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Adenine Deaminase

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Claudio Scazzocchio – 1st expert on this subject based on the ideXlab platform

  • the nada gene of aspergillus nidulans encoding Adenine Deaminase is subject to a unique regulatory pattern
    Fungal Genetics and Biology, 2008
    Co-Authors: Nathalie Oestreicher, Carin Ribard, Claudio Scazzocchio

    Abstract:

    The Adenine Deaminase of A. nidulans, encoded by nadA, can be considered both as a catabolic and a purine salvage enzyme. We show that its transcriptional regulation reflects this double metabolic role. As all other genes involved in purine utilisation it is induced by uric acid, and this induction is mediated by the UaY transcription factor. However, it is also independently and synergistically induced by adenosine by a UaY-independent mechanism. At variance with all other enzymes of purine catabolism it is not repressed but induced by ammonium. This is at least partly due to the ammonium responsive GATA factor, AreA, acting in the nadA promoter as a competitor rather than in synergy with UaY. The adB gene, encoding adenylo-succinate synthetase, which can be considered both a biosynthetic and a salvage pathway enzyme, shares with nadA both ammonium and adenosine induction.

  • sub families of α β barrel enzymes a new Adenine Deaminase family
    Journal of Molecular Biology, 2003
    Co-Authors: Carin Ribard, Michel Rochet, Bernard Labedan, Bertrand Daignanfornier, Pedro M Alzari, Claudio Scazzocchio, Nathalie Oestreicher

    Abstract:

    Abstract No gene coding for an Adenine Deaminase has been described in eukaryotes. However, physiological and genetical evidence indicates that Adenine Deaminases are present in the ascomycetes. We have cloned and characterised the genes coding for the Adenine Deaminases of Aspergillus nidulans, Saccharomyces cerevisiae and Schizosaccharomyces pombe. The A. nidulans gene was expressed in Escherichia coli and the purified enzyme shows Adenine but not adenosine Deaminase activity. The open reading frames coded by the three genes are very similar and obviously related to the bacterial and eukaryotic adenosine Deaminases rather than to the bacterial Adenine Deaminases. The latter are related to allantoinases, ureases and dihydroorotases. The fungal Adenine Deaminases and the homologous adenosine Deaminases differ in a number of residues, some of these being clearly involved in substrate specificity. Other prokaryotic enzymes in the database, while clearly related to the above, do not fit into either sub-class, and may even have a different specificity. These results imply that Adenine Deaminases have appeared twice in the course of evolution, from different ancestral enzymes constructed both around the α/β barrel scaffold.

  • Sub-families of α/β barrel enzymes: A new Adenine Deaminase family
    Journal of Molecular Biology, 2003
    Co-Authors: Carin Ribard, Michel Rochet, Bernard Labedan, Pedro M Alzari, Claudio Scazzocchio, Bertrand Daignan-fornier, Nathalie Oestreicher

    Abstract:

    Abstract No gene coding for an Adenine Deaminase has been described in eukaryotes. However, physiological and genetical evidence indicates that Adenine Deaminases are present in the ascomycetes. We have cloned and characterised the genes coding for the Adenine Deaminases of Aspergillus nidulans, Saccharomyces cerevisiae and Schizosaccharomyces pombe. The A. nidulans gene was expressed in Escherichia coli and the purified enzyme shows Adenine but not adenosine Deaminase activity. The open reading frames coded by the three genes are very similar and obviously related to the bacterial and eukaryotic adenosine Deaminases rather than to the bacterial Adenine Deaminases. The latter are related to allantoinases, ureases and dihydroorotases. The fungal Adenine Deaminases and the homologous adenosine Deaminases differ in a number of residues, some of these being clearly involved in substrate specificity. Other prokaryotic enzymes in the database, while clearly related to the above, do not fit into either sub-class, and may even have a different specificity. These results imply that Adenine Deaminases have appeared twice in the course of evolution, from different ancestral enzymes constructed both around the α/β barrel scaffold.

