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Ezeduru V, Shao ARQ, Venegas FA, McKay G, Rich J, Nguyen D, Thibodeaux CJ. Defining the functional properties of cyclopropane fatty acid synthase from Pseudomonas aeruginosa PAO1. J Biol Chem 2024; 300:107618. [PMID: 39095026 DOI: 10.1016/j.jbc.2024.107618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2024] [Revised: 07/20/2024] [Accepted: 07/22/2024] [Indexed: 08/04/2024] Open
Abstract
Cyclopropane fatty acid synthases (CFAS) catalyze the conversion of unsaturated fatty acids to cyclopropane fatty acids (CFAs) within bacterial membranes. This modification alters the biophysical properties of membranes and has been correlated with virulence in several human pathogens. Despite the central role played by CFAS enzymes in regulating bacterial stress responses, the mechanistic properties of the CFAS enzyme family and the consequences of CFA biosynthesis remain largely uncharacterized in most bacteria. We report the first characterization of the CFAS enzyme from Pseudomonas aeruginosa (PA), an opportunistic human pathogen with complex membrane biology that is frequently associated with antimicrobial resistance and high tolerance to various external stressors. We demonstrate that CFAs are produced by a single enzyme in PA and that cfas gene expression is upregulated during the transition to stationary phase and in response to oxidative stress. Analysis of PA lipid extracts reveal a massive increase in CFA production as PA cells enter stationary phase and help define the optimal membrane composition for in vitro assays. The purified PA-CFAS enzyme forms a stable homodimer and preferentially modifies phosphatidylglycerol lipid substrates and membranes with a higher content of unsaturated acyl chains. Bioinformatic analysis across bacterial phyla shows highly divergent amino acid sequences within the lipid-binding domain of CFAS enzymes, perhaps suggesting distinct membrane-binding properties among different orthologs. This work lays an important foundation for further characterization of CFAS in P. aeruginosa and for examining the functional differences between CFAS enzymes from different bacteria.
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Affiliation(s)
- Vivian Ezeduru
- Department of Chemistry, McGill University, Montreal, Quebec, Canada
| | - Annie R Q Shao
- Department of Chemistry, McGill University, Montreal, Quebec, Canada
| | - Felipe A Venegas
- Department of Chemistry, McGill University, Montreal, Quebec, Canada
| | - Geoffrey McKay
- Research Institute of the McGill University Health Center, McGill University, Montreal, Quebec, Canada
| | - Jacquelyn Rich
- Research Institute of the McGill University Health Center, McGill University, Montreal, Quebec, Canada; Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | - Dao Nguyen
- Research Institute of the McGill University Health Center, McGill University, Montreal, Quebec, Canada; Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada; Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Christopher J Thibodeaux
- Department of Chemistry, McGill University, Montreal, Quebec, Canada; Centre de Recherche en Biologie Structurale, McGill University, Montreal, Quebec, Canada.
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2
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Huang X, Xing Y, Jiang H, Pu Y, Yang S, Kang Z, Cai L. Nonphytotoxic and pH-responsive ZnO-ZIF‑8 loaded with honokiol as a "nanoweapon" effectively controls the soil-borne bacterial pathogen Ralstonia solanacearum. JOURNAL OF HAZARDOUS MATERIALS 2024; 472:134502. [PMID: 38743980 DOI: 10.1016/j.jhazmat.2024.134502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/15/2024] [Accepted: 04/29/2024] [Indexed: 05/16/2024]
Abstract
The development of intelligently released and environmentally safe nanocarriers not only aligns with the sustainable agricultural strategy but also offers a potential solution for controlling severe soil-borne bacterial diseases. Herein, the core-shell structured nanocarrier loaded with honokiol bactericide (honokiol@ZnO-ZIF-8) was synthesized via a one-pot method for the targeted control of Ralstonia solanacearum, the causative agent of tobacco bacterial wilt disease. Results indicated that honokiol@ZnO-ZIF-8 nanoparticles induced bacterial cell membrane and DNA damage through the production of excessive reactive oxygen species (ROS), thereby reducing bacterial cell viability and ultimately leading to bacterial death. Additionally, the dissociation mechanism of the nanocarriers was elucidated for the first time through thermodynamic computational simulation. The nanocarriers dissociate primarily due to H+ attacking the N atom on imidazole, causing the rupture of the Zn-N bond under acidic conditions and at room temperature. Furthermore, honokiol@ZnO-ZIF-8 exhibited potent inhibitory effects against other prominent Solanaceae pathogenic bacteria (Pseudomonas syringae pv. tabaci), demonstrating its broad-spectrum antibacterial activity. Biosafety assessment results indicated that honokiol@ZnO-ZIF-8 exhibited non-phytotoxicity towards tobacco and tomato plants, with its predominant accumulation in the roots and no translocation to aboveground tissues within a short period. This study provides potential application value for the intelligent release of green pesticides. ENVIRONMENT IMPLICATION: The indiscriminate use of agrochemicals poses a significant threat to environmental, ecological security, and sustainable development. Slow-release pesticides offer a green and durable strategy for crop disease control. In this study, we developed a non-phytotoxic and pH-responsive honokiol@ZnO-ZIF-8 nano-bactericide based on the pathogenesis of Ralstonia solanacearum. Thermodynamic simulation revealed the dissociation mechanism of ZIF-8, with different acidity controlling the dissociation rate. This provides a theoretical basis for on-demand pesticide release while reducing residue in the. Our findings provide strong evidence for effective soil-borne bacterial disease control and on-demand pesticide release.
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Affiliation(s)
- Xunliang Huang
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China; College of Tobacco Science of Guizhou University, Guizhou Key Laboratory for Tobacco Quality, Guiyang 550025, China
| | - Yue Xing
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Hao Jiang
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Ya Pu
- College of Tobacco Science of Guizhou University, Guizhou Key Laboratory for Tobacco Quality, Guiyang 550025, China
| | - Song Yang
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling 712100, China.
| | - Lin Cai
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China; College of Tobacco Science of Guizhou University, Guizhou Key Laboratory for Tobacco Quality, Guiyang 550025, China; State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling 712100, China.
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3
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da Cruz Nizer WS, Adams ME, Allison KN, Montgomery MC, Mosher H, Cassol E, Overhage J. Oxidative stress responses in biofilms. Biofilm 2024; 7:100203. [PMID: 38827632 PMCID: PMC11139773 DOI: 10.1016/j.bioflm.2024.100203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/22/2024] [Accepted: 05/22/2024] [Indexed: 06/04/2024] Open
Abstract
Oxidizing agents are low-molecular-weight molecules that oxidize other substances by accepting electrons from them. They include reactive oxygen species (ROS), such as superoxide anions (O2-), hydrogen peroxide (H2O2), and hydroxyl radicals (HO-), and reactive chlorine species (RCS) including sodium hypochlorite (NaOCl) and its active ingredient hypochlorous acid (HOCl), and chloramines. Bacteria encounter oxidizing agents in many different environments and from diverse sources. Among them, they can be produced endogenously by aerobic respiration or exogenously by the use of disinfectants and cleaning agents, as well as by the mammalian immune system. Furthermore, human activities like industrial effluent pollution, agricultural runoff, and environmental activities like volcanic eruptions and photosynthesis are also sources of oxidants. Despite their antimicrobial effects, bacteria have developed many mechanisms to resist the damage caused by these toxic molecules. Previous research has demonstrated that growing as a biofilm particularly enhances bacterial survival against oxidizing agents. This review aims to summarize the current knowledge on the resistance mechanisms employed by bacterial biofilms against ROS and RCS, focussing on the most important mechanisms, including the formation of biofilms in response to oxidative stressors, the biofilm matrix as a protective barrier, the importance of detoxifying enzymes, and increased protection within multi-species biofilm communities. Understanding the complexity of bacterial responses against oxidative stress will provide valuable insights for potential therapeutic interventions and biofilm control strategies in diverse bacterial species.
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Affiliation(s)
| | - Madison Elisabeth Adams
- Department of Health Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, ON, Canada
| | - Kira Noelle Allison
- Department of Health Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, ON, Canada
| | | | - Hailey Mosher
- Department of Health Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, ON, Canada
| | - Edana Cassol
- Department of Health Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, ON, Canada
| | - Joerg Overhage
- Department of Health Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, ON, Canada
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4
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Sharma A, Shuppara AM, Padron GC, Sanfilippo JE. Combining multiple stressors unexpectedly blocks bacterial migration and growth. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.27.595753. [PMID: 38853869 PMCID: PMC11160647 DOI: 10.1101/2024.05.27.595753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
In nature, organisms experience combinations of stressors. However, laboratory studies typically simplify reality and focus on the effects of an individual stressor. Here, we use a microfluidic approach to simultaneously provide a physical stressor (shear flow) and a chemical stressor (H 2 O 2 ) to the human pathogen Pseudomonas aeruginosa . By treating cells with levels of flow and H 2 O 2 that commonly co-occur in nature, we discover that previous reports significantly overestimate the H 2 O 2 levels required to block bacterial growth. Specifically, we establish that flow increases H 2 O 2 effectiveness 50-fold, explaining why previous studies lacking flow required much higher concentrations. Using natural H 2 O 2 levels, we identify the core H 2 O 2 regulon, characterize OxyR-mediated dynamic regulation, and dissect the redundant roles of multiple H 2 O 2 scavenging systems. By examining single-cell behavior, we serendipitously discover that the combined effects of H 2 O 2 and flow block pilus-driven surface migration. Thus, our results counter previous studies and reveal that natural levels of H 2 O 2 and flow synergize to restrict bacterial colonization and survival. By studying two stressors at once, our research highlights the limitations of oversimplifying nature and demonstrates that physical and chemical stress can combine to yield unpredictable effects.
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5
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Paliwal D, Rabiey M, Mauchline TH, Hassani-Pak K, Nauen R, Wagstaff C, Andrews S, Bass C, Jackson RW. Multiple toxins and a protease contribute to the aphid-killing ability of Pseudomonas fluorescens PpR24. Environ Microbiol 2024; 26:e16604. [PMID: 38561900 DOI: 10.1111/1462-2920.16604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 02/23/2024] [Indexed: 04/04/2024]
Abstract
Aphids are globally important pests causing damage to a broad range of crops. Due to insecticide resistance, there is an urgent need to develop alternative control strategies. In our previous work, we found Pseudomonas fluorescens PpR24 can orally infect and kill the insecticide-resistant green-peach aphid (Myzus persicae). However, the genetic basis of the insecticidal capability of PpR24 remains unclear. Genome sequencing of PpR24 confirmed the presence of various insecticidal toxins such as Tc (toxin complexes), Rhs (rearrangement hotspot) elements, and other insect-killing proteases. Upon aphids infection with PpR24, RNA-Seq analysis revealed 193 aphid genes were differentially expressed with down-regulation of 16 detoxification genes. In addition, 1325 PpR24 genes (542 were upregulated and 783 downregulated) were subject to differential expression, including genes responsible for secondary metabolite biosynthesis, the iron-restriction response, oxidative stress resistance, and virulence factors. Single and double deletion of candidate virulence genes encoding a secreted protease (AprX) and four toxin components (two TcA-like; one TcB-like; one TcC-like insecticidal toxins) showed that all five genes contribute significantly to aphid killing, particularly AprX. This comprehensive host-pathogen transcriptomic analysis provides novel insight into the molecular basis of bacteria-mediated aphid mortality and the potential of PpR24 as an effective biocontrol agent.
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Affiliation(s)
- Deepa Paliwal
- School of Biological Sciences, University of Reading, Reading, UK
| | - Mojgan Rabiey
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Tim H Mauchline
- Sustainable Soils and Crops, Rothamsted Research, Harpenden, UK
| | | | | | - Carol Wagstaff
- School of Chemistry, Food and Pharmacy, University of Reading, Reading, UK
| | - Simon Andrews
- School of Biological Sciences, University of Reading, Reading, UK
| | | | - Robert W Jackson
- School of Biological Sciences, University of Reading, Reading, UK
- School of Biosciences and Birmingham Institute of Forest Research, University of Birmingham, Birmingham, UK
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6
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Shikha S, Kumar V, Jain A, Dutta D, Bhattacharyya MS. Unraveling the mechanistic insights of sophorolipid-capped gold nanoparticle-induced cell death in Vibrio cholerae. Microbiol Spectr 2023; 11:e0017523. [PMID: 37811987 PMCID: PMC10715219 DOI: 10.1128/spectrum.00175-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 08/21/2023] [Indexed: 10/10/2023] Open
Abstract
IMPORTANCE Vibrio cholerae, a Gram-negative bacterium, is the causative agent of a fatal disease, "cholera." Prevention of cholera outbreak is possible by eliminating the bacteria from the environment. However, antimicrobial resistance developed in microorganisms has posed a threat and challenges to its treatment. Application of nanoparticles is a useful and effective option for the elimination of such microorganisms. Metal-based nanopaticles exhibit microbial toxicity through non-specific mechanisms. To prevent resistance development and increase antibacterial efficiency, rational designing of nanoparticles is required. Thus, knowledge on the exact mechanism of action of nanoparticles is highly essential. In this study, we explore the possible mechanisms of antibacterial activity of AuNPs-SL against V. cholerae. We show that the interaction of AuNPs-SL with V. cholerae enhances ROS production and membrane depolarization, change in permeability, and leakage of intracellular content. This action leads to the depletion of cellular ATP level, DNA damage, and subsequent cell death.
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Affiliation(s)
- Sristy Shikha
- Biochemical Engineering Research and Process Development Centre (BERPDC), CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India
| | - Vineet Kumar
- Molecular Microbiology Laboratory, CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India
| | - Ankita Jain
- Biochemical Engineering Research and Process Development Centre (BERPDC), CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India
| | - Dipak Dutta
- Molecular Microbiology Laboratory, CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India
| | - Mani Shankar Bhattacharyya
- Biochemical Engineering Research and Process Development Centre (BERPDC), CSIR-Institute of Microbial Technology (IMTECH), Chandigarh, India
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7
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da Cruz Nizer WS, Adams ME, Inkovskiy V, Beaulieu C, Overhage J. The secondary metabolite hydrogen cyanide protects Pseudomonas aeruginosa against sodium hypochlorite-induced oxidative stress. Front Microbiol 2023; 14:1294518. [PMID: 38033579 PMCID: PMC10687435 DOI: 10.3389/fmicb.2023.1294518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 11/01/2023] [Indexed: 12/02/2023] Open
Abstract
The high pathogenicity of Pseudomonas aeruginosa is attributed to the production of many virulence factors and its resistance to several antimicrobials. Among them, sodium hypochlorite (NaOCl) is a widely used disinfectant due to its strong antimicrobial effect. However, bacteria develop many mechanisms to survive the damage caused by this agent. Therefore, this study aimed to identify novel mechanisms employed by P. aeruginosa to resist oxidative stress induced by the strong oxidizing agent NaOCl. We analyzed the growth of the P. aeruginosa mutants ΔkatA, ΔkatE, ΔahpC, ΔahpF, ΔmsrA at 1 μg/mL NaOCl, and showed that these known H2O2 resistance mechanisms are also important for the survival of P. aeruginosa under NaOCl stress. We then conducted a screening of the P. aeruginosa PA14 transposon insertion mutant library and identified 48 mutants with increased susceptibility toward NaOCl. Among them were 10 mutants with a disrupted nrdJa, bvlR, hcnA, orn, sucC, cysZ, nuoJ, PA4166, opmQ, or thiC gene, which also exhibited a significant growth defect in the presence of NaOCl. We focussed our follow-up experiments (i.e., growth analyzes and kill-kinetics) on mutants with defect in the synthesis of the secondary metabolite hydrogen cyanide (HCN). We showed that HCN produced by P. aeruginosa contributes to its resistance toward NaOCl as it acts as a scavenger molecule, quenching the toxic effects of NaOCl.
