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Bientz V, Lanois A, Ginibre N, Pagès S, Ogier JC, George S, Rialle S, Brillard J. OxyR is required for oxidative stress resistance of the entomopathogenic bacterium Xenorhabdus nematophila and has a minor role during the bacterial interaction with its hosts. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001481. [PMID: 39058385 PMCID: PMC11281485 DOI: 10.1099/mic.0.001481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Accepted: 07/08/2024] [Indexed: 07/28/2024]
Abstract
Xenorhabdus nematophila is a Gram-negative bacterium, mutualistically associated with the soil nematode Steinernema carpocapsae, and this nemato-bacterial complex is parasitic for a broad spectrum of insects. The transcriptional regulator OxyR is widely conserved in bacteria and activates the transcription of a set of genes that influence cellular defence against oxidative stress. It is also involved in the virulence of several bacterial pathogens. The aim of this study was to identify the X. nematophila OxyR regulon and investigate its role in the bacterial life cycle. An oxyR mutant was constructed in X. nematophila and phenotypically characterized in vitro and in vivo after reassociation with its nematode partner. OxyR plays a major role during the X. nematophila resistance to oxidative stress in vitro. Transcriptome analysis allowed the identification of 59 genes differentially regulated in the oxyR mutant compared to the parental strain. In vivo, the oxyR mutant was able to reassociate with the nematode as efficiently as the control strain. These nemato-bacterial complexes harbouring the oxyR mutant symbiont were able to rapidly kill the insect larvae in less than 48 h after infestation, suggesting that factors other than OxyR could also allow X. nematophila to cope with oxidative stress encountered during this phase of infection in insect. The significantly increased number of offspring of the nemato-bacterial complex when reassociated with the X. nematophila oxyR mutant compared to the control strain revealed a potential role of OxyR during this symbiotic stage of the bacterial life cycle.
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Affiliation(s)
| | - Anne Lanois
- DGIMI, INRAE, Univ. Montpellier, Montpellier, France
| | | | - Sylvie Pagès
- DGIMI, INRAE, Univ. Montpellier, Montpellier, France
| | | | - Simon George
- MGX-Montpellier GenomiX, Univ. Montpellier, CNRS, INSERM, Montpellier, France
| | - Stéphanie Rialle
- MGX-Montpellier GenomiX, Univ. Montpellier, CNRS, INSERM, Montpellier, France
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2
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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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3
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Bessaiah H, Anamalé C, Sung J, Dozois CM. What Flips the Switch? Signals and Stress Regulating Extraintestinal Pathogenic Escherichia coli Type 1 Fimbriae (Pili). Microorganisms 2021; 10:5. [PMID: 35056454 PMCID: PMC8777976 DOI: 10.3390/microorganisms10010005] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/13/2021] [Accepted: 12/15/2021] [Indexed: 12/18/2022] Open
Abstract
Pathogens are exposed to a multitude of harmful conditions imposed by the environment of the host. Bacterial responses against these stresses are pivotal for successful host colonization and pathogenesis. In the case of many E. coli strains, type 1 fimbriae (pili) are an important colonization factor that can contribute to diseases such as urinary tract infections and neonatal meningitis. Production of type 1 fimbriae in E. coli is dependent on an invertible promoter element, fimS, which serves as a phase variation switch determining whether or not a bacterial cell will produce type 1 fimbriae. In this review, we present aspects of signaling and stress involved in mediating regulation of type 1 fimbriae in extraintestinal E. coli; in particular, how certain regulatory mechanisms, some of which are linked to stress response, can influence production of fimbriae and influence bacterial colonization and infection. We suggest that regulation of type 1 fimbriae is potentially linked to environmental stress responses, providing a perspective for how environmental cues in the host and bacterial stress response during infection both play an important role in regulating extraintestinal pathogenic E. coli colonization and virulence.
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Affiliation(s)
- Hicham Bessaiah
- Institut National de Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie, Laval, QC H7V 1B7, Canada; (H.B.); (C.A.); (J.S.)
