1
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Gulati M, Thomas JM, Ennis CL, Hernday AD, Rawat M, Nobile CJ. The bacillithiol pathway is required for biofilm formation in Staphylococcus aureus. Microb Pathog 2024; 191:106657. [PMID: 38649100 DOI: 10.1016/j.micpath.2024.106657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 04/16/2024] [Accepted: 04/18/2024] [Indexed: 04/25/2024]
Abstract
Staphylococcus aureus is a major human pathogen that can cause infections that range from superficial skin and mucosal infections to life threatening disseminated infections. S. aureus can attach to medical devices and host tissues and form biofilms that allow the bacteria to evade the host immune system and provide protection from antimicrobial agents. To counter host-generated oxidative and nitrosative stress mechanisms that are part of the normal host responses to invading pathogens, S. aureus utilizes low molecular weight (LMW) thiols, such as bacillithiol (BSH). Additionally, S. aureus synthesizes its own nitric oxide (NO), which combined with its downstream metabolites may also protect the bacteria against specific host responses. We have previously shown that LMW thiols are required for biofilm formation in Mycobacterium smegmatis and Pseudomonas aeruginosa. Here, we show that the S. aureus bshC mutant strain, which is defective in the last step of the BSH pathway and lacks BSH, is impaired in biofilm formation. We also identify a possible S-nitrosobacillithiol reductase (BSNOR), similar in sequence to an S-nitrosomycothiol reductase found in M. smegmatis and show that the putative S. aureus bsnoR mutant strain has reduced levels of BSH and decreased biofilm formation. Our studies also show that NO plays an important role in biofilm formation and that acidified sodium nitrite severely reduces biofilm thickness. These studies provide insight into the roles of oxidative and nitrosative stress mechanisms on biofilm formation and indicate that BSH and NO are key players in normal biofilm formation in S. aureus.
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Affiliation(s)
- Megha Gulati
- Department of Molecular and Cell Biology, University of California Merced, Merced, CA, USA
| | - Jason M Thomas
- Department of Biology, California State University-Fresno, Fresno, CA, USA
| | - Craig L Ennis
- Department of Molecular and Cell Biology, University of California Merced, Merced, CA, USA; Quantitative and Systems Biology Graduate Program, University of California, Merced, CA, USA
| | - Aaron D Hernday
- Department of Molecular and Cell Biology, University of California Merced, Merced, CA, USA; Health Sciences Research Institute, University of California, Merced, CA, USA
| | - Mamta Rawat
- Department of Biology, California State University-Fresno, Fresno, CA, USA.
| | - Clarissa J Nobile
- Department of Molecular and Cell Biology, University of California Merced, Merced, CA, USA; Health Sciences Research Institute, University of California, Merced, CA, USA.
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2
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Ashby LV, Springer R, Loi VV, Antelmann H, Hampton MB, Kettle AJ, Dickerhof N. Oxidation of bacillithiol during killing of Staphylococcus aureus USA300 inside neutrophil phagosomes. J Leukoc Biol 2022; 112:591-605. [PMID: 35621076 PMCID: PMC9796752 DOI: 10.1002/jlb.4hi1021-538rr] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 03/29/2022] [Indexed: 01/07/2023] Open
Abstract
Targeting immune evasion tactics of pathogenic bacteria may hold the key to treating recalcitrant bacterial infections. Staphylococcus aureus produces bacillithiol (BSH), its major low-molecular-weight thiol, which is thought to protect this opportunistic human pathogen against the bombardment of oxidants inside neutrophil phagosomes. Here, we show that BSH was oxidized when human neutrophils phagocytosed S. aureus, but provided limited protection to the bacteria. We used mass spectrometry to measure the oxidation of BSH upon exposure of S. aureus USA300 to either a bolus of hypochlorous acid (HOCl) or a flux generated by the neutrophil enzyme myeloperoxidase. Oxidation of BSH and loss of bacterial viability were strongly correlated (r = 0.99, p < 0.001). BSH was fully oxidized after exposure of S. aureus to lethal doses of HOCl. However, there was no relationship between the initial BSH levels and the dose of HOCl required for bacterial killing. In contrast to the HOCl systems, only 50% of total BSH was oxidized when neutrophils killed the majority of phagocytosed bacteria. Oxidation of BSH was decreased upon inhibition of myeloperoxidase, implicating HOCl in phagosomal BSH oxidation. A BSH-deficient S. aureus USA300 mutant was slightly more susceptible to treatment with either HOCl or ammonia chloramine, or to killing within neutrophil phagosomes. Collectively, our data show that myeloperoxidase-derived oxidants react with S. aureus inside neutrophil phagosomes, leading to partial BSH oxidation, and contribute to bacterial killing. However, BSH offers only limited protection against the neutrophil's multifaceted killing mechanisms.
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Affiliation(s)
- Louisa V Ashby
- Centre for Free Radical Research, Department of Pathology and Biomedical ScienceUniversity of Otago ChristchurchChristchurchNew Zealand
| | - Reuben Springer
- Centre for Free Radical Research, Department of Pathology and Biomedical ScienceUniversity of Otago ChristchurchChristchurchNew Zealand
| | - Vu Van Loi
- Freie Universität Berlin, Department of Biology, Chemistry, PharmacyInstitute of Biology‐MicrobiologyBerlinGermany
| | - Haike Antelmann
- Freie Universität Berlin, Department of Biology, Chemistry, PharmacyInstitute of Biology‐MicrobiologyBerlinGermany
| | - Mark B Hampton
- Centre for Free Radical Research, Department of Pathology and Biomedical ScienceUniversity of Otago ChristchurchChristchurchNew Zealand
| | - Anthony J Kettle
- Centre for Free Radical Research, Department of Pathology and Biomedical ScienceUniversity of Otago ChristchurchChristchurchNew Zealand
| | - Nina Dickerhof
- Centre for Free Radical Research, Department of Pathology and Biomedical ScienceUniversity of Otago ChristchurchChristchurchNew Zealand
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3
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Taïbi N, Ameraoui R, Kaced A, Abou-Mustapha M, Bouchama A, Djafri A, Taïbi A, Mellahi K, Hadjadj M, Touati S, Badri FZ, Djema S, Masmoudi Y, Belmiri S, Khammar F. Multifloral white honey outclasses manuka honey in methylglyoxal content: assessment of free and encapsulated methylglyoxal and anti-microbial peptides in liposomal formulation against toxigenic potential of Bacillus subtilis Subsp spizizenii strain. Food Funct 2022; 13:7591-7613. [PMID: 35731546 DOI: 10.1039/d2fo00566b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The therapeutic virtues of honey no longer need to be proven. Honey, which is rich in nutrients, is an excellent nutritional food because of its many properties; however, honey has been diverted from this primary function and used in clinical research. Evidence has shown that honey still possesses unknown properties and some of these aspects have never been addressed. In this work, two bioactive compounds found in honey (methylglyoxal and antimicrobial peptides) were evaluated for their anti-Bacillus subtilis activity with particular attention to their dilution factor. Although this bacterial strain does not possess an indigenous virulence factor gene, it becomes virulent by transferring plasmids with B. thuringiensis or expression of toxins from Bordetella pertussis. As is known, methylglyoxal is a toxic electrophile present in many eukaryotic and prokaryotic cells, which is generated by enzymatic and non-enzymatic reactions. Its overexpression successfully kills bacteria by inducing membrane disruption. Also, AMPs show potent inhibitory action against Gram-positive bacteria. Because of the lack of information concerning the main ingredients of honey, the microencapsulation process was used. Both methylglyoxal (MGO) and peptide-loaded liposomes were synthesized, characterized and compared to their free forms. The liposomal formulations contained a mixture of eggPC, cholesterol, and octadecylamine and their particle sizes were measured and their encapsulation efficacy calculated. The results revealed that Algerian multifloral white honey contained higher levels of MGO compared to manuka honey, which prevented bacterial growth and free MGO was relatively less effective. In fact, MGO killed BS in the loaded form with the same bacteriostatic and bactericidal index. However, the action of AMPs was different. Indeed, the investigation into the reactivity of MGO in the solvent indicated that regardless of the level of water added, honey is active at a fixed dilution. This data introduces the notion of dilution and abolishes the concept of concentration. Moreover, the synergistic antibacterial effect of the compounds in honey was diminished by the matrix effect. The degree of liposome-bacteria-fusion and the delay effect observed could be explain by both the composition and nature of the lipids used. Finally, this study reinforces the idea that under certain conditions, the metalloproteinases in honey produce AMPs.
