title: Binding of antitumor antibiotic daunomycin to histones in chromatin and in solution.
abstract: Daunomycin is an anticancer drug that is well-known to interact with DNA in chromatin. Using a compositionally defined chicken erythrocyte chromatin fraction, we have obtained conclusive evidence that the drug is also able to interact with chromatin-bound linker histones without any noticeable binding to core histones. The drug can interact in an equal fashion with both histone H1 and H5 and to a greater extent with core histones H3/H4 and H2A/H2B as free proteins in solution. Thus, the binding of daunomycin to linker histones in the chromatin fiber is most likely due to the well-known higher accessibility of these histones to the surrounding environment of the fiber. Binding of daunomycin to linker histones appears to primarily involve the trypsin-resistant (winged-helix) domain of these proteins. The studies described here reveal the occurrence of a previously undisclosed mechanism for the antitumor activity of anthracycline drugs at the chromatin level.
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
authors.forename: Azra
authors.initials: A
authors.lastname: Rabbani
authors.forename: Ron M
authors.initials: RM
authors.lastname: Finn
authors.forename: Anita A
authors.initials: AA
authors.lastname: Thambirajah
authors.forename: Juan
authors.initials: J
authors.lastname: Ausió
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D003630:Daunorubicin / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006657:Histones / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D014357:Trypsin / Q000378:metabolism
chemical_list: D000903:Antibiotics, Antineoplastic; D002843:Chromatin; D006657:Histones; D004247:DNA; D014357:Trypsin; D003630:Daunorubicin