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Mettert EL, Kiley PJ. Fe-S cluster homeostasis and beyond: The multifaceted roles of IscR. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119749. [PMID: 38763301 DOI: 10.1016/j.bbamcr.2024.119749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 03/29/2024] [Accepted: 05/08/2024] [Indexed: 05/21/2024]
Abstract
The role of IscR in regulating the transcription of genes involved in Fe-S cluster homeostasis has been well established for the model organism Escherichia coli K12. In this bacterium, IscR coordinates expression of the Isc and Suf Fe-S cluster assembly pathways to meet cellular Fe-S cluster demands shaped by a variety of environmental cues. However, since its initial discovery nearly 25 years ago, there has been growing evidence that IscR function extends well beyond Fe-S cluster homeostasis, not only in E. coli, but in bacteria of diverse lifestyles. Notably, pathogenic bacteria have exploited the ability of IscR to respond to changes in oxygen tension, oxidative and nitrosative stress, and iron availability to navigate their trajectory in their respective hosts as changes in these cues are frequently encountered during host infection. In this review, we highlight these broader roles of IscR in different cellular processes and, in particular, discuss the importance of IscR as a virulence factor for many bacterial pathogens.
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Affiliation(s)
- Erin L Mettert
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Patricia J Kiley
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, USA.
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2
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Fu T, Gifford DR, Knight CG, Brockhurst MA. Eco-evolutionary dynamics of experimental Pseudomonas aeruginosa populations under oxidative stress. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001396. [PMID: 37943284 PMCID: PMC10710836 DOI: 10.1099/mic.0.001396] [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: 06/27/2023] [Accepted: 09/26/2023] [Indexed: 11/10/2023]
Abstract
Within-host environments are likely to present a challenging and stressful environment for opportunistic pathogenic bacteria colonizing from the external environment. How populations of pathogenic bacteria respond to such environmental challenges and how this varies between strains is not well understood. Oxidative stress is one of the defences adopted by the human immune system to confront invading bacteria. In this study, we show that strains of the opportunistic pathogenic bacterium Pseudomonas aeruginosa vary in their eco-evolutionary responses to hydrogen peroxide stress. By quantifying their 24 h growth kinetics across hydrogen peroxide gradients we show that a transmissible epidemic strain isolated from a chronic airway infection of a cystic fibrosis patient, LESB58, is much more susceptible to hydrogen peroxide than either of the reference strains, PA14 or PAO1, with PAO1 showing the lowest susceptibility. Using a 12 day serial passaging experiment combined with a mathematical model, we then show that short-term susceptibility controls the longer-term survival of populations exposed to subinhibitory levels of hydrogen peroxide, but that phenotypic evolutionary responses can delay population extinction. Our model further suggests that hydrogen peroxide driven extinctions are more likely with higher rates of population turnover. Together, these findings suggest that hydrogen peroxide is likely to be an effective defence in host niches where there is high population turnover, which may explain the counter-intuitively high susceptibility of a strain isolated from chronic lung infection, where such ecological dynamics may be slower.
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Affiliation(s)
- Taoran Fu
- Division of Evolution, Infection and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Danna R. Gifford
- Division of Evolution, Infection and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Christopher G. Knight
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, The University of Manchester, Manchester M13 9PT, UK
| | - Michael A. Brockhurst
- Division of Evolution, Infection and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
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3
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Chautrand T, Depayras S, Souak D, Bouteiller M, Kondakova T, Barreau M, Ben Mlouka MA, Hardouin J, Konto-Ghiorghi Y, Chevalier S, Merieau A, Orange N, Duclairoir-Poc C. Detoxification Response of Pseudomonas fluorescens MFAF76a to Gaseous Pollutants NO 2 and NO. Microorganisms 2022; 10:microorganisms10081576. [PMID: 36013994 PMCID: PMC9414441 DOI: 10.3390/microorganisms10081576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/25/2022] [Accepted: 07/29/2022] [Indexed: 11/16/2022] Open
Abstract
Bacteria are often exposed to nitrosative stress from their environment, from atmospheric pollution or from the defense mechanisms of other organisms. Reactive nitrogen species (RNS), which mediate nitrosative stress, are notably involved in the mammalian immune response through the production of nitric oxide (NO) by the inducible NO synthase iNOS. RNS are highly reactive and can alter various biomolecules such as lipids, proteins and DNA, making them toxic for biological organisms. Resistance to RNS is therefore important for the survival of bacteria in various environments, and notably to successfully infect their host. The fuel combustion processes used in industries and transports are responsible for the emission of important quantities of two major RNS, NO and the more toxic nitrogen dioxide (NO2). Human exposure to NO2 is notably linked to increases in lung infections. While the response of bacteria to NO in liquid medium is well-studied, few data are available on their exposure to gaseous NO and NO2. This study showed that NO2 is much more toxic than NO at similar concentrations for the airborne bacterial strain Pseudomonas fluorescens MFAF76a. The response to NO2 involves a wide array of effectors, while the response to NO seemingly focuses on the Hmp flavohemoprotein. Results showed that NO2 induces the production of other RNS, unlike NO, which could explain the differences between the effects of these two molecules.
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Affiliation(s)
- Thibault Chautrand
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Ségolène Depayras
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
- Praxens, Normandy Health Security Center, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Djouhar Souak
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Mathilde Bouteiller
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Tatiana Kondakova
- LPS-BIOSCIENCES SAS, Domaine de l’Université Paris Sud, Bâtiment 430, Université Paris Saclay, 91400 Orsay, France
| | - Magalie Barreau
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Mohamed Amine Ben Mlouka
- Polymers, Biopolymers, Surface Laboratory, University of Rouen Normandy, INSA, CNRS, Bâtiment DULONG—Bd Maurice de Broglie, CEDEX, F-76821 Mont-Saint-Aignan, France
- PISSARO Proteomic Facility, IRIB, F-76820 Mont-Saint-Aignan, France
| | - Julie Hardouin
- Polymers, Biopolymers, Surface Laboratory, University of Rouen Normandy, INSA, CNRS, Bâtiment DULONG—Bd Maurice de Broglie, CEDEX, F-76821 Mont-Saint-Aignan, France
- PISSARO Proteomic Facility, IRIB, F-76820 Mont-Saint-Aignan, France
| | - Yoan Konto-Ghiorghi
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Sylvie Chevalier
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Annabelle Merieau
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Nicole Orange
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
| | - Cécile Duclairoir-Poc
- Research Unit Bacterial Communication and Anti-Infectious Strategies (UR CBSA), University of Rouen Normandy, 55 Rue Saint-Germain, 27000 Evreux, France
- Correspondence:
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Gupta V, Shekhawat SS, Kulshreshtha NM, Gupta AB. A systematic review on chlorine tolerance among bacteria and standardization of their assessment protocol in wastewater. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2022; 86:261-291. [PMID: 35906907 DOI: 10.2166/wst.2022.206] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Though chlorine is a cost-effective disinfectant for water and wastewaters, the bacteria surviving after chlorination pose serious public health and environmental problems. This review critically assesses the mechanism of chlorine disinfection as described by various researchers; factors affecting chlorination efficacy; and the re-growth potential of microbial contaminations in treated wastewater post chlorination to arrive at meaningful doses for ensuring health safety. Literature analysis shows procedural inconsistencies in the assessment of chlorine tolerant bacteria, making it extremely difficult to compare the tolerance characteristics of different reported tolerant bacteria. A comparison of logarithmic reduction after chlorination and the concentration-time values for prominent pathogens led to the generation of a standard protocol for the assessment of chlorine tolerance. The factors that need to be critically monitored include applied chlorine doses, contact time, determination of chlorine demands of the medium, and the consideration of bacterial counts immediately after chlorination and in post chlorinated samples (regrowth). The protocol devised here appropriately assesses the chlorine-tolerant bacteria and urges the scientific community to report the regrowth characteristics as well. This would increase the confidence in data interpretation that can provide a better understanding of chlorine tolerance in bacteria and aid in formulating strategies for effective chlorination.
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Affiliation(s)
- Vinayak Gupta
- Alumnus, Department of Civil and Environmental Engineering, National University of Singapore, Singapore; School of Environment and Society, Tokyo Institute of Technology, Tokyo, Japan
| | - Sandeep Singh Shekhawat
- Department of Civil Engineering, Malaviya National Institute of Technology, Jaipur, India E-mail: ; School of Life and Basic Sciences, SIILAS Campus, Jaipur National University Jaipur, India
| | - Niha Mohan Kulshreshtha
- Department of Civil Engineering, Malaviya National Institute of Technology, Jaipur, India E-mail:
| | - Akhilendra Bhushan Gupta
- Department of Civil Engineering, Malaviya National Institute of Technology, Jaipur, India E-mail:
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5
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García-Descalzo L, García-López E, Cid C. Comparative Proteomic Analysis of Psychrophilic vs. Mesophilic Bacterial Species Reveals Different Strategies to Achieve Temperature Adaptation. Front Microbiol 2022; 13:841359. [PMID: 35591995 PMCID: PMC9111180 DOI: 10.3389/fmicb.2022.841359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 03/08/2022] [Indexed: 11/16/2022] Open
Abstract
The old debate of nature (genes) vs. nurture (environmental variables) is once again topical concerning the effect of climate change on environmental microorganisms. Specifically, the Polar Regions are experiencing a drastic increase in temperature caused by the rise in greenhouse gas emissions. This study, in an attempt to mimic the molecular adaptation of polar microorganisms, combines proteomic approaches with a classical microbiological analysis in three bacterial species Shewanella oneidensis, Shewanella frigidimarina, and Psychrobacter frigidicola. Both shewanellas are members of the same genus but they live in different environments. On the other hand, Shewanella frigidimarina and Psychrobacter frigidicola share the same natural environment but belong to a different genus. The comparison of the strategies employed by each bacterial species estimates the contribution of genome vs. environmental variables in the adaptation to temperature. The results show a greater versatility of acclimatization for the genus Shewanella with respect to Psychrobacter. Besides, S. frigidimarina was the best-adapted species to thermal variations in the temperature range 4–30°C and displayed several adaptation mechanisms common with the other two species. Regarding the molecular machinery used by these bacteria to face the consequences of temperature changes, chaperones have a pivoting role. They form complexes with other proteins in the response to the environment, establishing cooperation with transmembrane proteins, elongation factors, and proteins for protection against oxidative damage.
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Affiliation(s)
- Laura García-Descalzo
- Centro de Astrobiología, Department of Planetology and Habitability, CSIC-INTA, Madrid, Spain
| | - Eva García-López
- Centro de Astrobiología, Department of Molecular Ecology, CSIC-INTA, Madrid, Spain
| | - Cristina Cid
- Centro de Astrobiología, Department of Molecular Ecology, CSIC-INTA, Madrid, Spain
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Zhang SP, Feng HZ, Wang Q, Quan SW, Yu XQ, Tao X, Wang Y, Guo DD, Peng L, Feng HY, He YX. Proteomic analysis reveals the mechanism of different environmental stress-induced tolerance of Pseudomonas aeruginosa to monochloramine disinfection. JOURNAL OF HAZARDOUS MATERIALS 2021; 417:126082. [PMID: 34020351 DOI: 10.1016/j.jhazmat.2021.126082] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 05/04/2021] [Accepted: 05/06/2021] [Indexed: 06/12/2023]
Abstract
Although drinking water disinfection proved to be an effective strategy to eliminate many pathogens, bacteria can still show disinfection tolerance in drinking water distribution systems. To date, the molecular mechanisms on how environmental stress affects the tolerance of Pseudomonas aeruginosa to monochloramine are not well understood. Here, we investigated how three stress conditions, namely starvation, low temperature, and starvation combined with low temperature, affected the monochloramine tolerance of Pseudomonas aeruginosa, an opportunistic pathogen commonly found in drinking water distribution systems. All stress conditions significantly promoted monochloramine tolerance, among which starvation had the most drastic effects. Proteomic analyses suggested that the three conditions not only triggered a positive antioxidant defense against oxidative damages but also prepared the bacteria to employ a passive defense mechanism against disinfectants via dormancy. Moreover, the expression of antioxidant enzymes reached the maximum under the starvation condition and further low temperature treatment had little effect on bacterial response to oxidative stress. Instead, we found further treatment of the starved cells with low temperature decreased the osmotic stress response and the stringent response, which generally play pivotal roles in disinfection tolerance. Taken together, these findings shed light on how abiotic factors influence the bacterial disinfection tolerance and will aid design of efficient strategies to eliminate Pseudomonas aeruginosa from drinking water.
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Affiliation(s)
- Si-Ping Zhang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| | - Han-Zhong Feng
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| | - Qian Wang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| | - Shuo-Wei Quan
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| | - Xiao-Quan Yu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| | - Xuanyu Tao
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA
| | - Yong Wang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| | - Ding-Ding Guo
- School of Pharmacy, Lanzhou University, Lanzhou 730000, PR China
| | - Liang Peng
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China
| | - Hu-Yuan Feng
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China.
| | - Yong-Xing He
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China.
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Rocha LS, Silva BPD, Correia TML, Silva RPD, Meireles DDA, Pereira R, Netto LES, Meotti FC, Queiroz RF. Peroxiredoxin AhpC1 protects Pseudomonas aeruginosa against the inflammatory oxidative burst and confers virulence. Redox Biol 2021; 46:102075. [PMID: 34315109 PMCID: PMC8327333 DOI: 10.1016/j.redox.2021.102075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 07/13/2021] [Accepted: 07/17/2021] [Indexed: 11/16/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic bacterium in patients with cystic fibrosis and hospital acquired infections. It presents a plethora of virulence factors and antioxidant enzymes that help to subvert the immune system. In this study, we identified the 2-Cys peroxiredoxin, alkyl-hydroperoxide reductase C1 (AhpC1), as a relevant scavenger of oxidants generated during inflammatory oxidative burst and a mechanism of P. aeruginosa (PA14) escaping from killing. Deletion of AhpC1 led to a higher sensitivity to hypochlorous acid (HOCl, IC50 3.2 ± 0.3 versus 19.1 ± 0.2 μM), hydrogen peroxide (IC50 91.2 ± 0.3 versus 496.5 ± 6.4 μM) and the organic peroxide urate hydroperoxide. ΔahpC1 strain was more sensitive to the killing by isolated neutrophils and less virulent in a mice model of infection. All mice intranasally instilled with ΔahpC1 survived as long as they were monitored (15 days), whereas 100% wild-type and ΔahpC1 complemented with ahpC1 gene (ΔahpC1 attB:ahpC1) died within 3 days. A significantly lower number of colonies was detected in the lung and spleen of ΔahpC1-infected mice. Total leucocytes, neutrophils, myeloperoxidase activity, pro-inflammatory cytokines, nitrite production and lipid peroxidation were much lower in lungs or bronchoalveolar liquid of mice infected with ΔahpC1. Purified AhpC neutralized the inflammatory organic peroxide, urate hydroperoxide, at a rate constant of 2.3 ± 0.1 × 106 M-1s-1, and only the ΔahpC1 strain was sensitive to this oxidant. Incubation of neutrophils with uric acid, the urate hydroperoxide precursor, impaired neutrophil killing of wild-type but improved the killing of ΔahpC1. Hyperuricemic mice presented higher levels of serum cytokines and succumbed much faster to PA14 infection when compared to normouricemic mice. In summary, ΔahpC1 PA14 presented a lower virulence, which was attributed to a poorer ability to neutralize the oxidants generated by inflammatory oxidative burst, leading to a more efficient killing by the host. The enzyme is particularly relevant in detoxifying the newly reported inflammatory organic peroxide, urate hydroperoxide.
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Affiliation(s)
- Leonardo Silva Rocha
- Programa Multicêntrico de Pós-graduação em Bioquímica e Biologia Molecular, Universidade Estadual do Sudoeste da Bahia, Brazil
| | | | - Thiago M L Correia
- Programa Multicêntrico de Pós-graduação Multicêntrico em Ciências Fisiológicas, Instituto Multidisciplinar de Saúde, Universidade Federal da Bahia, Brazil
| | | | - Diogo de Abreu Meireles
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Brazil
| | - Rafael Pereira
- Programa Multicêntrico de Pós-graduação em Bioquímica e Biologia Molecular, Universidade Estadual do Sudoeste da Bahia, Brazil; Programa Multicêntrico de Pós-graduação Multicêntrico em Ciências Fisiológicas, Instituto Multidisciplinar de Saúde, Universidade Federal da Bahia, Brazil; Departamento de Ciências Biológicas, Universidade Estadual do Sudoeste da Bahia, Brazil
| | - Luis Eduardo Soares Netto
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Brazil
| | - Flavia Carla Meotti
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Brazil.
| | - Raphael Ferreira Queiroz
- Programa Multicêntrico de Pós-graduação em Bioquímica e Biologia Molecular, Universidade Estadual do Sudoeste da Bahia, Brazil; Departamento de Ciências Naturais, Universidade Estadual do Sudoeste da Bahia, Brazil.
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Genome Scale Analysis Reveals IscR Directly and Indirectly Regulates Virulence Factor Genes in Pathogenic Yersinia. mBio 2021; 12:e0063321. [PMID: 34060331 PMCID: PMC8262890 DOI: 10.1128/mbio.00633-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The iron-sulfur cluster coordinating transcription factor IscR is important for the virulence of Yersinia pseudotuberculosis and a number of other bacterial pathogens. However, the IscR regulon has not yet been defined in any organism. To determine the Yersinia IscR regulon and identify IscR-dependent functions important for virulence, we employed chromatin immunoprecipitation sequencing (ChIP-Seq) and RNA sequencing (RNA-Seq) of Y. pseudotuberculosis expressing or lacking iscR following iron starvation conditions, such as those encountered during infection. We found that IscR binds to the promoters of genes involved in iron homeostasis, reactive oxygen species metabolism, and cell envelope remodeling and regulates expression of these genes in response to iron depletion. Consistent with our previous work, we also found that IscR binds in vivo to the promoter of the Ysc type III secretion system (T3SS) master regulator LcrF, leading to regulation of T3SS genes. Interestingly, comparative genomic analysis suggested over 93% of IscR binding sites were conserved between Y. pseudotuberculosis and the related plague agent Yersinia pestis. Surprisingly, we found that the IscR positively regulated sufABCDSE Fe-S cluster biogenesis pathway was required for T3SS activity. These data suggest that IscR regulates the T3SS in Yersinia through maturation of an Fe-S cluster protein critical for type III secretion, in addition to its known role in activating T3SS genes through LcrF. Altogether, our study shows that iron starvation triggers IscR to coregulate multiple, distinct pathways relevant to promoting bacterial survival during infection.
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Dulyayangkul P, Satapoomin N, Avison MB, Charoenlap N, Vattanaviboon P, Mongkolsuk S. Over-Expression of Hypochlorite Inducible Major Facilitator Superfamily (MFS) Pumps Reduces Antimicrobial Drug Susceptibility by Increasing the Production of MexXY Mediated by ArmZ in Pseudomonas aeruginosa. Front Microbiol 2021; 11:592153. [PMID: 33510718 PMCID: PMC7835679 DOI: 10.3389/fmicb.2020.592153] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/07/2020] [Indexed: 11/30/2022] Open
Abstract
Pseudomonas aeruginosa, a well-known cause of nosocomial infection, is frequently antibiotic resistant and this complicates treatment. Links between oxidative stress responses inducing antibiotic resistance through over-production of RND-type efflux pumps have been reported in P. aeruginosa, but this has not previously been associated with MFS-type efflux pumps. Two MFS efflux pumps encoded by mfs1 and mfs2 were selected for study because they were found to be sodium hypochlorite (NaOCl) inducible. Antibiotic susceptibility testing was used to define the importance of these MFS pumps in antibiotic resistance and proteomics was used to characterize the resistance mechanisms involved. The results revealed that mfs1 is NaOCl inducible whereas mfs2 is NaOCl, N-Ethylmaleimide and t-butyl hydroperoxide inducible. Deletion of mfs1 or mfs2 did not affect antibiotic or paraquat susceptibility. However, over-production of Mfs1 and Mfs2 reduced susceptibility to aminoglycosides, quinolones, and paraquat. Proteomics, gene expression analysis and targeted mutagenesis showed that over-production of the MexXY RND-type efflux pump in a manner dependent upon armZ, but not amgRS, is the cause of reduced antibiotic susceptibility upon over-production of Mfs1 and Mfs2. mexXY operon expression analysis in strains carrying various lengths of mfs1 and mfs2 revealed that at least three transmembrane domains are necessary for mexXY over-expression and decreased antibiotic susceptibility. Over-expression of the MFS-type efflux pump gene tetA(C) did not give the same effect. Changes in paraquat susceptibility were independent of mexXY and armZ suggesting that it is a substrate of Mfs1 and Mfs2. Altogether, this is the first evidence of cascade effects where the over-production of an MFS pump causes over-production of an RND pump, in this case MexXY via increased armZ expression.
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Affiliation(s)
- Punyawee Dulyayangkul
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Chulabhorn Royal Academy, Bangkok, Thailand.,School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | - Naphat Satapoomin
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Matthew B Avison
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | - Nisanart Charoenlap
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Paiboon Vattanaviboon
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Chulabhorn Royal Academy, Bangkok, Thailand.,Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
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10
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Chien J, Hwang JH, Nilaad S, Masso-Silva JA, Jeong Ahn S, McEachern EK, Moshensky A, Byun MK, Crotty Alexander LE. Cigarette Smoke Exposure Promotes Virulence of Pseudomonas aeruginosa and Induces Resistance to Neutrophil Killing. Infect Immun 2020; 88:e00527-20. [PMID: 32868344 PMCID: PMC7573448 DOI: 10.1128/iai.00527-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 08/28/2020] [Indexed: 01/19/2023] Open
Abstract
It is widely known that cigarette smoke damages host defenses and increases susceptibility to bacterial infections. Pseudomonas aeruginosa, a Gram-negative bacterium that commonly colonizes the airways of smokers and patients with chronic lung disease, can cause pneumonia and sepsis and can trigger exacerbations of lung diseases. Pseudomonas aeruginosa colonizing airways is consistently exposed to inhaled cigarette smoke. Here, we investigated whether cigarette smoke alters the ability of this clinically significant microbe to bypass host defenses and cause invasive disease. We found that cigarette smoke extract (CSE) exposure enhances resistance to human neutrophil killing, but this increase in pathogenicity was not due to resistance to neutrophil extracellular traps. Instead, Pseudomonas aeruginosa exposed to CSE (CSE-PSA) had increased resistance to oxidative stress, which correlated with increased expression of tpx, a gene essential for defense against oxidative stress. In addition, exposure to CSE induced enhanced biofilm formation and resistance to the antibiotic levofloxacin. Finally, CSE-PSA had increased virulence in a model of pneumonia, with 0% of mice infected with CSE-PSA alive at day 6, while 28% of controls survived. Altogether, these data show that cigarette smoke alters the phenotype of P. aeruginosa, increasing virulence and making it less susceptible to killing by neutrophils and more capable of causing invasive disease. These findings provide further explanation of the refractory nature of respiratory illnesses in smokers and highlight cigarette smoking as a potential driver of virulence in this important airway pathogen.
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Affiliation(s)
- Jason Chien
- Pulmonary and Critical Care Section, VA San Diego Healthcare System, La Jolla, California, USA
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - John H Hwang
- Pulmonary and Critical Care Section, VA San Diego Healthcare System, La Jolla, California, USA
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Sedtavut Nilaad
- Pulmonary and Critical Care Section, VA San Diego Healthcare System, La Jolla, California, USA
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Jorge A Masso-Silva
- Pulmonary and Critical Care Section, VA San Diego Healthcare System, La Jolla, California, USA
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Sae Jeong Ahn
- Pulmonary and Critical Care Section, VA San Diego Healthcare System, La Jolla, California, USA
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Elisa K McEachern
- Pulmonary and Critical Care Section, VA San Diego Healthcare System, La Jolla, California, USA
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Alexander Moshensky
- Pulmonary and Critical Care Section, VA San Diego Healthcare System, La Jolla, California, USA
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Min-Kwang Byun
- Pulmonary and Critical Care Section, VA San Diego Healthcare System, La Jolla, California, USA
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California San Diego, La Jolla, California, USA
- Division of Pulmonology, Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea
| | - Laura E Crotty Alexander
- Pulmonary and Critical Care Section, VA San Diego Healthcare System, La Jolla, California, USA
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California San Diego, La Jolla, California, USA
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11
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Rémy B, Plener L, Decloquement P, Armstrong N, Elias M, Daudé D, Chabrière É. Lactonase Specificity Is Key to Quorum Quenching in Pseudomonas aeruginosa. Front Microbiol 2020; 11:762. [PMID: 32390993 PMCID: PMC7193897 DOI: 10.3389/fmicb.2020.00762] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 03/30/2020] [Indexed: 12/31/2022] Open
Abstract
The human opportunistic pathogen Pseudomonas aeruginosa orchestrates the expression of many genes in a cell density-dependent manner by using quorum sensing (QS). Two acyl-homoserine lactones (AHLs) are involved in QS circuits and contribute to the regulation of virulence factors production, biofilm formation, and antimicrobial sensitivity. Disrupting QS, a strategy referred to as quorum quenching (QQ) can be achieved using exogenous AHL-degrading lactonases. However, the importance of enzyme specificity on quenching efficacy has been poorly investigated. Here, we used two lactonases both targeting the signal molecules N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12 HSL) and butyryl-homoserine lactone (C4 HSL) albeit with different efficacies on C4 HSL. Interestingly, both lactonases similarly decreased AHL concentrations and comparably impacted the expression of AHL-based QS genes. However, strong variations were observed in Pseudomonas Quinolone Signal (PQS) regulation depending on the lactonase used. Both lactonases were also found to decrease virulence factors production and biofilm formation in vitro, albeit with different efficiencies. Unexpectedly, only the lactonase with lower efficacy on C4 HSL was able to inhibit P. aeruginosa pathogenicity in vivo in an amoeba infection model. Similarly, proteomic analysis revealed large variations in protein levels involved in antibiotic resistance, biofilm formation, virulence and diverse cellular mechanisms depending on the chosen lactonase. This global analysis provides evidences that QQ enzyme specificity has a significant impact on the modulation of QS-associated behavior in P. aeruginosa PA14.
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Affiliation(s)
- Benjamin Rémy
- Aix Marseille University, Institut de Recherche pour le Développement, Assistance Publique - Hôpitaux de Marseille, Microbes Evolution Phylogeny and Infections, Institut Hospitalo-Universitaire-Méditerranée Infection, Marseille, France.,Gene&GreenTK, Marseille, France
| | | | - Philippe Decloquement
- Aix Marseille University, Institut de Recherche pour le Développement, Assistance Publique - Hôpitaux de Marseille, Microbes Evolution Phylogeny and Infections, Institut Hospitalo-Universitaire-Méditerranée Infection, Marseille, France
| | - Nicholas Armstrong
- Aix Marseille University, Institut de Recherche pour le Développement, Assistance Publique - Hôpitaux de Marseille, Microbes Evolution Phylogeny and Infections, Institut Hospitalo-Universitaire-Méditerranée Infection, Marseille, France
| | - Mikael Elias
- Department of Biochemistry, Molecular Biology and Biophysics - BioTechnology Institute, University of Minnesota, St. Paul, MN, United States
| | | | - Éric Chabrière
- Aix Marseille University, Institut de Recherche pour le Développement, Assistance Publique - Hôpitaux de Marseille, Microbes Evolution Phylogeny and Infections, Institut Hospitalo-Universitaire-Méditerranée Infection, Marseille, France
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12
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Baussier C, Fakroun S, Aubert C, Dubrac S, Mandin P, Py B, Barras F. Making iron-sulfur cluster: structure, regulation and evolution of the bacterial ISC system. Adv Microb Physiol 2020; 76:1-39. [PMID: 32408945 DOI: 10.1016/bs.ampbs.2020.01.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Iron sulfur (Fe-S) clusters rank among the most ancient and conserved prosthetic groups. Fe-S clusters containing proteins are present in most, if not all, organisms. Fe-S clusters containing proteins are involved in a wide range of cellular processes, from gene regulation to central metabolism, via gene expression, RNA modification or bioenergetics. Fe-S clusters are built by biogenesis machineries conserved throughout both prokaryotes and eukaryotes. We focus mostly on bacterial ISC machinery, but not exclusively, as we refer to eukaryotic ISC system when it brings significant complementary information. Besides covering the structural and regulatory aspects of Fe-S biogenesis, this review aims to highlight Fe-S biogenesis facets remaining matters of discussion, such as the role of frataxin, or the link between fatty acid metabolism and Fe-S homeostasis. Last, we discuss recent advances on strategies used by different species to make and use Fe-S clusters in changing redox environmental conditions.
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Affiliation(s)
- Corentin Baussier
- Laboratoire de Chimie Bactérienne, CNRS-Aix Marseille Université, UMR 7283, Institut de Microbiologie de la Méditerranée, Institut de Microbiologie, Bioénergies et Biotechnologies, Marseille, France
| | - Soufyan Fakroun
- Stress Adaptation and Metabolism Unit, Department of Microbiology, Institut Pasteur, Paris, France; ERL CNRS 6002, CNRS, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Corinne Aubert
- Laboratoire de Chimie Bactérienne, CNRS-Aix Marseille Université, UMR 7283, Institut de Microbiologie de la Méditerranée, Institut de Microbiologie, Bioénergies et Biotechnologies, Marseille, France
| | - Sarah Dubrac
- Stress Adaptation and Metabolism Unit, Department of Microbiology, Institut Pasteur, Paris, France; ERL CNRS 6002, CNRS, Paris, France
| | - Pierre Mandin
- Laboratoire de Chimie Bactérienne, CNRS-Aix Marseille Université, UMR 7283, Institut de Microbiologie de la Méditerranée, Institut de Microbiologie, Bioénergies et Biotechnologies, Marseille, France
| | - Béatrice Py
- Laboratoire de Chimie Bactérienne, CNRS-Aix Marseille Université, UMR 7283, Institut de Microbiologie de la Méditerranée, Institut de Microbiologie, Bioénergies et Biotechnologies, Marseille, France
| | - Frédéric Barras
- Stress Adaptation and Metabolism Unit, Department of Microbiology, Institut Pasteur, Paris, France; ERL CNRS 6002, CNRS, Paris, France
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13
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Lu J, Wang Y, Jin M, Yuan Z, Bond P, Guo J. Both silver ions and silver nanoparticles facilitate the horizontal transfer of plasmid-mediated antibiotic resistance genes. WATER RESEARCH 2020; 169:115229. [PMID: 31783256 DOI: 10.1016/j.watres.2019.115229] [Citation(s) in RCA: 154] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 08/04/2019] [Accepted: 10/24/2019] [Indexed: 05/21/2023]
Abstract
Antibiotic resistance in bacteria is a growing threat to global human health. Horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs) is recognized as the primary contributor to antibiotic resistance dissemination. Silver nanoparticles (AgNPs) are widely used in personal care products as antimicrobial agents. While heavy metals are known to induce antibiotic resistance in bacteria, it is not known whether AgNPs in the environment can stimulate the HGT of ARGs. Here, we report that both AgNPs and ionic silver Ag+, at environmentally relevant and sub-lethal concentrations, facilitate the conjugative transfer of plasmid-borne ARGs across bacterial genera (from the donor Escherichia coli K-12 LE392 to the recipient Pseudomonas putida KT2440). The underlying mechanisms of the Ag+- or AgNPs-promoted HGT were unveiled by detecting oxidative stress and cell membrane permeability, combined with genome-wide RNA sequencing and proteomic analyses. It was found that both Ag+ and AgNPs exposure induced various bacterial responses that included reactive oxygen species (ROS) generation, membrane damage and the SOS response. This study exposes the potential ecological risks of environmental levels of AgNPs and Ag+ for promoting the spread of ARGs and highlights concerns regarding the management of nanoparticles and heavy metals.
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Affiliation(s)
- Ji Lu
- Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia
| | - Yue Wang
- Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia
| | - Min Jin
- Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia
| | - Zhiguo Yuan
- Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia
| | - Philip Bond
- Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia
| | - Jianhua Guo
- Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia.
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14
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Moody S, Bull J, Dudley E, Loveridge E. The impact of combinatorial stress on the growth dynamics and metabolome of
Burkholderia mesoacidophila
demonstrates the complexity of tolerance mechanisms. J Appl Microbiol 2019; 127:1521-1531. [DOI: 10.1111/jam.14404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 07/19/2019] [Accepted: 07/23/2019] [Indexed: 12/15/2022]
Affiliation(s)
- S.C. Moody
- College of Science Swansea University Swansea UK
- School of Sport, Health and Social Sciences Solent University Southampton UK
| | - J.C. Bull
- College of Science Swansea University Swansea UK
| | - E. Dudley
- College of Medicine Swansea University Swansea UK
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15
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Saninjuk K, Romsang A, Duang-nkern J, Vattanaviboon P, Mongkolsuk S. Transcriptional regulation of the Pseudomonas aeruginosa iron-sulfur cluster assembly pathway by binding of IscR to multiple sites. PLoS One 2019; 14:e0218385. [PMID: 31251744 PMCID: PMC6599224 DOI: 10.1371/journal.pone.0218385] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 06/01/2019] [Indexed: 01/06/2023] Open
Abstract
Iron-sulfur ([Fe-S]) cluster proteins have essential functions in many biological processes. [Fe-S] homeostasis is crucial for bacterial survival under a wide range of environmental conditions. IscR is a global transcriptional regulator in Pseudomonas aeruginosa; it has been shown to regulate genes involved in [Fe-S] cluster biosynthesis, iron homeostasis, resistance to oxidants, and pathogenicity. Many aspects of the IscR transcriptional regulatory mechanism differ from those of other well-studied systems. This study demonstrates the mechanisms of IscR Type-1 binding to its target sites that mediate the repression of gene expression at the isc operon, nfuA, and tpx. The analysis of IscR binding to multiple binding sites in the promoter region of the isc operon reveals that IscR first binds to the high-affinity site B followed by binding to the low-affinity site A. The results of in vitro IscR binding assays and in vivo analysis of IscR-mediated repression of gene expression support the role of site B as the primary site, while site A has only a minor role in the efficiency of IscR repression of gene expression. Ligation of an [Fe-S] cluster to IscR is required for the binding of IscR to target sites and in vivo repression and stress-induced gene expression. Analysis of Type-1 sites in many bacteria, including P. aeruginosa, indicates that the first and the last three AT-rich bases were among the most highly conserved bases within all analyzed Type-1 sites. Herein, we first propose the putative sequence of P. aeruginosa IscR Type-1 binding motif as 5'AWWSSYRMNNWWWTNNNWSGGNYWW3'. This can benefit further studies in the identification of novel genes under the IscR regulon and the regulatory mechanism model of P. aeruginosa IscR as it contributes to the roles of an [Fe-S] cluster in several biologically important cellular activities.
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Affiliation(s)
- Kritsakorn Saninjuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jintana Duang-nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Chulabhorn Royal Academy, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology, EHT, Ministry of Education, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology, EHT, Ministry of Education, Bangkok, Thailand
- * E-mail:
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16
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Sevilla E, Bes MT, González A, Peleato ML, Fillat MF. Redox-Based Transcriptional Regulation in Prokaryotes: Revisiting Model Mechanisms. Antioxid Redox Signal 2019; 30:1651-1696. [PMID: 30073850 DOI: 10.1089/ars.2017.7442] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
SIGNIFICANCE The successful adaptation of microorganisms to ever-changing environments depends, to a great extent, on their ability to maintain redox homeostasis. To effectively maintain the redox balance, cells have developed a variety of strategies mainly coordinated by a battery of transcriptional regulators through diverse mechanisms. Recent Advances: This comprehensive review focuses on the main mechanisms used by major redox-responsive regulators in prokaryotes and their relationship with the different redox signals received by the cell. An overview of the corresponding regulons is also provided. CRITICAL ISSUES Some regulators are difficult to classify since they may contain several sensing domains and respond to more than one signal. We propose a classification of redox-sensing regulators into three major groups. The first group contains one-component or direct regulators, whose sensing and regulatory domains are in the same protein. The second group comprises the classical two-component systems involving a sensor kinase that transduces the redox signal to its DNA-binding partner. The third group encompasses a heterogeneous group of flavin-based photosensors whose mechanisms are not always fully understood and are often involved in more complex regulatory networks. FUTURE DIRECTIONS Redox-responsive transcriptional regulation is an intricate process as identical signals may be sensed and transduced by different transcription factors, which often interplay with other DNA-binding proteins with or without regulatory activity. Although there is much information about some key regulators, many others remain to be fully characterized due to the instability of their clusters under oxygen. Understanding the mechanisms and the regulatory networks operated by these regulators is essential for the development of future applications in biotechnology and medicine.
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Affiliation(s)
- Emma Sevilla
- 1 Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain.,2 Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), Universidad de Zaragoza, Zaragoza, Spain.,3 Grupo de Bioquímica, Biofísica y Biología Computacional (BIFI, UNIZAR), Unidad Asociada al CSIC, Zaragoza, Spain
| | - María Teresa Bes
- 1 Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain.,2 Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), Universidad de Zaragoza, Zaragoza, Spain.,3 Grupo de Bioquímica, Biofísica y Biología Computacional (BIFI, UNIZAR), Unidad Asociada al CSIC, Zaragoza, Spain
| | - Andrés González
- 2 Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), Universidad de Zaragoza, Zaragoza, Spain.,3 Grupo de Bioquímica, Biofísica y Biología Computacional (BIFI, UNIZAR), Unidad Asociada al CSIC, Zaragoza, Spain.,4 Instituto de Investigación Sanitaria Aragón (IIS Aragón), Zaragoza, Spain
| | - María Luisa Peleato
- 1 Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain.,2 Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), Universidad de Zaragoza, Zaragoza, Spain.,3 Grupo de Bioquímica, Biofísica y Biología Computacional (BIFI, UNIZAR), Unidad Asociada al CSIC, Zaragoza, Spain
| | - María F Fillat
- 1 Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain.,2 Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), Universidad de Zaragoza, Zaragoza, Spain.,3 Grupo de Bioquímica, Biofísica y Biología Computacional (BIFI, UNIZAR), Unidad Asociada al CSIC, Zaragoza, Spain
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17
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Wongsaroj L, Saninjuk K, Romsang A, Duang-nkern J, Trinachartvanit W, Vattanaviboon P, Mongkolsuk S. Pseudomonas aeruginosa glutathione biosynthesis genes play multiple roles in stress protection, bacterial virulence and biofilm formation. PLoS One 2018; 13:e0205815. [PMID: 30325949 PMCID: PMC6191110 DOI: 10.1371/journal.pone.0205815] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 10/02/2018] [Indexed: 01/06/2023] Open
Abstract
Pseudomonas aeruginosa PAO1 contains gshA and gshB genes, which encode enzymes involved in glutathione (GSH) biosynthesis. Challenging P. aeruginosa with hydrogen peroxide, cumene hydroperoxide, and t-butyl hydroperoxide increased the expression of gshA and gshB. The physiological roles of these genes in P. aeruginosa oxidative stress, bacterial virulence, and biofilm formation were examined using P. aeruginosa ΔgshA, ΔgshB, and double ΔgshAΔgshB mutant strains. These mutants exhibited significantly increased susceptibility to methyl viologen, thiol-depleting agent, and methylglyoxal compared to PAO1. Expression of functional gshA, gshB or exogenous supplementation with GSH complemented these phenotypes, which indicates that the observed mutant phenotypes arose from their inability to produce GSH. Virulence assays using a Drosophila melanogaster model revealed that the ΔgshA, ΔgshB and double ΔgshAΔgshB mutants exhibited attenuated virulence phenotypes. An analysis of virulence factors, including pyocyanin, pyoverdine, and cell motility (swimming and twitching), showed that these levels were reduced in these gsh mutants compared to PAO1. In contrast, biofilm formation increased in mutants. These data indicate that the GSH product and the genes responsible for GSH synthesis play multiple crucial roles in oxidative stress protection, bacterial virulence and biofilm formation in P. aeruginosa.
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Affiliation(s)
- Lampet Wongsaroj
- Molecular Medicine Graduate Program, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Kritsakorn Saninjuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jintana Duang-nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | | | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- * E-mail:
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18
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Pseudomonas aeruginosa nfuA: Gene regulation and its physiological roles in sustaining growth under stress and anaerobic conditions and maintaining bacterial virulence. PLoS One 2018; 13:e0202151. [PMID: 30092083 PMCID: PMC6084964 DOI: 10.1371/journal.pone.0202151] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 07/27/2018] [Indexed: 11/19/2022] Open
Abstract
The role of the nfuA gene encoding an iron-sulfur ([Fe-S]) cluster-delivery protein in the pathogenic bacterium Pseudomonas aeruginosa was investigated. The analysis of nfuA expression under various stress conditions showed that superoxide generators, a thiol-depleting agent and CuCl2 highly induced nfuA expression. The expression of nfuA was regulated by a global [2Fe-2S] cluster containing the transcription regulator IscR. Increased expression of nfuA in the ΔiscR mutant under uninduced conditions suggests that IscR acts as a transcriptional repressor. In vitro experiments revealed that IscR directly bound to a sequence homologous to the Escherichia coli Type-I IscR-binding motifs on a putative nfuA promoter that overlapped the -35 element. Binding of IscR prevented RNA polymerase from binding to the nfuA promoter, leading to repression of the nfuA transcription. Physiologically, deletion of nfuA reduced the bacterial ability to cope with oxidative stress, iron deprivation conditions and attenuated virulence in the Caenorhabditis elegans infection model. Site-directed mutagenesis analysis revealed that the conserved CXXC motif of the Nfu-type scaffold protein domain at the N-terminus was required for the NfuA functions in conferring the stress resistance phenotype. Furthermore, anaerobic growth of the ΔnfuA mutant in the presence of nitrate was drastically retarded. This phenotype was associated with a reduction in the [Fe-S] cluster containing nitrate reductase enzyme activity. However, NfuA was not required for the maturation of [Fe-S]-containing proteins such as aconitase, succinate dehydrogenase, SoxR and IscR. Taken together, our results indicate that NfuA functions in [Fe-S] cluster delivery to selected target proteins that link to many physiological processes such as anaerobic growth, bacterial virulence and stress responses in P. aeruginosa.
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19
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Romsang A, Duang-Nkern J, Khemsom K, Wongsaroj L, Saninjuk K, Fuangthong M, Vattanaviboon P, Mongkolsuk S. Pseudomonas aeruginosa ttcA encoding tRNA-thiolating protein requires an iron-sulfur cluster to participate in hydrogen peroxide-mediated stress protection and pathogenicity. Sci Rep 2018; 8:11882. [PMID: 30089777 PMCID: PMC6082896 DOI: 10.1038/s41598-018-30368-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 07/27/2018] [Indexed: 01/21/2023] Open
Abstract
During the translation process, transfer RNA (tRNA) carries amino acids to ribosomes for protein synthesis. Each codon of mRNA is recognized by a specific tRNA, and enzyme-catalysed modifications to tRNA regulate translation. TtcA is a unique tRNA-thiolating enzyme that requires an iron-sulfur ([Fe-S]) cluster to catalyse thiolation of tRNA. In this study, the physiological functions of a putative ttcA in Pseudomonas aeruginosa, an opportunistic human pathogen that causes serious problems in hospitals, were characterized. A P. aeruginosa ttcA-deleted mutant was constructed, and mutant cells were rendered hypersensitive to oxidative stress, such as hydrogen peroxide (H2O2) treatment. Catalase activity was lower in the ttcA mutant, suggesting that this gene plays a role in protecting against oxidative stress. Moreover, the ttcA mutant demonstrated attenuated virulence in a Drosophila melanogaster host model. Site-directed mutagenesis analysis revealed that the conserved cysteine motifs involved in [Fe-S] cluster ligation were required for TtcA function. Furthermore, ttcA expression increased upon H2O2 exposure, implying that enzyme levels are induced under stress conditions. Overall, the data suggest that P. aeruginosa ttcA plays a critical role in protecting against oxidative stress via catalase activity and is required for successful bacterial infection of the host.
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Affiliation(s)
- Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand. .,Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.
| | - Jintana Duang-Nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
| | - Khwannarin Khemsom
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Lampet Wongsaroj
- Molecular Medicine Graduate Program, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Kritsakorn Saninjuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Mayuree Fuangthong
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand.,Molecular Medicine Graduate Program, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
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20
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Rantasalo A, Kuivanen J, Penttilä M, Jäntti J, Mojzita D. Synthetic Toolkit for Complex Genetic Circuit Engineering in Saccharomyces cerevisiae. ACS Synth Biol 2018; 7:1573-1587. [PMID: 29750501 PMCID: PMC6150731 DOI: 10.1021/acssynbio.8b00076] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Sustainable production of chemicals, materials, and pharmaceuticals is increasingly performed by genetically engineered cell factories. Engineering of complex metabolic routes or cell behavior control systems requires robust and predictable gene expression tools. In this challenging task, orthogonality is a fundamental prerequisite for such tools. In this study, we developed and characterized in depth a comprehensive gene expression toolkit that allows accurate control of gene expression in Saccharomyces cerevisiae without marked interference with native cellular regulation. The toolkit comprises a set of transcription factors, designed to function as synthetic activators or repressors, and transcription-factor-dependent promoters, which together provide a broad expression range surpassing, at high end, the strongest native promoters. Modularity of the developed tools is demonstrated by establishing a novel bistable genetic circuit with robust performance to control a heterologous metabolic pathway and enabling on-demand switching between two alternative metabolic branches.
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Affiliation(s)
- Anssi Rantasalo
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 VTT Espoo, Finland
| | - Joosu Kuivanen
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 VTT Espoo, Finland
| | - Merja Penttilä
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 VTT Espoo, Finland
| | - Jussi Jäntti
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 VTT Espoo, Finland
| | - Dominik Mojzita
- VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 VTT Espoo, Finland
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21
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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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Boonma S, Romsang A, Duang-Nkern J, Atichartpongkul S, Trinachartvanit W, Vattanaviboon P, Mongkolsuk S. The FinR-regulated essential gene fprA, encoding ferredoxin NADP+ reductase: Roles in superoxide-mediated stress protection and virulence of Pseudomonas aeruginosa. PLoS One 2017; 12:e0172071. [PMID: 28187184 PMCID: PMC5302815 DOI: 10.1371/journal.pone.0172071] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 01/30/2017] [Indexed: 11/23/2022] Open
Abstract
Pseudomonas aeruginosa has two genes encoding ferredoxin NADP(+) reductases, denoted fprA and fprB. We show here that P. aeruginosa fprA is an essential gene. However, the ΔfprA mutant could only be successfully constructed in PAO1 strains containing an extra copy of fprA on a mini-Tn7 vector integrated into the chromosome or carrying it on a temperature-sensitive plasmid. The strain containing an extra copy of the ferredoxin gene (fdx1) could suppress the essentiality of FprA. Other ferredoxin genes could not suppress the requirement for FprA, suggesting that Fdx1 mediates the essentiality of FprA. The expression of fprA was highly induced in response to treatments with a superoxide generator, paraquat, or sodium hypochlorite (NaOCl). The induction of fprA by these treatments depended on FinR, a LysR-family transcription regulator. In vivo and in vitro analysis suggested that oxidized FinR acted as a transcriptional activator of fprA expression by binding to its regulatory box, located 20 bases upstream of the fprA -35 promoter motif. This location of the FinR box also placed it between the -35 and -10 motifs of the finR promoter, where the reduced regulator functions as a repressor. Under uninduced conditions, binding of FinR repressed its own transcription but had no effect on fprA expression. Exposure to paraquat or NaOCl converted FinR to a transcriptional activator, leading to the expression of both fprA and finR. The ΔfinR mutant showed an increased paraquat sensitivity phenotype and attenuated virulence in the Drosophila melanogaster host model. These phenotypes could be complemented by high expression of fprA, indicating that the observed phenotypes of the ΔfinR mutant arose from the inability to up-regulate fprA expression. In addition, increased expression of fprB was unable to rescue essentiality of fprA or the superoxide-sensitive phenotype of the ΔfinR mutant, suggesting distinct mechanisms of the FprA and FprB enzymes.
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Affiliation(s)
- Siriwan Boonma
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jintana Duang-Nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | | | | | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry Of Education, Bangkok, Thailand.,Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry Of Education, Bangkok, Thailand.,Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
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23
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Sethupathy S, Prasath KG, Ananthi S, Mahalingam S, Balan SY, Pandian SK. Proteomic analysis reveals modulation of iron homeostasis and oxidative stress response in Pseudomonas aeruginosa PAO1 by curcumin inhibiting quorum sensing regulated virulence factors and biofilm production. J Proteomics 2016; 145:112-126. [DOI: 10.1016/j.jprot.2016.04.019] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 04/15/2016] [Accepted: 04/17/2016] [Indexed: 01/01/2023]
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Kimyon Ö, Das T, Ibugo AI, Kutty SK, Ho KK, Tebben J, Kumar N, Manefield M. Serratia Secondary Metabolite Prodigiosin Inhibits Pseudomonas aeruginosa Biofilm Development by Producing Reactive Oxygen Species that Damage Biological Molecules. Front Microbiol 2016; 7:972. [PMID: 27446013 PMCID: PMC4922266 DOI: 10.3389/fmicb.2016.00972] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 06/06/2016] [Indexed: 11/13/2022] Open
Abstract
Prodigiosin is a heterocyclic bacterial secondary metabolite belonging to the class of tripyrrole compounds, synthesized by various types of bacteria including Serratia species. Prodigiosin has been the subject of intense research over the last decade for its ability to induce apoptosis in several cancer cell lines. Reports suggest that prodigiosin promotes oxidative damage to double-stranded DNA (dsDNA) in the presence of copper ions and consequently leads to inhibition of cell-cycle progression and cell death. However, prodigiosin has not been previously implicated in biofilm inhibition. In this study, the link between prodigiosin and biofilm inhibition through the production of redox active metabolites is presented. Our study showed that prodigiosin (500 μM) (extracted from Serratia marcescens culture) and a prodigiosin/copper(II) (100 μM each) complex have strong RNA and dsDNA cleaving properties while they have no pronounced effect on protein. Results support a role for oxidative damage to biomolecules by H2O2 and hydroxyl radical generation. Further, it was demonstrated that reactive oxygen species scavengers significantly reduced the DNA and RNA cleaving property of prodigiosin. P. aeruginosa cell surface hydrophobicity and biofilm integrity were significantly altered due to the cleavage of nucleic acids by prodigiosin or the prodigiosin/copper(II) complex. In addition, prodigiosin also facilitated the bactericidal activity. The ability of prodigiosinto cause nucleic acid degradation offers novel opportunities to interfere with extracellular DNA dependent bacterial biofilms.
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Affiliation(s)
- Önder Kimyon
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales Sydney, NSW, Australia
| | - Theerthankar Das
- School of Biotechnology and Biomolecular Sciences, The University of New South WalesSydney, NSW, Australia; Department of Infectious Diseases and Immunology, Sydney Medical School, The University of SydneySydney, NSW, Australia
| | - Amaye I Ibugo
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales Sydney, NSW, Australia
| | - Samuel K Kutty
- School of Chemistry, The University of New South Wales Sydney, NSW, Australia
| | - Kitty K Ho
- School of Chemistry, The University of New South Wales Sydney, NSW, Australia
| | - Jan Tebben
- Ecological Chemistry, Alfred Wegener Institute for Polar and Marine Research Institute Bremerhaven, Germany
| | - Naresh Kumar
- School of Chemistry, The University of New South Wales Sydney, NSW, Australia
| | - Mike Manefield
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales Sydney, NSW, Australia
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Zheng C, Ren S, Xu J, Zhao X, Shi G, Wu J, Li J, Chen H, Bei W. Contribution of NADH oxidase to oxidative stress tolerance and virulence of Streptococcus suis serotype 2. Virulence 2016; 8:53-65. [PMID: 27315343 DOI: 10.1080/21505594.2016.1201256] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Streptococcus suis is a major swine and zoonotic pathogen that causes severe infections. Previously, we identified 2 Spx regulators in S. suis, and demonstrated that SpxA1 affects oxidative stress tolerance and virulence. However, the mechanism behind SpxA1 function remains unclear. In this study, we targeted 4 genes that were expressed at significantly reduced levels in the spxA1 mutant, to determine their specific roles in adaptation to oxidative stress and virulence potential. The Δnox strain exhibited impaired growth under oxidative stress conditions, suggesting that NADH oxidase is involved in oxidative stress tolerance. Using murine and pig infection models, we demonstrate for the first time that NADH oxidase is required for virulence in S. suis 2. Furthermore, the enzymatic activity of NADH oxidase has a key role in oxidative stress tolerance and a secondary role in virulence. Collectively, our findings reveal that NADH oxidase plays an important part in SpxA1 function and provide a new insight into the pathogenesis of S. suis 2.