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Affiliation(s)
- Nadia Taïbi
- Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques CRAPC, BP 384, Bou-Ismail, 42004, Tipaza, Algeria. .,Université des Sciences et de la Technologie Houari Boumediene (USTHB), Faculté des Sciences Biologiques (FSB), Laboratoire de Recherche sur les Zones Arides, (LRZA), BP 32 El Alia 16111, Bab Ezzouar 16111, Algeria
| | - Rachid Ameraoui
- Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques CRAPC, BP 384, Bou-Ismail, 42004, Tipaza, Algeria.
| | - Amel Kaced
- Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques CRAPC, BP 384, Bou-Ismail, 42004, Tipaza, Algeria.
| | - Mohamed Abou-Mustapha
- Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques CRAPC, BP 384, Bou-Ismail, 42004, Tipaza, Algeria.
| | - Abdelghani Bouchama
- Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques CRAPC, BP 384, Bou-Ismail, 42004, Tipaza, Algeria.
| | - Ahmed Djafri
- Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques CRAPC, BP 384, Bou-Ismail, 42004, Tipaza, Algeria.
| | - Amina Taïbi
- Laboratoire de Parasitologie et Mycologie, Laboratoire de Recherche Santé et production Animale, École Nationale Supérieure Vétérinaire, B.P. 228, Oued Smar, Alger, Algeria
| | - Kahina Mellahi
- Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques CRAPC, BP 384, Bou-Ismail, 42004, Tipaza, Algeria.
| | - Mohamed Hadjadj
- Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques CRAPC, BP 384, Bou-Ismail, 42004, Tipaza, Algeria.
| | - Souad Touati
- Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques CRAPC, BP 384, Bou-Ismail, 42004, Tipaza, Algeria.
| | - Fatima-Zohra Badri
- Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques CRAPC, BP 384, Bou-Ismail, 42004, Tipaza, Algeria.
| | - Souhila Djema
- Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques CRAPC, BP 384, Bou-Ismail, 42004, Tipaza, Algeria.
| | - Yasmina Masmoudi
- Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques CRAPC, BP 384, Bou-Ismail, 42004, Tipaza, Algeria.
| | - Sarah Belmiri
- Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques CRAPC, BP 384, Bou-Ismail, 42004, Tipaza, Algeria.
| | - Farida Khammar
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Faculté des Sciences Biologiques (FSB), Laboratoire de Recherche sur les Zones Arides, (LRZA), BP 32 El Alia 16111, Bab Ezzouar 16111, Algeria
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4
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Linzner N, Loi VV, Fritsch VN, Antelmann H. Thiol-based redox switches in the major pathogen Staphylococcus aureus. Biol Chem 2020; 402:333-361. [PMID: 33544504 DOI: 10.1515/hsz-2020-0272] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 11/05/2020] [Indexed: 12/15/2022]
Abstract
Staphylococcus aureus is a major human pathogen, which encounters reactive oxygen, nitrogen, chlorine, electrophile and sulfur species (ROS, RNS, RCS, RES and RSS) by the host immune system, during cellular metabolism or antibiotics treatments. To defend against redox active species and antibiotics, S. aureus is equipped with redox sensing regulators that often use thiol switches to control the expression of specific detoxification pathways. In addition, the maintenance of the redox balance is crucial for survival of S. aureus under redox stress during infections, which is accomplished by the low molecular weight (LMW) thiol bacillithiol (BSH) and the associated bacilliredoxin (Brx)/BSH/bacillithiol disulfide reductase (YpdA)/NADPH pathway. Here, we present an overview of thiol-based redox sensors, its associated enzymatic detoxification systems and BSH-related regulatory mechanisms in S. aureus, which are important for the defense under redox stress conditions. Application of the novel Brx-roGFP2 biosensor provides new insights on the impact of these systems on the BSH redox potential. These thiol switches of S. aureus function in protection against redox active desinfectants and antimicrobials, including HOCl, the AGXX® antimicrobial surface coating, allicin from garlic and the naphthoquinone lapachol. Thus, thiol switches could be novel drug targets for the development of alternative redox-based therapies to combat multi-drug resistant S. aureus isolates.
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Affiliation(s)
- Nico Linzner
- Freie Universität Berlin, Institute of Biology-Microbiology, Königin-Luise-Straße 12-16, D-14195Berlin, Germany
| | - Vu Van Loi
- Freie Universität Berlin, Institute of Biology-Microbiology, Königin-Luise-Straße 12-16, D-14195Berlin, Germany
| | - Verena Nadin Fritsch
- Freie Universität Berlin, Institute of Biology-Microbiology, Königin-Luise-Straße 12-16, D-14195Berlin, Germany
| | - Haike Antelmann
- Freie Universität Berlin, Institute of Biology-Microbiology, Königin-Luise-Straße 12-16, D-14195Berlin, Germany
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5
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Dickerhof N, Paton L, Kettle AJ. Oxidation of bacillithiol by myeloperoxidase-derived oxidants. Free Radic Biol Med 2020; 158:74-83. [PMID: 32629107 DOI: 10.1016/j.freeradbiomed.2020.06.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/08/2020] [Accepted: 06/10/2020] [Indexed: 12/12/2022]
Abstract
Bacillithiol is a major low-molecular-weight thiol in gram-positive firmicutes including the human pathogen Staphylococcus aureus. Bacillithiol is regarded as an important defence mechanism against oxidants produced by the immune system, especially myeloperoxidase-derived hypochlorous acid (HOCl). However, it is unknown how fast BSH reacts with HOCl and what products are formed in the reaction. In the present study, we used sensitive MRM-based LC-MS methods to characterize the reaction of BSH with HOCl in cell-free solutions and in S. aureus. In the cell-free system, BSH formed predominantly the disulfide dimer (BSSB) at low mole ratios of HOCl and the sulfinic and sulfonic acids at higher oxidant concentrations. HOCl also promoted the formation of bacillithiol sulfonamide. In S. aureus, the oxidation pattern was similar except that a small proportion of BSH also formed mixed disulfides with protein thiols. Using competition with methionine, we determined the second-order rate constant for the reaction of HOCl with BSH to be 6 × 107 M-1s-1, which indicated a fast, near diffusion-controlled reaction. Other reactive halogen species, including hypothiocyanous acid (HOSCN), also produced bacillithiol sulfonamide, albeit to a smaller extent than HOCl. The sulfonamide was not produced by hydrogen peroxide, which instead formed BSSB. This study helps our understanding of BSH redox biology and provides tools for gauging the exposure of BSH-producing bacteria to oxidative stress.