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Saint-Hyacinthe, QC J2S 2M2, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, QC H3G 0B1, Canada
| | - Carole Anamalé
- Institut National de Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie, Laval, QC H7V 1B7, Canada; (H.B.); (C.A.); (J.S.)
| | - Jacqueline Sung
- Institut National de Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie, Laval, QC H7V 1B7, Canada; (H.B.); (C.A.); (J.S.)
- Department of Microbiology and Immunology, McGill University, Montreal, QC H3G 0B1, Canada
| | - Charles M. Dozois
- Institut National de Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie, Laval, QC H7V 1B7, Canada; (H.B.); (C.A.); (J.S.)
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Saint-Hyacinthe, QC J2S 2M2, Canada
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4
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Varatnitskaya M, Degrossoli A, Leichert LI. Redox regulation in host-pathogen interactions: thiol switches and beyond. Biol Chem 2020; 402:299-316. [PMID: 33021957 DOI: 10.1515/hsz-2020-0264] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 09/29/2020] [Indexed: 12/23/2022]
Abstract
Our organism is exposed to pathogens on a daily basis. Owing to this age-old interaction, both pathogen and host evolved strategies to cope with these encounters. Here, we focus on the consequences of the direct encounter of cells of the innate immune system with bacteria. First, we will discuss the bacterial strategies to counteract powerful reactive species. Our emphasis lies on the effects of hypochlorous acid (HOCl), arguably the most powerful oxidant produced inside the phagolysosome of professional phagocytes. We will highlight individual examples of proteins in gram-negative bacteria activated by HOCl via thiol-disulfide switches, methionine sulfoxidation, and N-chlorination of basic amino acid side chains. Second, we will discuss the effects of HOCl on proteins of the host. Recent studies have shown that both host and bacteria address failing protein homeostasis by activation of chaperone-like holdases through N-chlorination. After discussing the role of individual proteins in the HOCl-defense, we will turn our attention to the examination of effects on host and pathogen on a systemic level. Recent studies using genetically encoded redox probes and redox proteomics highlight differences in redox homeostasis in host and pathogen and give first hints at potential cellular HOCl signaling beyond thiol-disulfide switch mechanisms.
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Affiliation(s)
- Marharyta Varatnitskaya
- Institute for Biochemistry and Pathobiochemistry - Microbial Biochemistry, Ruhr University Bochum, Bochum, Germany
| | - Adriana Degrossoli
- Faculty of Health Science - Health Science Department, Federal University of Lavras, Lavras, Brazil
| | - Lars I Leichert
- Institute for Biochemistry and Pathobiochemistry - Microbial Biochemistry, Ruhr University Bochum, Bochum, Germany
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5
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Seth D, Hausladen A, Stamler JS. Anaerobic Transcription by OxyR: A Novel Paradigm for Nitrosative Stress. Antioxid Redox Signal 2020; 32:803-816. [PMID: 31691575 PMCID: PMC7074925 DOI: 10.1089/ars.2019.7921] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Significance: S-nitrosylation, the post-translational modification by nitric oxide (NO) to form S-nitrosothiols (SNOs), regulates diverse aspects of cellular function, and aberrant S-nitrosylation (nitrosative stress) is implicated in disease, from neurodegeneration to cancer. Essential roles for S-nitrosylation have been demonstrated in microbes, plants, and animals; notably, bacteria have often served as model systems for elucidation of general principles. Recent Advances: Recent conceptual advances include the idea of a molecular code through which proteins sense and differentiate S-nitrosothiol (SNO) from alternative oxidative modifications, providing the basis for specificity in SNO signaling. In Escherichia coli, S-nitrosylation relies on an enzymatic cascade that regulates, and is regulated by, the transcription factor OxyR under anaerobic conditions. S-nitrosylated OxyR activates an anaerobic regulon of >100 genes that encode for enzymes that both mediate S-nitrosylation and protect against nitrosative stress. Critical Issues: Mitochondria originated from endosymbiotic bacteria and generate NO under hypoxic conditions, analogous to conditions in E. coli. Nitrosative stress in mitochondria has been implicated in Alzheimer's and Parkinson's disease, among others. Many proteins that are S-nitrosylated in mitochondria are also S-nitrosylated in E. coli. Insights into enzymatic regulation of S-nitrosylation in E. coli may inform the identification of disease-relevant regulatory machinery in mammalian systems. Future Directions: Using E. coli as a model system, in-depth analysis of the anaerobic response controlled by OxyR may lead to the identification of enzymatic mechanisms regulating S-nitrosylation in particular, and hypoxic signaling more generally, providing novel insights into analogous mechanisms in mammalian cells and within dysfunctional mitochondria that characterize neurodegenerative diseases.