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Affiliation(s)
- Chengkun Zheng
- a State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University , Wuhan , China.,b Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, Huazhong Agricultural University , Wuhan , China.,c The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University , Wuhan , China
| | - Sujing Ren
- a State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University , Wuhan , China.,b Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, Huazhong Agricultural University , Wuhan , China.,c The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University , Wuhan , China
| | - Jiali Xu
- a State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University , Wuhan , China.,b Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, Huazhong Agricultural University , Wuhan , China.,c The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University , Wuhan , China
| | - Xigong Zhao
- a State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University , Wuhan , China.,b Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, Huazhong Agricultural University , Wuhan , China.,c The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University , Wuhan , China
| | - Guolin Shi
- a State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University , Wuhan , China.,b Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, Huazhong Agricultural University , Wuhan , China.,c The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University , Wuhan , China
| | - Jianping Wu
- a State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University , Wuhan , China
| | - Jinquan Li
- d College of Food Science and Technology, Huazhong Agricultural University , Wuhan , China
| | - Huanchun Chen
- a State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University , Wuhan , China.,b Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, Huazhong Agricultural University , Wuhan , China.,c The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University , Wuhan , China
| | - Weicheng Bei
- a State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University , Wuhan , China.,b Key Laboratory of Development of Veterinary Diagnostic Products, Ministry of Agriculture, Huazhong Agricultural University , Wuhan , China.,c The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University , Wuhan , China
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Davis R, Brown PD. Multiple antibiotic resistance index, fitness and virulence potential in respiratory Pseudomonas aeruginosa from Jamaica. J Med Microbiol 2016; 65:261-271. [PMID: 26860081 DOI: 10.1099/jmm.0.000229] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Rochell Davis
- Department of Basic Medical Sciences, University of the West Indies, Mona, Kingston 7, Jamaica
| | - Paul D. Brown
- Department of Basic Medical Sciences, University of the West Indies, Mona, Kingston 7, Jamaica
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27
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Romsang A, Duang-nkern J, Wirathorn W, Vattanaviboon P, Mongkolsuk S. Pseudomonas aeruginosa IscR-Regulated Ferredoxin NADP(+) Reductase Gene (fprB) Functions in Iron-Sulfur Cluster Biogenesis and Multiple Stress Response. PLoS One 2015; 10:e0134374. [PMID: 26230408 PMCID: PMC4521836 DOI: 10.1371/journal.pone.0134374] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Accepted: 07/08/2015] [Indexed: 12/14/2022] Open
Abstract
P. aeruginosa (PAO1) has two putative genes encoding ferredoxin NADP(+) reductases, denoted fprA and fprB. Here, the regulation of fprB expression and the protein’s physiological roles in [4Fe-4S] cluster biogenesis and stress protection are characterized. The fprB mutant has defects in [4Fe-4S] cluster biogenesis, as shown by reduced activities of [4Fe-4S] cluster-containing enzymes. Inactivation of the gene resulted in increased sensitivity to oxidative, thiol, osmotic and metal stresses compared with the PAO1 wild type. The increased sensitivity could be partially or completely suppressed by high expression of genes from the isc operon, which are involved in [Fe-S] cluster biogenesis, indicating that stress sensitivity in the fprB mutant is partially caused by a reduction in levels of [4Fe-4S] clusters. The pattern and regulation of fprB expression are in agreement with the gene physiological roles; fprB expression was highly induced by redox cycling drugs and diamide and was moderately induced by peroxides, an iron chelator and salt stress. The stress-induced expression of fprB was abolished by a deletion of the iscR gene. An IscR DNA-binding site close to fprB promoter elements was identified and confirmed by specific binding of purified IscR. Analysis of the regulation of fprB expression supports the role of IscR in directly regulating fprB transcription as a transcription activator. The combination of IscR-regulated expression of fprB and the fprB roles in response to multiple stressors emphasizes the importance of [Fe-S] cluster homeostasis in both gene regulation and stress protection.
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Affiliation(s)
- Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jintana Duang-nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Wilaiwan Wirathorn
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Center of Excellence on Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
- Program in Applied Biological Science: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Center of Excellence on Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology (EHT), Ministry Of Education, Bangkok, Thailand
- * E-mail:
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28
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Ranjani J, Pushpanathan M, Mahesh A, Niraimathi M, Gunasekaran P, Rajendhran J. Pseudomonas aeruginosa PAO1 induces distinct cell death mechanisms in H9C2 cells and its differentiated form. J Basic Microbiol 2015; 55:1191-202. [PMID: 26011149 DOI: 10.1002/jobm.201500037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 05/02/2015] [Indexed: 12/23/2022]
Abstract
Bacterial infections in myocardium may lead to the myocardial damage, which may progress to dilated cardiomyopathy and cardiac arrest. Pseudomonas aeruginosa has been reported to cause myocarditis and other systemic infections especially in immunocompromised patients. To understand the cellular responses during the establishment of infection in myocardium, we challenged differentiated H9C2 cells with P. aeruginosa PAO1. We also did comparison studies with infected undifferentiated form of H9C2 cells. Invasion studies revealed that PAO1 can invade both forms of cells and is able to survive and replicate within the host. Internalization of PAO1 was confirmed by live cell imaging and flow cytometry analysis. Though invasion of the pathogen triggered an increased ROS production in the host cells at earlier post-infection periods, it was decreased at later post-infection periods. Invasion of PAO1 induced cell death through apoptosis in differentiated H9C2 cells. Significant decrease in cell size, formation of polarized mitochondria, and nuclear fragmentation were observed in the infected differentiated cells. On the contrary, cell death preceded by multinucleation was observed in infected undifferentiated H9C2 cells. Morphological markers such as multinuclei and micro nuclei were observed. Cell cycle arrest in G2/M phase corroborates that the undifferentiated H9C2 cells experienced cell death preceded by multinucleation.
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Affiliation(s)
- Jothi Ranjani
- Department of Genetics, Centre for Excellence in Genomic Sciences, School of Biological Sciences, Madurai Kamaraj University, Madurai, Tamil Nadu, India
| | - Muthuirulan Pushpanathan
- Department of Genetics, Centre for Excellence in Genomic Sciences, School of Biological Sciences, Madurai Kamaraj University, Madurai, Tamil Nadu, India
| | - Ayyavu Mahesh
- IPLS Program, School of Biological Sciences, Madurai Kamaraj University, Madurai, Tamil Nadu, India
| | - Marimuthu Niraimathi
- IPLS Program, School of Biological Sciences, Madurai Kamaraj University, Madurai, Tamil Nadu, India
| | - Paramasamy Gunasekaran
- Department of Genetics, Centre for Excellence in Genomic Sciences, School of Biological Sciences, Madurai Kamaraj University, Madurai, Tamil Nadu, India.,Thiruvalluvar University, Vellore, Tamil Nadu, India
| | - Jeyaprakash Rajendhran
- Department of Genetics, Centre for Excellence in Genomic Sciences, School of Biological Sciences, Madurai Kamaraj University, Madurai, Tamil Nadu, India
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Srijaruskul K, Charoenlap N, Namchaiw P, Chattrakarn S, Giengkam S, Mongkolsuk S, Vattanaviboon P. Regulation by SoxR of mfsA, Which Encodes a Major Facilitator Protein Involved in Paraquat Resistance in Stenotrophomonas maltophilia. PLoS One 2015; 10:e0123699. [PMID: 25915643 PMCID: PMC4411124 DOI: 10.1371/journal.pone.0123699] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Accepted: 03/06/2015] [Indexed: 11/18/2022] Open
Abstract
Stenotrophomonas maltophilia MfsA (Smlt1083) is an efflux pump in the major facilitator superfamily (MFS). Deletion of mfsA renders the strain more susceptible to paraquat, but no alteration in the susceptibility levels of other oxidants is observed. The expression of mfsA is inducible upon challenge with redox cycling/superoxide-generating drug (paraquat, menadione and plumbagin) treatments and is directly regulated by SoxR, which is a transcription regulator and sensor of superoxide-generating agents. Analysis of mfsA expression patterns in wild-type and a soxR mutant suggests that oxidized SoxR functions as a transcription activator of the gene. soxR (smlt1084) is located in a head-to-head fashion with mfsA, and these genes share the -10 motif of their promoter sequences. Purified SoxR specifically binds to the putative mfsA promoter motifs that contain a region that is highly homologous to the consensus SoxR binding site, and mutation of the SoxR binding site abolishes binding of purified SoxR protein. The SoxR box is located between the putative -35 and -10 promoter motifs of mfsA; and this position is typical for a promoter in which SoxR acts as a transcriptional activator. At the soxR promoter, the SoxR binding site covers the transcription start site of the soxR transcript; thus, binding of SoxR auto-represses its own transcription. Taken together, our results reveal for the first time that mfsA is a novel member of the SoxR regulon and that SoxR binds and directly regulates its expression.
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Affiliation(s)
- Kriangsuk Srijaruskul
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, 10210, Thailand
| | - Nisanart Charoenlap
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
| | - Poommaree Namchaiw
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
| | - Sorayut Chattrakarn
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, 10210, Thailand
| | - Suparat Giengkam
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, 10210, Thailand
| | - Skorn Mongkolsuk
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
- Center of Emerging Bacterial Infection, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
- Center of Excellence on Environmental Health and Toxicology, Bangkok, Thailand
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, 10210, Thailand
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IscR plays a role in oxidative stress resistance and pathogenicity of a plant pathogen, Xanthomonas campestris. Microbiol Res 2015; 170:139-46. [DOI: 10.1016/j.micres.2014.08.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 08/01/2014] [Accepted: 08/11/2014] [Indexed: 12/20/2022]
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Sornchuer P, Namchaiw P, Kerdwong J, Charoenlap N, Mongkolsuk S, Vattanaviboon P. Copper chloride induces antioxidant gene expression but reduces ability to mediate H2O2 toxicity in Xanthomonas campestris. Microbiology (Reading) 2014; 160:458-466. [DOI: 10.1099/mic.0.072470-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Copper (Cu)-based biocides are currently used as control measures for both fungal and bacterial diseases in agricultural fields. In this communication, we show that exposure of the bacterial plant pathogen Xanthomonas campestris to nonlethal concentrations of Cu2+ ions (75 µM) enhanced expression of genes in OxyR, OhrR and IscR regulons. High levels of catalase, Ohr peroxidase and superoxide dismutase diminished Cu2+-induced gene expression, suggesting that the production of hydrogen peroxide (H2O2) and organic hydroperoxides is responsible for Cu2+-induced gene expression. Despite high expression of antioxidant genes, the CuCl2-treated cells were more susceptible to H2O2 killing treatment than the uninduced cells. This phenotype arose from lowered catalase activity in the CuCl2-pretreated cells. Thus, exposure to a nonlethal dose of Cu2+ renders X. campestris vulnerable to H2O2, even when various genes for peroxide-metabolizing enzymes are highly expressed. Moreover, CuCl2-pretreated cells are sensitive to treatment with the redox cycling drug, menadione. No physiological cross-protection response was observed in CuCl2-treated cells in a subsequent challenge with killing concentrations of an organic hydroperoxide. As H2O2 production is an important initial plant immune response, defects in H2O2 protection are likely to reduce bacterial survival in plant hosts and enhance the usefulness of copper biocides in controlling bacterial pathogens.
