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Se J, Xie Y, Ma Q, Zhu L, Fu Y, Xu X, Shen C, Nannipieri P. Drying-wetting cycle enhances stress resistance of Escherichia coli O157:H7 in a model soil. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 350:123988. [PMID: 38648967 DOI: 10.1016/j.envpol.2024.123988] [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: 12/28/2023] [Revised: 03/13/2024] [Accepted: 04/13/2024] [Indexed: 04/25/2024]
Abstract
Outbreaks of Escherichia coli (E. coli) O157:H7 in farms are often triggered by heavy rains and flooding. Most cells die with the decreasing of soil moisture, while few cells enter a dormant state and then resuscitate after rewetting. The resistance of dormant cells to stress has been extensively studied, whereas the molecular mechanisms of the cross-resistance development of the resuscitated cells are poorly known. We performed a comparative proteomic analysis on O157:H7 before and after undergoing soil dry-wet alternation. A differential expression of 820 proteins was identified in resuscitated cells compared to exponential-phase cells, as determined by proteomics analysis. The GO and KEGG pathway enrichment analyses revealed that up-regulated proteins were associated with oxidative phosphorylation, glycolysis/gluconeogenesis, the citrate cycle (TCA cycle), aminoacyl-tRNA biosynthesis, ribosome activity, and transmembrane transporters, indicating increased energy production and protein synthesis in resuscitated O157:H7. Moreover, proteins related to acid, osmotic, heat, oxidative, antibiotic stress and horizontal gene transfer efficiency were up-regulated, suggesting a potential improvement in stress resistance. Subsequent validation experiments demonstrated that the survival rates of the resuscitated cells were 476.54 and 7786.34 times higher than the exponential-phase cells, with pH levels of 1.5 and 2.5, respectively. Similarly, resuscitated cells showed higher survival rates under osmotic stress, with 7.5%, 15%, and 30% NaCl resulting in survival rates that were 460.58, 1974.55, and 3475.31 times higher. Resuscitated cells also exhibited increased resistance to heat stress, with survival rates 69.64 and 139.72 times higher at 55 °C and 90 °C, respectively. Furthermore, the horizontal gene transfer (HGT) efficiency of resuscitated cells was significantly higher (153.12-fold) compared to exponential phase cells. This study provides new insights into bacteria behavior under changing soil moisture and this may explain O157:H7 outbreaks following rainfall and flooding, as the dry-wet cycle promotes stress cross-resistance development.
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Affiliation(s)
- Jing Se
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou, 310058, China
| | - Yinan Xie
- Ministry of Education Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Qingxu Ma
- Ministry of Education Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Lin Zhu
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China
| | - Yulong Fu
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou, 310058, China
| | - Xin Xu
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou, 310058, China
| | - Chaofeng Shen
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou, 310058, China.
| | - Paolo Nannipieri
- Emeritus Professor, University of Firenze, Firenze, 50144, Italy
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Chowdhury-Paul S, Martínez-Ortíz IC, Pando-Robles V, Moreno S, Espín G, Merino E, Núñez C. The Azotobacter vinelandii AlgU regulon during vegetative growth and encysting conditions: A proteomic approach. PLoS One 2023; 18:e0286440. [PMID: 37967103 PMCID: PMC10651043 DOI: 10.1371/journal.pone.0286440] [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: 05/15/2023] [Accepted: 10/24/2023] [Indexed: 11/17/2023] Open
Abstract
In the Pseduomonadacea family, the extracytoplasmic function sigma factor AlgU is crucial to withstand adverse conditions. Azotobacter vinelandii, a closed relative of Pseudomonas aeruginosa, has been a model for cellular differentiation in Gram-negative bacteria since it forms desiccation-resistant cysts. Previous work demonstrated the essential role of AlgU to withstand oxidative stress and on A. vinelandii differentiation, particularly for the positive control of alginate production. In this study, the AlgU regulon was dissected by a proteomic approach under vegetative growing conditions and upon encystment induction. Our results revealed several molecular targets that explained the requirement of this sigma factor during oxidative stress and extended its role in alginate production. Furthermore, we demonstrate that AlgU was necessary to produce alkyl resorcinols, a type of aromatic lipids that conform the cell membrane of the differentiated cell. AlgU was also found to positively regulate stress resistance proteins such as OsmC, LEA-1, or proteins involved in trehalose synthesis. A position-specific scoring-matrix (PSSM) was generated based on the consensus sequence recognized by AlgU in P. aeruginosa, which allowed the identification of direct AlgU targets in the A. vinelandii genome. This work further expands our knowledge about the function of the ECF sigma factor AlgU in A. vinelandii and contributes to explains its key regulatory role under adverse conditions.
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Affiliation(s)
- Sangita Chowdhury-Paul
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México
| | - Iliana C. Martínez-Ortíz
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México
| | - Victoria Pando-Robles
- Instituto Nacional de Salud Pública, Centro de Investigación Sobre Enfermedades Infecciosas, Cuernavaca, Morelos, México
| | - Soledad Moreno
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México
| | - Guadalupe Espín
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México
| | - Enrique Merino
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México
| | - Cinthia Núñez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México
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3
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Qin J, Hong Y, Morona R, Totsika M. O antigen biogenesis sensitises Escherichia coli K-12 to bile salts, providing a plausible explanation for its evolutionary loss. PLoS Genet 2023; 19:e1010996. [PMID: 37792901 PMCID: PMC10578602 DOI: 10.1371/journal.pgen.1010996] [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: 05/23/2023] [Revised: 10/16/2023] [Accepted: 09/25/2023] [Indexed: 10/06/2023] Open
Abstract
Escherichia coli K-12 is a model organism for bacteriology and has served as a workhorse for molecular biology and biochemistry for over a century since its first isolation in 1922. However, Escherichia coli K-12 strains are phenotypically devoid of an O antigen (OAg) since early reports in the scientific literature. Recent studies have reported the presence of independent mutations that abolish OAg repeating-unit (RU) biogenesis in E. coli K-12 strains from the same original source, suggesting unknown evolutionary forces have selected for inactivation of OAg biogenesis during the early propagation of K-12. Here, we show for the first time that restoration of OAg in E. coli K-12 strain MG1655 synergistically sensitises bacteria to vancomycin with bile salts (VBS). Suppressor mutants surviving lethal doses of VBS primarily contained disruptions in OAg biogenesis. We present data supporting a model where the transient presence and accumulation of lipid-linked OAg intermediates in the periplasmic leaflet of the inner membrane interfere with peptidoglycan sacculus biosynthesis, causing growth defects that are synergistically enhanced by bile salts. Lastly, we demonstrate that continuous bile salt exposure of OAg-producing MG1655 in the laboratory, can recreate a scenario where OAg disruption is selected for as an evolutionary fitness benefit. Our work thus provides a plausible explanation for the long-held mystery of the selective pressure that may have led to the loss of OAg biogenesis in E. coli K-12; this opens new avenues for exploring long-standing questions on the intricate network coordinating the synthesis of different cell envelope components in Gram-negative bacteria.
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Affiliation(s)
- Jilong Qin
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Yaoqin Hong
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
- Max Planck Queensland Centre, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Renato Morona
- School of Biological Sciences, Department of Molecular & Biomedical Sciences, Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia
| | - Makrina Totsika
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
- Max Planck Queensland Centre, Queensland University of Technology, Brisbane, Queensland, Australia
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4
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Park JW, Kim M, Kim SY, Bae J, Kim TJ. Biodegradation of polystyrene by intestinal symbiotic bacteria isolated from mealworms, the larvae of Tenebrio molitor. Heliyon 2023; 9:e17352. [PMID: 37426801 PMCID: PMC10329137 DOI: 10.1016/j.heliyon.2023.e17352] [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: 11/17/2022] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 07/11/2023] Open
Abstract
Objectives Polystyrene is a plastic that leads to environmental pollution. In particular, expanded polystyrene is very light and takes up much space, causing additional environmental problems. The aim of this study was to isolate new symbiotic bacteria which degraded polystyrene from mealworms. Methods The population of polystyrene degrading bacteria was increased by enrichment culture of intestinal bacteria from mealworms with polystyrene as a sole carbon source. The degradation activity of isolated bacteria was evaluated by morphological change of micro-polystyrene particles and the surface change of polystyrene films. Results Eight isolated species (Acinetobacter septicus, Agrobacterium tumefaciens, Klebsiella grimontii, Pseudomonas multiresinivorans, Pseudomonas nitroreducens, Pseudomonas plecoglossicida, Serratia marcescens, and Yokenella regensburgei) were identified that degrade polystyrene. Conclusion Bacterial identification shows that a broad spectrum of bacteria decomposing polystyrene coexists in the intestinal tract of mealworms.
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Affiliation(s)
- Ji-Won Park
- Department of Forest Products and Biotechnology, College of Science and Technology, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Republic of Korea
| | - Minjun Kim
- Department of Forest Products and Biotechnology, College of Science and Technology, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Republic of Korea
| | - Seo-Young Kim
- Department of Forest Products and Biotechnology, College of Science and Technology, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Republic of Korea
| | - Jihye Bae
- Department of Forest Products and Biotechnology, College of Science and Technology, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Republic of Korea
| | - Tae-Jong Kim
- Department of Forest Products and Biotechnology, College of Science and Technology, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Republic of Korea
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5
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Yang HW, Lee JH, Zhao Y. RpoN Regulon in Erwinia amylovora Revealed by Transcriptional Profiling and In Silico Binding Site Analysis. PHYTOPATHOLOGY 2023; 113:183-193. [PMID: 35994732 DOI: 10.1094/phyto-07-22-0255-r] [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: 06/15/2023]
Abstract
Erwinia amylovora causes a devastating fire blight disease in apples and pears. One of the main virulence determinants in E. amylovora is the hypersensitive response (HR) and pathogenicity (hrp)-type III secretion system (T3SS), which is activated by the RpoN-HrpL sigma factor cascade. However, the RpoN regulon in E. amylovora has not been investigated. In this study, we determined the RpoN regulon in E. amylovora by combining RNA-seq transcriptomic analysis with in silico binding site analysis. RNA-seq revealed that 262 genes, approximately 7.5% genes in the genome of E. amylovora, were differentially transcribed in the rpoN mutant as compared with the wild type. Specifically, genes associated with virulence, motility, nitrogen assimilation, the PspF system, stress response, and arginine biosynthesis are positively regulated by RpoN, whereas genes associated with biosynthesis of amino acids and sorbitol transport are negatively regulated by RpoN. In silico binding site analysis identified 46 potential target genes with a putative RpoN binding site, and the upstream sequences of six, three, and three genes also contain putative GlnG, PspF, and YfhA binding sites, respectively. Overall, RpoN directly regulates genes associated with virulence, nitrogen assimilation, the PspF system, motility and the YfhA/YfhK two-component regulatory system.
