High mobility group proteins stimulate DNA cleavage by apoptotic endonuclease DFF40/CAD due to HMG-box interactions with DNA.
The DFF40/CAD endonuclease is primarily responsible for internucleosomal DNA cleavage during the terminal stages of apoptosis. It has been previously demonstrated that the major HMG-box-containing chromatin proteins HMGB1 and HMGB2 stimulate naked DNA cleavage by DFF40/CAD. Here we investigate the mechanism of this stimulation and show that HMGB1 neither binds to DFF40/CAD nor enhances its ability for stable binding to DNA. Comparison of the stimulatory activities of different truncated forms of HMGB1 protein indicates that a structural array of two HMG-boxes is required for such stimulation. HMG-boxes are known to confer specific local distortions of DNA structure upon binding. Interestingly, the presence of DNA strand cross-links formed by cisplatin or transplatin, which may somehow mimic distortions induced by HMG-boxes, also affects DNA cleavage by the nuclease. The data presented suggest that changes induced in DNA conformation upon HMG-box binding makes the substrate more accessible to cleavage by DFF40/CAD nuclease and thus may contribute to preferential linker DNA cleavage during apoptosis.
Kalinowska-Herok
Magdalena
M
Department of Experimental and Clinical Radiobiology, Maria Sklodowska-Curie Cancer Center and Institute of Oncology, Gliwice, Poland.
Widłak
Piotr
P
D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D002843:Chromatin / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004247:DNA / Q000737:chemistry*; D053837:DNA Cleavage; D003851:Deoxyribonucleases / Q000378:metabolism*; D005982:Glutathione Transferase / Q000737:chemistry; D024243:HMGB1 Protein / Q000378:metabolism; D024261:HMGB2 Protein / Q000378:metabolism; D006609:High Mobility Group Proteins / Q000378:metabolism*; D006801:Humans; D000075223:Poly-ADP-Ribose Binding Proteins; D011485:Protein Binding
D000970:Antineoplastic Agents; D002843:Chromatin; D003432:Cross-Linking Reagents; D024243:HMGB1 Protein; D024261:HMGB2 Protein; D006609:High Mobility Group Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; C034697:transplatin; D004247:DNA; D005982:Glutathione Transferase; C113696:DFFB protein, human; D003851:Deoxyribonucleases; D002945:Cisplatin