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Affiliation(s)
- Divya Seth
- Institute for Transformative Molecular Medicine and Department of Medicine, Case Western Reserve University School of Medicine and University Hospitals Cleveland Medical Center, Cleveland, Ohio
| | - Alfred Hausladen
- Institute for Transformative Molecular Medicine and Department of Medicine, Case Western Reserve University School of Medicine and University Hospitals Cleveland Medical Center, Cleveland, Ohio
| | - Jonathan S Stamler
- Institute for Transformative Molecular Medicine and Department of Medicine, Case Western Reserve University School of Medicine and University Hospitals Cleveland Medical Center, Cleveland, Ohio.,Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, Ohio
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Young D, Pedre B, Ezeriņa D, De Smet B, Lewandowska A, Tossounian MA, Bodra N, Huang J, Astolfi Rosado L, Van Breusegem F, Messens J. Protein Promiscuity in H 2O 2 Signaling. Antioxid Redox Signal 2019; 30:1285-1324. [PMID: 29635930 DOI: 10.1089/ars.2017.7013] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
SIGNIFICANCE Decrypting the cellular response to oxidative stress relies on a comprehensive understanding of the redox signaling pathways stimulated under oxidizing conditions. Redox signaling events can be divided into upstream sensing of oxidants, midstream redox signaling of protein function, and downstream transcriptional redox regulation. Recent Advances: A more and more accepted theory of hydrogen peroxide (H2O2) signaling is that of a thiol peroxidase redox relay, whereby protein thiols with low reactivity toward H2O2 are instead oxidized through an oxidative relay with thiol peroxidases. CRITICAL ISSUES These ultrareactive thiol peroxidases are the upstream redox sensors, which form the first cellular port of call for H2O2. Not all redox-regulated interactions between thiol peroxidases and cellular proteins involve a transfer of oxidative equivalents, and the nature of redox signaling is further complicated through promiscuous functions of redox-regulated "moonlighting" proteins, of which the precise cellular role under oxidative stress can frequently be obscured by "polygamous" interactions. An ultimate goal of redox signaling is to initiate a rapid response, and in contrast to prokaryotic oxidant-responsive transcription factors, mammalian systems have developed redox signaling pathways, which intersect both with kinase-dependent activation of transcription factors, as well as direct oxidative regulation of transcription factors through peroxiredoxin (Prx) redox relays. FUTURE DIRECTIONS We highlight that both transcriptional regulation and cell fate can be modulated either through oxidative regulation of kinase pathways, or through distinct redox-dependent associations involving either Prxs or redox-responsive moonlighting proteins with functional promiscuity. These protein associations form systems of crossregulatory networks with multiple nodes of potential oxidative regulation for H2O2-mediated signaling.