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Affiliation(s)
- Nina Dickerhof
- Centre for Free Radical Research, Department of Pathology and Biomedical Science, University of Otago Christchurch, Christchurch, New Zealand.
| | - Louise Paton
- Centre for Free Radical Research, Department of Pathology and Biomedical Science, University of Otago Christchurch, Christchurch, New Zealand
| | - Anthony J Kettle
- Centre for Free Radical Research, Department of Pathology and Biomedical Science, University of Otago Christchurch, Christchurch, New Zealand
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6
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Abstract
Staphylococcus aureus is clearly the most pathogenic member of the Staphylococcaceae. This is in large part due to the acquisition of an impressive arsenal of virulence factors that are coordinately regulated by a series of dedicated transcription factors. What is becoming more and more appreciated in the field is the influence of the metabolic state of S. aureus on the activity of these virulence regulators and their roles in modulating metabolic gene expression. Here I highlight recent advances in S. aureus metabolism as it pertains to virulence. Specifically, mechanisms of nutrient acquisition are outlined including carbohydrate and non-carbohydrate carbon/energy sources as well as micronutrient (Fe, Mn, Zn and S) acquisition. Additionally, energy producing strategies (respiration versus fermentation) are discussed and put in the context of pathogenesis. Finally, transcriptional regulators that coordinate metabolic gene expression are outlined, particularly those that affect the activities of major virulence factor regulators. This chapter essentially connects many recent observations that link the metabolism of S. aureus to its overall pathogenesis and hints that the mere presence of a plethora of virulence factors may not entirely explain the extraordinary pathogenic potential of S. aureus.
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7
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Royer CJ, Cook PD. A structural and functional analysis of the glycosyltransferase BshA from Staphylococcus aureus: Insights into the reaction mechanism and regulation of bacillithiol production. Protein Sci 2019; 28:1083-1094. [PMID: 30968475 DOI: 10.1002/pro.3617] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/05/2019] [Accepted: 04/08/2019] [Indexed: 01/20/2023]
Abstract
Bacillithiol is a glucosamine-derived antioxidant found in several pathogenic Gram-positive bacteria. The compound is involved in maintaining the appropriate redox state within the cell as well as detoxifying foreign agents like the antibiotic fosfomycin. Bacillithiol is produced via the action of three enzymes, including BshA, a retaining GT-B glycosyltransferase that utilizes UDP-N-acetylglucosamine and l-malate to produce N-acetylglucosaminyl-malate. Recent studies suggest that retaining GT-B glycosyltransferases like BshA utilize a substrate-assisted mechanism that goes through an SN i-like transition state. In a previous study, we relied on X-ray crystallography as well as computational simulations to hypothesize the manner in which substrates would bind the enzyme, but several questions about substrate binding and the role of one of the amino acid residues persisted. Another study demonstrated that BshA might be subject to feedback inhibition by bacillithiol, but this phenomenon was not analyzed further to determine the exact mechanism of inhibition. Here we present X-ray crystallographic structures and steady-state kinetics results that help elucidate both of these issues. Our ligand-bound crystal structures demonstrate that the active site provides an appropriate steric and geometric arrangement of ligands to facilitate the substrate-assisted mechanism. Finally, we show that bacillithiol is competitive for UDP-N-acetylglucosamine with a Ki value near 120-130 μM and likely binds within the BshA active site, suggesting that bacillithiol modulates BshA activity via feedback inhibition. The work presented here furthers our understanding of bacillithiol metabolism and can aid in the development of inhibitors to counteract resistance to antibiotics such as fosfomycin.
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Affiliation(s)
| | - Paul D Cook
- Department of Chemistry, Grand Valley State University, Allendale, Michigan
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8
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Rosario-Cruz Z, Eletsky A, Daigham NS, Al-Tameemi H, Swapna GVT, Kahn PC, Szyperski T, Montelione GT, Boyd JM. The copBL operon protects Staphylococcus aureus from copper toxicity: CopL is an extracellular membrane-associated copper-binding protein. J Biol Chem 2019; 294:4027-4044. [PMID: 30655293 PMCID: PMC6422080 DOI: 10.1074/jbc.ra118.004723] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 01/08/2019] [Indexed: 12/22/2022] Open
Abstract
As complications associated with antibiotic resistance have intensified, copper (Cu) is attracting attention as an antimicrobial agent. Recent studies have shown that copper surfaces decrease microbial burden, and host macrophages use Cu to increase bacterial killing. Not surprisingly, microbes have evolved mechanisms to tightly control intracellular Cu pools and protect against Cu toxicity. Here, we identified two genes (copB and copL) encoded within the Staphylococcus aureus arginine-catabolic mobile element (ACME) that we hypothesized function in Cu homeostasis. Supporting this hypothesis, mutational inactivation of copB or copL increased copper sensitivity. We found that copBL are co-transcribed and that their transcription is increased during copper stress and in a strain in which csoR, encoding a Cu-responsive transcriptional repressor, was mutated. Moreover, copB displayed genetic synergy with copA, suggesting that CopB functions in Cu export. We further observed that CopL functions independently of CopB or CopA in Cu toxicity protection and that CopL from the S. aureus clone USA300 is a membrane-bound and surface-exposed lipoprotein that binds up to four Cu+ ions. Solution NMR structures of the homologous Bacillus subtilis CopL, together with phylogenetic analysis and chemical-shift perturbation experiments, identified conserved residues potentially involved in Cu+ coordination. The solution NMR structure also revealed a novel Cu-binding architecture. Of note, a CopL variant with defective Cu+ binding did not protect against Cu toxicity in vivo Taken together, these findings indicate that the ACME-encoded CopB and CopL proteins are additional factors utilized by the highly successful S. aureus USA300 clone to suppress copper toxicity.
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Affiliation(s)
- Zuelay Rosario-Cruz
- From the Department of Biochemistry and Microbiology, Rutgers, the State University of New Jersey, New Brunswick, New Jersey 08901
| | - Alexander Eletsky
- the Department of Chemistry, State University of New York at Buffalo and Northeast Structural Genomics Consortium, Buffalo, New York 14260, and
| | - Nourhan S Daigham
- the Department of Molecular Biology and Biochemistry, Center for Advanced Biotechnology and Medicine, and Northeast Structural Genomics Consortium, Rutgers, the State University of New Jersey, Piscataway, New Jersey 08854
| | - Hassan Al-Tameemi
- From the Department of Biochemistry and Microbiology, Rutgers, the State University of New Jersey, New Brunswick, New Jersey 08901
| | - G V T Swapna
- the Department of Molecular Biology and Biochemistry, Center for Advanced Biotechnology and Medicine, and Northeast Structural Genomics Consortium, Rutgers, the State University of New Jersey, Piscataway, New Jersey 08854
| | - Peter C Kahn
- From the Department of Biochemistry and Microbiology, Rutgers, the State University of New Jersey, New Brunswick, New Jersey 08901
| | - Thomas Szyperski
- the Department of Chemistry, State University of New York at Buffalo and Northeast Structural Genomics Consortium, Buffalo, New York 14260, and
| | - Gaetano T Montelione
- the Department of Molecular Biology and Biochemistry, Center for Advanced Biotechnology and Medicine, and Northeast Structural Genomics Consortium, Rutgers, the State University of New Jersey, Piscataway, New Jersey 08854,
- the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, the State University of New Jersey, Piscataway, New Jersey 08854
| | - Jeffrey M Boyd
- From the Department of Biochemistry and Microbiology, Rutgers, the State University of New Jersey, New Brunswick, New Jersey 08901,
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9
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Mikheyeva IV, Thomas JM, Kolar SL, Corvaglia AR, Gaϊa N, Leo S, Francois P, Liu GY, Rawat M, Cheung AL. YpdA, a putative bacillithiol disulfide reductase, contributes to cellular redox homeostasis and virulence in Staphylococcus aureus. Mol Microbiol 2019; 111:1039-1056. [PMID: 30636083 DOI: 10.1111/mmi.14207] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/27/2018] [Indexed: 11/28/2022]
Abstract
The intracellular redox environment of Staphylococcus aureus is mainly buffered by bacillithiol (BSH), a low molecular weight thiol. The identity of enzymes responsible for the recycling of oxidized bacillithiol disulfide (BSSB) to the reduced form (BSH) remains elusive. We examined YpdA, a putative bacillithiol reductase, for its role in maintaining intracellular redox homeostasis. The ypdA mutant showed increased levels of BSSB and a lower bacillithiol redox ratio vs. the isogenic parent, indicating a higher level of oxidative stress within the bacterial cytosol. We showed that YpdA consumed NAD(P)H; and YpdA protein levels were augmented in response to stress. Wild type strains overexpressing YpdA showed increased tolerance to oxidants and electrophilic agents. Importantly, YpdA overexpression in the parental strain caused an increase in BSH levels accompanied by a decrease in BSSB concentration in the presence of stress, resulting in an increase in bacillithiol redox ratio vs. the vector control. Additionally, the ypdA mutant exhibited decreased survival in human neutrophils (PMNs) as compared with the parent, while YpdA overexpression protected the resulting strain from oxidative stress in vitro and from killing by human neutrophils ex vivo. Taken together, these data present a new role for YpdA in S. aureus physiology and virulence through the bacillithiol system.
