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García-Martín J, García-Abad L, Santamaría RI, Díaz M. Functional connexion of bacterioferritin in antibiotic production and morphological differentiation in Streptomyces coelicolor. Microb Cell Fact 2024; 23:234. [PMID: 39182107 PMCID: PMC11344345 DOI: 10.1186/s12934-024-02510-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 08/15/2024] [Indexed: 08/27/2024] Open
Abstract
BACKGROUND Several two-component systems of Streptomyces coelicolor, a model organism used for studying antibiotic production in Streptomyces, affect the expression of the bfr (SCO2113) gene that encodes a bacterioferritin, a protein involved in iron storage. In this work, we have studied the effect of the deletion mutant ∆bfr in S. coelicolor. RESULTS The ∆bfr mutant exhibits a delay in morphological differentiation and produces a lesser amount of the two pigmented antibiotics (actinorhodin and undecylprodigiosin) compared to the wild type on complex media. The effect of iron in minimal medium was tested in the wild type and ∆bfr mutant. Consequently, we also observed different levels of production of the two pigmented antibiotics between the two strains, depending on the iron concentration and the medium (solid or liquid) used. Contrary to expectations, no differences in intracellular iron concentration were detected between the wild type and ∆bfr mutant. However, a higher level of reactive oxygen species in the ∆bfr mutant and a higher tolerance to oxidative stress were observed. Proteomic analysis showed no variation in iron response proteins, but there was a lower abundance of proteins related to actinorhodin and ribosomal proteins, as well as others related to secondary metabolite production and differentiation. Additionally, a higher abundance of proteins related to various types of stress, such as respiration and hypoxia among others, was also revealed. Data are available via ProteomeXchange with identifier PXD050869. CONCLUSION This bacterioferritin in S. coelicolor (Bfr) is a new element in the complex regulation of secondary metabolism in S. coelicolor and, additionally, iron acts as a signal to modulate the biosynthesis of active molecules. Our model proposes an interaction between Bfr and iron-containing regulatory proteins. Thus, identifying these interactions would provide new information for improving antibiotic production in Streptomyces.
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Affiliation(s)
- Javier García-Martín
- Departamento de Microbiología y Genética, Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca (USAL), C/ Zacarías González, nº 2, Salamanca, 37007, Spain
| | - Laura García-Abad
- Departamento de Microbiología y Genética, Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca (USAL), C/ Zacarías González, nº 2, Salamanca, 37007, Spain
| | - Ramón I Santamaría
- Departamento de Microbiología y Genética, Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca (USAL), C/ Zacarías González, nº 2, Salamanca, 37007, Spain.
| | - Margarita Díaz
- Departamento de Microbiología y Genética, Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca (USAL), C/ Zacarías González, nº 2, Salamanca, 37007, Spain.
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2
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Bazurto JV, Nayak DD, Ticak T, Davlieva M, Lee JA, Hellenbrand CN, Lambert LB, Benski OJ, Quates CJ, Johnson JL, Patel JS, Ytreberg FM, Shamoo Y, Marx CJ. EfgA is a conserved formaldehyde sensor that leads to bacterial growth arrest in response to elevated formaldehyde. PLoS Biol 2021; 19:e3001208. [PMID: 34038406 PMCID: PMC8153426 DOI: 10.1371/journal.pbio.3001208] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 03/25/2021] [Indexed: 01/07/2023] Open
Abstract
Normal cellular processes give rise to toxic metabolites that cells must mitigate. Formaldehyde is a universal stressor and potent metabolic toxin that is generated in organisms from bacteria to humans. Methylotrophic bacteria such as Methylorubrum extorquens face an acute challenge due to their production of formaldehyde as an obligate central intermediate of single-carbon metabolism. Mechanisms to sense and respond to formaldehyde were speculated to exist in methylotrophs for decades but had never been discovered. Here, we identify a member of the DUF336 domain family, named efgA for enhanced formaldehyde growth, that plays an important role in endogenous formaldehyde stress response in M. extorquens PA1 and is found almost exclusively in methylotrophic taxa. Our experimental analyses reveal that EfgA is a formaldehyde sensor that rapidly arrests growth in response to elevated levels of formaldehyde. Heterologous expression of EfgA in Escherichia coli increases formaldehyde resistance, indicating that its interaction partners are widespread and conserved. EfgA represents the first example of a formaldehyde stress response system that does not involve enzymatic detoxification. Thus, EfgA comprises a unique stress response mechanism in bacteria, whereby a single protein directly senses elevated levels of a toxic intracellular metabolite and safeguards cells from potential damage.
