Destabilization of Zn2+ coordination in ADP-ribose transferase (polymerizing) by 6-nitroso-1,2-benzopyrone coincidental with inactivation of the polymerase but not the DNA binding function.
6-Nitroso-1,2-benzopyrone, an oxidation product of 6-amino-1,2-benzopyrone, binds to the DNA-recognizing domain of the ADP-ribose transferase protein and preferentially destabilizes Zn2+ from one of the two zinc finger polypeptide complexes present in the intact enzyme, as determined by the loss of 50% of 65Zn2+ from the 65Zn(2+)-isolated protein molecule, coincidental with the loss of 99% of enzymatic activity. The 50% zinc-deficient enzyme still binds to a DNA template, consisting of a 17-mer DNA primer annealed to M13 positive strand, resulting in the blocking of DNA synthesis by the Klenow fragment of Pol I. Auto-poly-ADP-ribosylated ADP-ribose transferase, which is the probable physiological state of this protein in intact cells, does not bind to primer-template DNA and does not block DNA synthesis by the Klenow fragment. On the basis of this in vitro model it is proposed that molecules which inhibit or inactivate ADP-ribose transferase in intact cells can induce significant alteration in DNA structure and replication.
Laboratory for Environmental Toxicology and Chemistry, Romberg Tiburon Centers, San Francisco State University, Tiburon, CA 94920.
K G
KG
Buki
P I
PI
Bauer
J
J
Mendeleyev
A
A
Hakam
E
E
Kun
D001483:Base Sequence; D003374:Coumarins / Q000494:pharmacology*; D004247:DNA / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors*; D008969:Molecular Sequence Data; D009603:Nitroso Compounds / Q000494:pharmacology; D009841:Oligonucleotides / Q000737:chemistry; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D015032:Zinc / Q000737:chemistry
D003374:Coumarins; D004268:DNA-Binding Proteins; D009603:Nitroso Compounds; D009841:Oligonucleotides; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; C071196:6-nitroso-1,2-benzopyrone; D004247:DNA; D015032:Zinc