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Affiliation(s)
| | | | | | | | - Joerg Overhage
- Department of Health Sciences, Carleton University, Ottawa, ON, Canada
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8
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Amato P, Mathonat F, Nuñez Lopez L, Péguilhan R, Bourhane Z, Rossi F, Vyskocil J, Joly M, Ervens B. The aeromicrobiome: the selective and dynamic outer-layer of the Earth's microbiome. Front Microbiol 2023; 14:1186847. [PMID: 37260685 PMCID: PMC10227452 DOI: 10.3389/fmicb.2023.1186847] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 04/24/2023] [Indexed: 06/02/2023] Open
Abstract
The atmosphere is an integral component of the Earth's microbiome. Abundance, viability, and diversity of microorganisms circulating in the air are determined by various factors including environmental physical variables and intrinsic and biological properties of microbes, all ranging over large scales. The aeromicrobiome is thus poorly understood and difficult to predict due to the high heterogeneity of the airborne microorganisms and their properties, spatially and temporally. The atmosphere acts as a highly selective dispersion means on large scales for microbial cells, exposing them to a multitude of physical and chemical atmospheric processes. We provide here a brief critical review of the current knowledge and propose future research directions aiming at improving our comprehension of the atmosphere as a biome.
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9
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Cornelis P, Tahrioui A, Lesouhaitier O, Bouffartigues E, Feuilloley M, Baysse C, Chevalier S. High affinity iron uptake by pyoverdine in Pseudomonas aeruginosa involves multiple regulators besides Fur, PvdS, and FpvI. Biometals 2023; 36:255-261. [PMID: 35171432 DOI: 10.1007/s10534-022-00369-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 02/03/2022] [Indexed: 11/02/2022]
Abstract
Pseudomonas aeruginosa is a Gram-negative bacterium which can cause serious infections among immune-depressed people including cystic fibrosis patients where it can colonize the lungs causing chronic infections. Iron is essential for P. aeruginosa and can be provided via three sources under aerobic conditions: its own siderophores pyochelin (PCH) and pyoverdine (PVD), xenosiderophores, or heme, respectively. Pyoverdine is the high affinity siderophore and its synthesis and uptake involve more than 30 genes organized in different operons. Its synthesis and uptake are triggered by iron scarcity via the Fur regulator and involves two extra cytoplasmic sigma factors (ECF), PvdS for the biosynthesis of PVD and FpvI for the uptake via the TonB-dependent FpvA outer membrane transporter and other periplasmic and inner membrane proteins. It appeared recently that the regulation of PVD biosynthesis and uptake involves other regulators, including other ECF factors, and LysR regulators. This is the case especially for the genes coding for periplasmic and inner membrane proteins involved in the reduction of Fe3+ to Fe2+ and the transport of ferrous iron to the cytoplasm that appears to represent a crucial step in the uptake process.
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Affiliation(s)
- Pierre Cornelis
- Laboratory of Microbiology Signals and Microenvironnements (LMSM) EA 4312, University of Rouen Normandy, 27000, Evreux, France.
- Laboratorium Microbiologie, Vrije Universiteit Brussel, Brussels, Belgium.
| | - Ali Tahrioui
- Laboratory of Microbiology Signals and Microenvironnements (LMSM) EA 4312, University of Rouen Normandy, 27000, Evreux, France
| | - Olivier Lesouhaitier
- Laboratory of Microbiology Signals and Microenvironnements (LMSM) EA 4312, University of Rouen Normandy, 27000, Evreux, France
| | - Emeline Bouffartigues
- Laboratory of Microbiology Signals and Microenvironnements (LMSM) EA 4312, University of Rouen Normandy, 27000, Evreux, France
| | - Marc Feuilloley
- Laboratory of Microbiology Signals and Microenvironnements (LMSM) EA 4312, University of Rouen Normandy, 27000, Evreux, France
| | - Christine Baysse
- CNRS, Institut de Génétique et de Développement de Rennes (IGDR), UMR6290, Université de Rennes, Rennes, France
| | - Sylvie Chevalier
- Laboratory of Microbiology Signals and Microenvironnements (LMSM) EA 4312, University of Rouen Normandy, 27000, Evreux, France
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10
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Padron GC, Shuppara AM, Sharma A, Koch MD, Palalay JJS, Radin JN, Kehl-Fie TE, Imlay JA, Sanfilippo JE. Shear rate sensitizes bacterial pathogens to H 2O 2 stress. Proc Natl Acad Sci U S A 2023; 120:e2216774120. [PMID: 36888662 PMCID: PMC10089187 DOI: 10.1073/pnas.2216774120] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 01/18/2023] [Indexed: 03/09/2023] Open
Abstract
Cells regularly experience fluid flow in natural systems. However, most experimental systems rely on batch cell culture and fail to consider the effect of flow-driven dynamics on cell physiology. Using microfluidics and single-cell imaging, we discover that the interplay of physical shear rate (a measure of fluid flow) and chemical stress trigger a transcriptional response in the human pathogen Pseudomonas aeruginosa. In batch cell culture, cells protect themselves by quickly scavenging the ubiquitous chemical stressor hydrogen peroxide (H2O2) from the media. In microfluidic conditions, we observe that cell scavenging generates spatial gradients of H2O2. High shear rates replenish H2O2, abolish gradients, and generate a stress response. Combining mathematical simulations and biophysical experiments, we find that flow triggers an effect like "wind-chill" that sensitizes cells to H2O2 concentrations 100 to 1,000 times lower than traditionally studied in batch cell culture. Surprisingly, the shear rate and H2O2 concentration required to generate a transcriptional response closely match their respective values in the human bloodstream. Thus, our results explain a long-standing discrepancy between H2O2 levels in experimental and host environments. Finally, we demonstrate that the shear rate and H2O2 concentration found in the human bloodstream trigger gene expression in the blood-relevant human pathogen Staphylococcus aureus, suggesting that flow sensitizes bacteria to chemical stress in natural environments.
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Affiliation(s)
- Gilberto C. Padron
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL61801
| | - Alexander M. Shuppara
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL61801
| | - Anuradha Sharma
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL61801
| | - Matthias D. Koch
- Department of Biology, Texas A&M University, College Station, TX77843
| | | | - Jana N. Radin
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL61801
| | - Thomas E. Kehl-Fie
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL61801
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL61801
| | - James A. Imlay
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL61801
| | - Joseph E. Sanfilippo
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL61801
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11
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Hernández-Ramírez KC, Valle-Maldonado MI, Patiño-Medina JA, Calo S, Jácome-Galarza IE, Garre V, Meza-Carmen V, Ramírez-Díaz MI. Role of PumB antitoxin as a transcriptional regulator of the PumAB type-II toxin-antitoxin system and its endoribonuclease activity on the PumA (toxin) transcript. Mol Genet Genomics 2023; 298:455-472. [PMID: 36604348 DOI: 10.1007/s00438-022-01988-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 12/20/2022] [Indexed: 01/07/2023]
Abstract
The PumAB type-II toxin-antitoxin (TA) system is encoded by pumAB genes that are organized into an operon. This system is encoded by the pUM505 plasmid, isolated from a Pseudomonas aeruginosa clinical strain. The pumA gene encodes a putative RelE toxin protein (toxic component), whereas the pumB gene encodes a putative HTH antitoxin protein. The expression of the PumAB system in Escherichia coli confers plasmid stability. In addition, PumA toxin overexpression in P. aeruginosa possesses the capability to increase bacterial virulence, an effect that is neutralized by the PumB antitoxin. The aim of this study was to establish the mechanism of regulation of the PumAB toxin-antitoxin system from pUM505. By an in silico analysis of the putative regulatory elements, we identified two putative internal promoters, PpumB and PpumB-AlgU (in addition to the already reported PpumAB), located upstream of pumB. By RT-qPCR assays, we determined that the pumAB genes are transcribed differentially, in that the mRNA of pumB is more abundant than the pumA transcript. We also observed that pumB could be expressed individually and that its mRNA levels decreased under oxidative stress, during individual expression as well as co-expression of pumAB. However, under stressful conditions, the pumA mRNA levels were not affected. This suggests the negative regulation of pumB by stressful conditions. The PumB purified protein was found to bind to a DNA region located between the PpumAB and the pumA coding region, and PumA participates in PumB binding, suggesting that a PumA-PumB complex co-regulates the transcription of the pumAB operon. Interestingly, the pumA mRNA levels decreased after incubation in vitro with PumB protein. This effect was repressed by ribonuclease inhibitors, suggesting that PumB could function as an RNAse toward the mRNA of the toxin. Taken together, we conclude that the PumAB TA system possesses multiple mechanisms to regulate its expression, as well as that the PumB antitoxin generates a decrease in the mRNA toxin levels, suggesting an RNase function. Our analysis provides new insights into the understanding of the control of TA systems from mobile plasmid-encoded genes from a human pathogen.
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Affiliation(s)
- K C Hernández-Ramírez
- Laboratorio de Microbiología, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio B-3, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico
| | - M I Valle-Maldonado
- Laboratorio de Diferenciación Celular, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico.,Laboratorio Estatal de Salud Pública, Secretaría de Salud Michoacán, Morelia, Mexico
| | - J A Patiño-Medina
- Laboratorio de Diferenciación Celular, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico
| | - S Calo
- School of Natural and Exact Sciences, Pontificia Universidad Católica Madre y Maestra, 51033, Santiago de los Caballeros, Dominican Republic
| | - I E Jácome-Galarza
- Laboratorio Estatal de Salud Pública, Secretaría de Salud Michoacán, Morelia, Mexico
| | - V Garre
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, 30100, Murcia, Spain
| | - V Meza-Carmen
- Laboratorio de Diferenciación Celular, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico
| | - M I Ramírez-Díaz
- Laboratorio de Microbiología, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio B-3, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico.
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12
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da Silva IC, Conceição EOA, Pereira DS, Rogez H, Muto NA. Evaluation of the Antimicrobial Capacity of Bacteria Isolated from Stingless Bee ( Scaptotrigona aff. postica) Honey Cultivated in Açai ( Euterpe oleracea) Monoculture. Antibiotics (Basel) 2023; 12:antibiotics12020223. [PMID: 36830134 PMCID: PMC9952800 DOI: 10.3390/antibiotics12020223] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/09/2023] [Accepted: 01/14/2023] [Indexed: 01/22/2023] Open
Abstract
Many antimicrobial compounds have been seeking to protect the human body against pathogenic microbial infections. In recent times, there has been considerable growth of pathogens resistant to existing drugs due to the inappropriate use of antibiotics. In the present study, bacteria isolated from the honey of stingless bees native to the Amazon called Scaptotrigona aff. postica and Apis mellifera were used to determine their potential antimicrobial properties and characterize the medium cultivated with isolated bacteria. The results showed inhibition of nine isolates. Among these isolates, SCA12, SCA13, and SCA15 showed inhibitory activity similar to that of vancomycin, which was used as a positive control. The SCA13 strain obtained the best results with antimicrobial extract against the tested pathogens; the species was identified as Enterococcus faecalis, and its lyophilized extract was characterized by temperature, pH, and trypsin, in which they showed antimicrobial activity. This work shows that bacteria isolated from the stingless bee honey, Scaptotrigona aff. postica, have the potential to produce antimicrobial substances.
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Affiliation(s)
- Iago Castro da Silva
- Centre for Valorization of Amazonian Bioactive Compounds & Biological Science Institute, Federal University of Pará, Belém 6075-110, PA, Brazil
| | - Eveson Oscar Almeida Conceição
- Centre for Valorization of Amazonian Bioactive Compounds & Biological Science Institute, Federal University of Pará, Belém 6075-110, PA, Brazil
| | | | - Hervé Rogez
- Centre for Valorization of Amazonian Bioactive Compounds & Biological Science Institute, Federal University of Pará, Belém 6075-110, PA, Brazil
| | - Nilton Akio Muto
- Centre for Valorization of Amazonian Bioactive Compounds & Biological Science Institute, Federal University of Pará, Belém 6075-110, PA, Brazil
- Correspondence:
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13
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Bairoliya S, Goel A, Mukherjee M, Koh Zhi Xiang J, Cao B. Monochloramine Induces Release of DNA and RNA from Bacterial Cells: Quantification, Sequencing Analyses, and Implications. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:15791-15804. [PMID: 36215406 DOI: 10.1021/acs.est.2c06632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Monochloramine (MCA) is a widely used secondary disinfectant to suppress microbial growth in drinking water distribution systems. In monochloraminated drinking water, a significant amount of extracellular DNA (eDNA) has been reported, which has many implications ranging from obscuring DNA-based drinking water microbiome analyses to posing potential health concerns. To address this, it is imperative for us to know the origin of the eDNA in drinking water. Using Pseudomonas aeruginosa as a model organism, we report for the first time that MCA induces the release of nucleic acids from both biofilms and planktonic cells. Upon exposure to 2 mg/L MCA, massive release of DNA from suspended cells in both MilliQ water and 0.9% NaCl was directly visualized using live cell imaging in a CellASIC ONIX2 microfluidic system. Exposing established biofilms to MCA also resulted in DNA release from the biofilms, which was confirmed by increased detection of eDNA in the effluent. Intriguingly, massive release of RNA was also observed, and the extracellular RNA (eRNA) was also found to persist in water for days. Sequencing analyses of the eDNA revealed that it could be used to assemble the whole genome of the model organism, while in the water, certain fragments of the genome were more persistent than others. RNA sequencing showed that the eRNA contains non-coding RNA and mRNA, implying its role as a possible signaling molecule in environmental systems and a snapshot of the past metabolic state of the bacterial cells.
