Synthesis of Sulfides and Persulfides Is Not Impeded by Disruption of Three Canonical Enzymes in Sulfur Metabolism

Abstract

Reactive sulfur species, or persulfides and polysulfides, such as cysteine hydropersulfide and glutathione persulfide, are endogenously produced in abundance in both prokaryotes and eukaryotes, including mammals. Various forms of reactive persulfides occur in both low-molecular-weight and protein-bound thiols. The chemical properties and great supply of these molecular species suggest a pivotal role for reactive persulfides/polysulfides in different cellular regulatory processes (e.g., energy metabolism and redox signaling). We demonstrated earlier that cysteinyl-tRNA synthetase (CARS) is a new cysteine persulfide synthase (CPERS) and is responsible for the in vivo production of most reactive persulfides (polysulfides). Some researchers continue to suggest that 3-mercaptopyruvate sulfurtransferase (3-MST), cystathionine β-synthase (CBS), and cystathionine γ-lyase (CSE) may also produce hydrogen sulfide and persulfides that may be generated during the transfer of sulfur from 3-mercaptopyruvate to the cysteine residues of 3-MST or direct synthesis from cysteine by CBS/CSE, respectively. We thus used integrated sulfur metabolome analysis, which we recently developed, with 3-MST knockout (KO) mice and CBS/CSE/3-MST triple-KO mice, to elucidate the possible contribution of 3-MST, CBS, and CSE to the production of reactive persulfides in vivo. We therefore quantified various sulfide metabolites in organs derived from these mutant mice and their wild-type littermates via this sulfur metabolome, which clearly revealed no significant difference between mutant mice and wild-type mice in terms of reactive persulfide production. This result indicates that 3-MST, CBS, and CSE are not major sources of endogenous reactive persulfide production; rather, CARS/CPERS is the principal enzyme that is actually involved in and even primarily responsible for the biosynthesis of reactive persulfides and polysulfides in vivo in mammals.

Hydrogen Sulfide (H2S)/Polysulfides (H2Sn) Signalling and TRPA1 Channels Modification on Sulfur Metabolism

“…If the intracellular cystine concentrations are above 5 µM, CSE may have a possibility to synthesize Cys-SSH in cells [88]. It was recently reported by the same group that the production of H 2 S, H 2 S n , Cys-SSH, and GSSH was not changed in mice with triple knock-out of CBS, CSE, and 3MST [89].…”

NRF2 signaling in cytoprotection and metabolism

“…3-Mercaptopyruvate sulfertransferase (3-MST) was also reported as the third enzyme generating H 2 S and supersulfides (Kimura et al, 2017). However, simultaneous disruption of the three enzymes, CBS, CSE and 3-MST, in mice does not eliminate supersulfide production in vivo (Zainol Abidin et al, 2023), strongly suggesting the presence of alternative compensatory mechanisms for supersulfide production. Indeed, cysteinyltRNA synthetase (CARS) has been found to possess cysteine persulfide synthesizing activity as a moonlighting function (Akaike et al, 2017).…”

Reactive Sulfur Species in Biology and Medicine

“…However, some researchers have proposed that H 2 S-producing enzymes 3-MST, CBS, and CSE also contribute to RSSH production. To determine hydropersulfide biosynthesis, Tsutsui, Akaike, and co-workers conducted research to elucidate the relative contributions of these enzymes to cysteine hydropersulfide biosynthesis [ 7 ]. They initiated their investigation by creating 3-MST knockout mice, which surprisingly exhibited no statistically significant differences in RSSH production when compared to wild-type mice.…”