title: Unusual Zn(II) Affinities of Zinc Fingers of Poly(ADP-ribose)Polymerase 1 (PARP-1) Nuclear Protein.
abstract: Poly(ADP-ribose) polymerase 1 (PARP-1) is a key eukaryotic enzyme,catalyzing the NAD+ dependent poly(ADP-ribosyl)ation of protein substrates, crucial for major DNA repair pathways, and involved in other fundamental cellular processes, such as transcription, cell cycle control, and apoptosis. Its ability to bind DNA depends on two CCHC zinc finger domains, in short, PARPzf1 and PARPzf2. Using spectroscopic methods and competitive titrations with Zn(II), Co(II), and Ni(II) ions, we determined conditional dissociation constants for Zn(II) complexes of PARPzf1 and PARPzf2 at pH 7.4 (HEPESbuffer) as 26 ± 4 nM and 4 ± 1 pM, respectively. The former value indicates an extremely low affinity of PARPzf1 toward metal ions, meaning that under cellular conditions PARP1zf might be largely present in a “metal-free” state. This finding provides a clue to the high susceptibility of PARP-1 to oxidative stress but also raises questions regarding the activation of PARPzf1 under cellular conditions. We also determined conditional dissociation constants for Ni(II) complexes of PARPzf1 and PARPzf2 under the same conditions as 0.78 ± 0.04 μM and 0.26 ± 0.05 nM, respectively.
authors.forename: Karolina
authors.initials: K
authors.lastname: Bossak
authors.forename: Wojciech
authors.initials: W
authors.lastname: Goch
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Piątek
authors.forename: Tomasz
authors.initials: T
authors.lastname: Frączyk
authors.forename: Jarosław
authors.initials: J
authors.lastname: Poznański
authors.forename: Arkadiusz
authors.initials: A
authors.lastname: Bonna
authors.forename: Claudia
authors.initials: C
authors.lastname: Keil
authors.forename: Andrea
authors.initials: A
authors.lastname: Hartwig
authors.forename: Wojciech
authors.initials: W
authors.lastname: Bal
mesh_terms: D002942:Circular Dichroism; D006801:Humans; D056004:Molecular Dynamics Simulation; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D011522:Protons; D013050:Spectrometry, Fluorescence; D015032:Zinc / Q000737:chemistry*; D016335:Zinc Fingers
chemical_list: D011522:Protons; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D015032:Zinc