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Cutugno L, Mc Cafferty J, Pané-Farré J, O'Byrne C, Boyd A. The Vibrio vulnificus stressosome is dispensable in nutrient-rich media. Access Microbiol 2023; 5:acmi000523.v4. [PMID: 37601438 PMCID: PMC10436020 DOI: 10.1099/acmi.0.000523.v4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 05/27/2023] [Indexed: 08/22/2023] Open
Abstract
The stressosome is a protein complex that senses environmental stresses and mediates the stress response in several Gram-positive bacteria through the activation of the alternative sigma factor SigB. The stressosome locus is found in 44 % of Gram-negative Vibrio vulnificus isolates. However, V. vulnificus does not possess SigB. Nonetheless, in nutrient-limited media, the stressosome modulates gene transcription and bacterial behaviour. In this work, the expression of the stressosome genes was proven during stationary phase in nutrient-rich media and co-transcription as one operonic unit of the stressosome locus and its putative downstream regulatory locus was demonstrated. The construction of a stressosome mutant lacking the genes encoding the four proteins constituting the stressosome complex (VvRsbR, VvRsbS, VvRsbT, VvRsbX) allowed us to examine the role of this complex in vivo. Extensive phenotypic characterization of the ΔRSTX mutant in nutrient-rich media showed that the stressosome does not contribute to growth of V. vulnificus . Moreover, the stressosome did not modulate the tolerance or survival response of V. vulnificus to the range of stresses tested, which included ethanol, hyperosmolarity, hypoxia, high temperature, acidity and oxidative stress. Furthermore, the stressosome was dispensable for motility and exoenzyme production of V. vulnificus in nutrient-rich media. Therefore, in conclusion, although stressosome gene transcription occurs in nutrient-rich media, the stressosome neither has an essential role in stress responses of V. vulnificus nor does it seem to modulate these activities in these conditions. We hypothesise that the stressosome is expressed in nutrient-rich conditions as a sensor complex, but that activation of the complex does not occur in this environment.
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Affiliation(s)
- Laura Cutugno
- School of Natural Sciences, University of Galway, Galway, Ireland
| | | | - Jan Pané-Farré
- Centre for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Conor O'Byrne
- School of Biological and Chemical Sciences, University of Galway, Galway, Ireland
| | - Aoife Boyd
- School of Natural Sciences, University of Galway, Galway, Ireland
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Dhungel L, Bonner R, Cook M, Henson D, Moulder T, Benbow ME, Jordan H. Impact of Temperature and Oxygen Availability on Gene Expression Patterns of Mycobacterium ulcerans. Microbiol Spectr 2023; 11:e0496822. [PMID: 36912651 PMCID: PMC10100886 DOI: 10.1128/spectrum.04968-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 01/29/2023] [Indexed: 03/14/2023] Open
Abstract
Buruli ulcer disease is a neglected tropical disease caused by the environmental pathogen Mycobacterium ulcerans. The M. ulcerans major virulence factor is mycolactone, a lipid cytotoxic compound whose genes are carried on a plasmid. Although an exact reservoir and mode(s) of transmission are unknown, data provide evidence of both. First, Buruli ulcer incidence and M. ulcerans presence have been linked to slow-moving water with low oxygen. M. ulcerans has also been suggested to be sensitive to UV due to termination in crtI, encoding a phytoene dehydrogenase, required for carotenoid production. Further, M. ulcerans has been shown to cause disease following puncture but not when introduced to open abrasion sites, suggesting that puncture is necessary for transmission and pathology. Despite these findings, the function and modulation of mycolactone and other genes in response to dynamic abiotic conditions such as UV, temperature, and oxygen have not been shown. In this study, we investigated modulation of mycolactone and other genes on exposure to changing UV and oxygen microenvironmental conditions. Mycolactone expression was downregulated on exposure to the single stress high temperature and did not change significantly with exposure to UV; however, it was upregulated when exposed to microaerophilic conditions. Mycolactone expression was downregulated under combined stresses of high temperature and low oxygen, but there was upregulation of several stress response genes. Taken together, results suggest that temperature shapes M. ulcerans metabolic response more so than UV exposure or oxygen requirements. These data help to define the environmental niche of M. ulcerans and metabolic responses during initial human infection. IMPORTANCE Buruli ulcer is a debilitating skin disease caused by the environmental pathogen Mycobacterium ulcerans. M. ulcerans produces a toxic compound, mycolactone, which leads to tissue necrosis and ulceration. Barriers to preventing Buruli ulcer include an incomplete understanding of M. ulcerans reservoirs, how the pathogen is transmitted, and under what circumstances mycolactone and other M. ulcerans genes are expressed and produced in its natural environment and in the host. We conducted a study to investigate M. ulcerans gene expression under several individual or combined abiotic conditions. Our data showed that mycolactone expression was downregulated under combined stresses of high temperature and low oxygen but there was upregulation of several stress response genes. These data are among only a few studies measuring modulation of mycolactone and other M. ulcerans genes that could be involved in pathogen fitness in its natural environment and virulence while within the host.