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Affiliation(s)
- Irina V Mikheyeva
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Jason M Thomas
- Biology Department, California State University, Fresno, Fresno, CA 93740, USA
| | - Stacey L Kolar
- Department of Pediatrics, Cedars Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Anna-Rita Corvaglia
- Genomic Research Laboratory, Service of Infectious Diseases, University Hospital of Geneva, 1205 Geneva 4, Switzerland
| | - Nadia Gaϊa
- Genomic Research Laboratory, Service of Infectious Diseases, University Hospital of Geneva, 1205 Geneva 4, Switzerland
| | - Stefano Leo
- Genomic Research Laboratory, Service of Infectious Diseases, University Hospital of Geneva, 1205 Geneva 4, Switzerland
| | - Patrice Francois
- Genomic Research Laboratory, Service of Infectious Diseases, University Hospital of Geneva, 1205 Geneva 4, Switzerland
| | - George Y Liu
- Department of Pediatrics, Cedars Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Mamta Rawat
- Biology Department, California State University, Fresno, Fresno, CA 93740, USA
| | - Ambrose L Cheung
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
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10
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Abstract
J. Hiras, S. V. Sharma, V. Raman, R. A. J. Tinson, et al. (mBio 9:e01603-18, 2018, https://doi.org/10.1128/mBio.01603-18) report on the identification of a novel thiol, N-methyl-bacillithiol (N-Me-BSH), in the green sulfur bacterium Chlorobium tepidum In N-methyl-bacillithiol, the amine of the cysteine is methylated by a novel S-adenosylmethioneine transferase designated N-methyl-bacillithiol synthase A (NmbA). The Hiras et al. study is significant because it is the first report of the presence of N-Me-BSH in anaerobic bacteria.
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Affiliation(s)
- Gerald L Newton
- Division of Biological Sciences, University of California, San Diego, San Diego, California, USA
| | - Mamta Rawat
- Department of Biology, California State University-Fresno, Fresno, California, USA
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11
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Imber M, Pietrzyk-Brzezinska AJ, Antelmann H. Redox regulation by reversible protein S-thiolation in Gram-positive bacteria. Redox Biol 2018; 20:130-145. [PMID: 30308476 PMCID: PMC6178380 DOI: 10.1016/j.redox.2018.08.017] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/09/2018] [Accepted: 08/23/2018] [Indexed: 12/21/2022] Open
Abstract
Low molecular weight (LMW) thiols play an important role as thiol-cofactors for many enzymes and are crucial to maintain the reduced state of the cytoplasm. Most Gram-negative bacteria utilize glutathione (GSH) as major LMW thiol. However, in Gram-positive Actinomycetes and Firmicutes alternative LMW thiols, such as mycothiol (MSH) and bacillithiol (BSH) play related roles as GSH surrogates, respectively. Under conditions of hypochlorite stress, MSH and BSH are known to form mixed disulfides with protein thiols, termed as S-mycothiolation or S-bacillithiolation that function in thiol-protection and redox regulation. Protein S-thiolations are widespread redox-modifications discovered in different Gram-positive bacteria, such as Bacillus and Staphylococcus species, Mycobacterium smegmatis, Corynebacterium glutamicum and Corynebacterium diphtheriae. S-thiolated proteins are mainly involved in cellular metabolism, protein translation, redox regulation and antioxidant functions with some conserved targets across bacteria. The reduction of protein S-mycothiolations and S-bacillithiolations requires glutaredoxin-related mycoredoxin and bacilliredoxin pathways to regenerate protein functions. In this review, we present an overview of the functions of mycothiol and bacillithiol and their physiological roles in protein S-bacillithiolations and S-mycothiolations in Gram-positive bacteria. Significant progress has been made to characterize the role of protein S-thiolation in redox-regulation and thiol protection of main metabolic and antioxidant enzymes. However, the physiological roles of the pathways for regeneration are only beginning to emerge as well as their interactions with other cellular redox systems. Future studies should be also directed to explore the roles of protein S-thiolations and their redox pathways in pathogenic bacteria under infection conditions to discover new drug targets and treatment options against multiple antibiotic resistant bacteria. Bacillithiol and mycothiol are major LMW thiols in many Gram-positive bacteria. HOCl leads to widespread protein S-mycothiolation and S-bacillithiolation which function in thiol-protection and redox regulation. Redox-sensitive metabolic and antioxidant enzymes are main targets for S-mycothiolation or S-bacillithiolation. Mycoredoxin and bacilliredoxin pathways mediate reduction of S-thiolations.
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Affiliation(s)
- Marcel Imber
- Freie Universität Berlin, Institute for Biology-Microbiology, Königin-Luise-Strasse 12-16, D-14195 Berlin, Germany
| | - Agnieszka J Pietrzyk-Brzezinska
- Freie Universität Berlin, Laboratory of Structural Biochemistry, D-14195 Berlin, Germany; Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Lodz 90-924, Poland
| | - Haike Antelmann
- Freie Universität Berlin, Institute for Biology-Microbiology, Königin-Luise-Strasse 12-16, D-14195 Berlin, Germany.
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12
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Pseudomonas aeruginosa gshA Mutant Is Defective in Biofilm Formation, Swarming, and Pyocyanin Production. mSphere 2018; 3:3/2/e00155-18. [PMID: 29669887 PMCID: PMC5907650 DOI: 10.1128/msphere.00155-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 03/24/2018] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa is a ubiquitous bacterium that can cause severe opportunistic infections, including many hospital-acquired infections. It is also a major cause of infections in patients with cystic fibrosis. P. aeruginosa is intrinsically resistant to a number of drugs and is capable of forming biofilms that are difficult to eradicate with antibiotics. The number of drug-resistant strains is also increasing, making treatment of P. aeruginosa infections very difficult. Thus, there is an urgent need to understand how P. aeruginosa causes disease in order to find novel ways to treat infections. We show that the principal redox buffer, glutathione (GSH), is involved in intrinsic resistance to the fosfomycin and rifampin antibiotics. We further demonstrate that GSH plays a role in P. aeruginosa disease and infection, since a mutant lacking GSH has less biofilm formation, is less able to swarm, and produces less pyocyanin, a pigment associated with infection. Pseudomonas aeruginosa is a ubiquitous Gram-negative bacterium that can cause severe opportunistic infections. The principal redox buffer employed by this organism is glutathione (GSH). To assess the role of GSH in the virulence of P. aeruginosa, a number of analyses were performed using a mutant strain deficient in gshA, which does not produce GSH. The mutant strain exhibited a growth delay in minimal medium compared to the wild-type strain. Furthermore, the gshA mutant was defective in biofilm and persister cell formation and in swimming and swarming motility and produced reduced levels of pyocyanin, a key virulence factor. Finally, the gshA mutant strain demonstrated increased sensitivity to methyl viologen (a redox cycling agent) as well as the thiol-reactive antibiotics fosfomycin and rifampin. Taken together, these data suggest a key role for GSH in the virulence of P. aeruginosa. IMPORTANCEPseudomonas aeruginosa is a ubiquitous bacterium that can cause severe opportunistic infections, including many hospital-acquired infections. It is also a major cause of infections in patients with cystic fibrosis. P. aeruginosa is intrinsically resistant to a number of drugs and is capable of forming biofilms that are difficult to eradicate with antibiotics. The number of drug-resistant strains is also increasing, making treatment of P. aeruginosa infections very difficult. Thus, there is an urgent need to understand how P. aeruginosa causes disease in order to find novel ways to treat infections. We show that the principal redox buffer, glutathione (GSH), is involved in intrinsic resistance to the fosfomycin and rifampin antibiotics. We further demonstrate that GSH plays a role in P. aeruginosa disease and infection, since a mutant lacking GSH has less biofilm formation, is less able to swarm, and produces less pyocyanin, a pigment associated with infection.