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Affiliation(s)
- David Young
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Brandan Pedre
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Daria Ezeriņa
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Barbara De Smet
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium.,4 Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.,5 Center for Plant Systems Biology, VIB, Ghent, Belgium
| | - Aleksandra Lewandowska
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium.,4 Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.,5 Center for Plant Systems Biology, VIB, Ghent, Belgium
| | - Maria-Armineh Tossounian
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Nandita Bodra
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium.,4 Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.,5 Center for Plant Systems Biology, VIB, Ghent, Belgium
| | - Jingjing Huang
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium.,4 Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.,5 Center for Plant Systems Biology, VIB, Ghent, Belgium
| | - Leonardo Astolfi Rosado
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Frank Van Breusegem
- 2 Brussels Center for Redox Biology, Brussels, Belgium.,4 Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.,5 Center for Plant Systems Biology, VIB, Ghent, Belgium
| | - Joris Messens
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
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7
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Abstract
The bacterial transcription factor OxyR is a model example of a highly sensitive and specific hydrogen peroxide (H2O2) sensor. H2O2 reduction by its active-site cysteine triggers protein structural changes leading to an increased transcription of antioxidant genes. By solving the crystal structures of full-length OxyR in both reduced and oxidized states, we provide molecular insight into these structural changes. We also present a H2O2-bound structure with a threonine activating the peroxide, and argue that this H2O2-bound structure may be catalytically more relevant than that seen previously in the study of a sulfinic acid-mimic mutant of the active-site cysteine. Finally, we discuss the commonalities and differences between the peroxidatic mechanisms of peroxiredoxins and OxyR. Hydrogen peroxide (H2O2) is a strong oxidant capable of oxidizing cysteinyl thiolates, yet only a few cysteine-containing proteins have exceptional reactivity toward H2O2. One such example is the prokaryotic transcription factor OxyR, which controls the antioxidant response in bacteria, and which specifically and rapidly reduces H2O2. In this study, we present crystallographic evidence for the H2O2-sensing mechanism and H2O2-dependent structural transition of Corynebacterium glutamicum OxyR by capturing the reduced and H2O2-bound structures of a serine mutant of the peroxidatic cysteine, and the full-length crystal structure of disulfide-bonded oxidized OxyR. In the H2O2-bound structure, we pinpoint the key residues for the peroxidatic reduction of H2O2, and relate this to mutational assays showing that the conserved active-site residues T107 and R278 are critical for effective H2O2 reduction. Furthermore, we propose an allosteric mode of structural change, whereby a localized conformational change arising from H2O2-induced intramolecular disulfide formation drives a structural shift at the dimerization interface of OxyR, leading to overall changes in quaternary structure and an altered DNA-binding topology and affinity at the catalase promoter region. This study provides molecular insights into the overall OxyR transcription mechanism regulated by H2O2.
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8
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Johnson JR, Magistro G, Clabots C, Porter S, Manges A, Thuras P, Schubert S. Contribution of yersiniabactin to the virulence of an Escherichia coli sequence type 69 ("clonal group A") cystitis isolate in murine models of urinary tract infection and sepsis. Microb Pathog 2018; 120:128-131. [PMID: 29702209 DOI: 10.1016/j.micpath.2018.04.048] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 03/30/2018] [Accepted: 04/23/2018] [Indexed: 11/15/2022]
Abstract
Escherichia coli sequence type 69 (ST69; "clonal group A") is an important extraintestinal pathogen. To clarify the yersiniabactin siderophore system's role in ST69's extraintestinal virulence we compared a wild-type ST69 cystitis isolate, isogenic irp2 (yersiniabactin) mutants, and irp2-complemented mutants in murine models of sepsis and urinary tract infection (UTI). irp2 mutants were attenuated mildly in the UTI model and profoundly in the sepsis model. In both models, complementation with a functional copy of irp2 restored full parental virulence. These findings suggest that in ST69 the yersiniabactin system has a minor role in urovirulence and a major role in sepsis causation.
