The Experts below are selected from a list of 36 Experts worldwide ranked by ideXlab platform

Hiroshi Ide - One of the best experts on this subject based on the ideXlab platform.

  • A novel Monofunctional DNA Glycosylase activity against thymine glycol in mouse cell nuclei.
    Journal of radiation research, 2008
    Co-Authors: Ryohei Yamamoto, Hiroshi Ide, Miyuki Akiyama, Kazuo Yamamoto, Satoshi Matsuyama, Kihei Kubo
    Abstract:

    Reactive oxygen species continuously oxidize DNA bases and threaten the genetic integrity. Thymine glycol (TG), one of the representative oxidized products, is repaired mainly by base excision repair (BER). In Escherichia coli, endonuclease III (Nth) and endonuclease VIII (Nei) are known to actively remove TG from DNA, and the homologs are well conserved in various organisms. These are bifunctional Glycosylases, also associated with apurinic/apyrimidinic (AP) lyase activity. In the present study, a Monofunctional TG-DNA Glycosylase activity is shown to be one of the predominant nuclear activities present in some mouse tissues. By combining hypertonic extraction and column chromatography, we successfully separated the novel activity from majority of the bifunctional activities. Since it has been reported that mNTH1 may not be a dominant nuclear activity, the Monofunctional Glycosylase activity, together with mNEIL1, may be the major TG-DNA Glycosylases in the mouse nucleus. The optimal reaction conditions for the Monofunctional activity were found to be pH 7-8 and 100-150 mM KCl, and the activity was resistant to 20 mM EDTA. High Monofunctional activity was detected in the spleen and stomach, while the level was significantly lower in the liver, suggesting that the contribution of the Monofunctional activity is variable among organs.

  • Mammalian 5-formyluracil-DNA Glycosylase. 1. Identification and characterization of a novel activity that releases 5-formyluracil from DNA.
    Biochemistry, 2003
    Co-Authors: Mayumi Matsubara, Aya Masaoka, Tamon Tanaka, Takayuki Miyano, Nagisa Kato, Hiroaki Terato, Yoshihiko Ohyama, Shigenori Iwai, Hiroshi Ide
    Abstract:

    5-Formyluracil (fU) is a major oxidative thymine lesion produced by reactive oxygen species and exhibits genotoxic and cytotoxic effects via several mechanisms. In the present study, we have searched for and characterized mammalian fU-DNA Glycosylase (FDG) using two approaches. In the first approach, the FDG activity was examined using purified base excision repair enzymes. Human and mouse endonuclease III homologues (NTH1) showed a very weak FDG activity, but the parameter analysis and NaBH(4) trapping assays of the Schiff base intermediate revealed that NTH1 was kinetically incompetent for repair of fU. In the second approach, FDG was partially purified (160-fold) from rat liver. The enzyme was a Monofunctional DNA Glycosylase and recognized fU in single-stranded (ss) and double-stranded (ds) DNA. The most purified FDG fraction also exhibited Monofunctional DNA Glycosylase activities for uracil (U), 5-hydroxyuracil (hoU), and 5-hydroxymethyluracil (hmU) in ssDNA and dsDNA. The fU-excising activity of FDG was competitively inhibited by dsDNA containing U.G, hoU.G, and hmU.A but not by intact dsDNA containing T.A. Furthermore, the activities of FDG for fU, hmU, hoU, and U in ssDNA and dsDNA were neutralized by the antibody raised against SMUG1 uracil-DNA Glycosylase, showing that FDG is a rat homologue of SMUG1.

  • Identification and characterization of mammalian 5-formyluracil-DNA Glycosylase.
    Nucleic acids research. Supplement (2001), 2003
    Co-Authors: Mayumi Matsubara, Aya Masaoka, Tamon Tanaka, Hiroaki Terato, Yoshihiko Ohyama, Hiroshi Ide
    Abstract:

    5-Formyluracil is a major oxidative thymine lesion with mutagenic and cytotoxic properties. In this study, we have partially purified and characterized a mammalian 5-formyluracil-DNA Glycosylase (FDG) from rat liver. FDG was a Monofunctional DNA Glycosylase and removed 5-formyluracil, uracil, 5-hydroxyuracil, 5-hydroxylmethyluracil in single-stranded and double-stranded DNA. Several lines of evidence indicate that FDG is a rat SMUG1 homologue. Human SMUG1 also exhibited similar enzymatic properties.

