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Gray MJ. The role of metals in hypothiocyanite resistance in Escherichia coli. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.07.583962. [PMID: 38496647 PMCID: PMC10942458 DOI: 10.1101/2024.03.07.583962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
The innate immune system employs a variety of antimicrobial oxidants to control and kill host-associated bacteria. Hypothiocyanite/hypothiocyanous acid (-OSCN/HOSCN) is one such antimicrobial oxidant that is synthesized by lactoperoxidase, myeloperoxidase, and eosinophil peroxidase at sites throughout the human body. HOSCN has potent antibacterial activity while being largely non-toxic towards human cells. The molecular mechanisms by which bacteria sense and defend themselves against HOSCN have only recently begun to be elaborated, notably by the discovery of bacterial HOSCN reductase (RclA), an HOSCN-degrading enzyme widely conserved among bacteria that live on epithelial surfaces. In this paper, I show that Ni2+ sensitizes Escherichia coli to HOSCN by inhibiting glutathione reductase, and that inorganic polyphosphate protects E. coli against this effect, probably by chelating Ni2+ ions. I also found that RclA is very sensitive to inhibition by Cu2+ and Zn2+, metals that are accumulated to high levels by innate immune cells, and that, surprisingly, thioredoxin and thioredoxin reductase are not involved in HOSCN stress resistance in E. coli. These results advance our understanding of the contribution of different oxidative stress response and redox buffering pathways to HOSCN resistance in E. coli and illustrate important interactions between metal ions and the enzymes bacteria use to defend themselves against oxidative stress.
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Affiliation(s)
- Michael J. Gray
- Department of Microbiology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Loi VV, Busche T, Schnaufer F, Kalinowski J, Antelmann H. The neutrophil oxidant hypothiocyanous acid causes a thiol-specific stress response and an oxidative shift of the bacillithiol redox potential in Staphylococcus aureus. Microbiol Spectr 2023; 11:e0325223. [PMID: 37930020 PMCID: PMC10715087 DOI: 10.1128/spectrum.03252-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 10/02/2023] [Indexed: 11/07/2023] Open
Abstract
IMPORTANCE Staphylococcus aureus colonizes the skin and the airways but can also lead to life-threatening systemic and chronic infections. During colonization and phagocytosis by immune cells, S. aureus encounters the thiol-reactive oxidant HOSCN. The understanding of the adaptation mechanisms of S. aureus toward HOSCN stress is important to identify novel drug targets to combat multi-resistant S. aureus isolates. As a defense mechanism, S. aureus uses the flavin disulfide reductase MerA, which functions as HOSCN reductase and protects against HOSCN stress. Moreover, MerA homologs have conserved functions in HOSCN detoxification in other bacteria, including intestinal and respiratory pathogens. In this work, we studied the comprehensive thiol-reactive mode of action of HOSCN and its effect on the reversible shift of the E BSH to discover new defense mechanisms against the neutrophil oxidant. These findings provide new leads for future drug design to fight the pathogen at the sites of colonization and infections.