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Affiliation(s)
- Ho-Wen Yang
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A
| | - Jae-Hoon Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A
- Department of Plant Pathology, WSU-IAREC, Prosser, WA 99350, U.S.A
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Meireles DA, da Silva Neto JF, Domingos RM, Alegria TGP, Santos LCM, Netto LES. Ohr - OhrR, a neglected and highly efficient antioxidant system: Structure, catalysis, phylogeny, regulation, and physiological roles. Free Radic Biol Med 2022; 185:6-24. [PMID: 35452809 DOI: 10.1016/j.freeradbiomed.2022.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Revised: 03/09/2022] [Accepted: 04/02/2022] [Indexed: 12/24/2022]
Abstract
Ohrs (organic hydroperoxide resistance proteins) are antioxidant enzymes that play central roles in the response of microorganisms to organic peroxides. Here, we describe recent advances in the structure, catalysis, phylogeny, regulation, and physiological roles of Ohr proteins and of its transcriptional regulator, OhrR, highlighting their unique features. Ohr is extremely efficient in reducing fatty acid peroxides and peroxynitrite, two oxidants relevant in host-pathogen interactions. The highly reactive Cys residue of Ohr, named peroxidatic Cys (Cp), composes together with an arginine and a glutamate the catalytic triad. The catalytic cycle of Ohrs involves a condensation between a sulfenic acid (Cp-SOH) and the thiol of the second conserved Cys, leading to the formation of an intra-subunit disulfide bond, which is then reduced by dihydrolipoamide or lipoylated proteins. A structural switch takes place during catalysis, with the opening and closure of the active site by the so-called Arg-loop. Ohr is part of the Ohr/OsmC super-family that also comprises OsmC and Ohr-like proteins. Members of the Ohr, OsmC and Ohr-like subgroups present low sequence similarities among themselves, but share a high structural conservation, presenting two Cys residues in their active site. The pattern of gene expression is also distinct among members of the Ohr/OsmC subfamilies. The expression of ohr genes increases upon organic hydroperoxides treatment, whereas the signals for the upregulation of osmC are entry into the stationary phase and/or osmotic stress. For many ohr genes, the upregulation by organic hydroperoxides is mediated by OhrR, a Cys-based transcriptional regulator that only binds to its target DNAs in its reduced state. Since Ohrs and OhrRs are involved in virulence of some microorganisms and are absent in vertebrate and vascular plants, they may represent targets for novel therapeutic approaches based on the disruption of this key bacterial organic peroxide defense system.
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Affiliation(s)
- Diogo A Meireles
- Laboratório de Fisiologia e Bioquímica de Microrganismos (LFBM) da Universidade Estadual do Norte Fluminense Darcy Ribeiro, Brazil
| | - José F da Silva Neto
- Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (FMRP-USP), Brazil
| | | | - Thiago G P Alegria
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Brazil
| | - Lene Clara M Santos
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Brazil
| | - Luis Eduardo S Netto
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Brazil.
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Lara P, Vega-Alvarado L, Sahonero-Canavesi DX, Koenen M, Villanueva L, Riveros-Mckay F, Morett E, Juárez K. Transcriptome Analysis Reveals Cr(VI) Adaptation Mechanisms in Klebsiella sp. Strain AqSCr. Front Microbiol 2021; 12:656589. [PMID: 34122372 PMCID: PMC8195247 DOI: 10.3389/fmicb.2021.656589] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 04/13/2021] [Indexed: 11/19/2022] Open
Abstract
Klebsiella sp. strain AqSCr, isolated from Cr(VI)-polluted groundwater, reduces Cr(VI) both aerobically and anaerobically and resists up 34 mM Cr(VI); this resistance is independent of the ChrA efflux transporter. In this study, we report the whole genome sequence and the transcriptional profile by RNA-Seq of strain AqSCr under Cr(VI)-adapted conditions and found 255 upregulated and 240 downregulated genes compared to controls without Cr(VI) supplementation. Genes differentially transcribed were mostly associated with oxidative stress response, DNA repair and replication, sulfur starvation response, envelope-osmotic stress response, fatty acid (FA) metabolism, ribosomal subunits, and energy metabolism. Among them, genes not previously associated with chromium resistance, for example, cybB, encoding a putative superoxide oxidase (SOO), gltA2, encoding an alternative citrate synthase, and des, encoding a FA desaturase, were upregulated. The sodA gene encoding a manganese superoxide dismutase was upregulated in the presence of Cr(VI), whereas sodB encoding an iron superoxide dismutase was downregulated. Cr(VI) resistance mechanisms in strain AqSCr seem to be orchestrated by the alternative sigma factors fecl, rpoE, and rpoS (all of them upregulated). Membrane lipid analysis of the Cr(IV)-adapted strain showed a lower proportion of unsaturated lipids with respect to the control, which we hypothesized could result from unsaturated lipid peroxidation followed by degradation, together with de novo synthesis mediated by the upregulated FA desaturase-encoding gene, des. This report helps to elucidate both Cr(VI) toxicity targets and global bacterial response to Cr(VI).
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Affiliation(s)
- Paloma Lara
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Leticia Vega-Alvarado
- Instituto de Ciencias Aplicadas y Tecnología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Diana X Sahonero-Canavesi
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Texel, Netherlands
| | - Michel Koenen
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Texel, Netherlands
| | - Laura Villanueva
- Department of Marine Microbiology and Biogeochemistry (MMB), NIOZ Royal Netherlands Institute for Sea Research, Texel, Netherlands.,Faculty of Geosciences, Department of Earth Sciences, Utrecht University, Utrecht, Netherlands
| | - Fernando Riveros-Mckay
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Enrique Morett
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Katy Juárez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
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Li QM, Zhou YL, Wei ZF, Wang Y. Phylogenomic Insights into Distribution and Adaptation of Bdellovibrionota in Marine Waters. Microorganisms 2021; 9:757. [PMID: 33916768 PMCID: PMC8067016 DOI: 10.3390/microorganisms9040757] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/26/2021] [Accepted: 04/01/2021] [Indexed: 11/23/2022] Open
Abstract
Bdellovibrionota is composed of obligate predators that can consume some Gram-negative bacteria inhabiting various environments. However, whether genomic traits influence their distribution and marine adaptation remains to be answered. In this study, we performed phylogenomics and comparative genomics studies using 132 Bdellovibrionota genomes along with five metagenome-assembled genomes (MAGs) from deep sea zones. Four phylogenetic groups, Oligoflexia, Bdello-group1, Bdello-group2 and Bacteriovoracia, were revealed by constructing a phylogenetic tree, of which 53.84% of Bdello-group2 and 48.94% of Bacteriovoracia were derived from the ocean. Bacteriovoracia was more prevalent in deep sea zones, whereas Bdello-group2 was largely distributed in the epipelagic zone. Metabolic reconstruction indicated that genes involved in chemotaxis, flagellar (mobility), type II secretion system, ATP-binding cassette (ABC) transporters and penicillin-binding protein were necessary for the predatory lifestyle of Bdellovibrionota. Genes involved in glycerol metabolism, hydrogen peroxide (H2O2) degradation, cell wall recycling and peptide utilization were ubiquitously present in Bdellovibrionota genomes. Comparative genomics between marine and non-marine Bdellovibrionota demonstrated that betaine as an osmoprotectant is probably widely used by marine Bdellovibrionota, and all the marine genomes have a number of genes for adaptation to marine environments. The genes encoding chitinase and chitin-binding protein were identified for the first time in Oligoflexia, which implied that Oligoflexia may prey on a wider spectrum of microbes. This study expands our knowledge on adaption strategies of Bdellovibrionota inhabiting deep seas and the potential usage of Oligoflexia for biological control.
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Affiliation(s)
- Qing-Mei Li
- Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China; (Q.-M.L.); (Y.-L.Z.); (Z.-F.W.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ying-Li Zhou
- Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China; (Q.-M.L.); (Y.-L.Z.); (Z.-F.W.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhan-Fei Wei
- Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China; (Q.-M.L.); (Y.-L.Z.); (Z.-F.W.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yong Wang
- Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China; (Q.-M.L.); (Y.-L.Z.); (Z.-F.W.)
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9
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Gottschlich L, Geiser P, Bortfeld-Miller M, Field CM, Vorholt JA. Complex general stress response regulation in Sphingomonas melonis Fr1 revealed by transcriptional analyses. Sci Rep 2019; 9:9404. [PMID: 31253827 PMCID: PMC6599016 DOI: 10.1038/s41598-019-45788-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 06/12/2019] [Indexed: 01/31/2023] Open
Abstract
The general stress response (GSR) represents an important trait to survive in the environment by leading to multiple stress resistance. In alphaproteobacteria, the GSR is under the transcriptional control of the alternative sigma factor EcfG. Here we performed transcriptome analyses to investigate the genes controlled by EcfG of Sphingomonas melonis Fr1 and the plasticity of this regulation under stress conditions. We found that EcfG regulates genes for proteins that are typically associated with stress responses. Moreover, EcfG controls regulatory proteins, which likely fine-tune the GSR. Among these, we identified a novel negative GSR feedback regulator, termed NepR2, on the basis of gene reporter assays, phenotypic analyses, and biochemical assays. Transcriptional profiling of signaling components upstream of EcfG under complex stress conditions showed an overall congruence with EcfG-regulated genes. Interestingly however, we found that the GSR is transcriptionally linked to the regulation of motility and biofilm formation via the single domain response regulator SdrG and GSR-activating histidine kinases. Altogether, our findings indicate that the GSR in S. melonis Fr1 underlies a complex regulation to optimize resource allocation and resilience in stressful and changing environments.
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Affiliation(s)
- Lisa Gottschlich
- Institute of Microbiology, Department of Biology, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland
| | - Petra Geiser
- Institute of Microbiology, Department of Biology, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland
| | - Miriam Bortfeld-Miller
- Institute of Microbiology, Department of Biology, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland
| | - Christopher M Field
- Institute of Microbiology, Department of Biology, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland
| | - Julia A Vorholt
- Institute of Microbiology, Department of Biology, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland.