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Affiliation(s)
- Laxmi Dhungel
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
| | - Raisa Bonner
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
| | - Meagan Cook
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
| | - Duncan Henson
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
| | - Trent Moulder
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
| | - M. Eric Benbow
- Department of Entomology, Michigan State University, East Lansing, Michigan, USA
- Ecology, Evolution and Behavior Program, Michigan State University, East Lansing, Michigan, USA
- AgBioResearch, Michigan State University, East Lansing, Michigan, USA
- Department of Osteopathic Medical Specialties, Michigan State University, East Lansing, Michigan, USA
| | - Heather Jordan
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
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Cutugno L, Tamayo BKS, Lens PN, O'Byrne C, Pané-Farré J, Boyd A. In vivo characterisation of the Vibrio vulnificus stressosome: A complex involved in reshaping glucose metabolism and motility regulation, in nutrient- and iron-limited growth conditions. CURRENT RESEARCH IN MICROBIAL SCIENCES 2023; 4:100186. [PMID: 36936406 PMCID: PMC10014275 DOI: 10.1016/j.crmicr.2023.100186] [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: 03/06/2023] Open
Abstract
Stressosomes are signal-sensing and integration hubs identified in many bacteria. At present, the role of the stressosome has only been investigated in Gram-positive bacteria. This work represents the first in vivo characterisation of the stressosome in a Gram-negative bacterium, Vibrio vulnificus. Previous in vitro characterisation of the complex has led to the hypothesis of a complex involved in iron metabolism and control of c-di-GMP levels. We demonstrate that the stressosome is probably involved in reshaping the glucose metabolism in Fe- and nutrient-limited conditions and mutations of the locus affect the activation of the glyoxylate shunt. Moreover, we show that the stressosome is needed for the transcription of fleQ and to promote motility, consistent with the hypothesis that the stressosome is involved in regulating c-di-GMP. This report highlights the potential role of the stressosome in a Gram-negative bacterium, with implications for the metabolism and motility of this pathogen.
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Affiliation(s)
- Laura Cutugno
- School of Natural Sciences, University of Galway, Ireland
| | | | - Piet N.L. Lens
- School of Biological and Chemical Sciences, University of Galway, Ireland
| | - Conor O'Byrne
- School of Biological and Chemical Sciences, University of Galway, Ireland
| | - Jan Pané-Farré
- Centre for synthetic Microbiology (SYNMIKRO) & Department of Chemistry, Philipps-University Marburg, Germany
| | - Aoife Boyd
- School of Natural Sciences, University of Galway, Ireland
- Corresponding author.
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Namadi P, Deng Z. Optimum environmental conditions controlling prevalence of vibrio parahaemolyticus in marine environment. MARINE ENVIRONMENTAL RESEARCH 2023; 183:105828. [PMID: 36423461 DOI: 10.1016/j.marenvres.2022.105828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 11/10/2022] [Accepted: 11/15/2022] [Indexed: 06/16/2023]
Abstract
This literature review presents major environmental indicators and their optimum variation ranges for the prevalence of Vibrio parahaemolyticus in the marine environment by critically reviewing and statistically analyzing more than one hundred studies from countries around the world. Results of this review indicated that the prevalence of Vibrio parahaemolyticus in the marine environment is primarily responsive to favorable environmental conditions that are described with environmental indicators. The importance of environmental indicators to the prevalence of Vibrio parahaemolyticus can be ranked from the highest to lowest as Sea Surface Temperature (SST), salinity, pH, chlorophyll a, and turbidity, respectively. It was also found in this study that each environmental indicator has an optimum variation range favoring the prevalence of Vibrio parahaemolyticus. Specifically, the SST range of 25.67 ± 2 °C, salinity range of 27.87 ± 3 ppt, and pH range of 7.96 ± 0.1 were found to be the optimum conditions for the prevalence of Vibrio parahaemolyticus. High vibrio concentrations were also observed in water samples with the chlorophyll a range of 16-25 μg/L. The findings provide new insights into the importance of environmental indicators and their optimum ranges, explaining not only the existence of both positive and negative associations reported in the literature but also the dynamic associations between the Vibrio presence and its environmental drivers.
