title: Interaction of DNA fragmentation factor (DFF) with DNA reveals an unprecedented mechanism for nuclease inhibition and suggests that DFF can be activated in a DNA-bound state.
abstract: DNA fragmentation factor (DFF) is a complex of the DNase DFF40 (CAD) and its chaperone/inhibitor DFF45 (ICAD-L) that can be activated during apoptosis to induce DNA fragmentation. Here, we demonstrate that DFF directly binds to DNA in vitro without promoting DNA cleavage. DNA binding by DFF is mediated by the nuclease subunit, which can also form stable DNA complexes after release from DFF. Recombinant and reconstituted DFF is catalytically inactive yet proficient in DNA binding, demonstrating that the nuclease subunit in DFF is inhibited in DNA cleavage but not in DNA binding, revealing an unprecedented mode of nuclease inhibition. Activation of DFF in the presence of naked DNA or isolated nuclei stimulates DNA degradation by released DFF40 (CAD). In transfected HeLa cells transiently expressed DFF associates with chromatin, suggesting that DFF could be activated during apoptosis in a DNA-bound state.
authors.affiliation: Institute of Biochemistry, Justus-Liebig-University Giessen, 35392 Giessen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Korn
authors.forename: Sebastian R
authors.initials: SR
authors.lastname: Scholz
authors.forename: Oleg
authors.initials: O
authors.lastname: Gimadutdinow
authors.forename: Rudi
authors.initials: R
authors.lastname: Lurz
authors.forename: Alfred
authors.initials: A
authors.lastname: Pingoud
authors.forename: Gregor
authors.initials: G
authors.lastname: Meiss
mesh_terms: D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D001483:Base Sequence; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D003851:Deoxyribonucleases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D008958:Models, Molecular; D000075223:Poly-ADP-Ribose Binding Proteins; D011485:Protein Binding; D011487:Protein Conformation; D021122:Protein Subunits / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D014162:Transfection
chemical_list: D051017:Apoptosis Regulatory Proteins; D002843:Chromatin; D000075223:Poly-ADP-Ribose Binding Proteins; D021122:Protein Subunits; D011506:Proteins; D011994:Recombinant Proteins; C109664:caspase-activated DNase inhibitor; D004247:DNA; D003851:Deoxyribonucleases; C499445:Dffb protein, mouse; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases