Staphylococcus aureus CstB Is a Novel Multidomain Persulfide Dioxygenase-Sulfurtransferase Involved in Hydrogen Sulfide Detoxification (original) (raw)
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mSphere
Staphylococcus aureus is a commensal human pathogen and a major cause of nosocomial infections. As gaseous signaling molecules, endogenous hydrogen sulfide (H2S) and nitric oxide (NO·) protect S. aureus from antibiotic stress synergistically, which we propose involves the intermediacy of nitroxyl (HNO). Here, we examine the effect of exogenous sulfide and HNO on the transcriptome and the formation of low-molecular-weight (LMW) thiol persulfides of bacillithiol, cysteine, and coenzyme A as representative of reactive sulfur species (RSS) in wild-type and ΔcstR strains of S. aureus. CstR is a per- and polysulfide sensor that controls the expression of a sulfide oxidation and detoxification system. As anticipated, exogenous sulfide induces the cst operon but also indirectly represses much of the CymR regulon which controls cysteine metabolism. A zinc limitation response is also observed, linking sulfide homeostasis to zinc bioavailability. Cellular RSS levels impact the expression of a ...
Journal of Bacteriology, 2004
In this report we describe the cloning, organization, and promoter analysis of the Staphylococcus aureus thioredoxin (trxA) and thioredoxin reductase (trxB) genes and their transcription in response to changes in oxygen concentration and to oxidative stress compounds. Northern analysis showed that the S. aureus trxA and trxB genes were transcribed equally well in aerobic and anaerobic conditions. Several oxidative stress compounds were found to rapidly induce transcription of the trxA and trxB genes. The most pronounced effects were seen with diamide, a thiol-specific oxidant that promotes disulfide bond formation; menadione, a redox cycling agent; and -butyl hydroperoxide, an organic peroxide. In each case the induction was independent of the general stress sigma factor B . These studies show that the S. aureus trxA and trxB genes are upregulated following exposure to these oxidative stress agents, resulting in increased disulfide bond formation. In contrast, no effect of hydrogen peroxide on induction of the trxA and trxB genes was seen. We also show that the S. aureus thioredoxin reductase appears to be essential for growth. This observation, coupled with structural differences between the bacterial and mammalian thioredoxin reductases, suggests that it may serve as a target for the development of new antimicrobials.
Biogenesis of reactive sulfur species for signaling by hydrogen sulfide oxidation pathways
Nature chemical biology, 2015
The chemical species involved in H2S signaling remain elusive despite the profound and pleiotropic physiological effects elicited by this molecule. The dominant candidate mechanism for sulfide signaling is persulfidation of target proteins. However, the relatively poor reactivity of H2S toward oxidized thiols, such as disulfides, the low concentration of disulfides in the reducing milieu of the cell and the low steady-state concentration of H2S raise questions about the plausibility of persulfide formation via reaction between an oxidized thiol and a sulfide anion or a reduced thiol and oxidized hydrogen disulfide. In contrast, sulfide oxidation pathways, considered to be primarily mechanisms for disposing of excess sulfide, generate a series of reactive sulfur species, including persulfides, polysulfides and thiosulfate, that could modify target proteins. We posit that sulfide oxidation pathways mediate sulfide signaling and that sulfurtransferases ensure target specificity.
The Journal of biological chemistry, 2017
Hydrogen sulfide (H2S) is a signaling molecule that is toxic at elevated concentrations. In eukaryotes, it is cleared via a mitochondrial sulfide oxidation pathway, which comprises sulfide quinone oxidoreductase, persulfide dioxygenase (PDO), rhodanese, and sulfite oxidase and converts H2S to thiosulfate and sulfate. Natural fusions between the non-heme iron containing PDO and rhodanese, a thiol sulfurtransferase, exist in some bacteria. However, little is known about the role of the PDO-rhodanese fusion (PRF) proteins in sulfur metabolism. Herein, we report the kinetic properties and the crystal structure of a PRF from the gram-negative endophytic bacterium, Burkholderia phytofirmans The crystal structures of wild-type PRF and a sulfurtransferase-inactivated C314S mutant with and without glutathione were determined at 1.8, 2.4, and 2.7 Å resolution, respectively. We found that the two active sites are distant and do not show evidence of direct communication. The B. phytofirmans PRF...
New Role of the Disulfide Stress Effector YjbH in -Lactam Susceptibility of Staphylococcus aureus
Staphylococcus aureus is exposed to multiple antimicrobial compounds, including oxidative burst products and antibiotics. The various mechanisms and regulatory pathways governing susceptibility or resistance are complex and only superficially understood. Bacillus subtilis recently has been shown to control disulfide stress responses by the thioredoxin-related YjbH protein, which binds to the transcriptional regulator Spx and controls its degradation via the proteasome-like ClpXP protease. We show that the S. aureus YjbH homolog has a role in susceptibility to the disulfide stress-inducing agent diamide that is similar to that in B. subtilis, and we demonstrate that the four cysteine residues in YjbH are required for this activity. In addition, the inactivation of YjbH led to moderate resistance to oxacillin and other -lactam antibiotics, and this phenotypic change was associated with higher penicillin-binding protein 4 levels and increased peptidoglycan crosslinking. Of note, the impact of YjbH on -lactam susceptibility still was observed when the four cysteines of YjbH were mutated, indicating that the roles of YjbH in disulfide stress and -lactam resistance rely on different types of interactions. These data suggest that the ClpXP adaptor YjbH has more target proteins than previously thought, and that oxidative burst and -lactam resistance mechanisms of S. aureus are closely linked.
Antioxidants
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-mercap...
Metal ions in life sciences, 2014
Sulfur is an essential element for the synthesis of cysteine, methionine, and other organo-sulfur compounds needed by living organisms. Additionally, some prokaryotes are capable of exploiting oxidation or reduction of inorganic sulfur compounds to energize cellular growth. Several anaerobic genera of Bacteria and Archaea produce hydrogen sulfide (H2S), as a result of using sulfate (SO(4)(2 -) ), elemental sulfur (S(0)), thiosulfate (S₂O(3)(2 -)), and tetrathionate (S(4)O(6)(2 -)) as terminal electron acceptors. Some phototrophic and aerobic sulfur bacteria are capable of using electrons from oxidation of sulfide to support chemolithotrophic growth. For the most part, biosulfur reduction or oxidation requires unique enzymatic activities with metal cofactors participating in electron transfer. This review provides an examination of cytochromes, iron-sulfur proteins, and sirohemes participating in electron movement in diverse groups of sulfate-reducing, sulfur-reducing, and sulfide-ox...
Significance of Four Methionine Sulfoxide Reductases in Staphylococcus aureus
PLOS ONE, 2015
Staphylococcus aureus is a major human pathogen and emergence of antibiotic resistance in clinical staphylococcal isolates raises concerns about our ability to control these infections. Cell wall-active antibiotics cause elevated synthesis of methionine sulfoxide reductases (Msrs: MsrA1 and MsrB) in S. aureus. MsrA and MsrB enzymes reduce S-epimers and R-epimers of methionine sulfoxide, respectively, that are generated under oxidative stress. In the S. aureus chromosome, there are three msrA genes (msrA1, msrA2 and msrA3) and one msrB gene. To understand the precise physiological roles of Msr proteins in S. aureus, mutations in msrA1, msrA2 and msrA3 and msrB genes were created by sitedirected mutagenesis. These mutants were combined to create a triple msrA (msrA1, msrA2 and msrA3) and a quadruple msrAB (msrA1, msrA2, msrA3, msrB) mutant. These mutants were used to determine the roles of Msr proteins in staphylococcal growth, antibiotic resistance, adherence to human lung epithelial cells, pigment production, and survival in mice relative to the wild-type strains. MsrA1-deficient strains were sensitive to oxidative stress conditions, less pigmented and less adherent to human lung epithelial cells, and showed reduced survival in mouse tissues. In contrast, MsrB-deficient strains were resistant to oxidants and were highly pigmented. Lack of MsrA2 and MsrA3 caused no apparent growth defect in S. aureus. In complementation experiments with the triple and quadruple mutants, it was MsrA1 and not MsrB that was determined to be critical for adherence and phagocytic resistance of S. aureus. Overall, the data suggests that MsrA1 may be an important virulence factor and MsrB probably plays a balancing act to counter the effect of MsrA1 in S. aureus.