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Affiliation(s)
- James R Johnson
- Veterans Affairs Medical Center, 1 Veterans Drive, Minneapolis, MN, USA; University of Minnesota, 420 Delaware St. SE, MMC 250, Minneapolis, MN 55455, USA.
| | - Giuseppe Magistro
- Department of Urology, Ludwig-Maximilians-University of Munich, Marchioninistrasse 15, 81377 Munich, Germany
| | - Connie Clabots
- Veterans Affairs Medical Center, 1 Veterans Drive, Minneapolis, MN, USA
| | - Stephen Porter
- Veterans Affairs Medical Center, 1 Veterans Drive, Minneapolis, MN, USA; University of Minnesota, 420 Delaware St. SE, MMC 250, Minneapolis, MN 55455, USA
| | - Amee Manges
- University of British Columbia, School of Population and Public Health, 137-2206 East Mall, Vancouver, BC V6T 1Z3, Canada
| | - Paul Thuras
- Veterans Affairs Medical Center, 1 Veterans Drive, Minneapolis, MN, USA; University of Minnesota, 420 Delaware St. SE, MMC 250, Minneapolis, MN 55455, USA
| | - Sören Schubert
- Max von Pettenkofer-Institut, Ludwig-Maximilians-University of Munich, Marchioninistrasse 17, 81377 Munich, Germany
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9
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OxyR of Haemophilus parasuis is a global transcriptional regulator important in oxidative stress resistance and growth. Gene 2018; 643:107-116. [DOI: 10.1016/j.gene.2017.12.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 12/05/2017] [Accepted: 12/07/2017] [Indexed: 11/17/2022]
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10
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Molecular and Structural Characterization of a Novel Escherichia coli Interleukin Receptor Mimic Protein. mBio 2016; 7:e02046. [PMID: 26980835 PMCID: PMC4807369 DOI: 10.1128/mbio.02046-15] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Urinary tract infection (UTI) is a disease of extremely high incidence in both community and nosocomial settings. UTIs cause significant morbidity and mortality, with approximately 150 million cases globally per year. Uropathogenic Escherichia coli (UPEC) is the primary cause of UTI and is generally treated empirically. However, the rapidly increasing incidence of UTIs caused by multidrug-resistant UPEC strains has led to limited available treatment options and highlights the urgent need to develop alternative treatment and prevention strategies. In this study, we performed a comprehensive analysis to define the regulation, structure, function, and immunogenicity of recently identified UPEC vaccine candidate C1275 (here referred to as IrmA). We showed that the irmA gene is highly prevalent in UPEC, is cotranscribed with the biofilm-associated antigen 43 gene, and is regulated by the global oxidative stress response OxyR protein. Localization studies identified IrmA in the UPEC culture supernatant. We determined the structure of IrmA and showed that it adopts a unique domain-swapped dimer architecture. The dimeric structure of IrmA displays similarity to those of human cytokine receptors, including the interleukin-2 receptor (IL-2R), interleukin-4 receptor (IL-4R), and interleukin-10 receptor (IL-10R) binding domains, and we showed that purified IrmA can bind to their cognate cytokines. Finally, we showed that plasma from convalescent urosepsis patients contains high IrmA antibody titers, demonstrating the strong immunogenicity of IrmA. Taken together, our results indicate that IrmA may play an important role during UPEC infection. Uropathogenic E. coli (UPEC) is the primary cause of urinary tract infection (UTI), a disease of major significance to human health. Globally, the incidence of UPEC-mediated UTI is strongly associated with increasing antibiotic resistance, making this extremely common infection a major public health concern. In this report, we describe the regulatory, structural, functional, and immunogenic properties of a candidate UPEC vaccine antigen, IrmA. We demonstrate that IrmA is a small UPEC protein that forms a unique domain-swapped dimer with structural mimicry to several human cytokine receptors. We also show that IrmA binds to IL-2, IL-4, and IL-10, is strongly immunogenic in urosepsis patients, and is coexpressed with factors associated with biofilm formation. Overall, this work suggests a potential novel contribution for IrmA in UPEC infection.
