The first and second zinc finger domains from Poly-ADP-ribose polymerase 1 (PARP1) are modified by hydrogen sulfide.

Poly(ADP-ribose) polymerase 1 (PARP1) is a Zinc Finger (ZF) protein that is involved in DNA damage response. PARP1 contains three zinc finger (ZF) domains, two with a Cys2HisCys (CCHC) ligand set and one with a Cys4 (CCCC) ligand set that coordinate zinc. Persulfidation of cysteine residues in proteins is a new type of post-translational modification (PTM), for which ZFs are emerging as frequently modified. PARP1 has been identified as persulfidated in several cellular based persulfide-specific proteomics studies across several different cell types. Here, we examine PARP1 persulfidation by H2S. Two PARP1 peptide constructs, shPARP1-ZF1 and shPARP1-ZF2, were synthesized, purified, and shown to bind zinc and fold, using Co(II)/Zn(II) UV-visible (UV) monitored titrations and circular dichroism (CD) spectroscopy. The reactivity of the PARP ZFs with H2S was assessed using a UV-visible monitored 4-chloro-7-nitrobenzofurazan (NBF-Cl)/dimedone switch-tagging approach. Persulfidation for both PARP1 peptide constructs was observed under zinc-bound, oxygenated conditions. Superoxide intermediates were detected during the reaction using both dihydroethidine fluorescence and superoxide dismutase trapping. Together, these findings provide evidence that CCHC-type PARP ZFs can undergo persulfidation when Zn is bound and provide support for persulfidation being a general post-translational (PTM) modification for ZFs with different secondary structural elements.