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Affiliation(s)
- Vu Van Loi
- Institute of Biology-Microbiology, Freie Universität Berlin, Berlin, Germany
| | - Tobias Busche
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Bielefeld, Germany
| | - Franziska Schnaufer
- Institute of Biology-Microbiology, Freie Universität Berlin, Berlin, Germany
| | - Jörn Kalinowski
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Bielefeld, Germany
| | - Haike Antelmann
- Institute of Biology-Microbiology, Freie Universität Berlin, Berlin, Germany
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Crompton ME, Gaessler LF, Tawiah PO, Polzer L, Camfield SK, Jacobson GD, Naudszus MK, Johnson C, Meurer K, Bennis M, Roseberry B, Sultana S, Dahl JU. Expression of RcrB confers resistance to hypochlorous acid in uropathogenic Escherichia coli. J Bacteriol 2023; 205:e0006423. [PMID: 37791752 PMCID: PMC10601744 DOI: 10.1128/jb.00064-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 08/25/2023] [Indexed: 10/05/2023] Open
Abstract
To eradicate bacterial pathogens, neutrophils are recruited to the sites of infection, where they engulf and kill microbes through the production of reactive oxygen and chlorine species (ROS/RCS). The most prominent RCS is the antimicrobial oxidant hypochlorous acid (HOCl), which rapidly reacts with various amino acid side chains, including those containing sulfur and primary/tertiary amines, causing significant macromolecular damage. Pathogens like uropathogenic Escherichia coli (UPEC), the primary causative agent of urinary tract infections, have developed sophisticated defense systems to protect themselves from HOCl. We recently identified the RcrR regulon as a novel HOCl defense strategy in UPEC. Expression of the rcrARB operon is controlled by the HOCl-sensing transcriptional repressor RcrR, which is oxidatively inactivated by HOCl resulting in the expression of its target genes, including rcrB. The rcrB gene encodes a hypothetical membrane protein, deletion of which substantially increases UPEC's susceptibility to HOCl. However, the mechanism behind protection by RcrB is unclear. In this study, we investigated whether (i) its mode of action requires additional help, (ii) rcrARB expression is induced by physiologically relevant oxidants other than HOCl, and (iii) expression of this defense system is limited to specific media and/or cultivation conditions. We provide evidence that RcrB expression is sufficient to protect E. coli from HOCl. Furthermore, RcrB expression is induced by and protects from several RCS but not from ROS. RcrB plays a protective role for RCS-stressed planktonic cells under various growth and cultivation conditions but appears to be irrelevant for UPEC's biofilm formation. IMPORTANCE Bacterial infections pose an increasing threat to human health, exacerbating the demand for alternative treatments. Uropathogenic Escherichia coli (UPEC), the most common etiological agent of urinary tract infections (UTIs), are confronted by neutrophilic attacks in the bladder, and must therefore be equipped with powerful defense systems to fend off the toxic effects of reactive chlorine species. How UPEC deal with the negative consequences of the oxidative burst in the neutrophil phagosome remains unclear. Our study sheds light on the requirements for the expression and protective effects of RcrB, which we recently identified as UPEC's most potent defense system toward hypochlorous acid (HOCl) stress and phagocytosis. Thus, this novel HOCl stress defense system could potentially serve as an attractive drug target to increase the body's own capacity to fight UTIs.
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Affiliation(s)
- Mary E. Crompton
- Microbiology, School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Luca F. Gaessler
- Microbiology, School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Patrick O. Tawiah
- Microbiology, School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Lisa Polzer
- Microbiology, School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Sydney K. Camfield
- Microbiology, School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Grady D. Jacobson
- Microbiology, School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Maren K. Naudszus
- Microbiology, School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Colton Johnson
- Microbiology, School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Kennadi Meurer
- Microbiology, School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Mehdi Bennis
- Microbiology, School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Brendan Roseberry
- Microbiology, School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Sadia Sultana
- Microbiology, School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Jan-Ulrik Dahl
- Microbiology, School of Biological Sciences, Illinois State University, Normal, Illinois, USA
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Crompton ME, Gaessler LF, Tawiah PO, Pfirsching L, Camfield SK, Johnson C, Meurer K, Bennis M, Roseberry B, Sultana S, Dahl JU. Expression of RcrB confers resistance to hypochlorous acid in uropathogenic Escherichia coli. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.01.543251. [PMID: 37398214 PMCID: PMC10312555 DOI: 10.1101/2023.06.01.543251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