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Abstract
SIGNIFICANCE Since the discovery and structural characterization of bacillithiol (BSH), the biochemical functions of BSH-biosynthesis enzymes (BshA/B/C) and BSH-dependent detoxification enzymes (FosB, Bst, GlxA/B) have been explored in Bacillus and Staphylococcus species. It was shown that BSH plays an important role in detoxification of reactive oxygen and electrophilic species, alkylating agents, toxins, and antibiotics. Recent Advances: More recently, new functions of BSH were discovered in metal homeostasis (Zn buffering, Fe-sulfur cluster, and copper homeostasis) and virulence control in Staphylococcus aureus. Unexpectedly, strains of the S. aureus NCTC8325 lineage were identified as natural BSH-deficient mutants. Modern mass spectrometry-based approaches have revealed the global reach of protein S-bacillithiolation in Firmicutes as an important regulatory redox modification under hypochlorite stress. S-bacillithiolation of OhrR, MetE, and glyceraldehyde-3-phosphate dehydrogenase (Gap) functions, analogous to S-glutathionylation, as both a redox-regulatory device and in thiol protection under oxidative stress. CRITICAL ISSUES Although the functions of the bacilliredoxin (Brx) pathways in the reversal of S-bacillithiolations have been recently addressed, significantly more work is needed to establish the complete Brx reduction pathway, including the major enzyme(s), for reduction of oxidized BSH (BSSB) and the targets of Brx action in vivo. FUTURE DIRECTIONS Despite the large number of identified S-bacillithiolated proteins, the physiological relevance of this redox modification was shown for only selected targets and should be a subject of future studies. In addition, many more BSH-dependent detoxification enzymes are evident from previous studies, although their roles and biochemical mechanisms require further study. This review of BSH research also pin-points these missing gaps for future research. Antioxid. Redox Signal. 28, 445-462.
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Affiliation(s)
- Pete Chandrangsu
- 1 Department of Microbiology, Cornell University , Ithaca, New York
| | - Vu Van Loi
- 2 Institute for Biology-Microbiology , Freie Universität Berlin, Berlin, Germany
| | - Haike Antelmann
- 2 Institute for Biology-Microbiology , Freie Universität Berlin, Berlin, Germany
| | - John D Helmann
- 1 Department of Microbiology, Cornell University , Ithaca, New York
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14
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Perera VR, Lapek JD, Newton GL, Gonzalez DJ, Pogliano K. Identification of the S-transferase like superfamily bacillithiol transferases encoded by Bacillus subtilis. PLoS One 2018; 13:e0192977. [PMID: 29451913 PMCID: PMC5815605 DOI: 10.1371/journal.pone.0192977] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 02/01/2018] [Indexed: 11/18/2022] Open
Abstract
Bacillithiol is a low molecular weight thiol found in Firmicutes that is analogous to glutathione, which is absent in these bacteria. Bacillithiol transferases catalyze the transfer of bacillithiol to various substrates. The S-transferase-like (STL) superfamily contains over 30,000 putative members, including bacillithiol transferases. Proteins in this family are extremely divergent and are related by structural rather than sequence similarity, leaving it unclear if all share the same biochemical activity. Bacillus subtilis encodes eight predicted STL superfamily members, only one of which has been shown to be a bacillithiol transferase. Here we find that the seven remaining proteins show varying levels of metal dependent bacillithiol transferase activity. We have renamed the eight enzymes BstA-H. Mass spectrometry and gene expression studies revealed that all of the enzymes are produced to varying levels during growth and sporulation, with BstB and BstE being the most abundant and BstF and BstH being the least abundant. Interestingly, several bacillithiol transferases are induced in the mother cell during sporulation. A strain lacking all eight bacillithiol transferases showed normal growth in the presence of stressors that adversely affect growth of bacillithiol-deficient strains, such as paraquat and CdCl2. Thus, the STL bacillithiol transferases represent a new group of proteins that play currently unknown, but potentially significant roles in bacillithiol-dependent reactions. We conclude that these enzymes are highly divergent, perhaps to cope with an equally diverse array of endogenous or exogenous toxic metabolites and oxidants.
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Affiliation(s)
- Varahenage R. Perera
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, United States of America
| | - John D. Lapek
- Department of Pharmacology and Pharmacy, School of Medicine, University of California, San Diego, La Jolla, CA, United States of America
| | - Gerald L. Newton
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, United States of America
| | - David J. Gonzalez
- Department of Pharmacology and Pharmacy, School of Medicine, University of California, San Diego, La Jolla, CA, United States of America
| | - Kit Pogliano
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, United States of America
- * E-mail:
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Bihani SC, Panicker L, Rajpurohit YS, Misra HS, Kumar V. drFrnE Represents a Hitherto Unknown Class of Eubacterial Cytoplasmic Disulfide Oxido-Reductases. Antioxid Redox Signal 2018; 28:296-310. [PMID: 28899103 DOI: 10.1089/ars.2016.6960] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
AIMS Living cells employ thioredoxin and glutaredoxin disulfide oxido-reductases to protect thiol groups in intracellular proteins. FrnE protein of Deinococcus radiodurans (drFrnE) is a disulfide oxido-reductase that is induced in response to Cd2+ exposure and is involved in cadmium and radiation tolerance. The aim of this study is to probe structure, function, and cellular localization of FrnE class of proteins. RESULTS Here, we show drFrnE as a novel cytoplasmic oxido-reductase that could be functional in eubacteria under conditions where thioredoxin/glutaredoxin systems are inhibited or absent. Crystal structure analysis of drFrnE reveals thioredoxin fold with an alpha helical insertion domain and a unique, flexible, and functionally important C-terminal tail. The C-tail harbors a novel 239-CX4C-244 motif that interacts with the active site 22-CXXC-25 motif. Crystal structures with different active site redox states, including mixed disulfide (Cys22-Cys244), are reported here. The biochemical data show that 239-CX4C-244 motif channels electrons to the active site cysteines. drFrnE is more stable in the oxidized form, compared with the reduced form, supporting its role as a disulfide reductase. Using bioinformatics analysis and fluorescence microscopy, we show cytoplasmic localization of drFrnE. We have found "true" orthologs of drFrnE in several eubacterial phyla and, interestingly, all these groups apparently lack a functional glutaredoxin system. Innovation and Conclusion: We show that drFrnE represents a new class of hitherto unknown intracellular oxido-reductases that are abundantly present in eubacteria. Unlike other well-known oxido-reductases, FrnE harbors an additional dithiol motif that acts as a conduit to channel electrons to the active site during catalytic turnover. Antioxid. Redox Signal. 28, 296-310.
