Chemoselective Proteomics, Zinc Fingers, and a Zinc(II) Model for H₂S Mediated Persulfidation

The gasotransmitter hydrogen sulfide (H₂S) is thought to be involved in the post-translational modification of cysteine residues to produce reactive persulfides. A persulfide-specific chemoselective proteomics approach with mammalian cells has identified a broad range of zinc finger (ZF) proteins as targets of persulfidation. Parallel studies with isolated ZFs show that persulfidation is mediated by Zn^II, O₂, and H₂S, with intermediates involving oxygen- and sulfur-based radicals detected by mass spectrometry and optical spectroscopies. A small molecule Zn^II complex exhibits analogous reactivity with H₂S and O₂, giving a persulfidated product. These data show that Zn^II is not just a biological structural element, but also plays a critical role in mediating H₂S-dependent persulfidation. ZF persulfidation appears to be a general post-translational modification and a possible conduit for H₂S signaling. This work has implications for our understanding of H₂S-mediated signaling and the regulation of ZFs in cellular physiology and development.