Metabolic and Structural Insights into Hydrogen Sulfide Mis-Regulation in Enterococcus faecalis

Abstract

Hydrogen sulfide (H2S) is implicated as a cytoprotective agent that bacteria employ in response to host-induced stressors, such as oxidative stress and antibiotics. The physiological benefits often attributed to H2S, however, are likely a result of downstream, more oxidized forms of sulfur, collectively termed reactive sulfur species (RSS) and including the organic persulfide (RSSH). Here, we investigated the metabolic response of the commensal gut microorganism Enterococcus faecalis to exogenous Na2S as a proxy for H2S/RSS toxicity. We found that exogenous sulfide increases protein abundance for enzymes responsible for the biosynthesis of coenzyme A (CoA). Proteome S-sulfuration (persulfidation), a posttranslational modification implicated in H2S signal transduction, is also widespread in this organism and is significantly elevated by exogenous sulfide in CstR, the RSS sensor, coenzyme A persulfide (CoASSH) reductase (CoAPR) and enzymes associated with de novo fatty acid biosynthesis and acetyl-CoA synthesis. Exogenous sulfide significantly impacts the speciation of fatty acids as well as cellular concentrations of acetyl-CoA, suggesting that protein persulfidation may impact flux through these pathways. Indeed, CoASSH is an inhibitor of E. faecalis phosphotransacetylase (Pta), suggesting that an important metabolic consequence of increased levels of H2S/RSS may be over-persulfidation of this key metabolite, which, in turn, inhibits CoA and acyl-CoA-utilizing enzymes. Our 2.05 Å crystallographic structure of CoA-bound CoAPR provides new structural insights into CoASSH clearance in E. faecalis.

The role of gut microbiota in intestinal disease: from an oxidative stress perspective

“…Moreover, empirical evidence suggests that the gut microbiota may contribute to the body’s defense against the deleterious consequences of oxidative stress ( Mazenc et al, 2022 ). Gut commensals produce significant quantities of hydrogen sulfide (H 2 S), which subsequently undergoes conversion by the epithelium into thiosulfate (S 2 O 3 2− ) ( Walsh et al, 2022 ). This conversion process serves to safeguard host cells against the detrimental effects associated with H 2 S ( Ran et al, 2022 ).…”

Mining proteomes for zinc finger persulfidation

“…This yielded sixteen studies that met the criteria for metaanalysis, and these studies were subsequently analyzed for the presence of persulfidated ZFs. [51][52][53][54][55][56][57][58][59][60][61][62][63][64][65] The proteomics data from these sixteen studies were from seven distinct species: H. sapiens, M. musculus, R. norvegicus, A. thaliana, Emiliania huxleyi (a single-celled phytoplankton), Staphylococcus aureus, and Enterococcus faecalis. Two of the species were bacteria, three were mammals, one was plant, and one was phytoplankton (Fig.…”

“…61 In the two bacterial data sets, no ZFs were identified as persulfidated. 64,65 There are only a handful of ZFs that have been identified in prokaryotes, suggesting that the paucity of ZFs in bacteria explains the lack of persulfidated ZFs observed. There were six reported proteomics data sets that involved M. musculus tissue samples.…”

Chemistry of Hydrogen Sulfide—Pathological and Physiological Functions in Mammalian Cells

“…These enzymes are known as cystathionine-γ-lyase (CSE), cystathionine-β-synthetase (CBS) and 3-mercaptopyruvate sulfurtransferase (3MST) [123]. Bacteria have been shown to produce H 2 S as a cytoprotective agent in response to host-induced stress, such as oxidative stress and antibiotics [124]. Endogenously produced H 2 S stimulates ROS-scavenging enzymes and interferes with the Fenton reaction, reducing the amount of ROS produced by cells and promoting antibiotic tolerance [125].…”