Magnar Bjørås - One of the best experts on this subject based on the ideXlab platform.

  • Human NEIL3 is mainly a Monofunctional DNA Glycosylase removing spiroimindiohydantoin and guanidinohydantoin.
    DNA repair, 2013
    Co-Authors: Silje Zandstra Krokeide, Jon K. Laerdahl, Medya Salah, Luisa Luna, F. Henning Cederkvist, Aaron M. Fleming, Cynthia J. Burrows, Bjørn Dalhus, Magnar Bjørås
    Abstract:

    Base excision repair is the major pathway for removal of oxidative DNA base damage. This pathway is initiated by DNA Glycosylases, which recognize and excise damaged bases from DNA. In this work, we have purified the Glycosylase domain (GD) of human DNA Glycosylase NEIL3. The substrate specificity has been characterized and we have elucidated the catalytic mechanisms. GD NEIL3 excised the hydantoin lesions spiroiminodihydantoin (Sp) and guanidinohydantoin (Gh) in single-stranded (ss) and double-stranded (ds) DNA efficiently. NEIL3 also removed 5-hydroxy-2'-deoxycytidine (5OHC) and 5-hydroxy-2'-deoxyuridine (5OHU) in ssDNA, but less efficiently than hydantoins. Unlike NEIL1 and NEIL2, which possess a β,δ-elimination activity, NEIL3 mainly incised damaged DNA by β-elimination. Further, the base excision and strand incision activities of NEIL3 exhibited a non-concerted action, indicating that NEIL3 mainly operate as a Monofunctional DNA Glycosylase. The site-specific NEIL3 mutant V2P, however, showed a concerted action, suggesting that the N-terminal amino group in Val2 is critical for the Monofunctional modus. Finally, we demonstrated that residue Lys81 is essential for catalysis.

  • Base excision repair activities required for yeast to attain a full chronological life span
    Aging cell, 2003
    Co-Authors: Morag Maclean, Magnar Bjørås, Randi M. Aamodt, Nicholas Harris, Ingrun Alseth, Erling Seeberg, Peter W. Piper
    Abstract:

    The chronological life span of yeast, the survival of stationary (G0) cells over time, provides a model for investigating certain of the factors that may influence the aging of non-dividing cells and tissues in higher organisms. This study measured the effects of defined defects in the base excision repair (BER) system for DNA repair on this life span. Stationary yeast survives longer when it is pre-grown on respiratory, as compared to fermentative (glucose), media. It is also less susceptible to viability loss as the result of defects in DNA Glycosylase/AP lyases (Ogg1p, Ntg1p, Ntg2p), apurinic/apyrimidinic (AP) endonucleases (Apn1p, Apn2p) and Monofunctional DNA Glycosylase (Mag1p). Whereas single BER Glycosylase/AP lyase defects exerted little influence over such optimized G0 survival, this survival was severely shortened with the loss of two or more such enzymes. Equally, the apn1delta and apn2delta single gene deletes survived as well as the wild type, whereas a apn1delta apn2delta double mutant totally lacking in any AP endonuclease activity survived poorly. Both this shortened G0 survival and the enhanced mutagenicity of apn1delta apn2delta cells were however rescued by the over-expression of either Apn1p or Apn2p. The results highlight the vital importance of BER in the prevention of mutation accumulation and the attainment of the full yeast chronological life span. They also reveal an appreciable overlap in the G0 maintenance functions of the different BER DNA Glycosylases and AP endonucleases.

Mayumi Matsubara - One of the best experts on this subject based on the ideXlab platform.

