title: Human AlkB homologue 1 (ABH1) exhibits DNA lyase activity at abasic sites.
abstract: Bacterial AlkB and three human AlkB homologues (ABH1, ABH2, and ABH3) are Fe(2+)/2-oxoglutarate-dependent oxygenases that directly repair alkylation-damaged DNA. Here, we show that ABH1 unexpectedly has a second activity, cleaving DNA at abasic (AP) sites such as those arising spontaneously from alkylation-dependent depurination reactions. The DNA cleavage activity of ABH1 does not require added Fe(2+) or 2-oxoglutarate, is not inhibited by EDTA, and is unaffected by mutation of the putative metal-binding residues, indicating that this activity arises from an active site distinct from that used for demethylation. AP-specific DNA cleavage was shown to occur by a lyase mechanism, rather than by hydrolysis, with the enzyme remaining associated with the DNA product. ABH1 can cleave at closely spaced AP-sites on opposite DNA strands yielding double-strand breaks in vitro and this reaction may relate to the physiological role of this unexpected AP lyase activity.
authors: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA.
authors: Tina A
authors: TA
authors: Müller
authors: Katheryn
authors: K
authors: Meek
authors: Robert P
authors: RP
authors: Hausinger
mesh_terms: D000818:Animals; D055162:Biocatalysis; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004247:DNA / Q000737:chemistry* / Q000378:metabolism*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D018411:Spodoptera; D013379:Substrate Specificity
chemical_list: D008565:Membrane Proteins; D004247:DNA; C476001:ABHD1 protein, human; D002265:Carboxylic Ester Hydrolases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase