HMGB1 is a cofactor in mammalian base excision repair

Mol Cell. 2007 Sep 7;27(5):829-41. doi: 10.1016/j.molcel.2007.06.029.


Deoxyribose phosphate (dRP) removal by DNA polymerase beta (Pol beta) is a pivotal step in base excision repair (BER). To identify BER cofactors, especially those with dRP lyase activity, we used a Pol beta null cell extract and BER intermediate as bait for sodium borohydride crosslinking. Mass spectrometry identified the high-mobility group box 1 protein (HMGB1) as specifically interacting with the BER intermediate. Purified HMGB1 was found to have weak dRP lyase activity and to stimulate AP endonuclease and FEN1 activities on BER substrates. Coimmunoprecipitation experiments revealed interactions of HMGB1 with known BER enzymes, and GFP-tagged HMGB1 was found to accumulate at sites of oxidative DNA damage in living cells. HMGB1(-/-) mouse cells were slightly more resistant to MMS than wild-type cells, probably due to the production of fewer strand-break BER intermediates. The results suggest HMGB1 is a BER cofactor capable of modulating BER capacity in cells.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Borohydrides / chemistry
  • DNA Damage
  • DNA Polymerase beta / metabolism
  • DNA Repair / physiology*
  • Flap Endonucleases / metabolism
  • Green Fluorescent Proteins / analysis
  • HMGB1 Protein / analysis
  • HMGB1 Protein / chemistry
  • HMGB1 Protein / physiology*
  • HeLa Cells
  • Humans
  • Mass Spectrometry
  • Mice
  • Oxidative Stress
  • Phosphorus-Oxygen Lyases / metabolism


  • Borohydrides
  • HMGB1 Protein
  • Green Fluorescent Proteins
  • sodium borohydride
  • 5'-deoxyribose phosphate lyase
  • DNA Polymerase beta
  • Flap Endonucleases
  • Phosphorus-Oxygen Lyases