AlkB homologue 2-mediated repair of ethenoadenine lesions in mammalian DNA.
Endogenous formation of the mutagenic DNA adduct 1,N(6)-ethenoadenine (epsilon A) originates from lipid peroxidation. Elevated levels of epsilon A in cancer-prone tissues suggest a role for this adduct in the development of some cancers. The base excision repair pathway has been considered the principal repair system for epsilon A lesions until recently, when it was shown that the Escherichia coli AlkB dioxygenase could directly reverse the damage. We report here kinetic analysis of the recombinant human AlkB homologue 2 (hABH2), which is able to repair epsilon A lesions in DNA. Furthermore, cation exchange chromatography of nuclear extracts from wild-type and mABH2(-/-) mice indicates that mABH2 is the principal dioxygenase for epsilon A repair in vivo. This is further substantiated by experiments showing that hABH2, but not hABH3, is able to complement the E. coli alkB mutant with respect to its defective repair of etheno adducts. We conclude that ABH2 is active in the direct reversal of epsilon A lesions, and that ABH2, together with the alkyl-N-adenine-DNA glycosylase, which is the most effective enzyme for the repair of epsilon A, comprise the cellular defense against epsilon A lesions.
Centre for Molecular Biology and Neuroscience, Institute of Medical Microbiology, Rikshospitalet HF and University of Oslo, Blindern, Oslo, Norway.
Jeanette
J
Ringvoll
Marivi N
MN
Moen
Line M
LM
Nordstrand
Lisiane B
LB
Meira
Bo
B
Pang
Anders
A
Bekkelund
Peter C
PC
Dedon
Svein
S
Bjelland
Leona D
LD
Samson
Pål Ø
PØ
Falnes
Arne
A
Klungland
D000079:Acetaldehyde / Q000031:analogs & derivatives / Q000633:toxicity; D000225:Adenine / Q000378:metabolism*; D000367:Age Factors; D000818:Animals; D001483:Base Sequence; D018736:DNA Adducts; D017931:DNA Primers; D004260:DNA Repair / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000502:physiology*; D007700:Kinetics; D013058:Mass Spectrometry; D051379:Mice; D006899:Mixed Function Oxygenases / Q000502:physiology*
D018736:DNA Adducts; D017931:DNA Primers; D029968:Escherichia coli Proteins; C004656:chloroacetaldehyde; D006899:Mixed Function Oxygenases; C466427:AlkB protein, E coli; D000079:Acetaldehyde; D000225:Adenine