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11
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Ishiga Y, Ichinose Y. Pseudomonas syringae pv. tomato OxyR Is Required for Virulence in Tomato and Arabidopsis. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2016; 29:119-31. [PMID: 26554736 DOI: 10.1094/mpmi-09-15-0204-r] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Reactive oxygen species (ROS) have been shown to have a crucial role in plant defense responses and signaling pathways. In addition, ROS also have direct toxicity against pathogens. However, the molecular mechanisms of plant ROS in the direct effects against pathogens is still unclear. To investigate the function of plant ROS in the interactions of plant and bacterial pathogens, we focused on oxyR, encoding an oxidative stress-regulated transcription factor in Pseudomonas syringae pv. tomato DC3000 (DC3000), and generated an ΔoxyR mutant. The DC3000 ΔoxyR mutant showed high sensitivity to oxidative stress in comparison with wild type and the complemented line. The host plants of DC3000, including tomato and Arabidopsis inoculated with the ΔoxyR mutant, clearly showed reduced disease symptoms as well as reduced bacterial populations. Expression profiles of DC3000 genes revealed that OxyR could regulate the expression of genes encoding ROS-detoxifying enzymes, including catalases (KatB and KatG), in response to ROS. We also demonstrated that the expression of katB could be regulated by OxyR during the infection of DC3000 in Arabidopsis. These results suggest that OxyR has an important role in the virulence of DC3000 by regulating the expression of genes related to oxidative stress.
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Affiliation(s)
- Yasuhiro Ishiga
- 1 Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Yuki Ichinose
- 2 Laboratory of Plant Pathology and Genetic Engineering, Graduate School of Environmental and Life Science, Okayama University, 1-1-1 Tsushima-naka, Okayama 700-8530, Japan
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12
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Green J, Rolfe MD, Smith LJ. Transcriptional regulation of bacterial virulence gene expression by molecular oxygen and nitric oxide. Virulence 2014; 5:794-809. [PMID: 25603427 PMCID: PMC4601167 DOI: 10.4161/viru.27794] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Molecular oxygen (O2) and nitric oxide (NO) are diatomic gases that play major roles in infection. The host innate immune system generates reactive oxygen species and NO as bacteriocidal agents and both require O2 for their production. Furthermore, the ability to adapt to changes in O2 availability is crucial for many bacterial pathogens, as many niches within a host are hypoxic. Pathogenic bacteria have evolved transcriptional regulatory systems that perceive these gases and respond by reprogramming gene expression. Direct sensors possess iron-containing co-factors (iron–sulfur clusters, mononuclear iron, heme) or reactive cysteine thiols that react with O2 and/or NO. Indirect sensors perceive the physiological effects of O2 starvation. Thus, O2 and NO act as environmental cues that trigger the coordinated expression of virulence genes and metabolic adaptations necessary for survival within a host. Here, the mechanisms of signal perception by key O2- and NO-responsive bacterial transcription factors and the effects on virulence gene expression are reviewed, followed by consideration of these aspects of gene regulation in two major pathogens, Staphylococcus aureus and Mycobacterium tuberculosis.
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Key Words
- AIP, autoinducer peptide
- Arc, Aerobic respiratory control
- FNR
- FNR, fumarate nitrate reduction regulator
- GAF, cGMP-specific phosphodiesterase-adenylyl cyclase-FhlA domain
- Isc, iron–sulfur cluster biosynthesis machinery
- Mycobacterium tuberculosis
- NOX, NADPH oxidase
- PAS, Per-Amt-Sim domain
- RNS, reactive nitrogen species
- ROS, reactive oxygen species
- Staphylococcus aureus
- TB, tuberculosis
- WhiB-like proteins
- iNOS, inducible nitric oxide synthase
- iron–sulfur cluster
- nitric oxide sensors
- oxygen sensors
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Affiliation(s)
- Jeffrey Green
- a Krebs Institute; Molecular Biology & Biotechnology; University of Sheffield ; Western Bank , Sheffield , UK
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13
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Development of 8-benzyloxy-substituted quinoline ethers and evaluation of their antimicrobial activities. Med Chem Res 2014. [DOI: 10.1007/s00044-014-1217-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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