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10
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Si M, Su T, Chen C, Wei Z, Gong Z, Li G. OsmC in Corynebacterium glutamicum was a thiol-dependent organic hydroperoxide reductase. Int J Biol Macromol 2019; 136:642-652. [PMID: 31195044 DOI: 10.1016/j.ijbiomac.2019.06.047] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 06/08/2019] [Accepted: 06/08/2019] [Indexed: 11/26/2022]
Abstract
Bacterial antioxidants play a vital role in the detoxification of exogenous peroxides. Several antioxidant defenses including low-molecular-weight thiols (LMWTs) and protective enzymes were developed to help the bacterium withstand the adverse stress. Although osmotically induced bacterial protein C (OsmC), classified as the organic hydroperoxide reductase (Ohr)/OsmC superfamily, has been demonstrated in some mycobacterial species, including M. tuberculosis and M. smegmatis, its physiological and biochemical functions in C. glutamicum remained elusive. Here we found the lack of C. glutamicum osmC gene resulted in decreased cell viability and increased intracellular reactive oxygen species accumulation under organic hydroperoxides (OHPs) stress conditions. The osmC expression was induced in the multiple antibiotic resistance regulator MarR-dependent manner by OHPs, and not by other oxidants or osmotic stress. Peroxide reductase activity showed that OsmC had a narrow range of substrates-only degrading OHPs, and detoxified OHPs mainly by linking the alkyl hydroperoxide reductase (AhpD) system (AhpD/dihydrolipoamide dehydrogenase (Lpd)/dihydrolipoamide acyltransferase (SucB)). Site-directed mutagenesis confirmed Cys48 was the peroxidatic cysteine, while Cys114 was the resolving Cys residue that formed an intramolecular disulfide bond with oxidized Cys48. Therefore, C. glutamicum OsmC was a thiol-dependent OHP reductase and played important role of protection against OHPs together with Ohr.
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Affiliation(s)
- Meiru Si
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China.
| | - Tao Su
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China
| | - Can Chen
- College of Life Science and Agronomy, Zhoukou Normal University, Zhoukou, Henan 466001, China.
| | - Zengfan Wei
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China
| | - Zhijin Gong
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China
| | - Guizhi Li
- College of Life Sciences, Qufu Normal University, Qufu, Shandong 273165, China
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Genome-Enabled Insights into the Ecophysiology of the Comammox Bacterium " Candidatus Nitrospira nitrosa". mSystems 2017; 2:mSystems00059-17. [PMID: 28905001 PMCID: PMC5596200 DOI: 10.1128/msystems.00059-17] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 08/15/2017] [Indexed: 02/03/2023] Open
Abstract
Nitrospira-like bacteria are among the most diverse and widespread nitrifiers in natural ecosystems and the dominant nitrite oxidizers in wastewater treatment plants (WWTPs). The recent discovery of comammox-like Nitrospira strains, capable of complete oxidation of ammonia to nitrate, raises new questions about specific traits responsible for the functional versatility and adaptation of this genus to a variety of environments. The availability of new Nitrospira genome sequences from both nitrite-oxidizing and comammox bacteria offers a way to analyze traits in different Nitrospira functional groups. Our comparative genomics analysis provided new insights into the adaptation of Nitrospira strains to specific lifestyles and environmental niches. The recently discovered comammox bacteria have the potential to completely oxidize ammonia to nitrate. These microorganisms are part of the Nitrospira genus and are present in a variety of environments, including biological nutrient removal (BNR) systems. However, the physiological traits within and between comammox and nitrite-oxidizing bacterium (NOB)-like Nitrospira species have not been analyzed in these ecosystems. In this study, we identified Nitrospira strains dominating the nitrifying community of a sequencing batch reactor (SBR) performing BNR under microaerobic conditions. We recovered metagenome-derived draft genomes from two Nitrospira strains: (i) Nitrospira sp. strain UW-LDO-01, a comammox-like organism classified as “Candidatus Nitrospira nitrosa,” and (ii) Nitrospira sp. strain UW-LDO-02, a nitrite-oxidizing strain belonging to the Nitrospira defluvii species. A comparative genomic analysis of these strains with other Nitrospira-like genomes identified genomic differences in “Ca. Nitrospira nitrosa” mainly attributed to each strain’s niche adaptation. Traits associated with energy metabolism also differentiate comammox from NOB-like genomes. We also identified several transcriptionally regulated adaptive traits, including stress tolerance, biofilm formation, and microaerobic metabolism, which might explain survival of Nitrospira under multiple environmental conditions. Overall, our analysis expanded our understanding of the genetic functional features of “Ca. Nitrospira nitrosa” and identified genomic traits that further illuminate the phylogenetic diversity and metabolic plasticity of the Nitrospira genus. IMPORTANCENitrospira-like bacteria are among the most diverse and widespread nitrifiers in natural ecosystems and the dominant nitrite oxidizers in wastewater treatment plants (WWTPs). The recent discovery of comammox-like Nitrospira strains, capable of complete oxidation of ammonia to nitrate, raises new questions about specific traits responsible for the functional versatility and adaptation of this genus to a variety of environments. The availability of new Nitrospira genome sequences from both nitrite-oxidizing and comammox bacteria offers a way to analyze traits in different Nitrospira functional groups. Our comparative genomics analysis provided new insights into the adaptation of Nitrospira strains to specific lifestyles and environmental niches. Author Video: An author video summary of this article is available.
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Bhagwat AA, Young L, Smith AD, Bhagwat M. Transcriptomic Analysis of the Swarm Motility Phenotype of Salmonella enterica Serovar Typhimurium Mutant Defective in Periplasmic Glucan Synthesis. Curr Microbiol 2017; 74:1005-1014. [PMID: 28593349 DOI: 10.1007/s00284-017-1267-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 05/14/2017] [Indexed: 12/19/2022]
Abstract
Movement of food-borne pathogens on moist surfaces enables them to migrate towards more favorable niches and facilitate their survival for extended periods of time. Salmonella enterica serovar Typhimurium mutants defective in Osmoregulated periplasmic glucans (OPG) synthesis are unable to exhibit motility on moist surfaces (swarming); however, their mobility in liquid (swim motility) remains unaffected. In order to understand the role of OPG in swarm motility, transcriptomic analysis was performed using cells growing on a moist agar surface. In opgGH deletion mutant, lack of OPG significantly altered transcription of 1039 genes out of total 4712 genes (22%). Introduction of a plasmid-borne copy of opgGH into opgGH deletion mutant restored normal expression of all but 30 genes, indicating a wide-range influence of OPG on gene expression under swarm motility condition. Major pathways that were differentially expressed in opgGH mutants were motility, virulence and invasion, and genes related to the secondary messenger molecule, cyclic di-GMP. These observations provide insights and help explain the pleiotropic nature of OPG mutants such as sub-optimal virulence and competitive organ colonization in mice, biofilm formation, and sensitivity towards detergent stress.
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Affiliation(s)
- Arvind A Bhagwat
- Environmental, Microbial, & Food Safety Laboratory, Beltsville Agriculture Research Center, USDA-ARS (USDA/ARS/EMFSL), 10300 Baltimore Ave., B173, Rm. 204, BARC-E, Beltsville, MD, 20705, USA.
| | - Lynn Young
- National Institutes of Health Library, Division of Library Services, Office of Research Services, National Institute of Health, Building 10, Bethesda, MD, 20892, USA
| | - Allen D Smith
- Diet, Genomics and Immunology Laboratory, Beltsville Human Nutrition Research Center, USDA-ARS, Beltsville, MD, 20705, USA.
| | - Medha Bhagwat
- National Institutes of Health Library, Division of Library Services, Office of Research Services, National Institute of Health, Building 10, Bethesda, MD, 20892, USA
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Meireles DA, Domingos RM, Gaiarsa JW, Ragnoni EG, Bannitz-Fernandes R, da Silva Neto JF, de Souza RF, Netto LES. Functional and evolutionary characterization of Ohr proteins in eukaryotes reveals many active homologs among pathogenic fungi. Redox Biol 2017; 12:600-609. [PMID: 28391181 PMCID: PMC5384416 DOI: 10.1016/j.redox.2017.03.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 03/17/2017] [Accepted: 03/24/2017] [Indexed: 01/31/2023] Open
Abstract
Ohr and OsmC proteins comprise two subfamilies within a large group of proteins that display Cys-based, thiol dependent peroxidase activity. These proteins were previously thought to be restricted to prokaryotes, but we show here, using iterated sequence searches, that Ohr/OsmC homologs are also present in 217 species of eukaryotes with a massive presence in Fungi (186 species). Many of these eukaryotic Ohr proteins possess an N-terminal extension that is predicted to target them to mitochondria. We obtained recombinant proteins for four eukaryotic members of the Ohr/OsmC family and three of them displayed lipoyl peroxidase activity. Further functional and biochemical characterization of the Ohr homologs from the ascomycete fungus Mycosphaerella fijiensis Mf_1 (MfOhr), the causative agent of Black Sigatoka disease in banana plants, was pursued. Similarly to what has been observed for the bacterial proteins, we found that: (i) the peroxidase activity of MfOhr was supported by DTT or dihydrolipoamide (dithiols), but not by β-mercaptoethanol or GSH (monothiols), even in large excess; (ii) MfOhr displayed preference for organic hydroperoxides (CuOOH and tBOOH) over hydrogen peroxide; (iii) MfOhr presented extraordinary reactivity towards linoleic acid hydroperoxides (k=3.18 (±2.13)×108 M−1 s−1). Both Cys87 and Cys154 were essential to the peroxidase activity, since single mutants for each Cys residue presented no activity and no formation of intramolecular disulfide bond upon treatment with hydroperoxides. The pKa value of the Cysp residue was determined as 5.7±0.1 by a monobromobimane alkylation method. Therefore, eukaryotic Ohr peroxidases share several biochemical features with prokaryotic orthologues and are preferentially located in mitochondria. Ohr/OsmC proteins are also present in lower eukaryotic organisms. While Ohr proteins are massively present among Fungi, OsmC proteins are restricted to the cellular slime molds. Eukaryotic Ohr and OsmC present a thiol dependent peroxidase activity similar to the bacterial counterparts. Most of these eukaryotic enzymes are predominantly present in mitochondria.
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Affiliation(s)
- D A Meireles
- Departmento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil.
| | - R M Domingos
- Departmento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
| | - J W Gaiarsa
- Departmento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
| | - E G Ragnoni
- Departmento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
| | - R Bannitz-Fernandes
- Departmento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
| | - J F da Silva Neto
- Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - R F de Souza
- Departmento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil
| | - L E S Netto
- Departmento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil.