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Affiliation(s)
- Jannell V. Bazurto
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, Idaho, United States of America
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, Idaho, United States of America
- Department of Plant and Microbial Biology, University of Minnesota, Twin Cities, Minnesota, United States of America
- Microbial and Plant Genomics Institute, University of Minnesota, Twin Cities, Minnesota, United States of America
- Biotechnology Institute, University of Minnesota, Twin Cities, Minnesota, United States of America
- * E-mail: (JVB); (CJM)
| | - Dipti D. Nayak
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America
- Department of Microbiology, University of Illinois, Urbana, Illinois, United States of America
| | - Tomislav Ticak
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, Idaho, United States of America
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, Idaho, United States of America
| | - Milya Davlieva
- Department of Biosciences, Rice University, Houston, Texas, United States of America
| | - Jessica A. Lee
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, Idaho, United States of America
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, Idaho, United States of America
- Space Biosciences Research Branch, NASA Ames Research Center, Moffett Field, California, United States of America
| | - Chandler N. Hellenbrand
- Department of Plant and Microbial Biology, University of Minnesota, Twin Cities, Minnesota, United States of America
| | - Leah B. Lambert
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
| | - Olivia J. Benski
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
| | - Caleb J. Quates
- Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, Idaho, United States of America
| | - Jill L. Johnson
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, Idaho, United States of America
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, Idaho, United States of America
| | - Jagdish Suresh Patel
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, Idaho, United States of America
| | - F. Marty Ytreberg
- Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, Idaho, United States of America
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, Idaho, United States of America
- Department of Physics, University of Idaho, Moscow, Idaho, United States of America
| | - Yousif Shamoo
- Department of Biosciences, Rice University, Houston, Texas, United States of America
| | - Christopher J. Marx
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, Idaho, United States of America
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, Idaho, United States of America
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America
- * E-mail: (JVB); (CJM)
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McLean TC, Lo R, Tschowri N, Hoskisson PA, Al Bassam MM, Hutchings MI, Som NF. Sensing and responding to diverse extracellular signals: an updated analysis of the sensor kinases and response regulators of Streptomyces species. MICROBIOLOGY-SGM 2020; 165:929-952. [PMID: 31334697 DOI: 10.1099/mic.0.000817] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Streptomyces venezuelae is a Gram-positive, filamentous actinomycete with a complex developmental life cycle. Genomic analysis revealed that S. venezuelae encodes a large number of two-component systems (TCSs): these consist of a membrane-bound sensor kinase (SK) and a cognate response regulator (RR). These proteins act together to detect and respond to diverse extracellular signals. Some of these systems have been shown to regulate antimicrobial biosynthesis in Streptomyces species, making them very attractive to researchers. The ability of S. venezuelae to sporulate in both liquid and solid cultures has made it an increasingly popular model organism in which to study these industrially and medically important bacteria. Bioinformatic analysis identified 58 TCS operons in S. venezuelae with an additional 27 orphan SK and 18 orphan RR genes. A broader approach identified 15 of the 58 encoded TCSs to be highly conserved in 93 Streptomyces species for which high-quality and complete genome sequences are available. This review attempts to unify the current work on TCS in the streptomycetes, with an emphasis on S. venezuelae.
