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Human ABH3 structure and key residues for oxidative demethylation to reverse DNA/RNA damage
Author(s) -
Sundheim Ottar,
Vågbø Cathrine B,
Bjørås Magnar,
Sousa Mirta ML,
Talstad Vivi,
Aas Per A,
Drabløs Finn,
Krokan Hans E,
Tainer John A,
Slupphaug Geir
Publication year - 2006
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601219
Subject(s) - alkb , biology , dna , biochemistry , rna , dna damage , escherichia coli , dioxygenase , nucleic acid , active site , binding site , nucleotide , dna repair , gene , enzyme
Methylating agents are ubiquitous in the environment, and central in cancer therapy. The 1‐methyladenine and 3‐methylcytosine lesions in DNA/RNA contribute to the cytotoxicity of such agents. These lesions are directly reversed by ABH3 (hABH3) in humans and AlkB in Escherichia coli . Here, we report the structure of the hABH3 catalytic core in complex with iron and 2‐oxoglutarate (2OG) at 1.5 Å resolution and analyse key site‐directed mutants. The hABH3 structure reveals the β‐strand jelly‐roll fold that coordinates a catalytically active iron centre by a conserved His 1 ‐X‐Asp/Glu‐X n ‐His 2 motif. This experimentally establishes hABH3 as a structural member of the Fe(II)/2OG‐dependent dioxygenase superfamily, which couples substrate oxidation to conversion of 2OG into succinate and CO 2 . A positively charged DNA/RNA binding groove indicates a distinct nucleic acid binding conformation different from that predicted in the AlkB structure with three nucleotides. These results uncover previously unassigned key catalytic residues, identify a flexible hairpin involved in nucleotide flipping and ss/ds‐DNA discrimination, and reveal self‐hydroxylation of an active site leucine that may protect against uncoupled generation of dangerous oxygen radicals.