Recognition of DNA adducts by edited and unedited forms of DNA glycosylase NEIL1
Autor: | Amanda K. McCullough, Martin Egli, Vladimir Vartanian, R. Stephen Lloyd, Jongchan Yeo, Miral Dizdaroglu, Naoto N. Tozaki, Erdem Coskun, Sanem Hosbas Coskun, Michael P. Stone, Pawel Jaruga, Irina G. Minko, Sheila S. David |
---|---|
Rok vydání: | 2020 |
Předmět: |
Models
Molecular RNA editing Thymine glycol Adenosine Deaminase Protein Conformation Hepatocellular carcinoma Biochemistry DNA Glycosylases Substrate Specificity chemistry.chemical_compound DNA Adducts 0302 clinical medicine Models Catalytic Domain Aflatoxin Cancer chemistry.chemical_classification Gene Editing 0303 health sciences RNA-Binding Proteins Base excision repair 030220 oncology & carcinogenesis medicine.drug NEIL1 Biology Article Gas Chromatography-Mass Spectrometry 03 medical and health sciences medicine Genetics Humans Inosine Molecular Biology 030304 developmental biology Formamidopyrimidines Molecular Cell Biology Molecular Weight genomic DNA Enzyme chemistry Amino Acid Substitution DNA glycosylase Biochemistry and Cell Biology DNA Developmental Biology |
Zdroj: | DNA Repair (Amst) |
Popis: | Pre-mRNA encoding human NEIL1 undergoes editing by adenosine deaminase ADAR1 that converts a single adenosine to inosine, and this conversion results in an amino acid change of lysine 242 to arginine. Previous investigations of the catalytic efficiencies of the two forms of the enzyme revealed differential release of thymine glycol (ThyGly) from synthetic oligodeoxynucleotides, with the unedited form, NEIL1 K242 being ≈30-fold more efficient than the edited NEIL1 K242R. In contrast, when these enzymes were reacted with oligodeoxynucleotides containing guanidinohydantoin or spiroiminohydantoin, the edited K242R form was ≈3-fold more efficient than the unedited NEIL1. However, no prior studies have investigated the efficiencies of these two forms of NEIL1 on either high-molecular weight DNA containing multiple oxidatively-induced base damages, or oligodeoxynucleotides containing a bulky alkylated formamidopyrimidine. To understand the extent of changes in substrate recognition, γ-irradiated calf thymus DNA was treated with either edited or unedited NEIL1 and the released DNA base lesions analyzed by gas chromatography-tandem mass spectrometry. Of all the measured DNA lesions, imidazole ring-opened 4,6-diamino-5-formamidopyrimidine (FapyAde) and 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) were preferentially released by both NEIL1 enzymes with K242R being ≈1.3 and 1.2-fold more efficient than K242 on excision of FapyAde and FapyGua, respectively. Consistent with the prior literature, large differences (≈7.5 to 12-fold) were measured in the excision of ThyGly from genomic DNA by the unedited versus edited NEIL1. In contrast, the edited NEIL1 was more efficient (≈3 to 5-fold) on release of 5-hydroxy-cytosine. Excision kinetics on DNA containing a site-specific aflatoxin B(1)-FapyGua adduct revealed an ≈1.4-fold higher rate by the unedited NEIL1. Molecular modeling provides insight into these differential substrate specificities. The results of this study and in particular, the comparison of substrate specificities of unedited and edited NEIL1 using biologically and clinically important base lesions, are critical for defining its role in preservation of genomic integrity. |
Databáze: | OpenAIRE |
Externí odkaz: |