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Affiliation(s)
- Thomas C McLean
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, UK
| | - Rebecca Lo
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, UK
| | - Natalia Tschowri
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Paul A Hoskisson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, UK
| | - Mahmoud M Al Bassam
- Department of Paediatrics, Division of Host-Microbe Systems and Therapeutics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Matthew I Hutchings
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, UK
| | - Nicolle F Som
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, UK
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Iron is a centrally bound cofactor of specifier proteins involved in glucosinolate breakdown. PLoS One 2018; 13:e0205755. [PMID: 30395611 PMCID: PMC6218027 DOI: 10.1371/journal.pone.0205755] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/01/2018] [Indexed: 12/14/2022] Open
Abstract
Glucosinolates, a group of sulfur-rich thioglucosides found in plants of the order Brassicales, have attracted a lot of interest as chemical defenses of plants and health promoting substances in human diet. They are accumulated separately from their hydrolyzing enzymes, myrosinases, within the intact plant, but undergo myrosinase-catalyzed hydrolysis upon tissue disruption. This results in various biologically active products, e.g. isothiocyanates, simple nitriles, epithionitriles, and organic thiocyanates. While formation of isothiocyanates proceeds by a spontaneous rearrangement of the glucosinolate aglucone, aglucone conversion to the other products involves specifier proteins under physiological conditions. Specifier proteins appear to act with high specificity, but their exact roles and the structural bases of their specificity are presently unknown. Previous research identified the motif EXXXDXXXH as potential iron binding site required for activity, but crystal structures of recombinant specifier proteins lacked the iron cofactor. Here, we provide experimental evidence for the presence of iron (most likely Fe2+) in purified recombinant thiocyanate-forming protein from Thlaspi arvense (TaTFP) using a Ferene S-based photometric assay as well as Inductively Coupled Plasma-Mass Spectrometry. Iron binding and activity depend on E266, D270, and H274 suggesting a direct interaction of Fe2+ with these residues. Furthermore, we demonstrate presence of iron in epithiospecifier protein and nitrile-specifier protein 3 from Arabidopsis thaliana (AtESP and AtNSP3). We also present a homology model of AtNSP3. In agreement with this model, iron binding and activity of AtNSP3 depend on E386, D390, and H394. The homology model further suggests that the active site of AtNSP3 imposes fewer restrictions to the glucosinolate aglucone conformation than that of TaTFP and AtESP due to its larger size. This may explain why AtNSP3 does not support epithionitrile or thiocyanate formation, which likely requires exact positioning of the aglucone thiolate relative to the side chain.
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5
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Busche T, Winkler A, Wedderhoff I, Rückert C, Kalinowski J, Ortiz de Orué Lucana D. Deciphering the Transcriptional Response Mediated by the Redox-Sensing System HbpS-SenS-SenR from Streptomycetes. PLoS One 2016; 11:e0159873. [PMID: 27541358 PMCID: PMC4991794 DOI: 10.1371/journal.pone.0159873] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 07/08/2016] [Indexed: 12/30/2022] Open
Abstract
The secreted protein HbpS, the membrane-embedded sensor kinase SenS and the cytoplasmic response regulator SenR from streptomycetes have been shown to form a novel type of signaling pathway. Based on structural biology as well as different biochemical and biophysical approaches, redox stress-based post-translational modifications in the three proteins were shown to modulate the activity of this signaling pathway. In this study, we show that the homologous system, named here HbpSc-SenSc-SenRc, from the model species Streptomyces coelicolor A3(2) provides this bacterium with an efficient defense mechanism under conditions of oxidative stress. Comparative analyses of the transcriptomes of the Streptomyces coelicolor A3(2) wild-type and the generated hbpSc-senSc-senRc mutant under native and oxidative-stressing conditions allowed to identify differentially expressed genes, whose products may enhance the anti-oxidative defense of the bacterium. Amongst others, the results show an up-regulated transcription of genes for biosynthesis of cysteine and vitamin B12, transport of methionine and vitamin B12, and DNA synthesis and repair. Simultaneously, transcription of genes for degradation of an anti-oxidant compound is down-regulated in a HbpSc-SenSc-SenRc-dependent manner. It appears that HbpSc-SenSc-SenRc controls the non-enzymatic response of Streptomyces coelicolor A3(2) to counteract the hazardous effects of oxidative stress. Binding of the response regulator SenRc to regulatory regions of some of the studied genes indicates that the regulation is direct. The results additionally suggest that HbpSc-SenSc-SenRc may act in concert with other regulatory modules such as a transcriptional regulator, a two-component system and the Streptomyces B12 riboswitch. The transcriptomics data, together with our previous in vitro results, enable a profound characterization of the HbpS-SenS-SenR system from streptomycetes. Since homologues to HbpS-SenS-SenR are widespread in different actinobacteria with ecological and medical relevance, the data presented here will serve as a basis to elucidate the biological role of these homologues.
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Affiliation(s)
- Tobias Busche
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany
| | - Anika Winkler
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany
| | - Ina Wedderhoff
- Applied Genetics of Microorganisms, Department of Biology and Chemistry, University of Osnabrueck, Osnabrueck, Barbarastraße 13, 49076, Osnabrueck, Germany
| | - Christian Rückert
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany
| | - Jörn Kalinowski
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Universitätsstraße 27, 33615, Bielefeld, Germany
| | - Darío Ortiz de Orué Lucana
- Applied Genetics of Microorganisms, Department of Biology and Chemistry, University of Osnabrueck, Osnabrueck, Barbarastraße 13, 49076, Osnabrueck, Germany
- * E-mail:
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6
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Ortiz de Orué Lucana D, Hickey N, Hensel M, Klare JP, Geremia S, Tiufiakova T, Torda AE. The Crystal Structure of the C-Terminal Domain of the Salmonella enterica PduO Protein: An Old Fold with a New Heme-Binding Mode. Front Microbiol 2016; 7:1010. [PMID: 27446048 PMCID: PMC4923194 DOI: 10.3389/fmicb.2016.01010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/14/2016] [Indexed: 02/05/2023] Open
Abstract
The two-domain protein PduO, involved in 1,2-propanediol utilization in the pathogenic Gram-negative bacterium Salmonella enterica is an ATP:Cob(I)alamin adenosyltransferase, but this is a function of the N-terminal domain alone. The role of its C-terminal domain (PduOC) is, however, unknown. In this study, comparative growth assays with a set of Salmonella mutant strains showed that this domain is necessary for effective in vivo catabolism of 1,2-propanediol. It was also shown that isolated, recombinantly-expressed PduOC binds heme in vivo. The structure of PduOC co-crystallized with heme was solved (1.9 Å resolution) showing an octameric assembly with four heme moieities. The four heme groups are highly solvent-exposed and the heme iron is hexa-coordinated with bis-His ligation by histidines from different monomers. Static light scattering confirmed the octameric assembly in solution, but a mutation of the heme-coordinating histidine caused dissociation into dimers. Isothermal titration calorimetry using the PduOC apoprotein showed strong heme binding (K d = 1.6 × 10(-7) M). Biochemical experiments showed that the absence of the C-terminal domain in PduO did not affect adenosyltransferase activity in vitro. The evidence suggests that PduOC:heme plays an important role in the set of cobalamin transformations required for effective catabolism of 1,2-propanediol. Salmonella PduO is one of the rare proteins which binds the redox-active metabolites heme and cobalamin, and the heme-binding mode of the C-terminal domain differs from that in other members of this protein family.
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Affiliation(s)
- Darío Ortiz de Orué Lucana
- Applied Genetics of Microorganisms, Department of Biology/Chemistry, University of OsnabrückOsnabrück, Germany
| | - Neal Hickey
- Centre of Excellence in Biocrystallography, Department of Chemical and Pharmaceutical Sciences, University of TriesteTrieste, Italy
| | - Michael Hensel
- Division of Microbiology, Department of Biology/Chemistry, University of OsnabrückOsnabrück, Germany
| | - Johann P. Klare
- Department of Physics, University of OsnabrückOsnabrück, Germany
| | - Silvano Geremia
- Centre of Excellence in Biocrystallography, Department of Chemical and Pharmaceutical Sciences, University of TriesteTrieste, Italy
| | | | - Andrew E. Torda
- Centre for Bioinformatics, University of HamburgHamburg, Germany
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Martins I, Romão CV, Goulart J, Cerqueira T, Santos RS, Bettencourt R. Activity of antioxidant enzymes in response to atmospheric pressure induced physiological stress in deep-sea hydrothermal vent mussel Bathymodiolus azoricus. MARINE ENVIRONMENTAL RESEARCH 2016; 114:65-73. [PMID: 26790096 DOI: 10.1016/j.marenvres.2016.01.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 12/21/2015] [Accepted: 01/07/2016] [Indexed: 06/05/2023]
Abstract
Deep sea hydrothermal Bathymodiolus azoricus mussels from Portuguese EEZ Menez Gwen hydrothermal field possess the remarkable ability to overcome decompression and survive successfully at atmospheric pressure conditions. We investigated the potential use of antioxidant defense enzymes in mussel B. azoricus as biomarkers of oxidative stress induced by long term acclimatization to atmospheric pressure conditions. Mussels collected at Menez Gwen hydrothermal field were acclimatized for two weeks in three distinct conditions suitable of promoting physiological stress, (i) in plain seawater for concomitant endosymbiont bacteria loss, (ii) in plain seawater under metal iron exposure, (iii) constant bubbling methane and pumped sulfide for endosymbiont bacteria survival. The enzymatic activities of superoxide dismutase (SOD), catalase (CAT), and iron storage proteins in addition to electrophoretic profiles were examined in vent mussel gills and digestive gland. Gills showed approximately 3 times more SOD specific activity than digestive glands. On the other hand, digestive glands showed approximately 6 times more CAT specific activity than gills. Iron storage proteins were identified in gill extracts from all experimental conditions mussels. However, in digestive gland extracts only fresh collected mussels and after 2 weeks in FeSO4 showed the presence of iron storage proteins. The differences between SOD, CAT specific activities and the presence of iron storage proteins in the examined tissues reflect dissimilar metabolic and antioxidant activities, as a result of tissue specificities and acclimatization conditions influences on the organism.