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Affiliation(s)
- Sakcham Bairoliya
- Singapore Centre for Environmental Life Sciences Engineering, Interdisciplinary Graduate Program, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
- School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore
| | - Apoorva Goel
- Singapore Centre for Environmental Life Sciences Engineering, Interdisciplinary Graduate Program, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Manisha Mukherjee
- Singapore Centre for Environmental Life Sciences Engineering, Interdisciplinary Graduate Program, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
- School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore
| | - Jonas Koh Zhi Xiang
- Singapore Centre for Environmental Life Sciences Engineering, Interdisciplinary Graduate Program, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Bin Cao
- Singapore Centre for Environmental Life Sciences Engineering, Interdisciplinary Graduate Program, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
- School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore
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14
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Wang J, Liu J, Zhao Y, Sun M, Yu G, Fan J, Tian Y, Hu B. OxyR contributes to virulence of Acidovorax citrulli by regulating anti-oxidative stress and expression of flagellin FliC and type IV pili PilA. Front Microbiol 2022; 13:977281. [PMID: 36204623 PMCID: PMC9530317 DOI: 10.3389/fmicb.2022.977281] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 08/31/2022] [Indexed: 11/25/2022] Open
Abstract
In many bacteria, OxyR acts as a transcriptional regulator that facilitates infection via degrading hydrogen peroxide (H2O2) generated by the host defense response. Previous studies showed that OxyR also plays an important role in regulating biofilm formation, cell motility, pili relate-genes expression, and surface polysaccharide production. However, the role of OxyR has not been determined in Acidovorax citrulli strain xjl12. In the current study, the qRT-PCR and western blot assays revealed that the expression level of oxyR was significantly induced by H2O2. The oxyR deletion mutant of A. citrulli was significantly impaired bacterial tolerance to oxidative stress and reduced catalase (CAT) activity. In addition, oxyR mutant resulted in reduced swimming motility, twitching motility, biofilm formation, virulence, and bacterial growth in planta by significantly affecting flagellin and type IV pili-related gene (fliC and pilA) expression. The qRT-PCR assays and western blot revealed that OxyR positively regulated the expression of fliC and pilA. Furthermore, bacterial one-hybrid assay demonstrated that OxyR directly affected pilA and fliC promoter. Through bacterial two-hybrid assay, it was found that OxyR can directly interact with PilA and FliC. These results suggest that OxyR plays a major role in the regulating of a variety of virulence traits, and provide a foundation for future research on the global effects of OxyR in A. citrulli.
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Affiliation(s)
- Jianan Wang
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
| | - Jun Liu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
- Institute of Plant Protection and Soil Fertilizer, Hubei Academy of Agricultural Sciences, Wuhan, China
| | - Yuqiang Zhao
- Institute of Botany, Jiangsu Province and Chinese Academy of Sciences (Nanjing Botanical Garden Mem. Sun Yat-Sen), Nanjing, China
| | - Minghui Sun
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
| | - Guixu Yu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
| | - Jiaqin Fan
- Laboratory of Bacteriology, Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China
| | - Yanli Tian
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
- *Correspondence: Yanli Tian,
| | - Baishi Hu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
- Baishi Hu,
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15
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Zhao Q, Guo W, Luo H, Wang H, Yu T, Liu B, Si Q, Ren N. Dissecting the roles of conductive materials in attenuating antibiotic resistance genes: Evolution of physiological features and bacterial community. JOURNAL OF HAZARDOUS MATERIALS 2022; 438:129411. [PMID: 35780739 DOI: 10.1016/j.jhazmat.2022.129411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 06/08/2022] [Accepted: 06/15/2022] [Indexed: 06/15/2023]
Abstract
Supplying conductive materials (CMs) into anaerobic bioreactors is considered as a promising technology for antibiotic wastewater treatment. However, whether and how CMs influence antibiotic resistance genes (ARGs) spread remains poorly known. Here, we investigated the effects of three CMs, i.e., magnetite, activated carbon (AC), and zero valent iron (ZVI), on ARGs dissemination during treating sulfamethoxazole wastewater, by dissecting the shifts of physiological features and microbial community. With the addition of magnetite, AC, and ZVI, the SMX removal was improved from 49.05 to 71.56-92.27 %, while the absolute abundance of ARGs reducing by 26.48 %, 61.95 %, 48.45 %, respectively. The reduced mobile genetic elements and antibiotic resistant bacteria suggested the inhibition of horizontal and vertical transfer of ARGs. The physiological features, including oxidative stress response, quorum sensing, and secretion system may regulate horizontal transfer of ARGs. The addition of all CMs relieved oxidative stress compared with no CMs, but ZVI may cause additional free radicals that needs to be concerned. Further, ZVI and AC also interfered with cell communication and secretion system. This research deepens the insights about the underlying mechanisms of CMs in regulating ARGs, and is expected to propose practical ways for mitigating ARGs proliferation.
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Affiliation(s)
- Qi Zhao
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, China
| | - Wanqian Guo
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, China.
| | - Haichao Luo
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, China
| | - Huazhe Wang
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, China
| | - Taiping Yu
- Yangtze Ecology and Environment Co. Ltd., Wuhan 430062, China
| | - Banghai Liu
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, China
| | - Qishi Si
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, China
| | - Nanqi Ren
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, China
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16
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Li N, Liu Z, Wang P, Suman K, Zhang J, Song Y. Effects of sodium hypochlorite treatment on the chlorophyll fluorescence in photosystem II of microalgae. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 833:155192. [PMID: 35421461 DOI: 10.1016/j.scitotenv.2022.155192] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/06/2022] [Accepted: 04/07/2022] [Indexed: 06/14/2023]
Abstract
Chlorophyll fluorescence-based method shows great potentials for on-site assessing the vitality of algae in treated ship's ballast water. However, there is very limited information on the mechanism of chlorophyll fluorescence in photosystem II (PSII) after the NaClO treatment. In this paper, the effects of NaClO treatments with five concentrations (0.01, 0.04, 0.08, 0.12 and 0.15 mg/L) and treating periods (6, 24 and 48 h) on the chlorophyll fluorescence kinetics and spectra of Chlorella vulgaris (C. vulgaris) and Platymonas helgolandica (P. helgolandica) were investigated. Experimental results showed that both exposure time and dose were important factors that affect the toxicity of NaClO to microalgae. Further analyses showed that the maximum photochemical quantum yield of PSII, photochemical quenching and yield decreased rapidly with the increase in NaClO concentrations in the range of 0.04 mg/L to 0.15 mg/L, suggesting that NaClO seriously inhibited PSII reaction centers of algae. In addition, the maxima value of fluorescence at excitation wavelength still appeared near 437 nm and 468 nm under NaClO stress, pointing to the pigments for fluorescence produced by algae were mainly chlorophyll a and chlorophyll b antenna. As compared to chlorophyll a, the relative fluorescence intensity of chlorophyll b decreased significantly in the all of NaClO treatments. According to the fluorescence emission spectra, treatment of NaClO resulted in a shift of the maximum peak of C. vulgaris and P. helgolandica from 685.2 nm to 681.9 nm and 685.2 nm to 680.5 within 6 h, respectively. This indicates that the structure of antenna light-absorbing pigments of PSII changed under NaClO stress. These results revealed that the chlorophyll fluorescence mechanism in PSII of damaged microalgae occurred variation, which was important for the reliable application of on-site analysis of ballast water indicator based on chlorophyll fluorescence detection.
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Affiliation(s)
- Na Li
- Department of Marine Engineering, Dalian Maritime University, Dalian 116026, China
| | - Zhen Liu
- Department of Marine Engineering, Dalian Maritime University, Dalian 116026, China
| | - Pengcheng Wang
- Department of Mechanical Engineering, University of Houston, Houston, TX 77204, USA
| | - Kapur Suman
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Hyderabad Campus, Telangana 500078, India
| | - Junyan Zhang
- Department of Marine Engineering, Dalian Maritime University, Dalian 116026, China
| | - Yongxin Song
- Department of Marine Engineering, Dalian Maritime University, Dalian 116026, China.
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17
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Gaur M, Dey S, Sahu A, Dixit S, Sarathbabu S, Zothanzama J, Sahoo RK, Behera DU, Subudhi E. Characterization and Comparative Genomic Analysis of a Highly Colistin-Resistant Chryseobacterium gallinarum: a Rare, Uncommon Pathogen. Front Cell Infect Microbiol 2022; 12:933006. [PMID: 35909954 PMCID: PMC9329510 DOI: 10.3389/fcimb.2022.933006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 06/09/2022] [Indexed: 11/13/2022] Open
Abstract
For the first time, we describe the whole genome of a yellow-pigmented, capsule-producing, pathogenic, and colistin-resistant Chryseobacterium gallinarum strain MGC42 isolated from a patient with urinary tract infection in India. VITEK 2 automated system initially identified this isolate as C. indologenes. However, 16S rRNA gene sequencing revealed that MGC42 shared 99.67% sequence identity with C. gallinarum–type strain DSM 27622. The draft genome of the strain MGC42 was 4,455,926 bp long with 37.08% Guanine-Cytosine (GC) content and was devoid of any plasmid. Antibiotic resistance, virulence, and toxin genes were predicted by implementing a machine learning classifier. Potential homologs of 340 virulence genes including hemolysin secretion protein D, metalloprotease, catalase peroxidases and autotransporter adhesins, type VI secretion system (T6SS) spike proteins, and 27 toxin factors including a novel toxin domain Ntox23 were identified in the genome. Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologs of 110 transporter proteins were predicted that were in agreement with moderate efflux activity. Twelve antibiotic resistance genes including two potentially novel putative β-lactamase genes sharing low similarity with known β-lactamase genes were also identified in the genome of this strain. The strain MGC42 was also resistant to several classes of antibiotics along with carbapenems and polymyxin. We also identified mutations in the orthologs of pmrB (M384T) and lpxD (I66V) that might be responsible for colistin resistance. The MGC42 strain shared 683 core genes with other environmental and clinical strains of Chryseobacterium species. Our findings suggest that the strain MGC42 is a multidrug-resistant, virulent pathogen and recommend 16S rRNA gene sequencing to identify clinical specimens of Chryseobacterium species.
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Affiliation(s)
- Mahendra Gaur
- Department of Biotechnology, Punjabi University, Patiala, India
- Centre for Biotechnology, School of Pharmaceutical Sciences, Siksha ‘O’ Anusandhan (Deemed to be University), Bhubaneswar, India
| | - Suchanda Dey
- Centre for Biotechnology, School of Pharmaceutical Sciences, Siksha ‘O’ Anusandhan (Deemed to be University), Bhubaneswar, India
| | - Anshuman Sahu
- Centre for Biotechnology, School of Pharmaceutical Sciences, Siksha ‘O’ Anusandhan (Deemed to be University), Bhubaneswar, India
| | - Sangita Dixit
- Centre for Biotechnology, School of Pharmaceutical Sciences, Siksha ‘O’ Anusandhan (Deemed to be University), Bhubaneswar, India
| | - S. Sarathbabu
- Department of Biotechnology, Mizoram University, Aizawl, India
| | - John Zothanzama
- Department of Biotechnology, Mizoram University, Aizawl, India
| | - Rajesh Kumar Sahoo
- Centre for Biotechnology, School of Pharmaceutical Sciences, Siksha ‘O’ Anusandhan (Deemed to be University), Bhubaneswar, India
| | - Dibyajyoti Uttameswar Behera
- Centre for Biotechnology, School of Pharmaceutical Sciences, Siksha ‘O’ Anusandhan (Deemed to be University), Bhubaneswar, India
| | - Enketeswara Subudhi
- Centre for Biotechnology, School of Pharmaceutical Sciences, Siksha ‘O’ Anusandhan (Deemed to be University), Bhubaneswar, India
- *Correspondence: Monika, ; Enketeswara Subudhi,
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18
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Fortuna A, Collalto D, Schiaffi V, Pastore V, Visca P, Ascenzioni F, Rampioni G, Leoni L. The Pseudomonas aeruginosa DksA1 protein is involved in H 2O 2 tolerance and within-macrophages survival and can be replaced by DksA2. Sci Rep 2022; 12:10404. [PMID: 35729352 PMCID: PMC9213440 DOI: 10.1038/s41598-022-14635-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 06/09/2022] [Indexed: 12/02/2022] Open
Abstract
In Gram-negative pathogens, the stringent response regulator DksA controls the expression of hundreds of genes, including virulence-related genes. Interestingly, Pseudomonas aeruginosa has two functional DksA paralogs: DksA1 is constitutively expressed and has a zinc-finger motif, while DksA2 is expressed only under zinc starvation conditions and does not contain zinc. DksA1 stimulates the production of virulence factors in vitro and is required for full pathogenicity in vivo. DksA2 can replace these DksA1 functions. Here, the role of dksA paralogs in P. aeruginosa tolerance to H2O2-induced oxidative stress has been investigated. The P. aeruginosa dksA1 dksA2 mutant showed impaired H2O2 tolerance in planktonic and biofilm-growing cultures and increased susceptibility to macrophages-mediated killing compared to the wild type. Complementation with either dksA1 or dksA2 genes restored the wild type phenotypes. The DksA-dependent tolerance to oxidative stress involves, at least in part, the positive transcriptional control of both katA and katE catalase-encoding genes. These data support the hypothesis that DksA1 and DksA2 are eco-paralogs with indistinguishable function but optimal activity under different environmental conditions, and highlight their mutual contribution to P. aeruginosa virulence.
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Affiliation(s)
| | | | - Veronica Schiaffi
- Department of Molecular and Cellular Biology "Charles Darwin", University Roma Sapienza, Rome, Italy
| | - Valentina Pastore
- Department of Molecular and Cellular Biology "Charles Darwin", University Roma Sapienza, Rome, Italy
| | - Paolo Visca
- Department of Science, University Roma Tre, Rome, Italy.,IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Fiorentina Ascenzioni
- Department of Molecular and Cellular Biology "Charles Darwin", University Roma Sapienza, Rome, Italy
| | - Giordano Rampioni
- Department of Science, University Roma Tre, Rome, Italy.,IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Livia Leoni
- Department of Science, University Roma Tre, Rome, Italy.
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19
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Li H, Xia Y, Tian Z, Jin Y, Bai F, Cheng Z, Swietnicki W, Wu W, Pan X. Dihydrolipoamide Acetyltransferase AceF Influences the Type III Secretion System and Resistance to Oxidative Stresses through RsmY/Z in Pseudomonas aeruginosa. Microorganisms 2022; 10:microorganisms10030666. [PMID: 35336241 PMCID: PMC8950878 DOI: 10.3390/microorganisms10030666] [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: 01/11/2022] [Revised: 03/10/2022] [Accepted: 03/17/2022] [Indexed: 01/27/2023] Open
Abstract
Carbon metabolism plays an important role in bacterial physiology and pathogenesis. The type III secretion system (T3SS) of Pseudomonas aeruginosa is a virulence factor that contributes to acute infections. It has been demonstrated that bacterial metabolism affects the T3SS. Meanwhile, expression of T3SS genes is negatively regulated by the small RNAs RsmY and RsmZ. In this study, we studied the relationship between the dihydrolipoamide acetyltransferase gene aceF and the T3SS. Our results reveal an upregulation of RsmY and RsmZ in the aceF mutant, which represses the expression of the T3SS genes. Meanwhile, the aceF mutant is more tolerant to hydrogen peroxide. We demonstrate that the expression levels of the catalase KatB and the alkyl hydroperoxide reductase AhpB are increased in the aceF mutant. The simultaneous deletion of rsmY and rsmZ in the aceF mutant restored the expression levels of katB and ahpB, as well as bacterial susceptibility to hydrogen peroxide. Thus, we identify a novel role of AceF in the virulence and oxidative response of P. aeruginosa.
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Affiliation(s)
- Haozhou Li
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Yushan Xia
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Zhenyang Tian
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Yongxin Jin
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Fang Bai
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Zhihui Cheng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Wieslaw Swietnicki
- Department of Immunology of Infectious Diseases, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, ul. R. Weigla 12, 53-114 Wroclaw, Poland;
| | - Weihui Wu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
| | - Xiaolei Pan
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (H.L.); (Y.X.); (Z.T.); (Y.J.); (F.B.); (Z.C.); (W.W.)
- Correspondence:
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20
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He K, Xue B, Yang X, Wang S, Li C, Zhang X, Zhao C, Wang X, Qiu Z, Shen Z, Wang J. Low-concentration of trichloromethane and dichloroacetonitrile promote the plasmid-mediated horizontal transfer of antibiotic resistance genes. JOURNAL OF HAZARDOUS MATERIALS 2022; 425:128030. [PMID: 34986571 DOI: 10.1016/j.jhazmat.2021.128030] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/29/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
Disinfection by-products (DBPs) are one of the unintended consequences of water disinfection that are commonly detected in various water environments. Although DBPs are known to induce antimicrobial resistance via stimulation of chromosomal mutations, it remains unclear whether low-concentration of DBPs could stimulate the conjugative transfer of antibiotic resistance genes (ARGs). The present study aimed to investigate the effect of two typical DBPs, namely trichloromethane (TCM) and dichloroacetonitrile (DCAN), on the conjugative transfer of RP4 plasmid in Escherichia coli genera. The results of the study demonstrated that exposure to low concentrations of TCM and DCAN significantly stimulated conjugative transfer of ARGs, wherein application of 25 μg/L of TCM and 10 μg/L of DCAN resulted in maximum fold change of ~5.5- and ~6.0-fold, respectively, at 16 h of exposure. Further, assessment of underlying mechanisms revealed the involvement of intracellular reactive oxygen species generation, SOS response, increase in cell membrane permeability, upregulation of expression of genes and proteins related to pilus generation, ATP synthesis, and RP4 gene expression. Our findings provided a better understanding of the hidden biological effects and the ecological risks of DBPs in the water environment, especially concerning their effect on the spread of antibiotic resistance.
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Affiliation(s)
- Kun He
- School of Environmental Science Engineering, Tiangong University, Tianjin 300387, China
| | - Bin Xue
- Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin 300050, China
| | - Xiaobo Yang
- Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin 300050, China
| | - Shang Wang
- Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin 300050, China
| | - Chenyu Li
- Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin 300050, China
| | - Xi Zhang
- Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin 300050, China
| | - Chen Zhao
- Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin 300050, China
| | - Xuan Wang
- School of Environmental Science Engineering, Tiangong University, Tianjin 300387, China
| | - Zhigang Qiu
- Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin 300050, China
| | - Zhiqiang Shen
- Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin 300050, China.
| | - Jingfeng Wang
- Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin 300050, China.
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Perry EK, Meirelles LA, Newman DK. From the soil to the clinic: the impact of microbial secondary metabolites on antibiotic tolerance and resistance. Nat Rev Microbiol 2022; 20:129-142. [PMID: 34531577 PMCID: PMC8857043 DOI: 10.1038/s41579-021-00620-w] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/02/2021] [Indexed: 02/08/2023]
Abstract
Secondary metabolites profoundly affect microbial physiology, metabolism and stress responses. Increasing evidence suggests that these molecules can modulate microbial susceptibility to commonly used antibiotics; however, secondary metabolites are typically excluded from standard antimicrobial susceptibility assays. This may in part account for why infections by diverse opportunistic bacteria that produce secondary metabolites often exhibit discrepancies between clinical antimicrobial susceptibility testing results and clinical treatment outcomes. In this Review, we explore which types of secondary metabolite alter antimicrobial susceptibility, as well as how and why this phenomenon occurs. We discuss examples of molecules that opportunistic and enteric pathogens either generate themselves or are exposed to from their neighbours, and the nuanced impacts these molecules can have on tolerance and resistance to certain antibiotics.
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Affiliation(s)
- Elena K Perry
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Lucas A Meirelles
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Dianne K Newman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA.
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22
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Functional Irreplaceability of Escherichia coli and Shewanella oneidensis OxyRs Is Critically Determined by Intrinsic Differences in Oligomerization. mBio 2022; 13:e0349721. [PMID: 35073744 PMCID: PMC8787470 DOI: 10.1128/mbio.03497-21] [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] [Indexed: 11/21/2022] Open
Abstract
LysR-type transcriptional regulators (LTTRs), which function in diverse biological processes in prokaryotes, are composed of a conserved structure with an N-terminal DNA-binding domain (DBD) and a C-terminal signal-sensing regulatory domain (RD). LTTRs that sense and respond to the same signal are often functionally exchangeable in bacterial species across wide phyla, but this phenomenon has not been demonstrated for the H2O2-sensing and -responding OxyRs. Here, we systematically examined the biochemical and structural determinants differentiating activator-only OxyRs from dual-activity ones by comparing OxyRs from two Gammaproteobacteria, Escherichia coli and Shewanella oneidensis. Our data show that EcOxyR could function as neither an activator nor a repressor in S. oneidensis. Using SoOxyR-based OxyR chimeras and mutants, we demonstrated that residues 283 to 289, which form the first half of the last C-terminal α-helix (α10), are critical for the proper function of SoOxyR and cannot be replaced with the EcOxyR counterpart. Crystal structural analysis reveals that α10 is important for the oligomerization of SoOxyR, which, unlike EcOxyR, forms several high-order oligomers upon DNA binding. As the mechanisms of OxyR oligomerization vary substantially among bacterial species, our findings underscore the importance of subtle structural features in determining regulatory activities of structurally similar proteins descending from a common ancestor. IMPORTANCE Evolution may drive homologous proteins to be functionally nonexchangeable in different organisms. However, much is unknown about the mechanisms underlying this phenomenon beyond amino acid substitutions. Here, we systematically examined the biochemical and structural determinants differentiating functionally nonexchangeable OxyRs, H2O2-responding transcriptional regulators from two Gammaproteobacteria, Escherichia coli and Shewanella oneidensis. Using SoOxyR-based OxyR chimeras and mutants, we demonstrated that residues 283 to 289, which form the first half of the last C-terminal α-helix (α10), are critical for the proper function of SoOxyR and cannot be replaced with the EcOxyR counterpart. Crystal structural analysis reveals that this last helix is critical for formation of high-order oligomers upon DNA binding, a phenomenon not observed with EcOxyR. Our findings provide a new dimension to differences in sequence and structural features among bacterial species in determining regulatory activities of homologous regulators.
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Méndez V, Rodríguez-Castro L, Durán RE, Padrón G, Seeger M. The OxyR and SoxR transcriptional regulators are involved in a broad oxidative stress response in Paraburkholderia xenovorans LB400. Biol Res 2022; 55:7. [PMID: 35184754 PMCID: PMC8859910 DOI: 10.1186/s40659-022-00373-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 01/13/2022] [Indexed: 11/29/2022] Open
Abstract
Background Aerobic metabolism generates reactive oxygen species that may cause critical harm to the cell. The aim of this study is the characterization of the stress responses in the model aromatic-degrading bacterium Paraburkholderia xenovorans LB400 to the oxidizing agents paraquat and H2O2. Methods Antioxidant genes were identified by bioinformatic methods in the genome of P. xenovorans LB400, and the phylogeny of its OxyR and SoxR transcriptional regulators were studied. Functionality of the transcriptional regulators from strain LB400 was assessed by complementation with LB400 SoxR of null mutant P. aeruginosa ΔsoxR, and the construction of P. xenovorans pIZoxyR that overexpresses OxyR. The effects of oxidizing agents on P. xenovorans were studied measuring bacterial susceptibility, survival and ROS formation after exposure to paraquat and H2O2. The effects of these oxidants on gene expression (qRT-PCR) and the proteome (LC–MS/MS) were quantified. Results P. xenovorans LB400 possesses a wide repertoire of genes for the antioxidant defense including the oxyR, ahpC, ahpF, kat, trxB, dpsA and gorA genes, whose orthologous genes are regulated by the transcriptional regulator OxyR in E. coli. The LB400 genome also harbors the soxR, fumC, acnA, sodB, fpr and fldX genes, whose orthologous genes are regulated by the transcriptional regulator SoxR in E. coli. The functionality of the LB400 soxR gene was confirmed by complementation of null mutant P. aeruginosa ΔsoxR. Growth, susceptibility, and ROS formation assays revealed that LB400 cells were more susceptible to paraquat than H2O2. Transcriptional analyses indicated the upregulation of the oxyR, ahpC1, katE and ohrB genes in LB400 cells after exposure to H2O2, whereas the oxyR, fumC, ahpC1, sodB1 and ohrB genes were induced in presence of paraquat. Proteome analysis revealed that paraquat induced the oxidative stress response proteins AhpCF and DpsA, the universal stress protein UspA and the RNA chaperone CspA. Both oxidizing agents induced the Ohr protein, which is involved in organic peroxide resistance. Notably, the overexpression of the LB400 oxyR gene in P. xenovorans significantly decreased the ROS formation and the susceptibility to paraquat, suggesting a broad OxyR-regulated antioxidant response. Conclusions This study showed that P. xenovorans LB400 possess a broad range oxidative stress response, which explain the high resistance of this strain to the oxidizing compounds paraquat and H2O2. Supplementary Information The online version contains supplementary material available at 10.1186/s40659-022-00373-7.
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Espinoza-Vergara J, Molina P, Walter M, Gulppi M, Vejar N, Melo F, Urzua M, Muñoz H, Zagal JH, Zhou X, Azocar MI, Paez MA. Effect of pH on the Electrochemical Behavior of Hydrogen Peroxide in the Presence of Pseudomonas aeruginosa. Front Bioeng Biotechnol 2021; 9:749057. [PMID: 34938720 PMCID: PMC8685425 DOI: 10.3389/fbioe.2021.749057] [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] [Received: 07/28/2021] [Accepted: 11/10/2021] [Indexed: 11/13/2022] Open
Abstract
The influence of pH on the electrochemical behavior of hydrogen peroxide in the presence of Pseudomonas aeruginosa was investigated using electrochemical techniques. Cyclic and square wave voltammetry were used to monitor the enzymatic activity. A modified cobalt phthalocyanine (CoPc) carbon electrode (OPG), a known catalyst for reducing O2 to H2O2, was used to detect species resulting from the enzyme activity. The electrolyte was a sterilized aqueous medium containing Mueller-Hinton (MH) broth. The open-circuit potential (OCP) of the Pseudomonas aeruginosa culture in MH decreased rapidly with time, reaching a stable state after 4 h. Peculiarities in the E / I response were observed in voltammograms conducted in less than 4 h of exposure to the culture medium. Such particular E/I responses are due to the catalase's enzymatic action related to the conversion of hydrogen peroxide to oxygen, confirming the authors' previous findings related to the behavior of other catalase-positive microorganisms. The enzymatic activity exhibits maximum activity at pH 7.5, assessed by the potential at which oxygen is reduced to hydrogen peroxide. At higher or lower pHs, the oxygen reduction reaction (ORR) occurs at higher overpotentials, i.e., at more negative potentials. In addition, and to assess the influence of bacterial adhesion on the electrochemical behavior, measurements of the bacterial-substrate metal interaction were performed at different pH using atomic force microscopy.
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Affiliation(s)
- Javier Espinoza-Vergara
- Departamento de Química de Los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.,Corrosion and Protection Center, Department of Materials, University of Manchester, Manchester, England, United Kingdom
| | - Paulo Molina
- Departamento de Química de Los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Mariana Walter
- Departamento de Química de Los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Miguel Gulppi
- Departamento de Química de Los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Nelson Vejar
- Chilean Air Force, Aerospace Sciences Research and Development Centre (CIDCA), San Bernardo, Santiago, Chile
| | - Francisco Melo
- Departamento de Física, Facultad de Ciencias, Universidad de Santiago de Santiago de Chile, Avenida Ecuador, Santiago, Chile
| | - Marcela Urzua
- Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Hugo Muñoz
- Departamento de Química de Los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - José H Zagal
- Departamento de Química de Los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Xiaorong Zhou
- Corrosion and Protection Center, Department of Materials, University of Manchester, Manchester, England, United Kingdom
| | - Manuel I Azocar
- Departamento de Química de Los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Maritza A Paez
- Departamento de Química de Los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
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25
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Bacillus velezensis: A Treasure House of Bioactive Compounds of Medicinal, Biocontrol and Environmental Importance. FORESTS 2021. [DOI: 10.3390/f12121714] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Bacillus velezensis gram-positive bacterium, is frequently isolated from diverse niches mainly soil, water, plant roots, and fermented foods. B. velezensis is ubiquitous, non-pathogenic and endospore forming. Being frequently isolated from diverse plant holobionts it is considered host adapted microorganism and recognized of high economic importance given its ability to promote plant growth under diverse biotic and abiotic stress conditions. Additionally, the species suppress many plant diseases, including bacterial, oomycete, and fungal diseases. It is also able after plant host root colonization to induce unique physiological situation of host plant called primed state. Primed host plants are able to respond more rapidly and/or effectively to biotic or abiotic stress. Moreover, B. velezenis have the ability to resist diverse environmental stresses and help host plants to cope with, including metal and xenobiotic stresses. Within species B. velezensis strains have unique abilities allowing them to adopt different life styles. Strain level abilities knowledge is warranted and could be inferred using the ever-expanding new genomes list available in genomes databases. Pangenome analysis and subsequent identification of core, accessory and unique genomes is actually of paramount importance to decipher species full metabolic capacities and fitness across diverse environmental conditions shaping its life style. Despite the crucial importance of the pan genome, its assessment among large number of strains remains sparse and systematic studies still needed. Extensive knowledge of the pan genome is needed to translate genome sequencing efforts into developing more efficient biocontrol agents and bio-fertilizers. In this study, a genome survey of B. velezensis allowed us to (a) highlight B. velezensis species boundaries and show that Bacillus suffers taxonomic imprecision that blurs the debate over species pangenome; (b) identify drivers of their successful acquisition of specific life styles and colonization of new niches; (c) describe strategies they use to promote plant growth and development; (d) reveal the unlocked strain specific orphan secondary metabolite gene clusters (biosynthetic clusters with corresponding metabolites unknown) that product identification is still awaiting to amend our knowledge of their putative role in suppression of pathogens and plant growth promotion, and (e) to describe a dynamic pangenome with a secondary metabolite rich accessory genome.
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de Oliveira EP, Rovida AFDS, Martins JG, Pileggi SAV, Schemczssen-Graeff Z, Pileggi M. Tolerance of Pseudomonas strain to the 2,4-D herbicide through a peroxidase system. PLoS One 2021; 16:e0257263. [PMID: 34855750 PMCID: PMC8638965 DOI: 10.1371/journal.pone.0257263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 11/16/2021] [Indexed: 01/22/2023] Open
Abstract
Herbicides are widely used in agricultural practices for preventing the proliferation of weeds. Upon reaching soil and water, herbicides can harm nontarget organisms, such as bacteria, which need an efficient defense mechanism to tolerate stress induced by herbicides. 2,4-Dichlorophenoxyacetic acid (2,4-D) is a herbicide that exerts increased oxidative stress among bacterial communities. Bacterial isolates were obtained from the biofilm of tanks containing washing water from the packaging of different pesticides, including 2,4-D. The Pseudomonas sp. CMA-7.3 was selected because of its tolerance against 2,4-D toxicity, among several sensitive isolates from the biofilm collection. This study aimed to evaluate the antioxidative response system of the selected strain to 2,4-D. It was analyzed the activity of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase GPX enzymes, that are poorly known in the literature for bacterial systems. The Pseudomonas sp. CMA-7.3 presented an efficient response system in balancing the production of hydrogen peroxide, even at 25x the dose of 2,4-D used in agriculture. The antioxidative system was composed of Fe–SOD enzymes, less common than Mn–SOD in bacteria, and through the activities of KatA and KatB isoforms, working together with APX and GPX, having their activities coordinated possibly by quorum sensing molecules. The peroxide control is poorly documented for bacteria, and this work is unprecedented for Pseudomonas and 2,4-D. Not all bacteria harbor efficient response system to herbicides, therefore they could affect the diversity and functionality of microbiome in contaminated soils, thereby impacting agricultural production, environment sustainability and human health.
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Affiliation(s)
- Elizangela Paz de Oliveira
- Departamento de Biotecnologia, Genética e Biologia Celular, Universidade Estadual de Maringá, Maringá, Brazil
| | | | - Juliane Gabriele Martins
- Departamento de Biologia Estrutural e Molecular e Genética, Laboratório de Microbiologia Ambiental, Setor de Ciências Biológicas e da Saúde, Universidade Estadual de Ponta Grossa, Ponta Grossa, Brazil
| | - Sônia Alvim Veiga Pileggi
- Departamento de Biologia Estrutural e Molecular e Genética, Laboratório de Microbiologia Ambiental, Setor de Ciências Biológicas e da Saúde, Universidade Estadual de Ponta Grossa, Ponta Grossa, Brazil
| | | | - Marcos Pileggi
- Departamento de Biologia Estrutural e Molecular e Genética, Laboratório de Microbiologia Ambiental, Setor de Ciências Biológicas e da Saúde, Universidade Estadual de Ponta Grossa, Ponta Grossa, Brazil
- * E-mail:
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Kong W, Tian Q, Yang Q, Liu Y, Wang G, Cao Y, Wang L, Xia S, Sun Y, Zhao C, Wang S. Sodium Selenite Enhances Antibiotics Sensitivity of Pseudomonas aeruginosa and Deceases Its Pathogenicity by Inducing Oxidative Stress and Inhibiting Quorum Sensing System. Antioxidants (Basel) 2021; 10:antiox10121873. [PMID: 34942975 PMCID: PMC8698442 DOI: 10.3390/antiox10121873] [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] [Received: 10/25/2021] [Revised: 11/18/2021] [Accepted: 11/19/2021] [Indexed: 12/22/2022] Open
Abstract
Pseudomonas aeruginosa, a Gram-negative opportunistic pathogen, is commonly found in clinical settings and immuno-compromised patients. It is difficult to be eradicated due to its strong antibiotic resistance, and novel inactivation strategies have yet to be developed. Selenium is an essential microelement for humans and has been widely used in dietary supplement and chemoprevention therapy. In this study, the physiological and biochemical effects of sodium selenite on P. aeruginosa PAO1 were investigated. The results showed that 0~5 mM sodium selenite did not impact the growth of PAO1, but increased the lethality rate of PAO1 with antibiotics or H2O2 treatment and the antibiotics susceptibility both in planktonic and biofilm states. In addition, sodium selenite significantly reduced the expression of quorum sensing genes and inhibited various virulence factors of this bacterium, including pyocyanin production, bacterial motilities, and the type III secretion system. Further investigation found that the content of ROS in cells was significantly increased and the expression levels of most genes involved in oxidative stress were up-regulated, which indicated that sodium selenite induced oxidative stress. The RNA-seq result confirmed the phenotypes of virulence attenuation and the expression of quorum sensing and antioxidant-related genes. The assays of Chinese cabbage and Drosophila melanogaster infection models showed that the combination of sodium selenite and antibiotics significantly alleviated the infection of PAO1. In summary, the results revealed that sodium selenite induced oxidative stress and inhibited the quorum sensing system of P. aeruginosa, which in turn enhanced the antibiotic susceptibility and decreased the pathogenicity of this bacterium. These findings suggest that sodium selenite may be used as an effective strategy for adjunct treatment of the infections caused by P. aeruginosa.
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Affiliation(s)
- Weina Kong
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi’an 710069, China; (W.K.); (Q.T.); (Q.Y.); (Y.L.); (G.W.); (Y.C.); (L.W.); (S.X.); (Y.S.); (C.Z.)
| | - Qianqian Tian
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi’an 710069, China; (W.K.); (Q.T.); (Q.Y.); (Y.L.); (G.W.); (Y.C.); (L.W.); (S.X.); (Y.S.); (C.Z.)
| | - Qiaoli Yang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi’an 710069, China; (W.K.); (Q.T.); (Q.Y.); (Y.L.); (G.W.); (Y.C.); (L.W.); (S.X.); (Y.S.); (C.Z.)
| | - Yu Liu
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi’an 710069, China; (W.K.); (Q.T.); (Q.Y.); (Y.L.); (G.W.); (Y.C.); (L.W.); (S.X.); (Y.S.); (C.Z.)
| | - Gongting Wang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi’an 710069, China; (W.K.); (Q.T.); (Q.Y.); (Y.L.); (G.W.); (Y.C.); (L.W.); (S.X.); (Y.S.); (C.Z.)
| | - Yanjun Cao
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi’an 710069, China; (W.K.); (Q.T.); (Q.Y.); (Y.L.); (G.W.); (Y.C.); (L.W.); (S.X.); (Y.S.); (C.Z.)
| | - Liping Wang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi’an 710069, China; (W.K.); (Q.T.); (Q.Y.); (Y.L.); (G.W.); (Y.C.); (L.W.); (S.X.); (Y.S.); (C.Z.)
| | - Sizhe Xia
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi’an 710069, China; (W.K.); (Q.T.); (Q.Y.); (Y.L.); (G.W.); (Y.C.); (L.W.); (S.X.); (Y.S.); (C.Z.)
| | - Yanmei Sun
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi’an 710069, China; (W.K.); (Q.T.); (Q.Y.); (Y.L.); (G.W.); (Y.C.); (L.W.); (S.X.); (Y.S.); (C.Z.)
| | - Cheng Zhao
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi’an 710069, China; (W.K.); (Q.T.); (Q.Y.); (Y.L.); (G.W.); (Y.C.); (L.W.); (S.X.); (Y.S.); (C.Z.)
| | - Shiwei Wang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi’an 710069, China; (W.K.); (Q.T.); (Q.Y.); (Y.L.); (G.W.); (Y.C.); (L.W.); (S.X.); (Y.S.); (C.Z.)
- Provincial Key Laboratory of Biotechnology of Shaanxi Province, College of Life Sciences, Northwest University, Xi’an 710069, China
- Correspondence:
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Campoccia D, Montanaro L, Arciola CR. Tracing the origins of extracellular DNA in bacterial biofilms: story of death and predation to community benefit. BIOFOULING 2021; 37:1022-1039. [PMID: 34823431 DOI: 10.1080/08927014.2021.2002987] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 10/28/2021] [Indexed: 06/13/2023]
Abstract
Extracellular DNA (eDNA) is a macromolecule copiously found in various natural microenvironments, but its origin and significance still remain partly mysterious phenomena. Here, the multifaceted origins of eDNA in bacterial biofilms are explored. The release of eDNA can follow a suicidal programmed bacterial apoptosis or a fratricide-induced death, under the control of quorum sensing systems or triggered by specific stressors. eDNA can be released into the extracellular space or as a free macromolecule or enclosed within membrane vesicles or even through an explosion of bubbles. eDNA can also be derived from host tissue cells through bacterial cytolytic/proapoptotic toxins or stolen from neutrophil extracellular traps (NETs). eDNA can alternatively be produced by lysis-independent mechanisms. Sub-inhibitory doses of antibiotics, by killing a fraction of bacteria, result in stimulating the release of eDNA. Even phages appear to play a role in favoring eDNA release. Unveiling the origins of eDNA is critical to correctly address biofilm-associated infections.
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Affiliation(s)
- Davide Campoccia
- Laboratorio di Patologia delle Infezioni Associate all'Impianto, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Lucio Montanaro
- Laboratorio di Patologia delle Infezioni Associate all'Impianto, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy
| | - Carla Renata Arciola
- Laboratorio di Patologia delle Infezioni Associate all'Impianto, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy
- Laboratorio di Immunoreumatologia e Rigenerazione Tissutale, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy
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Liu Y, Zhou Y, Qiao J, Yu W, Pan X, Zhang T, Liu Y, Lu SE. Phenazine-1-carboxylic Acid Produced by Pseudomonas chlororaphis YL-1 Is Effective against Acidovorax citrulli. Microorganisms 2021; 9:microorganisms9102012. [PMID: 34683333 PMCID: PMC8541086 DOI: 10.3390/microorganisms9102012] [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: 07/21/2021] [Revised: 09/19/2021] [Accepted: 09/20/2021] [Indexed: 11/16/2022] Open
Abstract
The bacterial pathogen Acidovorax citrulli causes the destructive fruit blotch (BFB) on cucurbit plants. Pseudomonas chlororaphis YL-1 is a bacterial strain isolated from Mississippi soil and its genome harbors some antimicrobial-related gene clusters, such as phenazine, pyrrolnitrin, and pyoverdine. Here, we evaluated the antimicrobial activity of strain YL-1 as compared with its deficient mutants of antimicrobial-related genes, which were obtained using a sacB-based site-specific mutagenesis strategy. We found that only phenazine-deficient mutants ΔphzE and ΔphzF almost lost the inhibitory effects against A. citrulli in LB plates compared with the wild-type strain YL-1, and that the main antibacterial compound produced by strain YL-1 in LB medium was phenazine-1-carboxylic acid (PCA) based on the liquid chromatography-mass spectrometry (LC-MS) analysis. Gene expression analyses revealed that PCA enhanced the accumulation of reactive oxygen species (ROS) and increased the activity of catalase (CAT) in A. citrulli. The inhibition effect of PCA against A. citrulli was lowered by adding exogenous CAT. PCA significantly upregulated the transcript level of katB from 6 to 10 h, which encodes CAT that helps to protect the bacteria against oxidative stress. Collectively, the findings of this research suggest PCA is one of the key antimicrobial metabolites of bacterial strain YL-1, a promising biocontrol agent for disease management of BFB of cucurbit plants.
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Affiliation(s)
- Youzhou Liu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; (Y.L.); (Y.Z.); (J.Q.); (X.P.)
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Starkville, MS 39759, USA
| | - Yaqiu Zhou
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; (Y.L.); (Y.Z.); (J.Q.); (X.P.)
| | - Junqing Qiao
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; (Y.L.); (Y.Z.); (J.Q.); (X.P.)
| | - Wenjie Yu
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; (W.Y.); (T.Z.)
| | - Xiayan Pan
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; (Y.L.); (Y.Z.); (J.Q.); (X.P.)
| | - Tingting Zhang
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; (W.Y.); (T.Z.)
| | - Yongfeng Liu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; (Y.L.); (Y.Z.); (J.Q.); (X.P.)
- Correspondence: (Y.L.); (S.-E.L.)
| | - Shi-En Lu
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Starkville, MS 39759, USA
- Correspondence: (Y.L.); (S.-E.L.)
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30
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Oxidative Stress Response in Pseudomonas aeruginosa. Pathogens 2021; 10:pathogens10091187. [PMID: 34578219 PMCID: PMC8466533 DOI: 10.3390/pathogens10091187] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/06/2021] [Accepted: 09/08/2021] [Indexed: 12/17/2022] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative environmental and human opportunistic pathogen highly adapted to many different environmental conditions. It can cause a wide range of serious infections, including wounds, lungs, the urinary tract, and systemic infections. The high versatility and pathogenicity of this bacterium is attributed to its genomic complexity, the expression of several virulence factors, and its intrinsic resistance to various antimicrobials. However, to thrive and establish infection, P. aeruginosa must overcome several barriers. One of these barriers is the presence of oxidizing agents (e.g., hydrogen peroxide, superoxide, and hypochlorous acid) produced by the host immune system or that are commonly used as disinfectants in a variety of different environments including hospitals. These agents damage several cellular molecules and can cause cell death. Therefore, bacteria adapt to these harsh conditions by altering gene expression and eliciting several stress responses to survive under oxidative stress. Here, we used PubMed to evaluate the current knowledge on the oxidative stress responses adopted by P. aeruginosa. We will describe the genes that are often differently expressed under oxidative stress conditions, the pathways and proteins employed to sense and respond to oxidative stress, and how these changes in gene expression influence pathogenicity and the virulence of P. aeruginosa. Understanding these responses and changes in gene expression is critical to controlling bacterial pathogenicity and developing new therapeutic agents.
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Dar D, Dar N, Cai L, Newman DK. Spatial transcriptomics of planktonic and sessile bacterial populations at single-cell resolution. Science 2021; 373:373/6556/eabi4882. [PMID: 34385369 DOI: 10.1126/science.abi4882] [Citation(s) in RCA: 113] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 06/25/2021] [Indexed: 01/02/2023]
Abstract
Capturing the heterogeneous phenotypes of microbial populations at relevant spatiotemporal scales is highly challenging. Here, we present par-seqFISH (parallel sequential fluorescence in situ hybridization), a transcriptome-imaging approach that records gene expression and spatial context within microscale assemblies at a single-cell and molecule resolution. We applied this approach to the opportunistic pathogen Pseudomonas aeruginosa, analyzing about 600,000 individuals across dozens of conditions in planktonic and biofilm cultures. We identified numerous metabolic- and virulence-related transcriptional states that emerged dynamically during planktonic growth, as well as highly spatially resolved metabolic heterogeneity in sessile populations. Our data reveal that distinct physiological states can coexist within the same biofilm just several micrometers away, underscoring the importance of the microenvironment. Our results illustrate the complex dynamics of microbial populations and present a new way of studying them at high resolution.
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Affiliation(s)
- Daniel Dar
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.,Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| | - Nina Dar
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Long Cai
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
| | - Dianne K Newman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA. .,Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
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OsaR (PA0056) functions as a repressor of the gene fleQ encoding an important motility regulator in Pseudomonas aeruginosa. J Bacteriol 2021; 203:e0014521. [PMID: 34339300 DOI: 10.1128/jb.00145-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
FleQ plays a crucial role in motility and biofilm formation by regulating flagellar and exopolysaccharide biosynthesis in Pseudomonas aeruginosa. It has been reported that the expression of FleQ is transcriptionally downregulated by the virulence factor regulator Vfr. Herein we demonstrated that a LysR-type transcriptional regulator, OsaR, is also capable of binding to the promoter region of fleQ and repressing its transcription. Through gel shift and DNase I footprinting assays, the OsaR binding site was identified and characterized as a dual LysR-type transcriptional regulator box (AT-N11-AT-N7-A-N11-T). Mutation of the A-T palindromic base pairs in fleQ promoter not only reduced the binding affinity of OsaR in vitro, but also de-repressed fleQ transcription in vivo. The OsaR binding site was found to cover the Vfr binding site; knockout of osaR or vfr separately exhibited no effect on the transcriptional level of fleQ; however, fleQ expression was repressed by overexpression of osaR or vfr. Furthermore, simultaneously deleting both osaR and vfr resulted in an upregulation of fleQ, but it could be complemented by the expression of either of the two repressors. In summary, our work revealed that OsaR and Vfr function as two transcriptional repressors of fleQ that bind to the same region of fleQ but work separately. IMPORTANCE Pseudomonas aeruginosa is a widespread human pathogen, which accounts for serious infections in the hospital, especially for lung infection in cystic fibrosis and chronic obstructive pulmonary disease patients. P. aeruginosa infection is closely associated with its motility and biofilm formation, which are both under the regulation of the important transcription factor FleQ. However, the upstream regulatory mechanisms of fleQ have not been fully elucidated. Therefore, our research identifying a novel regulator of fleQ as well as new regulatory mechanisms controlling its expression will be significant for better understanding the intricate gene regulatory mechanisms related to P. aeruginosa virulence and infection.
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The LysR-Type Transcriptional Regulator BsrA (PA2121) Controls Vital Metabolic Pathways in Pseudomonas aeruginosa. mSystems 2021; 6:e0001521. [PMID: 34254827 PMCID: PMC8407307 DOI: 10.1128/msystems.00015-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Pseudomonas aeruginosa, a facultative human pathogen causing nosocomial infections, has complex regulatory systems involving many transcriptional regulators. LTTR (LysR-Type Transcriptional Regulator) family proteins are involved in the regulation of various processes, including stress responses, motility, virulence, and amino acid metabolism. The aim of this study was to characterize the LysR-type protein BsrA (PA2121), previously described as a negative regulator of biofilm formation in P. aeruginosa. Genome wide identification of BsrA binding sites using chromatin immunoprecipitation and sequencing analysis revealed 765 BsrA-bound regions in the P. aeruginosa PAO1161 genome, including 367 sites in intergenic regions. The motif T-N11-A was identified within sequences bound by BsrA. Transcriptomic analysis showed altered expression of 157 genes in response to BsrA excess; of these, 35 had a BsrA binding site within their promoter regions, suggesting a direct influence of BsrA on the transcription of these genes. BsrA-repressed loci included genes encoding proteins engaged in key metabolic pathways such as the tricarboxylic acid cycle. The panel of loci possibly directly activated by BsrA included genes involved in pilus/fimbria assembly, as well as secretion and transport systems. In addition, DNA pull-down and regulatory analyses showed the involvement of PA2551, PA3398, and PA5189 in regulation of bsrA expression, indicating that this gene is part of an intricate regulatory network. Taken together, these findings reveal the existence of a BsrA regulon, which performs important functions in P. aeruginosa. IMPORTANCE This study shows that BsrA, a LysR-type transcriptional regulator from Pseudomonas aeruginosa, previously identified as a repressor of biofilm synthesis, is part of an intricate global regulatory network. BsrA acts directly and/or indirectly as the repressor and/or activator of genes from vital metabolic pathways (e.g., pyruvate, acetate, and tricarboxylic acid cycle) and is involved in control of transport functions and the formation of surface appendages. Expression of the bsrA gene is increased in the presence of antibiotics, which suggests its induction in response to stress, possibly reflecting the need to redirect metabolism under stressful conditions. This is particularly relevant for the treatment of infections caused by P. aeruginosa. In summary, the findings of this study demonstrate that the BsrA regulator performs important roles in carbon metabolism, biofilm formation, and antibiotic resistance in P. aeruginosa.
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Hou S, Zhang J, Ma X, Hong Q, Fang L, Zheng G, Huang J, Gao Y, Xu Q, Zhuang X, Song X. Role of rgsA in Oxidative Stress Resistance in Pseudomonas aeruginosa. Curr Microbiol 2021; 78:3133-3141. [PMID: 34185129 DOI: 10.1007/s00284-021-02580-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 06/13/2021] [Indexed: 10/21/2022]
Abstract
Pseudomonas aeruginosa is a common opportunistic pathogen that causes infections in vulnerable patients including those with metabolic disorders, hematologic diseases, and malignancies, and in those who have undergone surgery. In addition, P. aeruginosa exhibits high intrinsic resistance to numerous antibiotics and tends to form biofilms rendering it even more refractory to treatment. Among the mechanisms used by P. aeruginosa to adapt to environmental stresses are those involving small regulatory RNAs (sRNAs), which are 40-500 nucleotides long and are ubiquitous in bacteria. sRNAs play important regulatory roles in various vital processes in diverse bacteria, with their quantity and diversity of regulatory functions exceeding those of proteins. In this study, we show that deletion of the sRNA, rgsA, decreased the growth rate of P. aeruginosa. Furthermore, ΔrgsA P. aeruginosa exhibited decreased ability to resist the stress induced by exposure to different concentrations and durations of peroxides in both planktonic and biofilm growth modes compared with the wild-type strain. These results highlight the role of rgsA in the defense of P. aeruginosa against oxidative stress.
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Affiliation(s)
- Shuyi Hou
- Department of Clinical Laboratory, Xiang'an Hospital of Xiamen University, 2000 Xiangan Dong Road, Xiamen, 361000, Fujian, China
| | - Jiaqin Zhang
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361000, Fujian, China. .,Xiamen Key Laboratory of Genetic Testing, 55 Zhenhai Road, Xiamen, 361000, Fujian, China.
| | - Xiaobo Ma
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361000, Fujian, China
| | - Qiang Hong
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361000, Fujian, China
| | - Lili Fang
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361000, Fujian, China
| | - Gangsen Zheng
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361000, Fujian, China
| | - Jiaming Huang
- Department of Clinical Laboratory, The Second Affiliated Hospital of Fujian Medical University, 34 Zhongshan North Road, Quanzhou, 362000, Fujian, China
| | - Yingchun Gao
- Department of Clinical Laboratory, The First People's Hospital of Xiaoshan District, 199 Shixin Nan Road, Hangzhou, 311200, Zhejiang, China
| | - Qiaoli Xu
- Department of Clinical Laboratory, Zhangzhou Affiliated Hospital of Fujian Medical University, 59 Shengli Road, Zhangzhou, 363000, Fujian, China
| | - Xinguo Zhuang
- Department of Clinical Laboratory, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361000, Fujian, China
| | - Xiuyu Song
- Xiamen Blood Centre, 121 Hubin Nan Road, Xiamen, 361000, Fujian, China.
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Reigada I, San-Martin-Galindo P, Gilbert-Girard S, Chiaro J, Cerullo V, Savijoki K, Nyman TA, Fallarero A, Miettinen I. Surfaceome and Exoproteome Dynamics in Dual-Species Pseudomonas aeruginosa and Staphylococcus aureus Biofilms. Front Microbiol 2021; 12:672975. [PMID: 34248881 PMCID: PMC8267900 DOI: 10.3389/fmicb.2021.672975] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 05/21/2021] [Indexed: 01/12/2023] Open
Abstract
Bacterial biofilms are an important underlying cause for chronic infections. By switching into the biofilm state, bacteria can evade host defenses and withstand antibiotic chemotherapy. Despite the fact that biofilms at clinical and environmental settings are mostly composed of multiple microbial species, biofilm research has largely been focused on single-species biofilms. In this study, we investigated the interaction between two clinically relevant bacterial pathogens (Staphylococcus aureus and Pseudomonas aeruginosa) by label-free quantitative proteomics focusing on proteins associated with the bacterial cell surfaces (surfaceome) and proteins exported/released to the extracellular space (exoproteome). The changes observed in the surfaceome and exoproteome of P. aeruginosa pointed toward higher motility and lower pigment production when co-cultured with S. aureus. In S. aureus, lower abundances of proteins related to cell wall biosynthesis and cell division, suggesting increased persistence, were observed in the dual-species biofilm. Complementary phenotypic analyses confirmed the higher motility and the lower pigment production in P. aeruginosa when co-cultured with S. aureus. Higher antimicrobial tolerance associated with the co-culture setting was additionally observed in both species. To the best of our knowledge, this study is among the first systematic explorations providing insights into the dynamics of both the surfaceome and exoproteome of S. aureus and P. aeruginosa dual-species biofilms.
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Affiliation(s)
- Inés Reigada
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Paola San-Martin-Galindo
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Shella Gilbert-Girard
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Jacopo Chiaro
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Vincenzo Cerullo
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Kirsi Savijoki
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Tuula A Nyman
- Department of Immunology, Institute of Clinical Medicine, Rikshospitalet, University of Oslo, Oslo, Norway
| | - Adyary Fallarero
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Ilkka Miettinen
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
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36
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Hassett DJ, Kovall RA, Schurr MJ, Kotagiri N, Kumari H, Satish L. The Bactericidal Tandem Drug, AB569: How to Eradicate Antibiotic-Resistant Biofilm Pseudomonas aeruginosa in Multiple Disease Settings Including Cystic Fibrosis, Burns/Wounds and Urinary Tract Infections. Front Microbiol 2021; 12:639362. [PMID: 34220733 PMCID: PMC8245851 DOI: 10.3389/fmicb.2021.639362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 04/07/2021] [Indexed: 11/13/2022] Open
Abstract
The life-threatening pandemic concerning multi-drug resistant (MDR) bacteria is an evolving problem involving increased hospitalizations, billions of dollars in medical costs and a remarkably high number of deaths. Bacterial pathogens have demonstrated the capacity for spontaneous or acquired antibiotic resistance and there is virtually no pool of organisms that have not evolved such potentially clinically catastrophic properties. Although many diseases are linked to such organisms, three include cystic fibrosis (CF), burn/blast wounds and urinary tract infections (UTIs), respectively. Thus, there is a critical need to develop novel, effective antimicrobials for the prevention and treatment of such problematic infections. One of the most formidable, naturally MDR bacterial pathogens is Pseudomonas aeruginosa (PA) that is particularly susceptible to nitric oxide (NO), a component of our innate immune response. This susceptibility sets the translational stage for the use of NO-based therapeutics during the aforementioned human infections. First, we discuss how such NO therapeutics may be able to target problematic infections in each of the aforementioned infectious scenarios. Second, we describe a recent discovery based on years of foundational information, a novel drug known as AB569. AB569 is capable of forming a "time release" of NO from S-nitrosothiols (RSNO). AB569, a bactericidal tandem consisting of acidified NaNO2 (A-NO2 -) and Na2-EDTA, is capable of killing all pathogens that are associated with the aforementioned disorders. Third, we described each disease state in brief, the known or predicted effects of AB569 on the viability of PA, its potential toxicity and highly remote possibility for resistance to develop. Finally, we conclude that AB569 can be a viable alternative or addition to conventional antibiotic regimens to treat such highly problematic MDR bacterial infections for civilian and military populations, as well as the economical burden that such organisms pose.
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Affiliation(s)
- Daniel J Hassett
- Department of Molecular Genetics, Biochemistry and Microbiology, Cincinnati, OH, United States
| | - Rhett A Kovall
- Department of Molecular Genetics, Biochemistry and Microbiology, Cincinnati, OH, United States
| | - Michael J Schurr
- Department of Immunology and Microbiology, University of Colorado Health Sciences, Denver, CO, United States
| | - Nalinikanth Kotagiri
- Division of Pharmacy, University of Colorado Health Sciences, Denver, CO, United States
| | - Harshita Kumari
- Division of Pharmacy, University of Colorado Health Sciences, Denver, CO, United States
| | - Latha Satish
- Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, United States.,Shriners Hospitals for Children-Cincinnati, Cincinnati, OH, United States
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37
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Cianciulli Sesso A, Lilić B, Amman F, Wolfinger MT, Sonnleitner E, Bläsi U. Gene Expression Profiling of Pseudomonas aeruginosa Upon Exposure to Colistin and Tobramycin. Front Microbiol 2021; 12:626715. [PMID: 33995291 PMCID: PMC8120321 DOI: 10.3389/fmicb.2021.626715] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 03/31/2021] [Indexed: 11/22/2022] Open
Abstract
Pseudomonas aeruginosa (Pae) is notorious for its high-level resistance toward clinically used antibiotics. In fact, Pae has rendered most antimicrobials ineffective, leaving polymyxins and aminoglycosides as last resort antibiotics. Although several resistance mechanisms of Pae are known toward these drugs, a profounder knowledge of hitherto unidentified factors and pathways appears crucial to develop novel strategies to increase their efficacy. Here, we have performed for the first time transcriptome analyses and ribosome profiling in parallel with strain PA14 grown in synthetic cystic fibrosis medium upon exposure to polymyxin E (colistin) and tobramycin. This approach did not only confirm known mechanisms involved in colistin and tobramycin susceptibility but revealed also as yet unknown functions/pathways. Colistin treatment resulted primarily in an anti-oxidative stress response and in the de-regulation of the MexT and AlgU regulons, whereas exposure to tobramycin led predominantly to a rewiring of the expression of multiple amino acid catabolic genes, lower tricarboxylic acid (TCA) cycle genes, type II and VI secretion system genes and genes involved in bacterial motility and attachment, which could potentially lead to a decrease in drug uptake. Moreover, we report that the adverse effects of tobramycin on translation are countered with enhanced expression of genes involved in stalled ribosome rescue, tRNA methylation and type II toxin-antitoxin (TA) systems.
