Recognition of DNA adducts by edited and unedited forms of DNA glycosylase NEIL1

Published

November 2, 2019

Author(s)

Irina G. Minko, Vladimir Vartanian, Naoto Tozaki, Erdem Coskun, Sanem Hosbas Coskun, Pawel Jaruga, J Yeo, M.P. Stone, M Egli, Miral M. Dizdar, Amanda K. McCullough, R S. Lloyd

Abstract

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 (Gh) or spiroiminohydantoin (Sp), 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 DNA containing oxidatively-induced base damages, or oligodeoxynucleotides containing a bulky alkylated formamidopyrimidine (Fapy). To understand the extent of changes in substrate recognition, -irradiated calf thymus DNA was treated with either edited or unedited NEIL1 and the released bases analyzed by 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 (5- OH-Cyt). The rate of excision of a site-specific aflatoxin B1-induced FapyGua adduct that was measured under single turnover conditions, was ≈1.4-fold higher in reaction catalyzed by the unedited NEIL1. The results of this study expand the list of lesions that are differentially recognized

Citation

Dna Repair

Volume

85

Pub Type

Journals

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DOI Link

Keywords

base excision repair, RNA editing, formamidopyrimidines, thymine glycol, aflatoxin, hepatocellular carcinoma

Citation

Minko, I. , Vartanian, V. , Tozaki, N. , Coskun, E. , Hosbas Coskun, S. , Jaruga, P. , Yeo, J. , Stone, M. , Egli, M. , Dizdar, M. , McCullough, A. and Lloyd, R. (2019), Recognition of DNA adducts by edited and unedited forms of DNA glycosylase NEIL1, Dna Repair, [online], https://doi.org/10.1016/j.dnarep.2019.102741 (Accessed November 27, 2024)