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Affiliation(s)
- Phornphan Sornchuer
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok 10210, Thailand
| | - Poommaree Namchaiw
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210, Thailand
| | - Jarunee Kerdwong
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Nisanart Charoenlap
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210, Thailand
| | - Skorn Mongkolsuk
- Center of Excellence on Environmental Health and Toxicology, Bangkok, Thailand
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210, Thailand
| | - Paiboon Vattanaviboon
- Center of Excellence on Environmental Health and Toxicology, Bangkok, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210, Thailand
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok 10210, Thailand
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32
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Romsang A, Duang-Nkern J, Leesukon P, Saninjuk K, Vattanaviboon P, Mongkolsuk S. The iron-sulphur cluster biosynthesis regulator IscR contributes to iron homeostasis and resistance to oxidants in Pseudomonas aeruginosa. PLoS One 2014; 9:e86763. [PMID: 24466226 PMCID: PMC3899308 DOI: 10.1371/journal.pone.0086763] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 12/13/2013] [Indexed: 11/19/2022] Open
Abstract
IscR is a global transcription regulator responsible for governing various physiological processes during growth and stress responses. The IscR-mediated regulation of the Pseudomonas aeruginosa isc operon, which is involved in iron-sulphur cluster ([Fe-S]) biogenesis, was analysed. The expression of iscR was highly induced through the exposure of the bacteria to various oxidants, such as peroxides, redox-cycling drugs, intracellular iron-chelating agents, and high salts. Two putative type 1 IscR-binding sites were found around RNA polymerase recognition sites, in which IscR-promoter binding could preclude RNA polymerase from binding to the promoter and resulting in repression of the isc operon expression. An analysis of the phenotypes of mutants and cells with altered gene expression revealed the diverse physiological roles of this regulator. High-level IscR strongly inhibited anaerobic, but not aerobic, growth. iscR contributes significantly to the bacteria overall resistance to oxidative stress, as demonstrated through mutants with increased sensitivity to oxidants, such as peroxides and redox-cycling drugs. Moreover, the regulator also plays important roles in modulating intracellular iron homeostasis, potentially through sensing the levels of [Fe-S]. The increased expression of the isc operon in the mutant not only diverts iron away from the available pool but also reduces the total intracellular iron content, affecting many iron metabolism pathways leading to alterations in siderophores and haem levels. The diverse expression patterns and phenotypic changes of the mutant support the role of P. aeruginosa IscR as a global transcriptional regulator that senses [Fe-S] and directly represses or activates the transcription of genes affecting many physiological pathways.
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Affiliation(s)
- Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Jintana Duang-Nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Panithi Leesukon
- Molecular Medicine Graduate Program, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Kritsakorn Saninjuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Program in Applied Biological Science: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology, Ministry of Education, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology, Ministry of Education, Bangkok, Thailand
- * E-mail:
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Schumacher J, Waite CJ, Bennett MH, Perez MF, Shethi K, Buck M. Differential secretome analysis of Pseudomonas syringae pv tomato using gel-free MS proteomics. FRONTIERS IN PLANT SCIENCE 2014; 5:242. [PMID: 25071788 PMCID: PMC4082315 DOI: 10.3389/fpls.2014.00242] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 05/12/2014] [Indexed: 05/03/2023]
Abstract
The plant pathogen Pseudomonas syringae pv.tomato (DC3000) causes virulence by delivering effector proteins into host plant cells through its type three secretion system (T3SS). In response to the plant environment DC3000 expresses hypersensitive response and pathogenicity genes (hrp). Pathogenesis depends on the ability of the pathogen to manipulate the plant metabolism and to inhibit plant immunity, which depends to a large degree on the plant's capacity to recognize both pathogen and microbial determinants (PAMP/MAMP-triggered immunity). We have developed and employed MS-based shotgun and targeted proteomics to (i) elucidate the extracellular and secretome composition of DC3000 and (ii) evaluate temporal features of the assembly of the T3SS and the secretion process together with its dependence of pH. The proteomic screen, under hrp inducing in vitro conditions, of extracellular and cytoplasmatic fractions indicated the segregated presence of not only T3SS implicated proteins such as HopP1, HrpK1, HrpA1 and AvrPto1, but also of proteins not usually associated with the T3SS or with pathogenicity. Using multiple reaction monitoring MS (MRM-MS) to quantify HrpA1 and AvrPto1, we found that HrpA1 is rapidly expressed, at a strict pH-dependent rate and is post-translationally processed extracellularly. These features appear to not interfere with rapid AvrPto1 expression and secretion but may suggest some temporal post-translational regulatory mechanism of the T3SS assembly. The high specificity and sensitivity of the MRM-MS approach should provide a powerful tool to measure secretion and translocation in infected tissues.
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Affiliation(s)
- Jörg Schumacher
- *Correspondence: Jörg Schumacher and Martin Buck, Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, London, SW7 2AZ, UK e-mail: ;
| | | | | | | | | | - Martin Buck
- *Correspondence: Jörg Schumacher and Martin Buck, Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, London, SW7 2AZ, UK e-mail: ;
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Gene expression and physiological role of Pseudomonas aeruginosa methionine sulfoxide reductases during oxidative stress. J Bacteriol 2013; 195:3299-308. [PMID: 23687271 DOI: 10.1128/jb.00167-13] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Pseudomonas aeruginosa PAO1 has two differentially expressed methionine sulfoxide reductase genes: msrA (PA5018) and msrB (PA2827). The msrA gene is expressed constitutively at a high level throughout all growth phases, whereas msrB expression is highly induced by oxidative stress, such as sodium hypochlorite (NaOCl) treatment. Inactivation of either msrA or msrB or both genes (msrA msrB mutant) rendered the mutants less resistant than the parental PAO1 strain to oxidants such as NaOCl and H2O2. Unexpectedly, msr mutants have disparate resistance patterns when exposed to paraquat, a superoxide generator. The msrA mutant had a higher paraquat resistance level than the msrB mutant, which had a lower paraquat resistance level than the PAO1 strain. The expression levels of msrA showed an inverse correlation with the paraquat resistance level, and this atypical paraquat resistance pattern was not observed with msrB. Virulence testing using a Drosophila melanogaster model revealed that the msrA, msrB, and, to a greater extent, msrA msrB double mutants had an attenuated virulence phenotype. The data indicate that msrA and msrB are essential genes for oxidative stress protection and bacterial virulence. The pattern of expression and mutant phenotypes of P. aeruginosa msrA and msrB differ from previously characterized msr genes from other bacteria. Thus, as highly conserved genes, the msrA and msrB have diverse expression patterns and physiological roles that depend on the environmental niche where the bacteria thrive.
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Tribelli PM, Nikel PI, Oppezzo OJ, López NI. Anr, the anaerobic global regulator, modulates the redox state and oxidative stress resistance in Pseudomonas extremaustralis. MICROBIOLOGY-SGM 2012; 159:259-268. [PMID: 23223440 DOI: 10.1099/mic.0.061085-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The role of Anr in oxidative stress resistance was investigated in Pseudomonas extremaustralis, a polyhydroxybutyrate-producing Antarctic bacterium. The absence of Anr caused increased sensitivity to hydrogen peroxide under low oxygen tension. This phenomenon was associated with a decrease in the redox ratio, higher oxygen consumption and higher reactive oxygen species production. Physiological responses of the mutant to the oxidized state included an increase in NADP(H) content, catalase activity and exopolysaccharide production. The wild-type strain showed a sharp decrease in the reduced thiol pool when exposed to hydrogen peroxide, not observed in the mutant strain. In silico analysis of the genome sequence of P. extremaustralis revealed putative Anr binding sites upstream from genes related to oxidative stress. Genes encoding several chaperones and cold shock proteins, a glutathione synthase, a sulfate transporter and a thiol peroxidase were identified as potential targets for Anr regulation. Our results suggest a novel role for Anr in oxidative stress resistance and in redox balance maintenance under conditions of restricted oxygen supply.
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Affiliation(s)
- Paula M Tribelli
- Dpto de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Pablo I Nikel
- Instituto de Investigaciones Biotecnológicas 'Dr. Rodolfo A. Ugalde', IQUIBICEN-CONICET, Universidad Nacional de San Martín, Buenos Aires, Argentina.,Dpto de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Oscar J Oppezzo
- Departamento de Radiobiología, Comisión Nacional de Energía Atómica, Buenos Aires, Argentina
| | - Nancy I López
- Dpto de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
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