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

摘要: Pre-mRNA encoding human NEIL1 undergoes editing by adenosine deaminase ADAR1 that converts a single to inosine, and this conversion results in an amino acid change of lysine 242 arginine. Previous investigations the catalytic efficiencies two forms enzyme revealed differential release thymine glycol (ThyGly) from synthetic oligodeoxynucleotides, with unedited form, K242 being ≈30-fold more efficient than edited K242R. In contrast, when these enzymes were reacted oligodeoxynucleotides containing guanidinohydantoin or spiroiminohydantoin, K242R form was ≈3-fold NEIL1. However, no prior studies have investigated on either high-molecular weight DNA multiple oxidatively-induced base damages, bulky alkylated formamidopyrimidine. To understand extent changes substrate recognition, γ-irradiated calf thymus treated released lesions analyzed gas chromatography-tandem mass spectrometry. Of all measured lesions, imidazole ring-opened 4,6-diamino-5-formamidopyrimidine (FapyAde) 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) preferentially both ≈1.3 1.2-fold excision FapyAde FapyGua, respectively. Consistent literature, large differences (≈7.5 12-fold) ThyGly genomic versus (≈3 5-fold) 5-hydroxycytosine. Excision kinetics site-specific aflatoxin B1-FapyGua adduct ≈1.4-fold higher rate Molecular modeling provides insight into specificities. The study particular, comparison specificities using biologically clinically important are critical for defining its role preservation integrity.