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Affiliation(s)
- Subhash C Bihani
- 1 Protein Crystallography Section, Radiation Biology & Health Sciences Division, Bhabha Atomic Research Centre , Mumbai, India
| | - Lata Panicker
- 1 Protein Crystallography Section, Radiation Biology & Health Sciences Division, Bhabha Atomic Research Centre , Mumbai, India
| | | | - Hari S Misra
- 2 Molecular Biology Division, Bhabha Atomic Research Centre , Mumbai, India .,3 Life Sciences, Homi Bhabha National Institute , Mumbai, India
| | - Vinay Kumar
- 1 Protein Crystallography Section, Radiation Biology & Health Sciences Division, Bhabha Atomic Research Centre , Mumbai, India .,3 Life Sciences, Homi Bhabha National Institute , Mumbai, India
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16
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Loi VV, Harms M, Müller M, Huyen NTT, Hamilton CJ, Hochgräfe F, Pané-Farré J, Antelmann H. Real-Time Imaging of the Bacillithiol Redox Potential in the Human Pathogen Staphylococcus aureus Using a Genetically Encoded Bacilliredoxin-Fused Redox Biosensor. Antioxid Redox Signal 2017; 26:835-848. [PMID: 27462976 PMCID: PMC5444506 DOI: 10.1089/ars.2016.6733] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
AIMS Bacillithiol (BSH) is utilized as a major thiol-redox buffer in the human pathogen Staphylococcus aureus. Under oxidative stress, BSH forms mixed disulfides with proteins, termed as S-bacillithiolation, which can be reversed by bacilliredoxins (Brx). In eukaryotes, glutaredoxin-fused roGFP2 biosensors have been applied for dynamic live imaging of the glutathione redox potential. Here, we have constructed a genetically encoded bacilliredoxin-fused redox biosensor (Brx-roGFP2) to monitor dynamic changes in the BSH redox potential in S. aureus. RESULTS The Brx-roGFP2 biosensor showed a specific and rapid response to low levels of bacillithiol disulfide (BSSB) in vitro that required the active-site Cys of Brx. Dynamic live imaging in two methicillin-resistant S. aureus (MRSA) USA300 and COL strains revealed fast and dynamic responses of the Brx-roGFP2 biosensor under hypochlorite and hydrogen peroxide (H2O2) stress and constitutive oxidation of the probe in different BSH-deficient mutants. Furthermore, we found that the Brx-roGFP2 expression level and the dynamic range are higher in S. aureus COL compared with the USA300 strain. In phagocytosis assays with THP-1 macrophages, the biosensor was 87% oxidized in S. aureus COL. However, no changes in the BSH redox potential were measured after treatment with different antibiotics classes, indicating that antibiotics do not cause oxidative stress in S. aureus. Conclusion and Innovation: This Brx-roGFP2 biosensor catalyzes specific equilibration between the BSH and roGFP2 redox couples and can be applied for dynamic live imaging of redox changes in S. aureus and other BSH-producing Firmicutes. Antioxid. Redox Signal. 26, 835-848.
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Affiliation(s)
- Vu Van Loi
- 1 Institute for Biology-Microbiology, Freie Universität Berlin , Berlin, Germany
| | - Manuela Harms
- 2 Junior Research Group Pathoproteomics, Ernst-Moritz-Arndt-University of Greifswald , Greifswald, Germany
| | - Marret Müller
- 3 Institute for Microbiology, Ernst-Moritz-Arndt-University of Greifswald , Greifswald, Germany
| | - Nguyen Thi Thu Huyen
- 1 Institute for Biology-Microbiology, Freie Universität Berlin , Berlin, Germany
| | - Chris J Hamilton
- 4 School of Pharmacy, University of East Anglia , Norwich Research Park, Norwich, United Kingdom
| | - Falko Hochgräfe
- 2 Junior Research Group Pathoproteomics, Ernst-Moritz-Arndt-University of Greifswald , Greifswald, Germany
| | - Jan Pané-Farré
- 3 Institute for Microbiology, Ernst-Moritz-Arndt-University of Greifswald , Greifswald, Germany
| | - Haike Antelmann
- 1 Institute for Biology-Microbiology, Freie Universität Berlin , Berlin, Germany
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17
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Singh AR, Strankman A, Orkusyan R, Purwantini E, Rawat M. Lack of mycothiol and ergothioneine induces different protective mechanisms in Mycobacterium smegmatis. Biochem Biophys Rep 2016; 8:100-106. [PMID: 28220152 PMCID: PMC5315357 DOI: 10.1016/j.bbrep.2016.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Mycobacterium smegmatis contains the low molecular weight thiols, mycothiol (MSH) and ergothioneine (ESH). Examination of transposon mutants disrupted in mshC and egtA, involved in the biosynthesis of MSH and ESH respectively, demonstrated that both mutants were sensitive to oxidative, alkylating, and metal stress. However, the mshC mutant exhibited significantly more protein carbonylation and lipid peroxidation than wildtype, while the egtA mutant had less protein and lipid damage than wildtype. We further show that Ohr, KatN, and AhpC, involved in protection against oxidative stress, are upregulated in the egtA mutant. In the mshC mutant, an Usp and a putative thiol peroxidase are upregulated. In addition, mutants lacking MSH also contained higher levels of Coenzyme F420 as compared to wildtype and two Coenzyme F420 dependent enzymes were found to be upregulated. These results indicate that lack of MSH and ESH result in induction of different mechanisms for protecting against oxidative stress.
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Affiliation(s)
| | - Andrew Strankman
- Department of Biology, California State University, Fresno, Fresno, CA 93740, United States
| | - Ruzan Orkusyan
- Department of Biology, California State University, Fresno, Fresno, CA 93740, United States
| | - Endang Purwantini
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States
| | - Mamta Rawat
- Department of Biology, California State University, Fresno, Fresno, CA 93740, United States
- Corresponding author.
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18
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Beavers WN, Skaar EP. Neutrophil-generated oxidative stress and protein damage in Staphylococcus aureus. Pathog Dis 2016; 74:ftw060. [PMID: 27354296 DOI: 10.1093/femspd/ftw060] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/08/2016] [Indexed: 01/06/2023] Open
Abstract
Staphylococcus aureus is a ubiquitous, versatile and dangerous pathogen. It colonizes over 30% of the human population, and is one of the leading causes of death by an infectious agent. During S. aureus colonization and invasion, leukocytes are recruited to the site of infection. To combat S. aureus, leukocytes generate an arsenal of reactive species including superoxide, hydrogen peroxide, nitric oxide and hypohalous acids that modify and inactivate cellular macromolecules, resulting in growth defects or death. When S. aureus colonization cannot be cleared by the immune system, antibiotic treatment is necessary and can be effective. Yet, this organism quickly gains resistance to each new antibiotic it encounters. Therefore, it is in the interest of human health to acquire a deeper understanding of how S. aureus evades killing by the immune system. Advances in this field will have implications for the design of future S. aureus treatments that complement and assist the host immune response. In that regard, this review focuses on how S. aureus avoids host-generated oxidative stress, and discusses the mechanisms used by S. aureus to survive oxidative damage including antioxidants, direct repair of damaged proteins, sensing oxidant stress and transcriptional changes. This review will elucidate areas for studies to identify and validate future antimicrobial targets.
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Affiliation(s)
- William N Beavers
- Department of Pathology, Microbiology and Immunology, U.S. Department of Veteran Affairs, Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, 1161 21st Avenue South, Medical Center North, Nashville, TN 37232, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology and Immunology, U.S. Department of Veteran Affairs, Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, 1161 21st Avenue South, Medical Center North, Nashville, TN 37232, USA Tennessee Valley Healthcare System, U.S. Department of Veteran Affairs, Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, 1161 21st Avenue South, Nashville, TN 37232, USA
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19
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Rosario-Cruz Z, Boyd JM. Physiological roles of bacillithiol in intracellular metal processing. Curr Genet 2015; 62:59-65. [PMID: 26259870 DOI: 10.1007/s00294-015-0511-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 07/24/2015] [Accepted: 07/25/2015] [Indexed: 01/22/2023]
Abstract
Glutathione (GSH) is an abundantly produced low-molecular-weight (LMW) thiol in many organisms. However, a number of Gram-positive bacteria do not produce GSH, but instead produce bacillithiol (BSH) as one of the major LMW thiols. Similar to GSH, studies have found that BSH has various roles in the cell, including protection against hydrogen peroxide, hypochlorite and disulfide stress. BSH also participates in the detoxification of thiol-reactive antibiotics and the electrophilic metabolite methylglyoxal. Recently, a number of studies have highlighted additional roles for BSH in the processing of intracellular metals. Herein, we examine the potential functions of BSH in the biogenesis of Fe-S clusters, cytosolic metal buffering and the prevention of metal intoxication.
