Direct Zinc Finger Protein Persulfidation by H S Is Facilitated by Zn.

H S is a gaseous signaling molecule that modifies cysteine residues in proteins to form persulfides (P-SSH). One family of proteins modified by H S are zinc finger (ZF) proteins, which contain multiple zinc-coordinating cysteine residues. Herein, we report the reactivity of H S with a ZF protein called tristetraprolin (TTP). Rapid persulfidation leading to complete thiol oxidation of TTP mediated by H S was observed by low-temperature ESI-MS and fluorescence spectroscopy. Persulfidation of TTP required O  , which reacts with H S to form superoxide, as detected by ESI-MS, a hydroethidine fluorescence assay, and EPR spin trapping. H S was observed to inhibit TTP function (binding to TNFα mRNA) by an in vitro fluorescence anisotropy assay and to modulate TNFα in vivo. H S was unreactive towards TTP when the protein was bound to RNA, thus suggesting a protective effect of RNA.