins that interact with RNA, interspersed with a high density of glycine with regular spacing of tryptophan (WX(9-10)) in which X is often a glycine. Moreover, the C-terminal part of the ORF-C (aa 253-289) contains a motif that is strikingly similar (7-35% identity, 14-46% similarity over 28aa) to a short sequence (RNP1) comprising the consensus sequence RNA binding domain (CS-RBD) found in a number of proteins that interact with RNA. The aa sequence from the ORF-C localized downstream of the Tc52 gene showed significant homology to human adenosine deaminase acting on RNA (hADAT1) that specifically deaminates adenosine 37 to inosine in eukaryotic tRNA(Ala) and to its homologue yeast protein (Tad1p) (22-25% identity and an additional 38-40% similarity over 177aa). Moreover, highly similar motifs of the deaminase domain are present in the T. cruzi ORF-C. Furthermore, the 5' flanking regions of the genes contained repeat TATA and CAAT nucleotide sequences which resemble the motifs found upstream of the transcription initiation sites in eukaryotic promoters. Therefore, the characterization of novel T. cruzi genes encoding proteins which show similarity to components of RNA processing reactions provides new tools to investigate the gene expression regulation in these parasitic organisms. Moreover, our recent findings on the Tc52 encoding gene underline the interest of genetic manipulation of T. cruzi, not only making it possible to use more closely an in vitro approach to find out how genes function, but also to obtain 'attenuated' strains that could be used in the development of vaccinal strategies.
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PMID:Identification and molecular characterization of two novel Trypanosoma cruzi genes encoding polypeptides sharing sequence motifs found in proteins involved in RNA editing reactions. 1094 May 65


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