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Affiliation(s)
- Zuelay Rosario-Cruz
- Department of Biochemistry and Microbiology, Rutgers University, 76 Lipman Drive, New Brunswick, NJ, 08901, USA
| | - Jeffrey M Boyd
- Department of Biochemistry and Microbiology, Rutgers University, 76 Lipman Drive, New Brunswick, NJ, 08901, USA.
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20
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Rosario-Cruz Z, Chahal HK, Mike LA, Skaar EP, Boyd JM. Bacillithiol has a role in Fe-S cluster biogenesis in Staphylococcus aureus. Mol Microbiol 2015; 98:218-42. [PMID: 26135358 DOI: 10.1111/mmi.13115] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/30/2015] [Indexed: 01/20/2023]
Abstract
Staphylococcus aureus does not produce the low-molecular-weight (LMW) thiol glutathione, but it does produce the LMW thiol bacillithiol (BSH). To better understand the roles that BSH plays in staphylococcal metabolism, we constructed and examined strains lacking BSH. Phenotypic analysis found that the BSH-deficient strains cultured either aerobically or anaerobically had growth defects that were alleviated by the addition of exogenous iron (Fe) or the amino acids leucine and isoleucine. The activities of the iron-sulfur (Fe-S) cluster-dependent enzymes LeuCD and IlvD, which are required for the biosynthesis of leucine and isoleucine, were decreased in strains lacking BSH. The BSH-deficient cells also had decreased aconitase and glutamate synthase activities, suggesting a general defect in Fe-S cluster biogenesis. The phenotypes of the BSH-deficient strains were exacerbated in strains lacking the Fe-S cluster carrier Nfu and partially suppressed by multicopy expression of either sufA or nfu, suggesting functional overlap between BSH and Fe-S carrier proteins. Biochemical analysis found that SufA bound and transferred Fe-S clusters to apo-aconitase, verifying that it serves as an Fe-S cluster carrier. The results presented are consistent with the hypothesis that BSH has roles in Fe homeostasis and the carriage of Fe-S clusters to apo-proteins in S. aureus.
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Affiliation(s)
- Zuelay Rosario-Cruz
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Harsimranjit K Chahal
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Laura A Mike
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Jeffrey M Boyd
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ, 08901, USA
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21
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Perera VR, Newton GL, Pogliano K. Bacillithiol: a key protective thiol in Staphylococcus aureus. Expert Rev Anti Infect Ther 2015; 13:1089-107. [PMID: 26184907 DOI: 10.1586/14787210.2015.1064309] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Bacillithiol is a low-molecular-weight thiol analogous to glutathione and is found in several Firmicutes, including Staphylococcus aureus. Since its discovery in 2009, bacillithiol has been a topic of interest because it has been found to contribute to resistance during oxidative stress and detoxification of electrophiles, such as the antibiotic fosfomycin, in S. aureus. The rapid increase in resistance of methicillin-resistant Staphylococcus aureus (MRSA) to available therapeutic agents is a great health concern, and many research efforts are focused on identifying new drugs and targets to combat this organism. This review describes the discovery of bacillithiol, studies that have elucidated the physiological roles of this molecule in S. aureus and other Bacilli, and the contribution of bacillithiol to S. aureus fitness during pathogenesis. Additionally, the bacillithiol biosynthesis pathway is evaluated as a novel drug target that can be utilized in combination with existing therapies to treat S. aureus infections.
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Affiliation(s)
- Varahenage R Perera
- Division of Biological Sciences, University of California at San Diego, 9500 Gilman Drive, Natural Sciences Building 4113, La Jolla, CA 92093-0377, USA
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22
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Loi VV, Rossius M, Antelmann H. Redox regulation by reversible protein S-thiolation in bacteria. Front Microbiol 2015; 6:187. [PMID: 25852656 PMCID: PMC4360819 DOI: 10.3389/fmicb.2015.00187] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 02/20/2015] [Indexed: 12/31/2022] Open
Abstract
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.
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Affiliation(s)
- Vu Van Loi
- Institute of Microbiology, Ernst-Moritz-Arndt-University of Greifswald Greifswald, Germany
| | - Martina Rossius
- Institute of Microbiology, Ernst-Moritz-Arndt-University of Greifswald Greifswald, Germany
| | - Haike Antelmann
- Institute of Microbiology, Ernst-Moritz-Arndt-University of Greifswald Greifswald, Germany
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Begg SL, Eijkelkamp BA, Luo Z, Couñago RM, Morey JR, Maher MJ, Ong CLY, McEwan AG, Kobe B, O'Mara ML, Paton JC, McDevitt CA. Dysregulation of transition metal ion homeostasis is the molecular basis for cadmium toxicity in Streptococcus pneumoniae. Nat Commun 2015; 6:6418. [PMID: 25731976 PMCID: PMC4366526 DOI: 10.1038/ncomms7418] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 01/27/2015] [Indexed: 11/30/2022] Open
Abstract
Cadmium is a transition metal ion that is highly toxic in biological systems. Although relatively rare in the Earth’s crust, anthropogenic release of cadmium since industrialization has increased biogeochemical cycling and the abundance of the ion in the biosphere. Despite this, the molecular basis of its toxicity remains unclear. Here we combine metal-accumulation assays, high-resolution structural data and biochemical analyses to show that cadmium toxicity, in Streptococcus pneumoniae, occurs via perturbation of first row transition metal ion homeostasis. We show that cadmium uptake reduces the millimolar cellular accumulation of manganese and zinc, and thereby increases sensitivity to oxidative stress. Despite this, high cellular concentrations of cadmium (~17 mM) are tolerated, with negligible impact on growth or sensitivity to oxidative stress, when manganese and glutathione are abundant. Collectively, this work provides insight into the molecular basis of cadmium toxicity in prokaryotes, and the connection between cadmium accumulation and oxidative stress. The molecular basis for the high toxicity of cadmium is unclear. Here, Begg et al. use the bacterium Streptococcus pneumoniae as a model system, and show that cadmium uptake increases sensitivity to oxidative stress by reducing intracellular concentrations of manganese and zinc through different mechanisms.