To eradicate bacterial pathogens, neutrophils are recruited to the sites of infection, where they engulf and kill microbes through the production of reactive oxygen and chlorine species (ROS/RCS). The most prominent RCS is antimicrobial oxidant hypochlorous acid (HOCl), which rapidly reacts with various amino acids side chains, including those containing sulfur and primary/tertiary amines, causing significant macromolecular damage. Pathogens like uropathogenic Escherichia coli (UPEC), the primary causative agent of urinary tract infections (UTIs), have developed sophisticated defense systems to protect themselves from HOCl. We recently identified the RcrR regulon as a novel HOCl defense strategy in UPEC. The regulon is controlled by the HOCl-sensing transcriptional repressor RcrR, which is oxidatively inactivated by HOCl resulting in the expression of its target genes, including rcrB . rcrB encodes the putative membrane protein RcrB, deletion of which substantially increases UPEC's susceptibility to HOCl. However, many questions regarding RcrB's role remain open including whether (i) the protein's mode of action requires additional help, (ii) rcrARB expression is induced by physiologically relevant oxidants other than HOCl, and (iii) expression of this defense system is limited to specific media and/or cultivation conditions. Here, we provide evidence that RcrB expression is sufficient to E. coli 's protection from HOCl and induced by and protects from several RCS but not from ROS. RcrB plays a protective role for RCS-stressed planktonic cells under various growth and cultivation conditions but appears to be irrelevant for UPEC's biofilm formation. IMPORTANCE Bacterial infections pose an increasing threat to human health exacerbating the demand for alternative treatment options. UPEC, the most common etiological agent of urinary tract infections (UTIs), are confronted by neutrophilic attacks in the bladder, and must therefore be well equipped with powerful defense systems to fend off the toxic effects of RCS. How UPEC deal with the negative consequences of the oxidative burst in the neutrophil phagosome remains unclear. Our study sheds light on the requirements for the expression and protective effects of RcrB, which we recently identified as UPEC's most potent defense system towards HOCl-stress and phagocytosis. Thus, this novel HOCl-stress defense system could potentially serve as an attractive drug target to increase the body's own capacity to fight UTIs.
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Affiliation(s)
- Mary E. Crompton
- School of Biological Sciences, Illinois State University, Microbiology, Normal, IL, USA
| | - Luca F. Gaessler
- School of Biological Sciences, Illinois State University, Microbiology, Normal, IL, USA
| | - Patrick O. Tawiah
- School of Biological Sciences, Illinois State University, Microbiology, Normal, IL, USA
| | - Lisa Pfirsching
- School of Biological Sciences, Illinois State University, Microbiology, Normal, IL, USA
| | - Sydney K. Camfield
- School of Biological Sciences, Illinois State University, Microbiology, Normal, IL, USA
| | - Colton Johnson
- School of Biological Sciences, Illinois State University, Microbiology, Normal, IL, USA
| | - Kennadi Meurer
- School of Biological Sciences, Illinois State University, Microbiology, Normal, IL, USA
| | - Mehdi Bennis
- School of Biological Sciences, Illinois State University, Microbiology, Normal, IL, USA
| | - Brendan Roseberry
- School of Biological Sciences, Illinois State University, Microbiology, Normal, IL, USA
| | - Sadia Sultana
- School of Biological Sciences, Illinois State University, Microbiology, Normal, IL, USA
| | - Jan-Ulrik Dahl
- School of Biological Sciences, Illinois State University, Microbiology, Normal, IL, USA
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Hampton MB, Dickerhof N. Inside the phagosome: A bacterial perspective. Immunol Rev 2023; 314:197-209. [PMID: 36625601 DOI: 10.1111/imr.13182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The neutrophil phagosome is one of the most hostile environments that bacteria must face and overcome if they are to succeed as pathogens. Targeting bacterial defense mechanisms should lead to new therapies that assist neutrophils to kill pathogens, but this has not yet come to fruition. One of the limiting factors in this effort has been our incomplete knowledge of the complex biochemistry that occurs within the rapidly changing environment of the phagosome. The same compartmentalization that protects host tissue also limits our ability to measure events within the phagosome. In this review, we highlight the limitations in our knowledge, and how the contribution of bacteria to the phagosomal environment is often ignored. There appears to be significant heterogeneity among phagosomes, and it is important to determine whether survivors have more efficient defenses or whether they are ingested into less threatening environments than other bacteria. As part of these efforts, we discuss how monitoring or recovering bacteria from phagosomes can provide insight into the conditions they have faced. We also encourage the use of unbiased screening approaches to identify bacterial genes that are essential for survival inside neutrophil phagosomes.
