Direct zinc finger protein persulfidation by H(2)S is facilitated by Zn(2+)

H(2)S is a gaseous signaling molecule that modifies cysteine residues in proteins to form persulfides (P-SSH). One family of proteins modified by H(2)S are zinc finger (ZF) proteins, which contain multiple zinc coordinating cysteine residues. Herein, we report the reactivity of H(2)S with a ZF protein called Tristetraprolin (TTP). Rapid persulfidation leading to complete thiol oxidation of TTP mediated by H(2)S was observed by low temperature ESI-MS and fluorescence spectroscopy. Persulfidation of TTP required O(2), which reacts with H2S to form superoxide, as detected by ESI-MS, a hydroethidine fluorescence assay and EPR spin trap. H(2)S was observed to inhibit TTP function (binding to TNFα mRNA) via an in vitro fluorescence anisotropy assay and to modulate TNFα in vivo. H(2)S was unreactive towards TTP when the protein was bound to RNA, suggesting a protective effect of RNA