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Mumm K, Ainsaar K, Kasvandik S, Tenson T, Hõrak R. Responses of Pseudomonas putida to Zinc Excess Determined at the Proteome Level: Pathways Dependent and Independent of ColRS. J Proteome Res 2016; 15:4349-4368. [DOI: 10.1021/acs.jproteome.6b00420] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Karl Mumm
- Institute of Molecular and Cell Biology, University of Tartu, Tartu 51010, Estonia
| | - Kadi Ainsaar
- Institute of Molecular and Cell Biology, University of Tartu, Tartu 51010, Estonia
| | - Sergo Kasvandik
- Institute of Technology, University of Tartu, Tartu 50411, Estonia
| | - Tanel Tenson
- Institute of Technology, University of Tartu, Tartu 50411, Estonia
| | - Rita Hõrak
- Institute of Molecular and Cell Biology, University of Tartu, Tartu 51010, Estonia
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15
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Arts IS, Vertommen D, Baldin F, Laloux G, Collet JF. Comprehensively Characterizing the Thioredoxin Interactome In Vivo Highlights the Central Role Played by This Ubiquitous Oxidoreductase in Redox Control. Mol Cell Proteomics 2016; 15:2125-40. [PMID: 27081212 DOI: 10.1074/mcp.m115.056440] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Indexed: 12/12/2022] Open
Abstract
Thioredoxin (Trx) is a ubiquitous oxidoreductase maintaining protein-bound cysteine residues in the reduced thiol state. Here, we combined a well-established method to trap Trx substrates with the power of bacterial genetics to comprehensively characterize the in vivo Trx redox interactome in the model bacterium Escherichia coli Using strains engineered to optimize trapping, we report the identification of a total 268 Trx substrates, including 201 that had never been reported to depend on Trx for reduction. The newly identified Trx substrates are involved in a variety of cellular processes, ranging from energy metabolism to amino acid synthesis and transcription. The interaction between Trx and two of its newly identified substrates, a protein required for the import of most carbohydrates, PtsI, and the bacterial actin homolog MreB was studied in detail. We provide direct evidence that PtsI and MreB contain cysteine residues that are susceptible to oxidation and that participate in the formation of an intermolecular disulfide with Trx. By considerably expanding the number of Trx targets, our work highlights the role played by this major oxidoreductase in a variety of cellular processes. Moreover, as the dependence on Trx for reduction is often conserved across species, it also provides insightful information on the interactome of Trx in organisms other than E. coli.
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Affiliation(s)
- Isabelle S Arts
- From the ‡WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium, §de Duve Institute, Université catholique de Louvain (UCL), Avenue Hippocrate 75, 1200 Brussels, Belgium; ¶Brussels Center for Redox Biology, Avenue Hippocrate 75, 1200 Brussels, Belgium
| | - Didier Vertommen
- §de Duve Institute, Université catholique de Louvain (UCL), Avenue Hippocrate 75, 1200 Brussels, Belgium
| | - Francesca Baldin
- From the ‡WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium, §de Duve Institute, Université catholique de Louvain (UCL), Avenue Hippocrate 75, 1200 Brussels, Belgium
| | - Géraldine Laloux
- From the ‡WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium, §de Duve Institute, Université catholique de Louvain (UCL), Avenue Hippocrate 75, 1200 Brussels, Belgium; ¶Brussels Center for Redox Biology, Avenue Hippocrate 75, 1200 Brussels, Belgium
| | - Jean-François Collet
- From the ‡WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium, §de Duve Institute, Université catholique de Louvain (UCL), Avenue Hippocrate 75, 1200 Brussels, Belgium; ¶Brussels Center for Redox Biology, Avenue Hippocrate 75, 1200 Brussels, Belgium
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16
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Nývltová E, Smutná T, Tachezy J, Hrdý I. OsmC and incomplete glycine decarboxylase complex mediate reductive detoxification of peroxides in hydrogenosomes of Trichomonas vaginalis. Mol Biochem Parasitol 2016; 206:29-38. [PMID: 26794804 DOI: 10.1016/j.molbiopara.2016.01.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 01/05/2016] [Accepted: 01/12/2016] [Indexed: 01/30/2023]
Abstract
Osmotically inducible protein (OsmC) and organic hydroperoxide resistance protein (Ohr) are small, thiol-dependent peroxidases that comprise a family of prokaryotic protective proteins central to the defense against deleterious effects of organic hydroperoxides, which are reactive molecules that are formed during interactions between the host immune system and pathogens. Trichomonas vaginalis, a sexually transmitted parasite of humans, possesses OsmC homologues in its hydrogenosomes, anaerobic mitochondrial organelles that harbor enzymes and pathways that are sensitive to oxidative damage. The glycine decarboxylase complex (GDC), which consists of four proteins (i.e., L, H, P and T), is in eukaryotes exclusively mitochondrial enzymatic system that catalyzes oxidative decarboxylation and deamination of glycine. However, trichomonad hydrogenosomes contain only the L and H proteins, whose physiological functions are unknown. Here, we found that the hydrogenosomal L and H proteins constitute a lipoate-dependent redox system that delivers electrons from reduced nicotinamide adenine dinucleotide (NADH) to OsmC for the reductive detoxification of peroxides. Our searches of genome databases revealed that, in addition to prokaryotes, homologues of OsmC/Ohr family proteins with predicted mitochondrial localization are present in various eukaryotic lineages. Therefore, we propose that the novel OsmC-GDC-based redox system may not be limited to T. vaginalis.
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Affiliation(s)
- Eva Nývltová
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Tamara Smutná
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Jan Tachezy
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic
| | - Ivan Hrdý
- Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic.
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17
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Fan Y, Wu J, Ung MH, De Lay N, Cheng C, Ling J. Protein mistranslation protects bacteria against oxidative stress. Nucleic Acids Res 2015; 43:1740-8. [PMID: 25578967 PMCID: PMC4330365 DOI: 10.1093/nar/gku1404] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Accurate flow of genetic information from DNA to protein requires faithful translation. An increased level of translational errors (mistranslation) has therefore been widely considered harmful to cells. Here we demonstrate that surprisingly, moderate levels of mistranslation indeed increase tolerance to oxidative stress in Escherichia coli. Our RNA sequencing analyses revealed that two antioxidant genes katE and osmC, both controlled by the general stress response activator RpoS, were upregulated by a ribosomal error-prone mutation. Mistranslation-induced tolerance to hydrogen peroxide required rpoS, katE and osmC. We further show that both translational and post-translational regulation of RpoS contribute to peroxide tolerance in the error-prone strain, and a small RNA DsrA, which controls translation of RpoS, is critical for the improved tolerance to oxidative stress through mistranslation. Our work thus challenges the prevailing view that mistranslation is always detrimental, and provides a mechanism by which mistranslation benefits bacteria under stress conditions.
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Affiliation(s)
- Yongqiang Fan
- Department of Microbiology and Molecular Genetics, Medical School, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Jiang Wu
- Department of Microbiology and Molecular Genetics, Medical School, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Matthew H Ung
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Nicholas De Lay
- Department of Microbiology and Molecular Genetics, Medical School, University of Texas Health Science Center, Houston, TX 77030, USA Graduate School of Biomedical Sciences, Houston, TX 77030, USA
| | - Chao Cheng
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Jiqiang Ling
- Department of Microbiology and Molecular Genetics, Medical School, University of Texas Health Science Center, Houston, TX 77030, USA Graduate School of Biomedical Sciences, Houston, TX 77030, USA
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18
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Sohm B, Immel F, Bauda P, Pagnout C. Insight into the primary mode of action of TiO2 nanoparticles on Escherichia coli in the dark. Proteomics 2014; 15:98-113. [PMID: 25346333 DOI: 10.1002/pmic.201400101] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 09/22/2014] [Accepted: 10/20/2014] [Indexed: 11/09/2022]
Abstract
Large-scale production and incorporation of titanium dioxide nanoparticles (NP-TiO2 ) in consumer products leads to their potential release into the environment and raises the question of their toxicity. The bactericidal mechanism of NP-TiO2 under UV light is known to involve oxidative stress due to the generation of reactive oxygen species. In the dark, several studies revealed that NP-TiO2 can exert toxicological effects. However, the mode of action of these nanoparticles is still controversial. In the present study, we used a combination of fluorescent probes to show that NP-TiO2 causes Escherichia coli membrane depolarization and loss of integrity, leading to higher cell permeability. Using both transcriptomic and proteomic global approaches we showed that this phenomenon translates into a cellular response to osmotic stress, metabolism of cell envelope components and uptake/metabolism of endogenous and exogenous compounds. This primary mechanism of bacterial NP-TiO2 toxicity is supported by the observed massive cell leakage of K(+) /Mg(2+) concomitant with the entrance of extracellular Na(+), and by the depletion of intracellular ATP level.
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Affiliation(s)
- Bénédicte Sohm
- Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC), UMR 7360, Université de Lorraine, Metz, France; CNRS, LIEC, UMR 7360, Metz, France
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19
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Functional characterization of osmotically inducible protein C (MG_427) from Mycoplasma genitalium. J Bacteriol 2013; 196:1012-9. [PMID: 24363346 DOI: 10.1128/jb.00954-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Mycoplasma genitalium is the smallest self-replicating bacterium and an important human pathogen responsible for a range of urogenital infections and pathologies. Due to its limited genome size, many genes conserved in other bacteria are missing in M. genitalium. Genes encoding catalase and superoxide dismutase are absent, and how this pathogen overcomes oxidative stress remains poorly understood. In this study, we characterized MG_427, a homolog of the conserved osmC, which encodes hydroperoxide peroxidase, shown to protect bacteria against oxidative stress. We found that recombinant MG_427 protein reduced organic and inorganic peroxide substrates. Also, we showed that a deletion mutant of MG_427 was highly sensitive to killing by tert-butyl hydroperoxide and H2O2 compared to the sensitivity of the wild type. Further, the fully complemented mutant strain reversed its oxidative sensitivity. Examination of the expression pattern of MG_427 during osmotic shock, oxidative stress, and other stress conditions revealed its lack of induction, distinguishing MG_427 from other previously characterized osmC genes.
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20
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Rosenkrantz JT, Aarts H, Abee T, Rolfe MD, Knudsen GM, Nielsen MB, Thomsen LE, Zwietering MH, Olsen JE, Pin C. Non-essential genes form the hubs of genome scale protein function and environmental gene expression networks in Salmonella enterica serovar Typhimurium. BMC Microbiol 2013; 13:294. [PMID: 24345035 PMCID: PMC3878590 DOI: 10.1186/1471-2180-13-294] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 12/10/2013] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Salmonella Typhimurium is an important pathogen of human and animals. It shows a broad growth range and survives in harsh conditions. The aim of this study was to analyze transcriptional responses to a number of growth and stress conditions as well as the relationship of metabolic pathways and/or cell functions at the genome-scale-level by network analysis, and further to explore whether highly connected genes (hubs) in these networks were essential for growth, stress adaptation and virulence. RESULTS De novo generated as well as published transcriptional data for 425 selected genes under a number of growth and stress conditions were used to construct a bipartite network connecting culture conditions and significantly regulated genes (transcriptional network). Also, a genome scale network was constructed for strain LT2. The latter connected genes with metabolic pathways and cellular functions. Both networks were shown to belong to the family of scale-free networks characterized by the presence of highly connected nodes or hubs which are genes whose transcription is regulated when responding to many of the assayed culture conditions or genes encoding products involved in a high number of metabolic pathways and cell functions.The five genes with most connections in the transcriptional network (wraB, ygaU, uspA, cbpA and osmC) and in the genome scale network (ychN, siiF (STM4262), yajD, ybeB and dcoC) were selected for mutations, however mutagenesis of ygaU and ybeB proved unsuccessful. No difference between mutants and the wild type strain was observed during growth at unfavorable temperatures, pH values, NaCl concentrations and in the presence of H2O2. Eight mutants were evaluated for virulence in C57/BL6 mice and none differed from the wild type strain. Notably, however, deviations of phenotypes with respect to the wild type were observed when combinations of these genes were deleted. CONCLUSION Network analysis revealed the presence of hubs in both transcriptional and functional networks of S. Typhimurium. Hubs theoretically confer higher resistance to random mutation but a greater susceptibility to directed attacks, however, we found that genes that formed hubs were dispensable for growth, stress adaptation and virulence, suggesting that evolution favors non-essential genes as main connectors in cellular networks.
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Affiliation(s)
- Jesper T Rosenkrantz
- Department of Veterinary Disease Biology, University of Copenhagen, Stigbøjlen 4, 1870 Frederiksberg, C, Denmark
| | - Henk Aarts
- Centre for Infectious disease control, National Institute for Public Health, PO box 1, 3720 BA Bilthoven, The Netherlands
| | - Tjakko Abee
- Wageningen University and Research Centre, Laboratory of Food Microbiology, P.O. Box 17, 6700 AA Wageningen, Netherlands
| | - Matthew D Rolfe
- Institute of Food Research, Norwich Research Park, Norwich NR4 7UA, UK
| | - Gitte M Knudsen
- Institute of Food Research, Norwich Research Park, Norwich NR4 7UA, UK
- National Food Institute, Danish Technical University, Soelvtofts Plads, 2800 Kgs. Lyngby, Denmark
| | - Maj-Britt Nielsen
- Department of Veterinary Disease Biology, University of Copenhagen, Stigbøjlen 4, 1870 Frederiksberg, C, Denmark
- Present address: DANSTEM Laboratory, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, N, Denmark
| | - Line E Thomsen
- Department of Veterinary Disease Biology, University of Copenhagen, Stigbøjlen 4, 1870 Frederiksberg, C, Denmark
| | - Marcel H Zwietering
- Wageningen University and Research Centre, Laboratory of Food Microbiology, P.O. Box 17, 6700 AA Wageningen, Netherlands
| | - John E Olsen
- Department of Veterinary Disease Biology, University of Copenhagen, Stigbøjlen 4, 1870 Frederiksberg, C, Denmark
| | - Carmen Pin
- Institute of Food Research, Norwich Research Park, Norwich NR4 7UA, UK
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Yue J, Sun G, Hu X, Huang J. The scale and evolutionary significance of horizontal gene transfer in the choanoflagellate Monosiga brevicollis. BMC Genomics 2013; 14:729. [PMID: 24156600 PMCID: PMC4046809 DOI: 10.1186/1471-2164-14-729] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 10/17/2013] [Indexed: 12/29/2022] Open
Abstract
Background It is generally agreed that horizontal gene transfer (HGT) is common in phagotrophic protists. However, the overall scale of HGT and the cumulative impact of acquired genes on the evolution of these organisms remain largely unknown. Results Choanoflagellates are phagotrophs and the closest living relatives of animals. In this study, we performed phylogenomic analyses to investigate the scale of HGT and the evolutionary importance of horizontally acquired genes in the choanoflagellate Monosiga brevicollis. Our analyses identified 405 genes that are likely derived from algae and prokaryotes, accounting for approximately 4.4% of the Monosiga nuclear genome. Many of the horizontally acquired genes identified in Monosiga were probably acquired from food sources, rather than by endosymbiotic gene transfer (EGT) from obsolete endosymbionts or plastids. Of 193 genes identified in our analyses with functional information, 84 (43.5%) are involved in carbohydrate or amino acid metabolism, and 45 (23.3%) are transporters and/or involved in response to oxidative, osmotic, antibiotic, or heavy metal stresses. Some identified genes may also participate in biosynthesis of important metabolites such as vitamins C and K12, porphyrins and phospholipids. Conclusions Our results suggest that HGT is frequent in Monosiga brevicollis and might have contributed substantially to its adaptation and evolution. This finding also highlights the importance of HGT in the genome and organismal evolution of phagotrophic eukaryotes. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-14-729) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | - Jinling Huang
- Department of Biology, East Carolina University, Greenville, NC 27858, USA.
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22
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Abstract
Bacteria, which are often considered as avid reproductive organisms under constant selective pressure to utilize available nutrients to proliferate, might seem an inappropriate model to study aging. However, environmental conditions are rarely supporting the exponential growth that is most often studied in laboratories. In the wild, Escherichia coli inhabits environments of relative nutritional paucity. Not surprisingly, under such circumstances, members of an E. coli population age and progressively lose the ability to reproduce, even when environmental conditions provide such an opportunity. Here, we review the methods to study chronological aging in bacteria and some of the mechanisms that may contribute to their age-dependent loss of viability.
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Abstract
ibeA is a virulence factor found in some extraintestinal pathogenic Escherichia coli (ExPEC) strains from the B2 phylogenetic group and particularly in newborn meningitic and avian pathogenic strains. It was shown to be involved in the invasion process of the newborn meningitic strain RS218. In a previous work, we showed that in the avian pathogenic E. coli (APEC) strain BEN2908, isolated from a colibacillosis case, ibeA was rather involved in adhesion to eukaryotic cells by modulating type 1 fimbria synthesis (M. A. Cortes et al., Infect. Immun. 76:4129-4136, 2008). In this study, we demonstrate a new role for ibeA in oxidative stress resistance. We showed that an ibeA mutant of E. coli BEN2908 was more sensitive than its wild-type counterpart to H(2)O(2) killing. This phenotype was also observed in a mutant deleted for the whole GimA genomic region carrying ibeA and might be linked to alterations in the expression of a subset of genes involved in the oxidative stress response. We also showed that RpoS expression was not altered by the ibeA deletion. Moreover, the transfer of an ibeA-expressing plasmid into an E. coli K-12 strain, expressing or not expressing type 1 fimbriae, rendered it more resistant to an H(2)O(2) challenge. Altogether, these results show that ibeA by itself is able to confer increased H(2)O(2) resistance to E. coli. This feature could partly explain the role played by ibeA in the virulence of pathogenic strains.
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24
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Abstract
In their stressful natural environments, bacteria often are in stationary phase and use their limited resources for maintenance and stress survival. Underlying this activity is the general stress response, which in Escherichia coli depends on the σS (RpoS) subunit of RNA polymerase. σS is closely related to the vegetative sigma factor σ70 (RpoD), and these two sigmas recognize similar but not identical promoter sequences. During the postexponential phase and entry into stationary phase, σS is induced by a fine-tuned combination of transcriptional, translational, and proteolytic control. In addition, regulatory "short-cuts" to high cellular σS levels, which mainly rely on the rapid inhibition of σS proteolysis, are triggered by sudden starvation for various nutrients and other stressful shift conditons. σS directly or indirectly activates more than 500 genes. Additional signal input is integrated by σS cooperating with various transcription factors in complex cascades and feedforward loops. Target gene products have stress-protective functions, redirect metabolism, affect cell envelope and cell shape, are involved in biofilm formation or pathogenesis, or can increased stationary phase and stress-induced mutagenesis. This review summarizes these diverse functions and the amazingly complex regulation of σS. At the molecular level, these processes are integrated with the partitioning of global transcription space by sigma factor competition for RNA polymerase core enzyme and signaling by nucleotide second messengers that include cAMP, (p)ppGpp, and c-di-GMP. Physiologically, σS is the key player in choosing between a lifestyle associated with postexponential growth based on nutrient scavenging and motility and a lifestyle focused on maintenance, strong stress resistance, and increased adhesiveness. Finally, research with other proteobacteria is beginning to reveal how evolution has further adapted function and regulation of σS to specific environmental niches.
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25
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Lau SK, Fan RY, Ho TC, Wong GK, Tsang AK, Teng JL, Chen W, Watt RM, Curreem SO, Tse H, Yuen KY, Woo PC. Environmental adaptability and stress tolerance of Laribacter hongkongensis: a genome-wide analysis. Cell Biosci 2011; 1:22. [PMID: 21711489 PMCID: PMC3135505 DOI: 10.1186/2045-3701-1-22] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Accepted: 06/14/2011] [Indexed: 12/31/2022] Open
Abstract
Background Laribacter hongkongensis is associated with community-acquired gastroenteritis and traveler's diarrhea and it can reside in human, fish, frogs and water. In this study, we performed an in-depth annotation of the genes in its genome related to adaptation to the various environmental niches. Results L. hongkongensis possessed genes for DNA repair and recombination, basal transcription, alternative σ-factors and 109 putative transcription factors, allowing DNA repair and global changes in gene expression in response to different environmental stresses. For acid stress, it possessed a urease gene cassette and two arc gene clusters. For alkaline stress, it possessed six CDSs for transporters of the monovalent cation/proton antiporter-2 and NhaC Na+:H+ antiporter families. For heavy metals acquisition and tolerance, it possessed CDSs for iron and nickel transport and efflux pumps for other metals. For temperature stress, it possessed genes related to chaperones and chaperonins, heat shock proteins and cold shock proteins. For osmotic stress, 25 CDSs were observed, mostly related to regulators for potassium ion, proline and glutamate transport. For oxidative and UV light stress, genes for oxidant-resistant dehydratase, superoxide scavenging, hydrogen peroxide scavenging, exclusion and export of redox-cycling antibiotics, redox balancing, DNA repair, reduction of disulfide bonds, limitation of iron availability and reduction of iron-sulfur clusters are present. For starvation, it possessed phosphorus and, despite being asaccharolytic, carbon starvation-related CDSs. Conclusions The L. hongkongensis genome possessed a high variety of genes for adaptation to acid, alkaline, temperature, osmotic, oxidative, UV light and starvation stresses and acquisition of and tolerance to heavy metals.
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Affiliation(s)
- Susanna Kp Lau
- State Key Laboratory of Emerging Infectious Diseases, Hong Kong.,Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong.,Carol Yu Centre of Infection, The University of Hong Kong, Hong Kong.,Department of Microbiology, The University of Hong Kong, Hong Kong
| | - Rachel Yy Fan
- Department of Microbiology, The University of Hong Kong, Hong Kong
| | - Tom Cc Ho
- Department of Microbiology, The University of Hong Kong, Hong Kong
| | - Gilman Km Wong
- Department of Microbiology, The University of Hong Kong, Hong Kong
| | - Alan Kl Tsang
- Department of Microbiology, The University of Hong Kong, Hong Kong
| | - Jade Ll Teng
- Department of Microbiology, The University of Hong Kong, Hong Kong
| | - Wenyang Chen
- Faculty of Dentistry, The University of Hong Kong, Hong Kong
| | - Rory M Watt
- Faculty of Dentistry, The University of Hong Kong, Hong Kong
| | | | - Herman Tse
- State Key Laboratory of Emerging Infectious Diseases, Hong Kong.,Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong.,Carol Yu Centre of Infection, The University of Hong Kong, Hong Kong.,Department of Microbiology, The University of Hong Kong, Hong Kong
| | - Kwok-Yung Yuen
- State Key Laboratory of Emerging Infectious Diseases, Hong Kong.,Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong.,Carol Yu Centre of Infection, The University of Hong Kong, Hong Kong.,Department of Microbiology, The University of Hong Kong, Hong Kong
| | - Patrick Cy Woo
- State Key Laboratory of Emerging Infectious Diseases, Hong Kong.,Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong.,Carol Yu Centre of Infection, The University of Hong Kong, Hong Kong.,Department of Microbiology, The University of Hong Kong, Hong Kong
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26
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Barkovits K, Schubert B, Heine S, Scheer M, Frankenberg-Dinkel N. Function of the bacteriophytochrome BphP in the RpoS/Las quorum-sensing network of Pseudomonas aeruginosa. Microbiology (Reading) 2011; 157:1651-1664. [DOI: 10.1099/mic.0.049007-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The bacterial phytochrome of Pseudomonas aeruginosa (PaBphP) is an in vitro-active red/far-red light sensor histidine kinase of a two-component regulatory system. Despite solid biochemical data, its function in this heterotrophic, opportunistic pathogen is still unknown. Previous studies established that the genes encoding the two necessary phytochrome components BphO, a chromophore-producing haem oxygenase, and BphP, the apo-phytochrome, are co-transcribed in a bicistronic operon. Transcription has been shown to be induced in the stationary phase and to be dependent on the alternative sigma factor RpoS. Here we show an additional regulation of bphP expression through the quorum-sensing (QS) regulator LasR. This regulation is also reflected in a combination of expression profile experiments and proteome analyses of wild-type and phytochrome-deficient strains. While PaBphP has a pleiotropic effect on global gene expression, 66 % of the downregulated genes in the phytochrome mutant display a link to the Las QS system. Most of these genes seem to be indirectly regulated by LasR through BphP and the unknown response regulator BphR. A model of phytochrome function within the Las QS network is presented.
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Affiliation(s)
- Katalin Barkovits
- Physiology of Microorganisms, Ruhr-University Bochum, Universitaetsstr. 150, 44780 Bochum, Germany
| | - Britta Schubert
- Physiology of Microorganisms, Ruhr-University Bochum, Universitaetsstr. 150, 44780 Bochum, Germany
| | - Sabrina Heine
- Physiology of Microorganisms, Ruhr-University Bochum, Universitaetsstr. 150, 44780 Bochum, Germany
| | - Maurice Scheer
- Institute for Microbiology, Technical University Braunschweig, 38106 Braunschweig, Germany
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27
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Gonidakis S, Finkel SE, Longo VD. Genome-wide screen identifies Escherichia coli TCA-cycle-related mutants with extended chronological lifespan dependent on acetate metabolism and the hypoxia-inducible transcription factor ArcA. Aging Cell 2010; 9:868-81. [PMID: 20707865 DOI: 10.1111/j.1474-9726.2010.00618.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Single-gene mutants with extended lifespan have been described in several model organisms. We performed a genome-wide screen for long-lived mutants in Escherichia coli, which revealed strains lacking tricarboxylic acid (TCA)-cycle-related genes that exhibit longer stationary-phase survival and increased resistance to heat stress compared to wild-type. Extended lifespan in the sdhA mutant, lacking subunit A of succinate dehydrogenase, is associated with the reduced production of superoxide and increased stress resistance. On the other hand, the longer lifespan of the lipoic acid synthase mutant (lipA) is associated with reduced oxygen consumption and requires the acetate-producing enzyme pyruvate oxidase, as well as acetyl-CoA synthetase, the enzyme that converts extracellular acetate to acetyl-CoA. The hypoxia-inducible transcription factor ArcA, acting independently of acetate metabolism, is also required for maximum lifespan extension in the lipA and lpdA mutants, indicating that these mutations promote entry into a mode normally associated with a low-oxygen environment. Because analogous changes from respiration to fermentation have been observed in long-lived Saccharomyces cerevisiae and Caenorhabditis elegans strains, such metabolic alterations may represent an evolutionarily conserved strategy to extend lifespan.
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Affiliation(s)
- Stavros Gonidakis
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
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28
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Gourion B, Sulser S, Frunzke J, Francez-Charlot A, Stiefel P, Pessi G, Vorholt JA, Fischer HM. The PhyR-sigma(EcfG) signalling cascade is involved in stress response and symbiotic efficiency in Bradyrhizobium japonicum. Mol Microbiol 2009; 73:291-305. [PMID: 19555458 DOI: 10.1111/j.1365-2958.2009.06769.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PhyR is an unusual type of response regulator consisting of a receiver domain and an extracytoplasmic function (ECF) sigma factor-like domain. It was recently described as a master regulator of general stress response in Methylobacterium extorquens. Orthologues of this regulator are present in essentially all free-living Alphaproteobacteria. In most of them, phyR is genetically closely linked to a gene encoding an ECF sigma factor. Here, we investigate the role of these two regulators in the soybean symbiont Bradyrhizobium japonicum USDA110. Using deletion mutants and phenotypic assays, we showed that PhyR and the ECF sigma factor sigma(EcfG) are involved in heat shock and desiccation resistance upon carbon starvation. Both mutants had symbiotic defects on the plant hosts Glycine max (soybean) and Vigna radiata (mungbean). They induced fewer nodules than the wild type and these nodules were smaller, less pigmented, and their specific nitrogenase activity was drastically reduced 2 or 3 weeks after inoculation. Four weeks after infection, soybean nodule development caught up to a large extent whereas most mungbean nodules remained defective even 5 weeks after infection. Remarkably, both mutants triggered aberrant nodules on the different host plants with ectopically emerging roots. Microarray analysis revealed that PhyR and sigma(EcfG) control congruent regulons suggesting both regulators are part of the same signalling cascade. This finding was further substantiated by in vitro protein-protein interaction studies which are in line with a partner-switching mechanism controlling gene regulation triggered by phosphorylation of PhyR. The large number of genes of unknown function present in the PhyR/sigma(EcfG) regulon and the conspicuous symbiotic phenotype suggest that these regulators are involved in the Bradyrhizobium-legume interaction via yet undisclosed mechanisms.
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29
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Barth E, Gora KV, Gebendorfer KM, Settele F, Jakob U, Winter J. Interplay of cellular cAMP levels, {sigma}S activity and oxidative stress resistance in Escherichia coli. MICROBIOLOGY-SGM 2009; 155:1680-1689. [PMID: 19372151 DOI: 10.1099/mic.0.026021-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Hypochlorous acid (HOCl), the active ingredient of household bleach, functions as a powerful antimicrobial that is used not only in numerous industrial applications but also in mammalian host defence. Here we show that multicopy expression of cpdA, encoding the cAMP phosphodiesterase, leads to a dramatically increased resistance of Escherichia coli to HOCl stress as well as to the unrelated hydrogen peroxide (H(2)O(2)) stress. This general oxidative stress resistance is apparently caused by the CpdA-mediated decrease in cellular cAMP levels, which leads to the partial inactivation of the global transcriptional regulator cAMP receptor protein (CRP). Downregulation of CRP in turn causes the derepression of rpoS, encoding the alternative sigma factor sigma(S), which activates the general stress response in E. coli. We found that these highly oxidative stress-resistant cells have a substantially increased capacity to combat HOCl-mediated insults and to degrade reactive oxygen species. Mutational analysis revealed that the DNA-protecting protein Dps, the catalase KatE, and the exonuclease III XthA play the predominant roles in conferring the high resistance of rpoS-overexpressing strains towards HOCl and H(2)O(2) stress. Our results demonstrate the close regulatory interplay between cellular cAMP levels, sigma(S) activity and oxidative stress resistance in E. coli.
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Affiliation(s)
- Evelyn Barth
- Department Chemie, Biotechnologie, Technische Universität München, Lichtenbergstraße 4, 85747 Garching, Germany
| | - Katherine V Gora
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
| | - Katharina M Gebendorfer
- Center for Integrated Protein Science Munich (CiPSM), 81377 Munich, Germany.,Department Chemie, Biotechnologie, Technische Universität München, Lichtenbergstraße 4, 85747 Garching, Germany
| | - Florian Settele
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
| | - Ursula Jakob
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
| | - Jeannette Winter
- Center for Integrated Protein Science Munich (CiPSM), 81377 Munich, Germany.,Department Chemie, Biotechnologie, Technische Universität München, Lichtenbergstraße 4, 85747 Garching, Germany
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30
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Drevinek P, Holden MTG, Ge Z, Jones AM, Ketchell I, Gill RT, Mahenthiralingam E. Gene expression changes linked to antimicrobial resistance, oxidative stress, iron depletion and retained motility are observed when Burkholderia cenocepacia grows in cystic fibrosis sputum. BMC Infect Dis 2008; 8:121. [PMID: 18801206 PMCID: PMC2559838 DOI: 10.1186/1471-2334-8-121] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Accepted: 09/19/2008] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Bacteria from the Burkholderia cepacia complex (Bcc) are the only group of cystic fibrosis (CF) respiratory pathogens that may cause death by an invasive infection known as cepacia syndrome. Their large genome (> 7000 genes) and multiple pathways encoding the same putative functions make virulence factor identification difficult in these bacteria. METHODS A novel microarray was designed to the genome of Burkholderia cenocepacia J2315 and transcriptomics used to identify genes that were differentially regulated when the pathogen was grown in a CF sputum-based infection model. Sputum samples from CF individuals infected with the same B. cenocepacia strain as genome isolate were used, hence, other than a dilution into a minimal growth medium (used as the control condition), no further treatment of the sputum was carried out. RESULTS A total of 723 coding sequences were significantly altered, with 287 upregulated and 436 downregulated; the microarray-observed expression was validated by quantitative PCR on five selected genes. B. cenocepacia genes with putative functions in antimicrobial resistance, iron uptake, protection against reactive oxygen and nitrogen species, secretion and motility were among the most altered in sputum. Novel upregulated genes included: a transmembrane ferric reductase (BCAL0270) implicated in iron metabolism, a novel protease (BCAL0849) that may play a role in host tissue destruction, an organic hydroperoxide resistance gene (BCAM2753), an oxidoreductase (BCAL1107) and a nitrite/sulfite reductase (BCAM1676) that may play roles in resistance to the host defenses. The assumptions of growth under iron-depletion and oxidative stress formulated from the microarray data were tested and confirmed by independent growth of B. cenocepacia under each respective environmental condition. CONCLUSION Overall, our first full transcriptomic analysis of B. cenocepacia demonstrated the pathogen alters expression of over 10% of the 7176 genes within its genome when it grows in CF sputum. Novel genetic pathways involved in responses to antimicrobial resistance, oxidative stress, and iron metabolism were revealed by the microarray analysis. Virulence factors such as the cable pilus and Cenocepacia Pathogenicity Island were unaltered in expression. However, B. cenocepacia sustained or increased expression of motility-associated genes in sputum, maintaining a potentially invasive phenotype associated with cepacia syndrome.
