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High mobility group proteins stimulate DNA cleavage by apoptotic endonuclease DFF40/CAD due to HMG-box interactions

Magdalena Kalinowska-Herok1, Piotr Widłak

  • 1Department of Experimental and Clinical Radiobiology, Maria Sklodowska-Curie Cancer Center and Institute of Oncology, Gliwice, Poland.

Acta Biochimica Polonica
|February 2, 2008
PubMed

Insights

High-mobility group box (HMGB) proteins like HMGB1 stimulate DNA cleavage by DFF40/CAD during apoptosis. This occurs by altering DNA conformation, not by direct protein binding, facilitating internucleosomal DNA fragmentation.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • The DFF40/CAD endonuclease is crucial for DNA fragmentation during apoptosis.
  • High-mobility group box (HMGB) proteins HMGB1 and HMGB2 are known to stimulate DFF40/CAD activity on naked DNA.

Purpose of the Study:

  • To elucidate the mechanism by which HMGB1 and HMGB2 stimulate DFF40/CAD-mediated DNA cleavage.
  • To investigate the role of HMG-box domains in this stimulation process.

Main Methods:

  • Analysis of HMGB1 binding to DFF40/CAD and DNA.
  • Assessment of DNA cleavage activity using truncated HMGB1 proteins.
  • Investigation of the effect of DNA cross-linking agents (cisplatin, transplatin) on DNA cleavage.

Main Results:

  • HMGB1 does not bind to DFF40/CAD or enhance its stable DNA binding.
  • A structural array of two HMG-boxes in HMGB1 is necessary for stimulation.
  • DNA distortions, mimicked by cross-linking agents, influence DFF40/CAD activity.

Conclusions:

  • HMGB proteins stimulate DFF40/CAD by inducing conformational changes in DNA, making it more accessible for cleavage.
  • This mechanism likely contributes to the preferential cleavage of linker DNA during apoptosis.

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