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Affiliation(s)
- Stephanie L Begg
- Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 4072, Australia
| | - Bart A Eijkelkamp
- Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 4072, Australia
| | - Zhenyao Luo
- 1] School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia [2] Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland 4072, Australia [3] Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Rafael M Couñago
- 1] School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia [2] Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland 4072, Australia [3] Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Jacqueline R Morey
- Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 4072, Australia
| | - Megan J Maher
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia
| | - Cheryl-Lynn Y Ong
- 1] School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia [2] Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Alastair G McEwan
- 1] School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia [2] Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Bostjan Kobe
- 1] School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia [2] Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland 4072, Australia [3] Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Megan L O'Mara
- 1] School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia [2] School of Mathematics and Physics, University of Queensland, Brisbane, Queensland 4072, Australia
| | - James C Paton
- Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 4072, Australia
| | - Christopher A McDevitt
- Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 4072, Australia
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24
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Perera VR, Newton GL, Parnell JM, Komives EA, Pogliano K. Purification and characterization of the Staphylococcus aureus bacillithiol transferase BstA. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1840:2851-61. [PMID: 24821014 PMCID: PMC4802972 DOI: 10.1016/j.bbagen.2014.05.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 04/30/2014] [Accepted: 05/02/2014] [Indexed: 11/26/2022]
Abstract
BACKGROUND Gram-positive bacteria in the phylum Firmicutes synthesize the low molecular weight thiol bacillithiol rather than glutathione or mycothiol. The bacillithiol transferase YfiT from Bacillus subtilis was identified as a new member of the recently discovered DinB/YfiT-like Superfamily. Based on structural similarity using the Superfamily program, we have determined 30 of 31 Staphylococcus aureus strains encode a single bacillithiol transferase from the DinB/YfiT-like Superfamily, while the remaining strain encodes two proteins. METHODS We have cloned, purified, and confirmed the activity of a recombinant bacillithiol transferase (henceforth called BstA) encoded by the S. aureus Newman ORF NWMN_2591. Moreover, we have studied the saturation kinetics and substrate specificity of this enzyme using in vitro biochemical assays. RESULTS BstA was found to be active with the co-substrate bacillithiol, but not with other low molecular weight thiols tested. BstA catalyzed bacillithiol conjugation to the model substrates monochlorobimane, 1-chloro-2,4-dinitrobenzene, and the antibiotic cerulenin. Several other molecules, including the antibiotic rifamycin S, were found to react directly with bacillithiol, but the addition of BstA did not enhance the rate of reaction. Furthermore, cells growing in nutrient rich medium exhibited low BstA activity. CONCLUSIONS BstA is a bacillithiol transferase from S. aureus that catalyzes the detoxification of cerulenin. Additionally, we have determined that bacillithiol itself might be capable of directly detoxifying electrophilic molecules. GENERAL SIGNIFICANCE BstA is an active bacillithiol transferase from S. aureus Newman and is the first DinB/YfiT-like Superfamily member identified from this organism. Interestingly, BstA is highly divergent from B. subtilis YfiT.
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Affiliation(s)
- Varahenage R Perera
- Division of Biological Sciences, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0377
| | - Gerald L Newton
- Division of Biological Sciences, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0377
| | - Jonathan M Parnell
- Department of Chemistry and Biochemistry, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0378
| | - Elizabeth A Komives
- Department of Chemistry and Biochemistry, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0378
| | - Kit Pogliano
- Division of Biological Sciences, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0377.
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25
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Thompson MK, Keithly ME, Goodman MC, Hammer ND, Cook PD, Jagessar KL, Harp J, Skaar EP, Armstrong RN. Structure and function of the genomically encoded fosfomycin resistance enzyme, FosB, from Staphylococcus aureus. Biochemistry 2014; 53:755-65. [PMID: 24447055 PMCID: PMC3985756 DOI: 10.1021/bi4015852] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
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The
Gram-positive pathogen Staphylococcus aureus is a
leading cause of global morbidity and mortality. Like many
multi-drug-resistant organisms, S. aureus contains
antibiotic-modifying enzymes that facilitate resistance to a multitude
of antimicrobial compounds. FosB is a Mn2+-dependent fosfomycin-inactivating
enzyme found in S. aureus that catalyzes nucleophilic
addition of either l-cysteine (l-Cys) or bacillithiol
(BSH) to the antibiotic, resulting in a modified compound with no
bactericidal properties. The three-dimensional X-ray crystal structure
of FosB from S. aureus (FosBSa) has been determined to a resolution of 1.15 Å. Cocrystallization
of FosBSa with either l-Cys or
BSH results in a disulfide bond between the exogenous thiol and the
active site Cys9 of the enzyme. An analysis of the structures suggests
that a highly conserved loop region of the FosB enzymes must change
conformation to bind fosfomycin. While two crystals of FosBSa contain Zn2+ in the active site, kinetic
analyses of FosBSa indicated that the
enzyme is inhibited by Zn2+ for l-Cys transferase
activity and only marginally active for BSH transferase activity.
Fosfomycin-treated disk diffusion assays involving S. aureus Newman and the USA300 JE2 methicillin-resistant S. aureus demonstrate a marked increase in the sensitivity of the organism
to the antibiotic in either the BSH or FosB null strains, indicating
that both are required for survival of the organism in the presence
of the antibiotic. This work identifies FosB as a primary fosfomycin-modifying
pathway of S. aureus and establishes the enzyme as
a potential therapeutic target for increased efficacy of fosfomycin
against the pathogen.
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Affiliation(s)
- Matthew K Thompson
- Department of Biochemistry, Vanderbilt University School of Medicine , Nashville, Tennessee 37232, United States
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Sharma SV, Arbach M, Roberts AA, Macdonald CJ, Groom M, Hamilton CJ. Biophysical features of bacillithiol, the glutathione surrogate of Bacillus subtilis and other firmicutes. Chembiochem 2013; 14:2160-8. [PMID: 24115506 PMCID: PMC4065351 DOI: 10.1002/cbic.201300404] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Indexed: 11/28/2022]
Abstract
Bacillithiol (BSH) is the major low-molecular-weight (LMW) thiol in many low-G+C Gram-positive bacteria (Firmicutes). Evidence now emerging suggests that BSH functions as an important LMW thiol in redox regulation and xenobiotic detoxification, analogous to what is already known for glutathione and mycothiol in other microorganisms. The biophysical properties and cellular concentrations of such LMW thiols are important determinants of their biochemical efficiency both as biochemical nucleophiles and as redox buffers. Here, BSH has been characterised and compared with other LMW thiols in terms of its thiol pKa , redox potential and thiol-disulfide exchange reactivity. Both the thiol pKa and the standard thiol redox potential of BSH are shown to be significantly lower than those of glutathione whereas the reactivities of the two compounds in thiol-disulfide reactions are comparable. The cellular concentration of BSH in Bacillus subtilis varied over different growth phases and reached up to 5 mM, which is significantly greater than previously observed from single measurements taken during mid-exponential growth. These results demonstrate that the biophysical characteristics of BSH are distinctively different from those of GSH and that its cellular concentrations can reach levels much higher than previously reported.
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Affiliation(s)
- Sunil V Sharma
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ (UK)
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27
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Importance of bacillithiol in the oxidative stress response of Staphylococcus aureus. Infect Immun 2013; 82:316-32. [PMID: 24166956 DOI: 10.1128/iai.01074-13] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In Staphylococcus aureus, the low-molecular-weight thiol called bacillithiol (BSH), together with cognate S-transferases, is believed to be the counterpart to the glutathione system of other organisms. To explore the physiological role of BSH in S. aureus, we constructed mutants with the deletion of bshA (sa1291), which encodes the glycosyltransferase that catalyzes the first step of BSH biosynthesis, and fosB (sa2124), which encodes a BSH-S-transferase that confers fosfomycin resistance, in several S. aureus strains, including clinical isolates. Mutation of fosB or bshA caused a 16- to 60-fold reduction in fosfomycin resistance in these S. aureus strains. High-pressure liquid chromatography analysis, which quantified thiol extracts, revealed some variability in the amounts of BSH present across S. aureus strains. Deletion of fosB led to a decrease in BSH levels. The fosB and bshA mutants of strain COL and a USA300 isolate, upon further characterization, were found to be sensitive to H2O2 and exhibited decreased NADPH levels compared with those in the isogenic parents. Microarray analyses of COL and the isogenic bshA mutant revealed increased expression of genes involved in staphyloxanthin synthesis in the bshA mutant relative to that in COL under thiol stress conditions. However, the bshA mutant of COL demonstrated decreased survival compared to that of the parent in human whole-blood survival assays; likewise, the naturally BSH-deficient strain SH1000 survived less well than its BSH-producing isogenic counterpart. Thus, the survival of S. aureus under oxidative stress is facilitated by BSH, possibly via a FosB-mediated mechanism, independently of its capability to produce staphyloxanthin.
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