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Affiliation(s)
- Peyman Namadi
- Department of Civil and Environmental Engineering, Louisiana State University, Baton Rouge, LA, 70803, United States
| | - Zhiqiang Deng
- Department of Civil and Environmental Engineering, Louisiana State University, Baton Rouge, LA, 70803, United States.
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The Vibrio vulnificus stressosome is an oxygen-sensor involved in regulating iron metabolism. Commun Biol 2022; 5:622. [PMID: 35761021 PMCID: PMC9237108 DOI: 10.1038/s42003-022-03548-w] [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: 05/27/2021] [Accepted: 05/31/2022] [Indexed: 11/08/2022] Open
Abstract
Stressosomes are stress-sensing protein complexes widely conserved among bacteria. Although a role in the regulation of the general stress response is well documented in Gram-positive bacteria, the activating signals are still unclear, and little is known about the physiological function of stressosomes in the Gram-negative bacteria. Here we investigated the stressosome of the Gram-negative marine pathogen Vibrio vulnificus. We demonstrate that it senses oxygen and identified its role in modulating iron-metabolism. We determined a cryo-electron microscopy structure of the VvRsbR:VvRsbS stressosome complex, the first solved from a Gram-negative bacterium. The structure points to a variation in the VvRsbR and VvRsbS stoichiometry and a symmetry breach in the oxygen sensing domain of VvRsbR, suggesting how signal-sensing elicits a stress response. The findings provide a link between ligand-dependent signaling and an output – regulation of iron metabolism - for a stressosome complex. A cryo-electron microscopy reconstruction of a stressosome complex from a Gram-negative bacterium, Vibrio vulnificus, reveals variations in subunit composition and symmetry, which could serve to adjust the activation threshold in the response to low levels of oxygen and starvation.
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Vezzulli L, Baker-Austin C, Kirschner A, Pruzzo C, Martinez-Urtaza J. Global emergence of environmental non-O1/O139 Vibrio cholerae infections linked with climate change: a neglected research field? Environ Microbiol 2020; 22:4342-4355. [PMID: 32337781 DOI: 10.1111/1462-2920.15040] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Accepted: 04/22/2020] [Indexed: 12/20/2022]
Abstract
The bacterium Vibrio cholerae is a natural inhabitant of aquatic ecosystems across the planet. V. cholerae serogroups O1 and O139 are responsible for cholera outbreaks in developing countries accounting for 3-5 million infections worldwide and 28.800-130.000 deaths per year according to the World Health Organization. In contrast, V. cholerae serogroups other than O1 and O139, also designated as V. cholerae non-O1/O139 (NOVC), are not associated with epidemic cholera but can cause other illnesses that may range in severity from mild (e.g. gastroenteritis, otitis, etc.) to life-threatening (e.g. necrotizing fasciitis). Although generally neglected, NOVC-related infections are on the rise and represent one of the most striking examples of emerging human diseases linked to climate change. NOVC strains are also believed to potentially contribute to the emergence of new pathogenic strains including strains with epidemic potential as a direct consequence of genetic exchange mechanisms such as horizontal gene transfer and genetic recombination. Besides general features concerning the biology and ecology of NOVC strains and their associated diseases, this review aims to highlight the most relevant aspects related to the emergence and potential threat posed by NOVC strains under a rapidly changing environmental and climatic scenario.
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Affiliation(s)
- Luigi Vezzulli
- Department of Earth, Environmental and Life Sciences (DISTAV), University of Genoa, Genoa, Italy
| | - Craig Baker-Austin
- Centre for Environment, Fisheries and Aquaculture Science, CEFAS, Weymouth, UK
| | - Alexander Kirschner
- Institute for Hygiene and Applied Immunology - Water Microbiology, Medical University of Vienna, Vienna, Austria.,Division Water Quality and Health, Karl Landsteiner University of Health Sciences, Krems, Austria
| | - Carla Pruzzo
- Department of Earth, Environmental and Life Sciences (DISTAV), University of Genoa, Genoa, Italy
| | - Jaime Martinez-Urtaza
- Centre for Environment, Fisheries and Aquaculture Science, CEFAS, Weymouth, UK.,Department of Genetics and Microbiology, Facultat de Biociéncies, Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Barcelona, Spain
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