DNA N-glycosylases are base excision-repair proteins that locate and cleave damaged bases from DNA as the first step in restoring the genetic blueprint. The human enzyme 3-methyladenine DNA glycosylase removes a diverse group of damaged bases from DNA, including cytotoxic and mutagenic alkylation adducts of purines. We report the crystal structure of human 3-methyladenine DNA glycosylase comple...

We have determined the complete nucleotide sequence of the tag gene, encoding 3-methyladenine DNA glycosylase I from Escherichia coli. From the nucleotide sequence it is deduced that the tag enzyme consists of 187 amino-acids and has a calculated molecular weight of 21.1 kdaltons. The tag enzyme is unusually rich in cysteine (8 residues) with a cluster of three consecutive cysteines near the C-...

Recent work has uncovered a novel DNA repair enzyme: the AlkB protein of Escherichia coli, which oxidises the methyl groups of 1-methyladenine and 3-methylcytosine to hydroxymethyl moieties; the oxidised groups are subsequently released as formaldehyde, regenerating the unmodified bases.

The gas-phase acidities of adenine, 9-ethyladenine, and 3-methyladenine have been investigated for the first time, using computational and experimental methods to provide an understanding of the intrinsic reactivity of adenine. Adenine is found to have two acidic sites, with the N9 site being 19 kcal mol(-1) more acidic than the N10 site; the bracketed acidities are 333 +/- 2 and 352 +/- 4 kcal...

The Escherichia coli AlkB protein repairs 1-methyladenine (1-meA) and 3-methylcytosine (3-meC) lesions in DNA and RNA by oxidative demethylation, a reaction requiring ferrous iron and 2-oxoglutarate as cofactor and co-substrate, respectively. Here, we have studied the activity of AlkB proteins on 3-methylthymine (3-meT) and 1-methylguanine (1-meG), two minor lesions which are structurally analo...

Ten normally occurring methylated trace bases of cytoplasmic RNA extracted from P815 ascites cells were identified as thymine, 3-methylcytosine, 5-methylcytosine, jV2-methylguanine, JV2, A^-dimethylguanine, 1-methylguanine, 7-methylguanine, 1-methyladenine, 6-methyladenine, and jV*,yV6-dimethyladenine. When the carcinostatic drug, l-methyl-2-(p-isopropylcarbamoyl)benzylhydrazine hydrochloride (...