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Updated: Jul 2, 2026

Specificity Analysis of Protein Lysine Methyltransferases Using SPOT Peptide Arrays
Published on: November 29, 2014
AlkB demethylases flip out in different ways.
Ottar Sundheim1, Vivi A Talstad, Cathrine Broberg Vågbø
1Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Erling Skjalgssons Gate 1, Trondheim, Norway.
Researchers visualized DNA repair proteins AlkB and hABH2 interacting with DNA. Differences in how these proteins bind DNA explain their distinct preferences for single-stranded versus double-stranded DNA repair.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biology
Background:
- DNA methylation is repaired by base excision repair (BER) and direct repair mechanisms.
- AlkB-type oxidative demethylases are key players in DNA repair.
Purpose of the Study:
- To determine the crystal structure of AlkB and human AlkB homolog 2 (hABH2) in complex with DNA.
- To elucidate the structural basis for DNA repair mechanism differences between AlkB and hABH2.
Main Methods:
- Utilized an ingenious crosslinking strategy to stabilize DNA-protein complexes.
- Solved crystal structures of AlkB-DNA and hABH2-DNA complexes.
Main Results:
- AlkB and hABH2 share similar catalytic domains but differ in DNA recognition motifs.
- hABH2 interacts with both DNA strands, flipping out the damaged base without significant helix distortion.
- AlkB interacts mainly with the damaged strand, maintaining the base stack by squeezing flanking bases.
Conclusions:
- Structural differences explain the distinct substrate preferences of AlkB (single-stranded DNA) and hABH2 (double-stranded DNA).
- The study reveals an unprecedented base-flipping mechanism in hABH2-mediated DNA repair.
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