title: 3-Methyladenine DNA glycosylase I is an unexpected helix-hairpin-helix superfamily member.
abstract: The Escherichia coli enzyme 3-methyladenine DNA glycosylase I (TAG) hydrolyzes the glycosidic bond of 3-methyladenine (3-MeA) in DNA and is found in many bacteria and some higher eukaryotes. TAG shows little primary sequence identity with members of the well-known helix-hairpin-helix (HhH) superfamily of DNA repair glycosylases, which consists of AlkA, EndoIII, MutY and hOGG1. Unexpectedly, the three-dimensional solution structure reported here reveals TAG as member of this superfamily. The restricted specificity of TAG for 3-MeA bases probably arises from its unique aromatic rich 3-MeA binding pocket and the absence of a catalytic aspartate that is present in all other HhH family members.
authors.affiliation: Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, Maryland 21205-2185, USA.
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Drohat
authors.forename: Keehwan
authors.initials: K
authors.lastname: Kwon
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Krosky
authors.forename: James T
authors.initials: JT
authors.lastname: Stivers
mesh_terms: D000595:Amino Acid Sequence; D045647:DNA Glycosylases; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D013050:Spectrometry, Fluorescence
chemical_list: C021565:3-methyladenine-DNA glycosylase; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases