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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.

SUBMITTER: Muller TA

PROVIDER: S-EPMC2818486 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature

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Human AlkB homologue 1 (ABH1) exhibits DNA lyase activity at abasic sites.

Müller Tina A TA Meek Katheryn K Hausinger Robert P RP

DNA repair 20091202 1

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 met ...[more]

PMID: 19959401

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