Direct Zinc Finger Protein Persulfidation by H2S Is Facilitated by Zn2+

摘要

H2S is a gaseous signaling molecule that modifies cysteine residues in proteins to form persulfides (P-SSH). One family of proteins modified by H2S are zinc finger (ZF) proteins, which contain multiple zinc-coordinating cysteine residues. Herein, we report the reactivity of H2S with a ZF protein called tristetraprolin (TTP). Rapid persulfidation leading to complete thiol oxidation of TTP mediated by H2S 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 trapping. H2S was observed to inhibit TTP function (binding to TNF alpha mRNA) by an in vitro fluorescence anisotropy assay and to modulate TNF alpha in vivo. H2S was unreactive towards TTP when the protein was bound to RNA, thus suggesting a protective effect of RNA.