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Affiliation(s)
- Anastasia Cianciulli Sesso
- Max Perutz Labs, Vienna Biocenter (VBC), Department of Microbiology, Immunobiology and Genetics, University of Vienna, Vienna, Austria
| | - Branislav Lilić
- Max Perutz Labs, Vienna Biocenter (VBC), Department of Microbiology, Immunobiology and Genetics, University of Vienna, Vienna, Austria
| | - Fabian Amman
- Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria
| | - Michael T Wolfinger
- Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria.,Research Group Bioinformatics and Computational Biology, Faculty of Computer Science, University of Vienna, Vienna, Austria
| | - Elisabeth Sonnleitner
- Max Perutz Labs, Vienna Biocenter (VBC), Department of Microbiology, Immunobiology and Genetics, University of Vienna, Vienna, Austria
| | - Udo Bläsi
- Max Perutz Labs, Vienna Biocenter (VBC), Department of Microbiology, Immunobiology and Genetics, University of Vienna, Vienna, Austria
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Xu Y, Yang S, You G, Hou J. Antibiotic resistance genes attenuation in anaerobic microorganisms during iron uptake from zero valent iron: An iron-dependent form of homeostasis and roles as regulators. WATER RESEARCH 2021; 195:116979. [PMID: 33690012 DOI: 10.1016/j.watres.2021.116979] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 02/17/2021] [Accepted: 02/24/2021] [Indexed: 06/12/2023]
Abstract
Zero valent iron (ZVI) has been previously documented to attenuate the propagation of antibiotic resistance genes (ARGs) in microbes, while how ZVI affects the evolution of ARGs remains unclear. Herein, we investigated the influences of ZVI on ARGs dissemination in anaerobic bioreactor treating oxytetracycline (tet) containing wastewater, by deciphering the roles of iron homeostasis and regulatory effects. A net reduction of tet gene targets ranging from 0.75 to 1.88 and 0.67 to 2.08 log unit in intracellular and extracellular DNA was achieved at the optimal dosage of 5 g/L ZVI, whereas 20 g/L ZVI made no effects on ARGs reduction. The reduced ARGs abundance by ZVI was directly related to the inhibited horizontal transfer of ARGs and decreased proliferation of resistant strains (mainly Paludibacter and WCHB1-32). The potential mechanisms included the increased antioxidant capacity, the depressed efflux pump system and the weakened energy driving force by Fur regulon in microbes (especially for Cloacibacterium and Dechloromonas). The negligible influence of 20 g/L ZVI on ARGs reduction was ascribed to the iron-catalyzed oxidative damage and reduced physiological activity. This study firstly illustrated the potential relationships among activation of iron uptake regulator leading to protection against oxidative stress, alternation of physiological metabolisms and reduction of ARGs dissemination. This work extents our understanding about the priority of ZVI in mitigating ARGs proliferation and sheds light on its potential application in wastewater treatment plants.
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Affiliation(s)
- Yi Xu
- College of Agricultural Engineering, Hohai University, Nanjing, 210098, PR China; Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, PR China
| | - Shihong Yang
- College of Agricultural Engineering, Hohai University, Nanjing, 210098, PR China
| | - Guoxiang You
- Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, PR China
| | - Jun Hou
- Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, PR China.
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Sen A, Imlay JA. How Microbes Defend Themselves From Incoming Hydrogen Peroxide. Front Immunol 2021; 12:667343. [PMID: 33995399 PMCID: PMC8115020 DOI: 10.3389/fimmu.2021.667343] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 03/19/2021] [Indexed: 12/02/2022] Open
Abstract
Microbes rely upon iron as a cofactor for many enzymes in their central metabolic processes. The reactive oxygen species (ROS) superoxide and hydrogen peroxide react rapidly with iron, and inside cells they can generate both enzyme and DNA damage. ROS are formed in some bacterial habitats by abiotic processes. The vulnerability of bacteria to ROS is also apparently exploited by ROS-generating host defense systems and bacterial competitors. Phagocyte-derived O 2 - can toxify captured bacteria by damaging unidentified biomolecules on the cell surface; it is unclear whether phagocytic H2O2, which can penetrate into the cell interior, also plays a role in suppressing bacterial invasion. Both pathogenic and free-living microbes activate defensive strategies to defend themselves against incoming H2O2. Most bacteria sense the H2O2via OxyR or PerR transcription factors, whereas yeast uses the Grx3/Yap1 system. In general these regulators induce enzymes that reduce cytoplasmic H2O2 concentrations, decrease the intracellular iron pools, and repair the H2O2-mediated damage. However, individual organisms have tailored these transcription factors and their regulons to suit their particular environmental niches. Some bacteria even contain both OxyR and PerR, raising the question as to why they need both systems. In lab experiments these regulators can also respond to nitric oxide and disulfide stress, although it is unclear whether the responses are physiologically relevant. The next step is to extend these studies to natural environments, so that we can better understand the circumstances in which these systems act. In particular, it is important to probe the role they may play in enabling host infection by microbial pathogens.
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Affiliation(s)
| | - James A. Imlay
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
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40
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Novel ε-polylysine/polyethyleneimine -coated Ag nanoparticles for in vitro treatment of Pseudomonas aeruginosa. Biochem Eng J 2021. [DOI: 10.1016/j.bej.2021.107937] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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41
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Redox Protein OsaR (PA0056) Regulates dsbM and the Oxidative Stress Response in Pseudomonas aeruginosa. Antimicrob Agents Chemother 2021; 65:AAC.01771-20. [PMID: 33361299 DOI: 10.1128/aac.01771-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 12/14/2020] [Indexed: 11/20/2022] Open
Abstract
Bacteria have evolved distinct molecular mechanisms as a defense against oxidative stress. The foremost regulator of the oxidative stress response has been found to be OxyR. However, the molecular details of regulation upstream of OxyR remain largely unknown and need further investigation. Here, we characterize an oxidative stress and antibiotic tolerance regulator, OsaR (PA0056), produced by Pseudomonas aeruginosa Knocking out of osaR increased bacterial tolerance to aminoglycoside and β-lactam antibiotics, as well as to hydrogen peroxide. Expression of the oxyR regulon genes oxyR, katAB, and ahpBCF was increased in the osaR mutant. However, the OsaR protein does not regulate the oxyR regulon genes through direct binding to their promoters. PA0055, osaR, PA0057, and dsbM are in the same gene cluster, and we provide evidence that expression of those genes involved in oxidant tolerance is controlled by the binding of OsaR to the intergenic region between osaR and PA0057, which contain two divergent promoters. The gene cluster is also regulated by PA0055 via an indirect effect. We further discovered that OsaR formed intramolecular disulfide bonds when exposed to oxidative stress, resulting in a change of its DNA binding affinity. Taken together, our results indicate that OsaR is inactivated by oxidative stress and plays a role in the tolerance of P. aeruginosa to aminoglycoside and β-lactam antibiotics.
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Response of Pseudomonas aeruginosa to the Innate Immune System-Derived Oxidants Hypochlorous Acid and Hypothiocyanous Acid. J Bacteriol 2020; 203:JB.00300-20. [PMID: 33106346 PMCID: PMC7950407 DOI: 10.1128/jb.00300-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 10/08/2020] [Indexed: 01/06/2023] Open
Abstract
The bacterial pathogen Pseudomonas aeruginosa causes devastating infections in immunocompromised hosts, including chronic lung infections in cystic fibrosis patients. To combat infection, the host’s immune system produces the antimicrobial oxidants hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN). Little is known about how P. aeruginosa responds to and survives attack from these oxidants. To address this, we carried out two approaches: a mutant screen and transcriptional study. We identified the P. aeruginosa transcriptional regulator, RclR, which responds specifically to HOCl and HOSCN stress and is essential for protection against both oxidants. We uncovered a link between the P. aeruginosa transcriptional response to these oxidants and physiological processes associated with pathogenicity, including antibiotic resistance and the type 3 secretion system. Pseudomonas aeruginosa is a significant nosocomial pathogen and is associated with lung infections in cystic fibrosis (CF). Once established, P. aeruginosa infections persist and are rarely eradicated despite host immune cells producing antimicrobial oxidants, including hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN). There is limited knowledge as to how P. aeruginosa senses, responds to, and protects itself against HOCl and HOSCN and the contribution of such responses to its success as a CF pathogen. To investigate the P. aeruginosa response to these oxidants, we screened 707 transposon mutants, with mutations in regulatory genes, for altered growth following HOCl exposure. We identified regulators of antibiotic resistance, methionine biosynthesis, catabolite repression, and PA14_07340, the homologue of the Escherichia coli HOCl-sensor RclR (30% identical), which are required for protection against HOCl. We have shown that RclR (PA14_07340) protects specifically against HOCl and HOSCN stress and responds to both oxidants by upregulating the expression of a putative peroxiredoxin, rclX (PA14_07355). Transcriptional analysis revealed that while there was specificity in the response to HOCl (231 genes upregulated) and HOSCN (105 genes upregulated), there was considerable overlap, with 74 genes upregulated by both oxidants. These included genes encoding the type 3 secretion system, sulfur and taurine transport, and the MexEF-OprN efflux pump. RclR coordinates part of the response to both oxidants, including upregulation of pyocyanin biosynthesis genes, and, in the presence of HOSCN, downregulation of chaperone genes. These data indicate that the P. aeruginosa response to HOCl and HOSCN is multifaceted, with RclR playing an essential role. IMPORTANCE The bacterial pathogen Pseudomonas aeruginosa causes devastating infections in immunocompromised hosts, including chronic lung infections in cystic fibrosis patients. To combat infection, the host’s immune system produces the antimicrobial oxidants hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN). Little is known about how P. aeruginosa responds to and survives attack from these oxidants. To address this, we carried out two approaches: a mutant screen and transcriptional study. We identified the P. aeruginosa transcriptional regulator, RclR, which responds specifically to HOCl and HOSCN stress and is essential for protection against both oxidants. We uncovered a link between the P. aeruginosa transcriptional response to these oxidants and physiological processes associated with pathogenicity, including antibiotic resistance and the type 3 secretion system.
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Niu W, Zhang Y, Liu J, Wen T, Miao T, Basit A, Jiang W. OxyR controls magnetosome formation by regulating magnetosome island (MAI) genes, iron metabolism, and redox state. Free Radic Biol Med 2020; 161:272-282. [PMID: 33075503 DOI: 10.1016/j.freeradbiomed.2020.10.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 10/13/2020] [Accepted: 10/14/2020] [Indexed: 12/25/2022]
Abstract
Magnetospirillum gryphiswaldense MSR-1 uses chains of magnetosomes, membrane-enveloped magnetite (Fe(II)Fe(III)2O4) nanocrystals, to align along magnetic field. The process of magnetosome biomineralization requires a precise biological control of redox conditions to maintain a balanced amounts of ferric and ferrous iron. Here, we identified functions of the global regulator OxyR (MGMSRv2_4250, OxyR-4250) in MSR-1 during magnetosome formation. OxyR deletion mutant ΔoxyR-4250 displayed reduced magnetic response, and increased levels of intracellular ROS (reactive oxygen species). OxyR-4250 protein upregulated expression of six antioxidant genes (ahpC1, ahpC2, katE, katG, sodB, trxA), four iron metabolism-related regulator genes (fur, irrA, irrB, irrC), a bacterioferritin gene (bfr), and a DNA protection gene (dps). OxyR-4250 was shown, for the first time, to directly regulate magnetosome island (MAI) genes mamGFDC, mamXY, and feoAB1 operons. Taken together, our findings indicate that OxyR-4250 helps maintain a proper redox environment for magnetosome formation by eliminating excess ROS, regulating iron homeostasis and participating in regulation of Fe2+/Fe3+ ratio within the magnetosome vesicle through regulating MAI genes.
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Affiliation(s)
- Wei Niu
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Yunpeng Zhang
- Agricultural Utilization Research Center, Nutrition and Health Research Institute, COFCO Corporation, Beijing, 102209, China
| | - Junquan Liu
- Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Tong Wen
- Department of Biology Science and Technology, Baotou Teacher's College, Baotou, 014030, China
| | - Ting Miao
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Abdul Basit
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Wei Jiang
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
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Wille J, Teirlinck E, Sass A, Van Nieuwerburgh F, Kaever V, Braeckmans K, Coenye T. Does the mode of dispersion determine the properties of dispersed Pseudomonas aeruginosa biofilm cells? Int J Antimicrob Agents 2020; 56:106194. [PMID: 33039591 DOI: 10.1016/j.ijantimicag.2020.106194] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 06/30/2020] [Accepted: 09/26/2020] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Actively dispersed Pseudomonas aeruginosa biofilm cells differ from planktonic cells, as they have a lower intracellular cyclic di-guanosine monophosphate (c-di-GMP) concentration and show increased virulence. In addition, the nature of the dispersion trigger has been shown to influence the antibiotic susceptibility of dispersed cells. However, properties of passively-dispersed cells, in which the dispersion trigger directly releases cells from the biofilm, have not been described. The present study determined c-di-GMP concentration, virulence in Galleria mellonella and antibiotic susceptibility of P. aeruginosa cells dispersed from biofilm using various triggers. MATERIALS AND METHODS P. aeruginosa biofilms grown in flow-cells were dispersed actively [exposure to the nitric oxide (NO)-donor sodium nitroprusside (SNP) or to glutamate] or passively [by stopping and restarting the flow or exposure to laser-induced vapor nanobubbles (VNB)], and properties of these dispersed cells were compared to those of spontaneously-dispersed cells. RESULTS The passively dispersed P. aeruginosa biofilm cells had significantly lower intracellular c-di-GMP levels than actively-dispersed cells. However, this did not result in differences in virulence in Galleria mellonella, nor in tobramycin and ciprofloxacin susceptibility. Passively-dispersed cells were more susceptible to colistin than actively- and spontaneously-dispersed cells. In cells dispersed by interrupting the flow, increased susceptibility to colistin was immediate, whereas this was delayed for VNB-dispersed cells. CONCLUSION Passively-dispersed P. aeruginosa biofilm cells have a decreased intracellular c-di-GMP concentration and an increased colistin susceptibility compared to actively-dispersed cells. No differences in virulence or susceptibility to tobramycin or colistin were observed.
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Affiliation(s)
- Jasper Wille
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium
| | - Eline Teirlinck
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ghent, Belgium; Centre for Nano- and Biophotonics, Ghent University, Ghent, Belgium
| | - Andrea Sass
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium
| | | | - Volkhard Kaever
- Research Core Unit Metabolomics, Hannover Medical School, Hannover, Germany
| | - Kevin Braeckmans
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ghent, Belgium; Centre for Nano- and Biophotonics, Ghent University, Ghent, Belgium
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium.