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Affiliation(s)
- Pavel Drevinek
- Cardiff School of Biosciences, Cardiff University, Cardiff, UK
| | | | - Zhaoping Ge
- Center for Bioinformatics, University of North Carolina, Chapel Hill, NC, USA
| | - Andrew M Jones
- Bradbury Cystic Fibrosis Unit, Wythenshawe Hospital, Manchester, UK
| | - Ian Ketchell
- Cardiff Adult Cystic Fibrosis Centre, Llandough Hospital, Penarth, UK
| | - Ryan T Gill
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO, USA
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31
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Abstract
Peroxiredoxins constitute an important component of the bacterial defense against toxic peroxides. These enzymes use reactive cysteine thiols to reduce peroxides with electrons ultimately derived from reduced pyridine dinucleotides. Studies examining the regulation and physiological roles of AhpC, Tpx, Ohr and OsmC reveal the multilayered nature of bacterial peroxide defense. AhpC is localized in the cytoplasm and has a wide substrate range that includes H2O2, organic peroxides and peroxynitrite. This enzyme functions in both the control of endogenous peroxides, as well as in the inducible defense response to exogenous peroxides or general stresses. Ohr, OsmC and Tpx are organic peroxide specific. Tpx is localized to the periplasm and can be involved in either constitutive peroxide defense or participate in oxidative stress inducible responses depending on the organism. Ohr is an organic peroxide specific defense system that is under the control of the organic peroxide sensing repressor OhrR. In some organisms Ohr homologs are regulated in response to general stress. Clear evidence indicates that AhpC, Tpx and Ohr are involved in virulence. The role of OsmC is less clear. Regulation of OsmC expression is not oxidative stress inducible, but is controlled by multiple general stress responsive regulators.
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Affiliation(s)
- James M Dubbs
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
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32
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PhyR is involved in the general stress response of Methylobacterium extorquens AM1. J Bacteriol 2007; 190:1027-35. [PMID: 18024517 DOI: 10.1128/jb.01483-07] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PhyR represents a novel alphaproteobacterial family of response regulators having a structure consisting of two domains; a predicted amino-terminal extracytoplasmic function (ECF) sigma factor-like domain and a carboxy-terminal receiver domain. PhyR was first described in Methylobacterium extorquens AM1, in which it has been shown to be essential for plant colonization, probably due to its suggested involvement in the regulation of a number of stress proteins. Here we investigated the PhyR regulon using microarray technology. We found that the PhyR regulon is rather large and that most of the 246 targets are under positive control. Mapping of transcriptional start sites revealed candidate promoters for PhyR-mediated regulation. One of these promoters, an ECF-type promoter, was identified upstream of one-third of the target genes by in silico analysis. Among the PhyR targets are genes predicted to be involved in multiple stress responses, including katE, osmC, htrA, dnaK, gloA, dps, and uvrA. The induction of these genes is consistent with our phenotypic analyses which revealed that PhyR is involved in resistance to heat shock and desiccation, as well as oxidative, UV, ethanol, and osmotic stresses, in M. extorquens AM1. The finding that PhyR is involved in the general stress response was further substantiated by the finding that carbon starvation induces protection against heat shock and that this protection is at least in part dependent on PhyR.
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33
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Bogel G, Schrempf H, Ortiz de Orué Lucana D. DNA-binding characteristics of the regulator SenR in response to phosphorylation by the sensor histidine autokinase SenS from Streptomyces reticuli. FEBS J 2007; 274:3900-13. [PMID: 17617222 DOI: 10.1111/j.1742-4658.2007.05923.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The two-component system SenS-SenR from Streptomyces reticuli has been shown to influence the production of the redox regulator FurS, the mycelium-associated enzyme CpeB, which displays heme-dependent catalase and peroxidase activity as well as heme-independent manganese peroxidase activity, and the extracellular heme-binding protein HbpS. In addition, it was suggested to participate in the sensing of redox changes. In this work, the tagged cytoplasmic domain of SenS (SenS(c)), as well as the full-length differently tagged SenR, and corresponding mutant proteins carrying specific amino acid exchanges were purified after heterologous expression in Escherichia coli. In vitro, SenS(c) is autophosphorylated to SenS(c) approximately P at the histidine residue at position 199, transfers the phosphate group to the aspartic acid residue at position 65 in SenR, and acts as a phosphatase for SenR approximately P. Bandshift and footprinting assays in combination with competition and mutational analyses revealed that only unphosphorylated SenR binds to specific sites upstream of the furS-cpeB operon. Further specific sites within the regulatory region, common to the oppositely orientated senS and hbpS genes, were recognized by SenR. Upon its phosphorylation, the DNA-binding affinity of this area was enhanced. These data, together with previous in vivo studies using mutants lacking functional senS and senR, indicate that the two-component SenS-SenR system governs the transcription of the furS-cpeB operon, senS-senR and the hbpS gene. Comparative analyses reveal that only the genomes of a few actinobacteria encode two-component systems that are closely related to SenS-SenR.
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Affiliation(s)
- Gabriele Bogel
- FB Biologie/Chemie, Universität Osnabrück, Osnabrück, Germany
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34
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Ravirala RS, Barabote RD, Wheeler DM, Reverchon S, Tatum O, Malouf J, Liu H, Pritchard L, Hedley PE, Birch PRJ, Toth IK, Payton P, San Francisco MJD. Efflux pump gene expression in Erwinia chrysanthemi is induced by exposure to phenolic acids. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2007; 20:313-20. [PMID: 17378434 DOI: 10.1094/mpmi-20-3-0313] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Salicylic acid (SA) is an important signaling molecule in local and systemic plant resistance. Following infection by microbial pathogens and the initial oxidative burst in plants, SA accumulation functions in the amplification of defense gene expression. Production of pathogenesis-related proteins and toxic antimicrobial chemicals serves to protect the plant from infection. Successful microbial pathogens utilize a variety of mechanisms to rid themselves of toxic antimicrobial compounds. Important among these mechanisms are multidrug-resistance pumps that bring about the active efflux of toxic compounds from microbial cells. Here, we show that a combination SA and its precursors, t-cinnamic acid and benzoic acid, can activate expression of specific multidrug efflux pump-encoding genes in the plant pathogen Erwinia chrysanthemi and enhance survival of the bacterium in the presence of model as well as plant-derived antimicrobial chemicals. This ability of plant-pathogenic bacteria to co-opt plant defense-signaling molecules to activate multidrug efflux pumps may have evolved to ensure bacterial survival in susceptible host plants.
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Affiliation(s)
- Ramani S Ravirala
- Department of Biological Sciences, Center for Biotechnology and Genomics, Texas Tech University, Lubbock 79409, UA
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35
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Lesniak J, Barton WA, Nikolov DB. Structural and functional features of the Escherichia coli hydroperoxide resistance protein OsmC. Protein Sci 2004; 12:2838-43. [PMID: 14627744 PMCID: PMC2366992 DOI: 10.1110/ps.03375603] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The osmotically inducible protein OsmC, like its better-characterized homolog, the organic hydroperoxide protein Ohr, is involved in defense against oxidative stress caused by exposure to organic hydroperoxides. The crystal structure of Escherichia coli OsmC reported here reveals that the protein is a tightly folded domain-swapped dimer with two active sites located at the monomer interface on opposite sides of the molecule. We demonstrate that OsmC preferentially metabolizes organic hydroperoxides over inorganic hydrogen peroxide. On the basis of structural and enzymatic similarities, we propose that the OsmC catalytic mechanism is analogous to that of the Ohr proteins and of the structurally unrelated peroxiredoxins, directly using highly reactive cysteine thiol groups to elicit hydroperoxide reduction.
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Affiliation(s)
- Jacob Lesniak
- Joan and Sanford I. Weill Graduate School of Medical Sciences of Cornell University, New York, New York 10021, USA
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36
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Rehse PH, Ohshima N, Nodake Y, Tahirov TH. Crystallographic structure and biochemical analysis of the Thermus thermophilus osmotically inducible protein C. J Mol Biol 2004; 338:959-68. [PMID: 15111059 DOI: 10.1016/j.jmb.2004.03.050] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2003] [Revised: 03/16/2004] [Accepted: 03/18/2004] [Indexed: 11/19/2022]
Abstract
The X-ray crystallographic structure of osmotically inducible Protein C from the thermophilic bacterium, Thermus thermophilus HB8, was solved to 1.6A using the multiple wavelength anomalous dispersion method and a selenomethionine incorporated protein (Se-MAD). The crystal space group was P1 with cell dimensions of a=37.58 A, b=40.95 A, c=48.14 A, alpha=76.9 degrees, beta=74.0 degrees and gamma=64.1 degrees. The two tightly interacting monomers in the asymmetric unit are related by a non-crystallographic 2-fold. The dimer structure is defined primarily by two very long anti-parallel, over-lapping alpha-helices at the core, with a further six-stranded anti-parallel beta-sheet on the outside of the structure. With respect to the beta-sheets, both A and B monomers contribute three strands each resulting in an intertwining of the structure. The active site consists of two cysteine residues from one monomer and an arginine and glutamic acid from the other. Enzymatic assays have revealed that T.thermophilus OsmC has a hydroperoxide peroxidase activity.
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Affiliation(s)
- Peter H Rehse
- Highthroughput Factory, RIKEN Harima Institute, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5148, Japan
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37
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Meunier-Jamin C, Kapp U, Leonard GA, McSweeney S. The structure of the organic hydroperoxide resistance protein from Deinococcus radiodurans. Do conformational changes facilitate recycling of the redox disulfide? J Biol Chem 2004; 279:25830-7. [PMID: 15054099 DOI: 10.1074/jbc.m312983200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The three-dimensional structure of the organic hydroperoxide resistance protein (OHRP) from Deinococcus radiodurans as determined using single crystal xray diffraction techniques is reported. Comparison of the structure with that obtained for OHRP from Pseudomonas aeruginosa reveals that the polypeptide chain of OHRPs can adopt two significantly different conformations ("in" and "out") in the region of the active site disulfide moiety. It is postulated that the closed configuration is consistent with efficient catalysis of the reduction of organic hydroperoxides, whereas the open form is required for enzyme recycling. Comparison of the structures of OHRP and that of the osmotically induced protein C (OsmC) from Mycoplasma pneumoniae shows that OHRPs and OsmCs are structurally homologous, perhaps indicating related functions for the two families of proteins.