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Affiliation(s)
- Mark B Hampton
- Centre for Free Radical Research, Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - Nina Dickerhof
- Centre for Free Radical Research, Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
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Seddon AR, Das AB, Hampton MB, Stevens AJ. Site-specific decreases in DNA methylation in replicating cells following exposure to oxidative stress. Hum Mol Genet 2022; 32:632-648. [PMID: 36106794 PMCID: PMC9896486 DOI: 10.1093/hmg/ddac232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 09/01/2022] [Accepted: 09/03/2022] [Indexed: 02/07/2023] Open
Abstract
Oxidative stress is a common feature of inflammation-driven cancers, and it promotes genomic instability and aggressive tumour phenotypes. It is known that oxidative stress transiently modulates gene expression through the oxidation of transcription factors and associated regulatory proteins. Neutrophils are our most abundant white blood cells and accumulate at sites of infection and inflammation. Activated neutrophils produce hypochlorous acid and chloramines, which can disrupt DNA methylation by oxidizing methionine. The goal of the current study was to determine whether chloramine exposure results in sequence-specific modifications in DNA methylation that enable long-term alterations in transcriptional output. Proliferating Jurkat T-lymphoma cells were exposed to sublethal doses of glycine chloramine and differential methylation patterns were compared using Illumina EPIC 850 K bead chip arrays. There was a substantial genome-wide decrease in methylation 4 h after exposure that correlated with altered RNA expression for 24 and 48 h, indicating sustained impacts on exposed cells. A large proportion of the most significant differentially methylated CpG sites were situated towards chromosomal ends, suggesting that these regions are most susceptible to inhibition of maintenance DNA methylation. This may contribute to epigenetic instability of chromosomal ends in rapidly dividing cells, with potential implications for the regulation of telomere length and cellular longevity.
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Affiliation(s)
- Annika R Seddon
- University of Otago, Christchurch, Department of Pathology and Biomedical Science, Christchurch, 8011, New Zealand
| | - Andrew B Das
- University of Otago, Christchurch, Department of Pathology and Biomedical Science, Christchurch, 8011, New Zealand,Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia,Sir Peter MacCallum Department of Oncology, The University of Melbourne, Victoria 3010, Australia
| | - Mark B Hampton
- University of Otago, Christchurch, Department of Pathology and Biomedical Science, Christchurch, 8011, New Zealand
| | - Aaron J Stevens
- To whom correspondence should be addressed at: Department of Pathology, University of Otago, Wellington, 23 Mein St, Newtown, Wellington 6021, New Zealand. Tel: +64 43855541; Fax: +64 4 389 5725;
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Redox-Mediated Inactivation of the Transcriptional Repressor RcrR is Responsible for Uropathogenic Escherichia coli's Increased Resistance to Reactive Chlorine Species. mBio 2022; 13:e0192622. [PMID: 36073817 PMCID: PMC9600549 DOI: 10.1128/mbio.01926-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The ability to overcome stressful environments is critical for pathogen survival in the host. One challenge for bacteria is the exposure to reactive chlorine species (RCS), which are generated by innate immune cells as a critical part of the oxidative burst. Hypochlorous acid (HOCl) is the most potent antimicrobial RCS and is associated with extensive macromolecular damage in the phagocytized pathogen. However, bacteria have evolved defense strategies to alleviate the effects of HOCl-mediated damage. Among these are RCS-sensing transcriptional regulators that control the expression of HOCl-protective genes under non-stress and HOCl stress. Uropathogenic Escherichia coli (UPEC), the major causative agent of urinary tract infections (UTIs), is particularly exposed to infiltrating neutrophils during pathogenesis; however, their responses to and defenses from HOCl are still completely unexplored. Here, we present evidence that UPEC strains tolerate higher levels of HOCl and are better protected from neutrophil-mediated killing compared with other E. coli. Transcriptomic analysis of HOCl-stressed UPEC revealed the upregulation of an operon consisting of three genes, one of which encodes the transcriptional regulator RcrR. We identified RcrR as a HOCl-responsive transcriptional repressor, which, under non-stress conditions, is bound to the operator and represses the expression of its target genes. During HOCl exposure, however, the repressor forms reversible intermolecular disulfide bonds and dissociates from the DNA resulting in the derepression of the operon. Deletion of one of the target genes renders UPEC significantly more susceptible to HOCl and phagocytosis indicating that the HOCl-mediated induction of the regulon plays a major role for UPEC’s HOCl resistance.