Bertrand Daignanfornier – 2nd expert on this subject based on the ideXlab platform

  • proteasome and scf dependent degradation of yeast Adenine Deaminase upon transition from proliferation to quiescence requires a new f box protein named saf1p
    Molecular Microbiology, 2006
    Co-Authors: Stephanie Escusa, Jurgi Camblong, Jeanmarc Galan, Benoit Pinson, Bertrand Daignanfornier

    Abstract:

    Summary
    In response to nutrient limitation, Saccharomyces cerevisiae cells enter into a non-proliferating state termed quiescence. This transition is associated with profound changes in gene expression patterns. The Adenine Deaminase encoding gene AAH1 is among the most precociously and tightly downregulated gene upon entry into quiescence. We show that AAH1 downregulation is not specifically due to glucose exhaustion but is a more general response to nutrient limitation. We also found that Aah1p level is tightly correlated to RAS activity indicating thus an important role for the protein kinase A pathway in this regulation process. We have isolated three deletion mutants, srb10, srb11 and saf1 (ybr280c) affecting AAH1 expression during post-diauxic growth and in early stationary phase. We show that the Srb10p cyclin-dependent kinase and its cyclin, Srb11p, regulate AAH1 expression at the transcriptional level. By contrast, Saf1p, a previously uncharacterized F-box protein, acts at a post-transcriptional level by promoting degradation of Aah1p. This post-transcriptional regulation is abolished by mutations affecting the proteasome or constant subunits of the SCF (Skp1–Cullin–F-box) complex. We propose that Saf1p targets Aah1p for proteasome-dependent degradation upon entry into quiescence. This work provides the first direct evidence for active degradation of proteins in quiescent yeast cells.

  • sub families of α β barrel enzymes a new Adenine Deaminase family
    Journal of Molecular Biology, 2003
    Co-Authors: Carin Ribard, Michel Rochet, Bernard Labedan, Bertrand Daignanfornier, Pedro M Alzari, Claudio Scazzocchio, Nathalie Oestreicher

    Abstract:

    Abstract No gene coding for an Adenine Deaminase has been described in eukaryotes. However, physiological and genetical evidence indicates that Adenine Deaminases are present in the ascomycetes. We have cloned and characterised the genes coding for the Adenine Deaminases of Aspergillus nidulans, Saccharomyces cerevisiae and Schizosaccharomyces pombe. The A. nidulans gene was expressed in Escherichia coli and the purified enzyme shows Adenine but not adenosine Deaminase activity. The open reading frames coded by the three genes are very similar and obviously related to the bacterial and eukaryotic adenosine Deaminases rather than to the bacterial Adenine Deaminases. The latter are related to allantoinases, ureases and dihydroorotases. The fungal Adenine Deaminases and the homologous adenosine Deaminases differ in a number of residues, some of these being clearly involved in substrate specificity. Other prokaryotic enzymes in the database, while clearly related to the above, do not fit into either sub-class, and may even have a different specificity. These results imply that Adenine Deaminases have appeared twice in the course of evolution, from different ancestral enzymes constructed both around the α/β barrel scaffold.

Joan M. Hevel – 3rd expert on this subject based on the ideXlab platform

  • Assays for S-adenosylmethionine (AdoMet/SAM)-dependent methyltransferases.
    Current protocols in toxicology, 2020
    Co-Authors: Whitney L. Wooderchak, Zhaohui Sunny Zhou, Joan M. Hevel

    Abstract:

    Modification of small molecules and proteins by methyltransferases impacts a wide range of biological processes. Here we report two methods for measuring methyltransferase activity. First we describe an enzyme-coupled continuous spectrophotometric assay used to quantitatively characterize S-adenosyl-L-methionine (AdoMet or SAM)-dependent methyltransferase activity. In this assay, S-adenosyl-L-homocysteine (AdoHcy or SAH), the transmethylation product of AdoMet-dependent methyltransferase, is hydrolyzed to S-ribohomocysteine and Adenine by recombinant AdoHcy nucleosidase. Subsequently, the Adenine generated from AdoHcy is further hydrolyzed to homoxanthine and ammonia by recombinant Adenine Deaminase. This deamination is associated with a decrease in absorbance at 265 nm that can be monitored continuously. Secondly, we describe a discontinuous assay that follows radiolabel incorporation into the methyl receptor. An advantage of both assays is the destruction of AdoHcy by AdoHcy nucleosidase, which alleviates AdoHcy product feedback inhibition of S-adenosylmethionine-dependent methyltransferases. Importantly both methods are inexpensive, robust, and amenable to high throughput.

