Iron-catalysed oxidation intermediates captured in a DNA repair dioxygenase.
Nature
; 468(7321): 330-3, 2010 Nov 11.
Article
em En
| MEDLINE
| ID: mdl-21068844
ABSTRACT
Mononuclear iron-containing oxygenases conduct a diverse variety of oxidation functions in biology, including the oxidative demethylation of methylated nucleic acids and histones. Escherichia coli AlkB is the first such enzyme that was discovered to repair methylated nucleic acids, which are otherwise cytotoxic and/or mutagenic. AlkB human homologues are known to play pivotal roles in various processes. Here we present structural characterization of oxidation intermediates for these demethylases. Using a chemical cross-linking strategy, complexes of AlkB-double stranded DNA (dsDNA) containing 1,N(6)-etheno adenine (εA), N(3)-methyl thymine (3-meT) and N(3)-methyl cytosine (3-meC) are stabilized and crystallized, respectively. Exposing these crystals, grown under anaerobic conditions containing iron(II) and α-ketoglutarate (αKG), to dioxygen initiates oxidation in crystallo. Glycol (from εA) and hemiaminal (from 3-meT) intermediates are captured; a zwitterionic intermediate (from 3-meC) is also proposed, based on crystallographic observations and computational analysis. The observation of these unprecedented intermediates provides direct support for the oxidative demethylation mechanism for these demethylases. This study also depicts a general mechanistic view of how a methyl group is oxidatively removed from different biological substrates.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Escherichia coli
/
Dioxigenases
/
Reparo do DNA
/
Escherichia coli
/
Oxigenases de Função Mista
/
Ferro
Limite:
Humans
Idioma:
En
Revista:
Nature
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Estados Unidos