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Affiliation(s)
- Cécile Meunier-Jamin
- Macromolecular Crystallography Group, European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble Cedex, France
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Conter A. Plasmid DNA supercoiling and survival in long-term cultures of Escherichia coli: role of NaCl. J Bacteriol 2003; 185:5324-7. [PMID: 12923111 PMCID: PMC180992 DOI: 10.1128/jb.185.17.5324-5327.2003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The relationship between the survival of Escherichia coli during long-term starvation in rich medium and the supercoiling of a reporter plasmid (pBR322) has been studied. In aerated continuously shaken cultures, E. coli lost the ability to form colonies earlier in rich NaCl-free Luria-Bertani medium than in NaCl-containing medium, and the negative supercoiling of plasmid pBR322 declined more rapidly in the absence of NaCl. Addition of NaCl at the 24th hour restored both viability and negative supercoiling in proportion to the concentration of added NaCl. Addition of ofloxacin, a quinolone inhibitor of gyrase, abolished rescue by added NaCl in proportion to the ofloxacin added. This observation raises the possibility that cells had the ability to recover plasmid supercoiling even if nutrients were not available and could survive during long-term starvation in a manner linked, at least in part, to the topological state of DNA and gyrase activity.
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Affiliation(s)
- Annie Conter
- Laboratoire de Microbiologie et Génétique Moléculaire, UMR 5100 du CNRS, 118 Route de Narbonne 31062, Toulouse cedex, France.
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Abstract
Pseudomonas aeruginosa is the dominant pathogen causing chronic respiratory infections in cystic fibrosis (CF). After an initial phase characterized by intermittent infections, a chronic colonization is established in CF upon the conversion of P. aeruginosa to the mucoid, exopolysaccharide alginate-overproducing phenotype. The emergence of mucoid P. aeruginosa in CF is associated with respiratory decline and poor prognosis. The switch to mucoidy in most CF isolates is caused by mutations in the mucA gene encoding an anti-sigma factor. The mutations in mucA result in the activation of the alternative sigma factor AlgU, the P. aeruginosa ortholog of Escherichia coli extreme stress sigma factor sigma(E). Because of the global nature of the regulators of mucoidy, we have hypothesized that other genes, in addition to those specific for alginate production, must be induced upon conversion to mucoidy, and their production may contribute to the pathogenesis in CF. Here we applied microarray analysis to identify on the whole-genome scale those genes that are coinduced with the AlgU sigmulon upon conversion to mucoidy. Gene expression profiles of AlgU-dependent conversion to mucoidy revealed coinduction of a specific subset of known virulence determinants (the major protease elastase gene, alkaline metalloproteinase gene aprA, and the protease secretion factor genes aprE and aprF) or toxic factors (cyanide synthase) that may have implications for disease in CF. Analysis of promoter regions of the most highly induced genes (>40-fold, P < or = 10(-4)) revealed a previously unrecognized, putative AlgU promoter upstream of the osmotically inducible gene osmE. This newly identified AlgU-dependent promoter of osmE was confirmed by mapping the mRNA 5' end by primer extension. The recognition of genes induced in mucoid P. aeruginosa, other than those associated with alginate biosynthesis, reported here revealed the identity of previously unappreciated factors potentially contributing to the morbidity and mortality caused by mucoid P. aeruginosa in CF.
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Affiliation(s)
- Aaron M Firoved
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109-0620, USA
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Lesniak J, Barton WA, Nikolov DB. Structural and functional characterization of the Pseudomonas hydroperoxide resistance protein Ohr. EMBO J 2002; 21:6649-59. [PMID: 12485986 PMCID: PMC139091 DOI: 10.1093/emboj/cdf670] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Bacteria have developed complex strategies to detoxify and repair damage caused by reactive oxygen species. These compounds, produced during bacterial aerobic respiration as well as by the host immune system cells as a defense mechanism against the pathogenic microorganisms, have the ability to damage nucleic acids, proteins and phospholipid membranes. Here we describe the crystal structure of Pseudomonas aeruginosa Ohr, a member of a recently discovered family of organic hydroperoxide resistance proteins. Ohr is a tightly folded homodimer, with a novel alpha/beta fold, and contains two active sites located at the monomer interface on opposite sides of the molecule. Using in vitro assays, we demonstrate that Ohr functions directly as a hydroperoxide reductase, converting both inorganic and organic hydroperoxides to less toxic metabolites. Site-directed mutagenesis confirms that the two conserved cysteines in each active site are essential for catalytic activity. We propose that the Ohr catalytic mechanism is similar to that of the structurally unrelated peroxiredoxins, directly utilizing highly reactive cysteine thiol groups to elicit hydroperoxide reduction.
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Affiliation(s)
- Jacob Lesniak
- Joan and Sanford I.Weill Graduate School of Medical Sciences of Cornell University and Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York City, NY 10021, USA Corresponding author e-mail:
| | - William A. Barton
- Joan and Sanford I.Weill Graduate School of Medical Sciences of Cornell University and Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York City, NY 10021, USA Corresponding author e-mail:
| | - Dimitar B. Nikolov
- Joan and Sanford I.Weill Graduate School of Medical Sciences of Cornell University and Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York City, NY 10021, USA Corresponding author e-mail:
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Weber A, Jung K. Profiling early osmostress-dependent gene expression in Escherichia coli using DNA macroarrays. J Bacteriol 2002; 184:5502-7. [PMID: 12218039 PMCID: PMC135335 DOI: 10.1128/jb.184.19.5502-5507.2002] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
DNA macroarray technology was used to monitor early transcriptional alterations of Escherichia coli in response to an osmotic upshift imposed by the addition of 0.4 M NaCl. Altered mRNA levels of 152 genes were detected; 45 genes showed increased expression while the expression of the remaining 107 genes was reduced. Northern blot analysis of several selected genes differing in their relative expression values confirmed the results obtained by the array technology.
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Affiliation(s)
- Arnim Weber
- Abteilung Mikrobiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, D-49069 Osnabrück, Germany
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42
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Toesca I, Perard C, Bouvier J, Gutierrez C, Conter A. The transcriptional activator NhaR is responsible for the osmotic induction of osmC(p1), a promoter of the stress-inducible gene osmC in Escherichia coli. MICROBIOLOGY (READING, ENGLAND) 2001; 147:2795-2803. [PMID: 11577158 DOI: 10.1099/00221287-147-10-2795] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Two overlapping promoters, osmC(p1) and osmC(p2), direct the transcription of the osmC gene of Escherichia coli. The proximal promoter, osmC(p2), is induced upon entry into stationary phase under the control of Esigma(s), the RNA polymerase that uses the sigma(s) (RpoS) sigma factor. Transcription from the distal promoter, osmC(p1), is independent of sigma(s). Previous analysis demonstrated that the osmolarity of the growth medium modulates expression of both promoters. The use of an E. coli genomic library showed that the cloned nhaR gene was able to stimulate transcription of an osmC-lac reporter fusion. NhaR is a positive regulator of the LysR family, previously identified as an activator of nhaA, a gene encoding a Na+/H+ antiporter involved in adaptation to Na+ and alkaline pH in E. coli and other enteric bacteria. NhaR was shown to activate only the expression of osmC(p1) and to be necessary for the induction of this promoter by LiCl, NaCl and sucrose. Therefore, activation by NhaR is responsible for the osmotic induction of osmC(p1). In contrast to its action on nhaA, NhaR activation of osmC(p1) is independent of H-NS. Activation of osmC(p1) by NhaR requires a site located just upstream of the atypical -35 region of the promoter.
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Affiliation(s)
- Isabelle Toesca
- Laboratoire de Microbiologie et Génétique Moléculaire, UMR 5100 CNRS - Université Toulouse III, 118 Route de Narbonne, F-31062, Toulouse Cedex, France1
| | - Catherine Perard
- Laboratoire de Microbiologie et Génétique Moléculaire, UMR 5100 CNRS - Université Toulouse III, 118 Route de Narbonne, F-31062, Toulouse Cedex, France1
| | - Jean Bouvier
- Laboratoire de Microbiologie et Génétique Moléculaire, UMR 5100 CNRS - Université Toulouse III, 118 Route de Narbonne, F-31062, Toulouse Cedex, France1
| | - Claude Gutierrez
- Laboratoire de Microbiologie et Génétique Moléculaire, UMR 5100 CNRS - Université Toulouse III, 118 Route de Narbonne, F-31062, Toulouse Cedex, France1
| | - Annie Conter
- Laboratoire de Microbiologie et Génétique Moléculaire, UMR 5100 CNRS - Université Toulouse III, 118 Route de Narbonne, F-31062, Toulouse Cedex, France1
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Atichartpongkul S, Loprasert S, Vattanaviboon P, Whangsuk W, Helmann JD, Mongkolsuk S. Bacterial Ohr and OsmC paralogues define two protein families with distinct functions and patterns of expression. MICROBIOLOGY (READING, ENGLAND) 2001; 147:1775-1782. [PMID: 11429455 DOI: 10.1099/00221287-147-7-1775] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Xanthomonas campestris Ohr (a protein involved in organic peroxide protection) and Escherichia coli OsmC (an osmotically inducible protein of unknown function) are related proteins. Database searches and phylogenetic analyses reveal that Ohr and OsmC homologues cluster into two related subfamilies of proteins widely distributed in both Gram-negative and Gram-positive bacteria. To determine if these two subfamilies are functionally distinct, ohr and osmC in Pseudomonas aeruginosa (a bacterium with one representative from each subfamily) were analysed. Only ohr mutants are hypersensitive to organic peroxide, and this phenotype can be restored by complementation with ohr but not osmC. In addition, expression of ohr was highly induced only by organic peroxides, and not by other oxidants or stresses. In contrast, osmC was induced by ethanol and osmotic stress. A similar pattern of regulation was observed for Ohr and OsmC homologues in the Gram-positive bacterium Deinococcus radiodurans, though uninduced expression was much higher and induction lower in this species. These data clearly support the conclusion that Ohr and OsmC define two functionally distinct subfamilies with distinct patterns of regulation.
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Affiliation(s)
- Sopapan Atichartpongkul
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand1
| | - Suvit Loprasert
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand1
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand1
| | - Wirongrong Whangsuk
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand1
| | - John D Helmann
- Department of Microbiology, Wing Hall, Cornell University, Ithaca, NY 14853-8101, USA3
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand2
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand1
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