  • Current Protocols in Toxicology – Assays for S-adenosylmethionine (AdoMet/SAM)-dependent methyltransferases.
    Current protocols in immunology, 2008
    Co-Authors: Whitney L. Wooderchak, Zhaohui Sunny Zhou, Joan M. Hevel

    Abstract:

    Modification of small molecules and proteins by methyltransferases impacts a wide range of biological processes. Here we report two methods for measuring methyltransferase activity. First we describe an enzyme-coupled continuous spectrophotometric assay used to quantitatively characterize S-adenosyl-l-methionine (AdoMet or SAM)–dependent methyltransferase activity. In this assay, S-adenosyl-l-homocysteine (AdoHcy or SAH), the transmethylation product of AdoMet-dependent methyltransferase, is hydrolyzed to S-ribohomocysteine and Adenine by recombinant AdoHcy nucleosidase. Subsequently, the Adenine generated from AdoHcy is further hydrolyzed to homoxanthine and ammonia by recombinant Adenine Deaminase. This deamination is associated with a decrease in absorbance at 265 nm that can be monitored continuously. Secondly, we describe a discontinuous assay that follows radiolabel incorporation into the methyl receptor. An advantage of both assays is the destruction of AdoHcy by AdoHcy nucleosidase, which alleviates AdoHcy product feedback inhibition of S-adenosylmethionine-dependent methyltransferases. Importantly both methods are inexpensive, robust, and amenable to high throughput. Curr. Protoc. Toxicol. 38:4.26.1-4.26.12. © 2008 by John Wiley & Sons, Inc.

    Keywords:

    methyltransferase;
    SAM;
    AdoMet;
    S-adenosyl methionine;
    assays;
    SAH;
    AdoHcy nucleosidase;
    Adenine Deaminase;
    S-ribosylhomocysteine;
    Adenine

  • An enzyme-coupled continuous spectrophotometric assay for S-adenosylmethionine-dependent methyltransferases.
    Analytical Biochemistry, 2006
    Co-Authors: Kathleen M. Dorgan, Whitney L. Wooderchak, Zhaohui Sunny Zhou, Donraphael P. Wynn, Erin L. Karschner, Joshua F. Alfaro, Joan M. Hevel

    Abstract:

    Abstract Modification of small molecules and proteins by methyltransferases affects a wide range of biological processes. Here, we report an enzyme-coupled continuous spectrophotometric assay to quantitatively characterize S -adenosyl- l -methionine (AdoMet/SAM)-dependent methyltransferase activity. In this assay, S -adenosyl- l -homocysteine (AdoHcy/SAH), the transmethylation product of AdoMet-dependent methyltransferases, is hydrolyzed to S -ribosylhomocysteine and Adenine by recombinant S -adenosylhomocysteine/5′-methylthioadenosine nucleosidase (SAHN/MTAN, EC 3.2.2.9). Subsequently, Adenine generated from AdoHcy is further hydrolyzed to hypoxanthine and ammonia by recombinant Adenine Deaminase (EC 3.5.4.2). This deamination is associated with a decrease in absorbance at 265 nm that can be monitored continuously. Coupling enzymes are recombinant and easily purified. The utility of this assay was shown using recombinant rat protein arginine N -methyltransferase 1 (PRMT1, EC 2.1.1.125), which catalyzes the mono- and dimethylation of guanidino nitrogens of arginine residues in select proteins. Using this assay, the kinetic parameters of PRMT1 with three synthetic peptides were determined. An advantage of this assay is the destruction of AdoHcy by AdoHcy nucleosidase, which alleviates AdoHcy product feedback inhibition of S -adenosylmethionine-dependent methyltransferases. Finally, this method may be used to assay other enzymes that produce AdoHcy, 5′-methylthioadenosine, or compounds that can be cleaved by AdoHcy nucleosidase.