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Abstract
Hypothiocyanite and hypothiocyanous acid (OSCN-/HOSCN) are pseudohypohalous acids released by the innate immune system which are capable of rapidly oxidizing sulfur-containing amino acids, causing significant protein aggregation and damage to invading bacteria. HOSCN is abundant in saliva and airway secretions and has long been considered a highly specific antimicrobial that is nearly harmless to mammalian cells. However, certain bacteria, commensal and pathogenic, are able to escape damage by HOSCN and other harmful antimicrobials during inflammation, which allows them to continue to grow and, in some cases, cause severe disease. The exact genes or mechanisms by which bacteria respond to HOSCN have not yet been elucidated. We have found, in Escherichia coli, that the flavoprotein RclA, previously implicated in reactive chlorine resistance, reduces HOSCN to thiocyanate with near-perfect catalytic efficiency and strongly protects E. coli against HOSCN toxicity. This is notable in E. coli because this species thrives in the chronically inflamed environment found in patients with inflammatory bowel disease and is able to compete with and outgrow other important commensal organisms, suggesting that HOSCN may be a relevant antimicrobial in the gut, which has not previously been explored. RclA is conserved in a variety of epithelium-colonizing bacteria, implicating its HOSCN reductase activity in a variety of host-microbe interactions. We show that an rclA mutant of the probiotic Limosilactobacillus reuteri is sensitive to HOSCN and that RclA homologs from Staphylococcus aureus, Streptococcus pneumoniae, and Bacteroides thetaiotaomicron all have potent protective activity against HOSCN when expressed in E. coli.
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Taylor JP, Tse HM. The role of NADPH oxidases in infectious and inflammatory diseases. Redox Biol 2021; 48:102159. [PMID: 34627721 PMCID: PMC8487856 DOI: 10.1016/j.redox.2021.102159] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 09/30/2021] [Accepted: 09/30/2021] [Indexed: 02/06/2023] Open
Abstract
Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOX) are enzymes that generate superoxide or hydrogen peroxide from molecular oxygen utilizing NADPH as an electron donor. There are seven enzymes in the NOX family: NOX1-5 and dual oxidase (DUOX) 1-2. NOX enzymes in humans play important roles in diverse biological functions and vary in expression from tissue to tissue. Importantly, NOX2 is involved in regulating many aspects of innate and adaptive immunity, including regulation of type I interferons, the inflammasome, phagocytosis, antigen processing and presentation, and cell signaling. DUOX1 and DUOX2 play important roles in innate immune defenses at epithelial barriers. This review discusses the role of NOX enzymes in normal physiological processes as well as in disease. NOX enzymes are important in autoimmune diseases like type 1 diabetes and have also been implicated in acute lung injury caused by infection with SARS-CoV-2. Targeting NOX enzymes directly or through scavenging free radicals may be useful therapies for autoimmunity and acute lung injury where oxidative stress contributes to pathology.
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Affiliation(s)
- Jared P Taylor
- Department of Microbiology, Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Hubert M Tse
- Department of Microbiology, Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, USA.
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