Cysteine Trisulfide Protects E. coli from Electrophile-Induced Death through the Generation of Cysteine Hydropersulfide

Abstract

Hydropersulfide and polysulfide species have recently been shown to elicit a wide variety of biological and physiological responses. In this study, we examine the effects of cysteine trisulfide (Cys-SSS-Cys; also known as thiocystine) treatment on E. coli. Previous studies in mammalian cells have shown that Cys-SSS-Cys treatment results in protection from the electrophiles. Here, we show that the protective effect of Cys-SSS-Cys treatment against electrophile-induced cell death is conserved in E. coli. This protection correlates with the rapid generation of cysteine hydropersulfide (Cys-SSH) in the culture media. We go on to demonstrate that an exogenous phosphatase expressed in E. coli, containing only a single catalytic cysteine, is protected from electrophile-induced inactivation in the presence of hydropersulfides. These data together demonstrate that E. coli can utilize Cys-SSS-Cys to generate Cys-SSH and that the Cys-SSH can protect cellular thiols from reactivity with the electrophiles.

Cysteine trisulfide oxidizes protein thiols and induces electrophilic stress in human cells

“…Therefore, we conclude that Cys-S 3 administration to cells can deliver cysteine persulfide in situ , however this is concomitant with protein oxidation and cytotoxicity, consistent with other dialkyl and diaryl trisulfide compounds [ [43] , [44] , [45] ]. Our findings are counter to recent reports on the cellular protective effects of Cys-S 3 at similar concentrations in E. coli and human cells [ 13 , 24 ], however differing experimental design and conditions may account for some of this discrepancy.…”

“…Due to their reactive nature, persulfides engage in multiple equlibiria with other sulfur-species, such as H 2 S, disulfides and polysulfides [ 21 ]. To more directly investigate persulfide biology, Cys-S 3 has been used as an in situ persulfide donor [ 13 , 24 ]. While Cys-S 3 reacts with cellular thiols to produce persulfide, the electrophilc nature of Cys-S 3 appears to dominate the cellular response.…”

“…However these tools are not suitable for in vitro cellular or in vivo experimentation. Cys-S 3 has been utilized as a cellular persulfide donor by reacting with intracellular thiols (reaction 2) [ 13 , 23 , 24 ]. …”

“…While these studies have focused on the effects of persulfide formation [ 13 , 24 ], the oxidation of cellular thiols by Cys-S 3 has not been examined. Cells respond to electrophilic stress by cysteine-mediated sensing molecules such as p38, KEAP1 and PDIs [ [25] , [26] , [27] ].…”

“…Cells respond to electrophilic stress by cysteine-mediated sensing molecules such as p38, KEAP1 and PDIs [ [25] , [26] , [27] ]. While Cys-S 3 has been shown to protect cells from further electrophilic insult [ 13 , 24 ], the cellular effect of the electrophile Cys-S 3 on cellular and endoplasmic reticulum (ER) stress has not been investigated. Here we show that despite forming cysteine persulfide, Cys-S 3 also results in global protein thiol oxidation, the induction of cellular and ER-stress responses and inhibited cell proliferation.…”