  • Mammalian 5-formyluracil-DNA Glycosylase. 1. Identification and characterization of a novel activity that releases 5-formyluracil from DNA.
    Biochemistry, 2003
    Co-Authors: Mayumi Matsubara, Aya Masaoka, Tamon Tanaka, Takayuki Miyano, Nagisa Kato, Hiroaki Terato, Yoshihiko Ohyama, Shigenori Iwai, Hiroshi Ide
    Abstract:

    5-Formyluracil (fU) is a major oxidative thymine lesion produced by reactive oxygen species and exhibits genotoxic and cytotoxic effects via several mechanisms. In the present study, we have searched for and characterized mammalian fU-DNA Glycosylase (FDG) using two approaches. In the first approach, the FDG activity was examined using purified base excision repair enzymes. Human and mouse endonuclease III homologues (NTH1) showed a very weak FDG activity, but the parameter analysis and NaBH(4) trapping assays of the Schiff base intermediate revealed that NTH1 was kinetically incompetent for repair of fU. In the second approach, FDG was partially purified (160-fold) from rat liver. The enzyme was a Monofunctional DNA Glycosylase and recognized fU in single-stranded (ss) and double-stranded (ds) DNA. The most purified FDG fraction also exhibited Monofunctional DNA Glycosylase activities for uracil (U), 5-hydroxyuracil (hoU), and 5-hydroxymethyluracil (hmU) in ssDNA and dsDNA. The fU-excising activity of FDG was competitively inhibited by dsDNA containing U.G, hoU.G, and hmU.A but not by intact dsDNA containing T.A. Furthermore, the activities of FDG for fU, hmU, hoU, and U in ssDNA and dsDNA were neutralized by the antibody raised against SMUG1 uracil-DNA Glycosylase, showing that FDG is a rat homologue of SMUG1.

  • Identification and characterization of mammalian 5-formyluracil-DNA Glycosylase.
    Nucleic acids research. Supplement (2001), 2003
    Co-Authors: Mayumi Matsubara, Aya Masaoka, Tamon Tanaka, Hiroaki Terato, Yoshihiko Ohyama, Hiroshi Ide
    Abstract:

    5-Formyluracil is a major oxidative thymine lesion with mutagenic and cytotoxic properties. In this study, we have partially purified and characterized a mammalian 5-formyluracil-DNA Glycosylase (FDG) from rat liver. FDG was a Monofunctional DNA Glycosylase and removed 5-formyluracil, uracil, 5-hydroxyuracil, 5-hydroxylmethyluracil in single-stranded and double-stranded DNA. Several lines of evidence indicate that FDG is a rat SMUG1 homologue. Human SMUG1 also exhibited similar enzymatic properties.

Hiroaki Terato - One of the best experts on this subject based on the ideXlab platform.

  • Mammalian 5-formyluracil-DNA Glycosylase. 1. Identification and characterization of a novel activity that releases 5-formyluracil from DNA.
    Biochemistry, 2003
    Co-Authors: Mayumi Matsubara, Aya Masaoka, Tamon Tanaka, Takayuki Miyano, Nagisa Kato, Hiroaki Terato, Yoshihiko Ohyama, Shigenori Iwai, Hiroshi Ide
    Abstract:

    5-Formyluracil (fU) is a major oxidative thymine lesion produced by reactive oxygen species and exhibits genotoxic and cytotoxic effects via several mechanisms. In the present study, we have searched for and characterized mammalian fU-DNA Glycosylase (FDG) using two approaches. In the first approach, the FDG activity was examined using purified base excision repair enzymes. Human and mouse endonuclease III homologues (NTH1) showed a very weak FDG activity, but the parameter analysis and NaBH(4) trapping assays of the Schiff base intermediate revealed that NTH1 was kinetically incompetent for repair of fU. In the second approach, FDG was partially purified (160-fold) from rat liver. The enzyme was a Monofunctional DNA Glycosylase and recognized fU in single-stranded (ss) and double-stranded (ds) DNA. The most purified FDG fraction also exhibited Monofunctional DNA Glycosylase activities for uracil (U), 5-hydroxyuracil (hoU), and 5-hydroxymethyluracil (hmU) in ssDNA and dsDNA. The fU-excising activity of FDG was competitively inhibited by dsDNA containing U.G, hoU.G, and hmU.A but not by intact dsDNA containing T.A. Furthermore, the activities of FDG for fU, hmU, hoU, and U in ssDNA and dsDNA were neutralized by the antibody raised against SMUG1 uracil-DNA Glycosylase, showing that FDG is a rat homologue of SMUG1.