Microbiology, 2007
The significance of the soxS gene product on chemotrophic sulfur oxidation of Paracoccus pantotrophus was investigated. The thioredoxin SoxS was purified, and the N-terminal amino acid sequence identified SoxS as the soxS gene product. The wild-type formed thiosulfate-oxidizing activity and Sox proteins during mixotrophic growth with succinate plus thiosulfate, while there was no activity, and only traces of Sox proteins, under heterotrophic conditions. The homogenote mutant strain GBVS is unable to express the soxSR genes, of which soxR encodes a transcriptional regulator. Strain GBVS cultivated mixotrophically showed about 22 % of the specific thiosulfate-dependent O 2 uptake rate of the wild-type, and when cultivated heterotrophically it produced 35 % activity. However, under both mixotrophic and heterotrophic conditions, strain GBVS formed Sox proteins essential for sulfur oxidation in vitro at the same high level as the wild-type produced them during mixotrophic growth. Genetic complementation of strain GBVS with soxS restored the activity upon mixotrophic and heterotrophic growth. Chemical complementation by reductants such as L-cysteine, DTT and tris(2-carboxyethyl)phosphine also restored the activity of strain GBVS in the presence of chloramphenicol, which is an inhibitor of de novo protein synthesis. The data demonstrate that SoxS plays a key role in activation of the Sox enzyme system, and this suggests that SoxS is part of a novel type of redox control in P. pantotrophus.
Redox regulation by reversible protein S-thiolation in bacteria
Frontiers in Microbiology, 2015
Low molecular weight (LMW) thiols function as thiol-redox buffers to maintain the reduced state of the cytoplasm. The best studied LMW thiol is the tripeptide glutathione (GSH) present in all eukaryotes and Gram-negative bacteria. Firmicutes bacteria, including Bacillus and Staphylococcus species utilize the redox buffer bacillithiol (BSH) while Actinomycetes produce the related redox buffer mycothiol (MSH). In eukaryotes, proteins are post-translationally modified to S-glutathionylated proteins under conditions of oxidative stress. S-glutathionylation has emerged as major redox-regulatory mechanism in eukaryotes and protects active site cysteine residues against overoxidation to sulfonic acids. First studies identified S-glutathionylated proteins also in Gram-negative bacteria. Advances in mass spectrometry have further facilitated the identification of protein S-bacillithiolations and S-mycothiolation as BSH-and MSH-mixed protein disulfides formed under oxidative stress in Firmicutes and Actinomycetes, respectively. In Bacillus subtilis, protein S-bacillithiolation controls the activities of the redox-sensing OhrR repressor and the methionine synthase MetE in vivo. In Corynebacterium glutamicum, protein S-mycothiolation was more widespread and affected the functions of the maltodextrin phosphorylase MalP and thiol peroxidase (Tpx). In addition, novel bacilliredoxins (Brx) and mycoredoxins (Mrx1) were shown to function similar to glutaredoxins in the reduction of BSH-and MSH-mixed protein disulfides. Here we review the current knowledge about the functions of the bacterial thiol-redox buffers glutathione, bacillithiol, and mycothiol and the role of protein S-thiolation in redox regulation and thiol protection in model and pathogenic bacteria.