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Martins D, McKay GA, English AM, Nguyen D. Sublethal Paraquat Confers Multidrug Tolerance in Pseudomonas aeruginosa by Inducing Superoxide Dismutase Activity and Lowering Envelope Permeability. Front Microbiol 2020; 11:576708. [PMID: 33101252 PMCID: PMC7546422 DOI: 10.3389/fmicb.2020.576708] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 08/31/2020] [Indexed: 12/17/2022] Open
Abstract
Stressors and environmental cues shape the physiological state of bacteria, and thus how they subsequently respond to antibiotic toxicity. To understand how superoxide stress can modulate survival to bactericidal antibiotics, we examined the effect of intracellular superoxide generators, paraquat and menadione, on stationary-phase antibiotic tolerance of the opportunistic pathogen, Pseudomonas aeruginosa. We tested how pre-challenge with sublethal paraquat and menadione alters the tolerance to ofloxacin and meropenem in wild-type P. aeruginosa and mutants lacking superoxide dismutase (SOD) activity (sodAB), the paraquat responsive regulator soxR, (p)ppGpp signaling (relA spoT mutant), or the alternative sigma factor rpoS. We confirmed that loss of SOD activity impairs ofloxacin and meropenem tolerance in stationary phase cells, and found that sublethal superoxide generators induce drug tolerance by stimulating SOD activity. This response is rapid, requires de novo protein synthesis, and is RpoS-dependent but does not require (p)ppGpp signaling nor SoxR. We further showed that pre-challenge with sublethal paraquat induces a SOD-dependent reduction in cell-envelope permeability and ofloxacin penetration. Our results highlight a novel mechanism of hormetic protection by superoxide generators, which may have important implications for stress-induced antibiotic tolerance in P. aeruginosa cells.
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Affiliation(s)
- Dorival Martins
- Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, QC, Canada.,Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
| | - Geoffrey A McKay
- Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Ann M English
- Department of Chemistry and Biochemistry, Concordia University, Montreal, QC, Canada
| | - Dao Nguyen
- Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, QC, Canada.,Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada.,Department of Medicine, McGill University, Montreal, QC, Canada
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Rodríguez-González V, Obregón S, Patrón-Soberano OA, Terashima C, Fujishima A. An approach to the photocatalytic mechanism in the TiO 2-nanomaterials microorganism interface for the control of infectious processes. APPLIED CATALYSIS. B, ENVIRONMENTAL 2020; 270:118853. [PMID: 32292243 DOI: 10.1016/j.apcatb.2020.118857] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 02/27/2020] [Accepted: 03/03/2020] [Indexed: 05/21/2023]
Abstract
The approach of this timely review considers the current literature that is focused on the interface nanostructure/cell-wall microorganism to understand the annihilation mechanism. Morphological studies use optical and electronic microscopes to determine the physical damage on the cell-wall and the possible cell lysis that confirms the viability and microorganism death. The key parameters of the tailoring the surface of the photoactive nanostructures such as the metal functionalization with bacteriostatic properties, hydrophilicity, textural porosity, morphology and the formation of heterojunction systems, can achieve the effective eradication of the microorganisms under natural conditions, ranging from practical to applications in environment, agriculture, and so on. However, to our knowledge, a comprehensive review of the microorganism/nanomaterial interface approach has rarely been conducted. The final remarks point the ideal photocatalytic way for the effective prevention/eradication of microorganisms, considering the resistance that the microorganism could develop without the appropriate regulatory aspects for human and ecosystem safety.
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Affiliation(s)
- Vicente Rodríguez-González
- Photocatalysis International Research Center, Research Institute for Science & Technology, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
- Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), División de Materiales Avanzados, Camino a la Presa San José 2055, Lomas 4a, Sección, 78216, San Luis Potosí, Mexico
| | - Sergio Obregón
- Universidad Autónoma de Nuevo León, UANL, CICFIM-Facultad de Ciencias Físico Matemáticas, Av. Universidad S/N, San Nicolás de los Garza, 66455, Nuevo León, Mexico
| | - Olga A Patrón-Soberano
- Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), División de Biología Molecular, Camino a la Presa San José 2055, Lomas 4a, Sección, 78216, San Luis Potosí, Mexico
| | - Chiaki Terashima
- Photocatalysis International Research Center, Research Institute for Science & Technology, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Akira Fujishima
- Photocatalysis International Research Center, Research Institute for Science & Technology, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
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Rodríguez-González V, Obregón S, Patrón-Soberano OA, Terashima C, Fujishima A. An approach to the photocatalytic mechanism in the TiO 2-nanomaterials microorganism interface for the control of infectious processes. APPLIED CATALYSIS. B, ENVIRONMENTAL 2020; 270:118853. [PMID: 32292243 PMCID: PMC7111711 DOI: 10.1016/j.apcatb.2020.118853] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 02/27/2020] [Accepted: 03/03/2020] [Indexed: 05/08/2023]
Abstract
The approach of this timely review considers the current literature that is focused on the interface nanostructure/cell-wall microorganism to understand the annihilation mechanism. Morphological studies use optical and electronic microscopes to determine the physical damage on the cell-wall and the possible cell lysis that confirms the viability and microorganism death. The key parameters of the tailoring the surface of the photoactive nanostructures such as the metal functionalization with bacteriostatic properties, hydrophilicity, textural porosity, morphology and the formation of heterojunction systems, can achieve the effective eradication of the microorganisms under natural conditions, ranging from practical to applications in environment, agriculture, and so on. However, to our knowledge, a comprehensive review of the microorganism/nanomaterial interface approach has rarely been conducted. The final remarks point the ideal photocatalytic way for the effective prevention/eradication of microorganisms, considering the resistance that the microorganism could develop without the appropriate regulatory aspects for human and ecosystem safety.
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Affiliation(s)
- Vicente Rodríguez-González
- Photocatalysis International Research Center, Research Institute for Science & Technology, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
- Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), División de Materiales Avanzados, Camino a la Presa San José 2055, Lomas 4a, Sección, 78216, San Luis Potosí, Mexico
| | - Sergio Obregón
- Universidad Autónoma de Nuevo León, UANL, CICFIM-Facultad de Ciencias Físico Matemáticas, Av. Universidad S/N, San Nicolás de los Garza, 66455, Nuevo León, Mexico
| | - Olga A. Patrón-Soberano
- Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), División de Biología Molecular, Camino a la Presa San José 2055, Lomas 4a, Sección, 78216, San Luis Potosí, Mexico
| | - Chiaki Terashima
- Photocatalysis International Research Center, Research Institute for Science & Technology, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Akira Fujishima
- Photocatalysis International Research Center, Research Institute for Science & Technology, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
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Abstract
The increasing bacterial antibiotic resistance imposes a severe threat to human health. For the development of effective treatment and prevention strategies, it is critical to understand the mechanisms employed by bacteria to grow in the human body. Posttranscriptional regulation plays an important role in bacterial adaptation to environmental changes. RNases and small RNAs are key players in this regulation. In this study, we demonstrate critical roles of the RNase YbeY in the virulence of the pathogenic bacterium Pseudomonas aeruginosa. We further identify the small RNA ReaL as the direct target of YbeY and elucidate the YbeY-regulated pathway on the expression of bacterial virulence factors. Our results shed light on the complex regulatory network of P. aeruginosa and indicate that inference with the YbeY-mediated regulatory pathway might be a valid strategy for the development of a novel treatment strategy. Posttranscriptional regulation plays an essential role in the quick adaptation of pathogenic bacteria to host environments, and RNases play key roles in this process by modifying small RNAs and mRNAs. We find that the Pseudomonas aeruginosa endonuclease YbeY is required for rRNA processing and the bacterial virulence in a murine acute pneumonia model. Transcriptomic analyses reveal that knocking out the ybeY gene results in downregulation of oxidative stress response genes, including the catalase genes katA and katB. Consistently, the ybeY mutant is more susceptible to H2O2 and neutrophil-mediated killing. Overexpression of katA restores the bacterial tolerance to H2O2 and neutrophil killing as well as virulence. We further find that the downregulation of the oxidative stress response genes is due to defective expression of the stationary-phase sigma factor RpoS. We demonstrate an autoregulatory mechanism of RpoS and find that ybeY mutation increases the level of a small RNA, ReaL, which directly represses the translation of rpoS through the 5′ UTR of its mRNA and subsequently reduces the expression of the oxidative stress response genes. In vitro assays demonstrate direct degradation of ReaL by YbeY. Deletion of reaL or overexpression of rpoS in the ybeY mutant restores the bacterial tolerance to oxidative stress and the virulence. We also demonstrate that YbeZ binds to YbeY and is involved in the 16S rRNA processing and regulation of reaL and rpoS as well as the bacterial virulence. Overall, our results reveal pleiotropic roles of YbeY and the YbeY-mediated regulation of rpoS through ReaL.
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Perraud Q, Cantero P, Roche B, Gasser V, Normant VP, Kuhn L, Hammann P, Mislin GLA, Ehret-Sabatier L, Schalk IJ. Phenotypic Adaption of Pseudomonas aeruginosa by Hacking Siderophores Produced by Other Microorganisms. Mol Cell Proteomics 2020; 19:589-607. [PMID: 32024770 PMCID: PMC7124469 DOI: 10.1074/mcp.ra119.001829] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/23/2019] [Indexed: 12/31/2022] Open
Abstract
Bacteria secrete siderophores to access iron, a key nutrient poorly bioavailable and the source of strong competition between microorganisms in most biotopes. Many bacteria also use siderophores produced by other microorganisms (exosiderophores) in a piracy strategy. Pseudomonas aeruginosa, an opportunistic pathogen, produces two siderophores, pyoverdine and pyochelin, and is also able to use a panel of exosiderophores. We first investigated expression of the various iron-uptake pathways of P. aeruginosa in three different growth media using proteomic and RT-qPCR approaches and observed three different phenotypic patterns, indicating complex phenotypic plasticity in the expression of the various iron-uptake pathways. We then investigated the phenotypic plasticity of iron-uptake pathway expression in the presence of various exosiderophores (present individually or as a mixture) under planktonic growth conditions, as well as in an epithelial cell infection assay. In all growth conditions tested, catechol-type exosiderophores were clearly more efficient in inducing the expression of their corresponding transporters than the others, showing that bacteria opt for the use of catechol siderophores to access iron when they are present in the environment. In parallel, expression of the proteins of the pyochelin pathway was significantly repressed under most conditions tested, as well as that of proteins of the pyoverdine pathway, but to a lesser extent. There was no effect on the expression of the heme and ferrous uptake pathways. Overall, these data provide precise insights on how P. aeruginosa adjusts the expression of its various iron-uptake pathways (phenotypic plasticity and switching) to match varying levels of iron and competition.
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Affiliation(s)
- Quentin Perraud
- Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France; CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France
| | - Paola Cantero
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France
| | - Béatrice Roche
- Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France; CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France
| | - Véronique Gasser
- Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France; CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France
| | - Vincent P Normant
- Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France; CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France
| | - Lauriane Kuhn
- Plateforme Proteomique Strasbourg - Esplanade, Institut de Biologie Moléculaire et Cellulaire, CNRS, FR1589, 15 rue Descartes, F-67084 Strasbourg Cedex, France
| | - Philippe Hammann
- Plateforme Proteomique Strasbourg - Esplanade, Institut de Biologie Moléculaire et Cellulaire, CNRS, FR1589, 15 rue Descartes, F-67084 Strasbourg Cedex, France
| | - Gaëtan L A Mislin
- Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France; CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France
| | - Laurence Ehret-Sabatier
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France
| | - Isabelle J Schalk
- Université de Strasbourg, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France; CNRS, UMR7242, ESBS, Bld Sébastien Brant, F-67413 Illkirch, Strasbourg, France.
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Li LH, Shih YL, Huang JY, Wu CJ, Huang YW, Huang HH, Tsai YC, Yang TC. Protection from hydrogen peroxide stress relies mainly on AhpCF and KatA2 in Stenotrophomonas maltophilia. J Biomed Sci 2020; 27:37. [PMID: 32093695 PMCID: PMC7041247 DOI: 10.1186/s12929-020-00631-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 02/17/2020] [Indexed: 11/10/2022] Open
Abstract
Background Aerobically-grown bacteria can be challenged by hydrogen peroxide stress from endogenous aerobic metabolism and exogenously generated reactive oxygen species. Catalase (Kat), alkyl hydroperoxidase (Ahp), and glutathione peroxidase (Gpx) systems are major adaptive responses to H2O2 stress in bacteria. Stenotrophomonas maltophilia is a ubiquitous Gram-negative bacterium equipped with four Kats (KatA1, KatA2, KatMn, and KatE), one Ahp (AhpCF), and three Gpxs (Gpx1, Gpx2, and Gpx3). Here, we systematically investigated how the eight H2O2 scavenging genes differentially contribute to the low-micromolar levels of H2O2 generated from aerobic metabolism and high-millimolar levels of H2O2 from exogenous sources. Methods Gene expression was assessed and quantified by reverse transcription-PCR (RT-PCR) and real time quantitative PCR (qRT-PCR), respectively. The contribution of these enzymes to H2O2 stress was assessed using mutant construction and functional investigation. Results Of the eight genes, katA2, ahpCF, and gpx3 were intrinsically expressed in response to low-micromolar levels of H2O2 from aerobic metabolism, and the expression of katA2 and ahpCF was regulated by OxyR. AhpCF and KatA2 were responsible for alleviating aerobic growth-mediated low concentration H2O2 stress and AhpCF played a critical role for stationary-phase cells. KatA2 was upregulated to compensate for AhpCF in the case of ahpCF inactivation. After exposure to millimolar levels of H2O2, katA2 and ahpCF were upregulated in an OxyR-dependent manner. KatA2 was the critical enzyme for dealing with high concentration H2O2. Loss-of-function of KatA2 increased bacterial susceptibility to high concentration H2O2. Conclusions AhpCF and KatA2 are key enzymes protecting S. maltophilia from hydrogen peroxide stress.
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Affiliation(s)
- Li-Hua Li
- Department of Pathology and Laboratory Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Program of Medical Biotechnology, Taipei Medical University, Taipei, Taiwan
| | - Yung-Luen Shih
- Department of Pathology and Laboratory Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan.,School of Medical Laboratory Science and Biotechnology, Taipei Medical University, Taipei, Taiwan.,School of Medicine, College of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan
| | - Jing-Yun Huang
- Department of Laboratory Medicine, Chang-Gung Memorial Hospital, LinKou, Taiwan.,Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Chao-Jung Wu
- Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Yi-Wei Huang
- Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Hsin-Hui Huang
- Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Yu-Chieh Tsai
- Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Tsuey-Ching Yang
- Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan.
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