  • Identification and characterization of mammalian 5-formyluracil-DNA Glycosylase.
    Nucleic acids research. Supplement (2001), 2003
    Co-Authors: Mayumi Matsubara, Aya Masaoka, Tamon Tanaka, Hiroaki Terato, Yoshihiko Ohyama, Hiroshi Ide
    Abstract:

    5-Formyluracil is a major oxidative thymine lesion with mutagenic and cytotoxic properties. In this study, we have partially purified and characterized a mammalian 5-formyluracil-DNA Glycosylase (FDG) from rat liver. FDG was a Monofunctional DNA Glycosylase and removed 5-formyluracil, uracil, 5-hydroxyuracil, 5-hydroxylmethyluracil in single-stranded and double-stranded DNA. Several lines of evidence indicate that FDG is a rat SMUG1 homologue. Human SMUG1 also exhibited similar enzymatic properties.

Yoshihiko Ohyama - One of the best experts on this subject based on the ideXlab platform.

  • Mammalian 5-formyluracil-DNA Glycosylase. 1. Identification and characterization of a novel activity that releases 5-formyluracil from DNA.
    Biochemistry, 2003
    Co-Authors: Mayumi Matsubara, Aya Masaoka, Tamon Tanaka, Takayuki Miyano, Nagisa Kato, Hiroaki Terato, Yoshihiko Ohyama, Shigenori Iwai, Hiroshi Ide
    Abstract:

    5-Formyluracil (fU) is a major oxidative thymine lesion produced by reactive oxygen species and exhibits genotoxic and cytotoxic effects via several mechanisms. In the present study, we have searched for and characterized mammalian fU-DNA Glycosylase (FDG) using two approaches. In the first approach, the FDG activity was examined using purified base excision repair enzymes. Human and mouse endonuclease III homologues (NTH1) showed a very weak FDG activity, but the parameter analysis and NaBH(4) trapping assays of the Schiff base intermediate revealed that NTH1 was kinetically incompetent for repair of fU. In the second approach, FDG was partially purified (160-fold) from rat liver. The enzyme was a Monofunctional DNA Glycosylase and recognized fU in single-stranded (ss) and double-stranded (ds) DNA. The most purified FDG fraction also exhibited Monofunctional DNA Glycosylase activities for uracil (U), 5-hydroxyuracil (hoU), and 5-hydroxymethyluracil (hmU) in ssDNA and dsDNA. The fU-excising activity of FDG was competitively inhibited by dsDNA containing U.G, hoU.G, and hmU.A but not by intact dsDNA containing T.A. Furthermore, the activities of FDG for fU, hmU, hoU, and U in ssDNA and dsDNA were neutralized by the antibody raised against SMUG1 uracil-DNA Glycosylase, showing that FDG is a rat homologue of SMUG1.

  • Identification and characterization of mammalian 5-formyluracil-DNA Glycosylase.
    Nucleic acids research. Supplement (2001), 2003
    Co-Authors: Mayumi Matsubara, Aya Masaoka, Tamon Tanaka, Hiroaki Terato, Yoshihiko Ohyama, Hiroshi Ide
    Abstract:

    5-Formyluracil is a major oxidative thymine lesion with mutagenic and cytotoxic properties. In this study, we have partially purified and characterized a mammalian 5-formyluracil-DNA Glycosylase (FDG) from rat liver. FDG was a Monofunctional DNA Glycosylase and removed 5-formyluracil, uracil, 5-hydroxyuracil, 5-hydroxylmethyluracil in single-stranded and double-stranded DNA. Several lines of evidence indicate that FDG is a rat SMUG1 homologue. Human SMUG1 also exhibited similar enzymatic properties.