Unusual Zn(II) Affinities of Zinc Fingers of Poly(ADP-ribose) Polymerase 1 (PARP-1) Nuclear Protein

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• 作者：Karolina Bossak ; Wojciech Goch ; Katarzyna Pi膮tek ; Tomasz Fr膮czyk ; Jaros艂aw Pozna艅ski ; Arkadiusz Bonna ; Claudia Keil ; Andrea Hartwig ; Wojciech Bal
• 刊名：Chemical Research in Toxicology
• 出版年：2015
• 出版时间：February 16, 2015
• 年：2015
• 卷：28
• 期：2
• 页码：191-201
• 全文大小：596K
• ISSN：1520-5010

文摘

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 (HEPES buffer) as 26 卤 4 nM and 4 卤 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 鈥渕etal-free鈥?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 卤 0.04 渭M and 0.26 卤 0.05 nM, respectively.