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Affiliation(s)
- Inês Martins
- MARE - Marine and Environmental Sciences Centre, University of Azores, 9901-862 Horta, Portugal; IMAR/Department of Oceanography and Fisheries, University of Azores, 9901-862 Horta, Portugal.
| | - Célia V Romão
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras, Portugal
| | - Joana Goulart
- MARE - Marine and Environmental Sciences Centre, University of Azores, 9901-862 Horta, Portugal; IMAR/Department of Oceanography and Fisheries, University of Azores, 9901-862 Horta, Portugal
| | - Teresa Cerqueira
- MARE - Marine and Environmental Sciences Centre, University of Azores, 9901-862 Horta, Portugal; IMAR/Department of Oceanography and Fisheries, University of Azores, 9901-862 Horta, Portugal
| | - Ricardo S Santos
- MARE - Marine and Environmental Sciences Centre, University of Azores, 9901-862 Horta, Portugal; IMAR/Department of Oceanography and Fisheries, University of Azores, 9901-862 Horta, Portugal
| | - Raul Bettencourt
- MARE - Marine and Environmental Sciences Centre, University of Azores, 9901-862 Horta, Portugal; IMAR/Department of Oceanography and Fisheries, University of Azores, 9901-862 Horta, Portugal
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8
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The ferrous iron-responsive BqsRS two-component system activates genes that promote cationic stress tolerance. mBio 2015; 6:e02549. [PMID: 25714721 PMCID: PMC4358008 DOI: 10.1128/mbio.02549-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
UNLABELLED The physiological resistance of pathogens to antimicrobial treatment is a severe problem in the context of chronic infections. For example, the mucus-filled lungs of cystic fibrosis (CF) patients are readily colonized by diverse antibiotic-resistant microorganisms, including Pseudomonas aeruginosa. Previously, we showed that bioavailable ferrous iron [Fe(II)] is present in CF sputum at all stages of infection and constitutes a significant portion of the iron pool at advanced stages of lung function decline [R. C. Hunter et al., mBio 4(4):e00557-13, 2013]. P. aeruginosa, a dominant CF pathogen, senses Fe(II) using a two-component signal transduction system, BqsRS, which is transcriptionally active in CF sputum [R. C. Hunter et al., mBio 4(4):e00557-13, 2013; N. N. Kreamer, J. C. Wilks, J. J. Marlow, M. L. Coleman, and D. K. Newman, J Bacteriol 194:1195-1204, 2012]. Here, we show that an RExxE motif in BqsS is required for BqsRS activation. Once Fe(II) is sensed, BqsR binds a tandem repeat DNA sequence, activating transcription. The BqsR regulon--defined through iterative bioinformatic predictions and experimental validation--includes several genes whose products are known to drive antibiotic resistance to aminoglycosides and polymyxins. Among them are genes encoding predicted determinants of polyamine transport and biosynthesis. Compared to the wild type, bqsS and bqsR deletion mutants are sensitive to high levels of Fe(II), produce less spermidine in high Fe(II), and are more sensitive to tobramycin and polymyxin B but not arsenate, chromate, or cefsulodin. BqsRS thus mediates a physiological response to Fe(II) that guards the cell against positively charged molecules but not negatively charged stressors. These results suggest Fe(II) is an important environmental signal that, via BqsRS, bolsters tolerance of a variety of cationic stressors, including clinically important antimicrobial agents. IMPORTANCE Clearing chronic infections is challenging due to the physiological resistance of opportunistic pathogens to antibiotics. Effective treatments are hindered by a lack of understanding of how these organisms survive in situ. Fe(II) is typically present at micromolar levels in soils and sedimentary habitats, as well as in CF sputum. All P. aeruginosa strains possess a two-component system, BqsRS, that specifically senses extracellular Fe(II) at low micromolar concentrations. Our work shows that BqsRS protects the cell against cationic perturbations to the cell envelope as well as low pH and reduction potential (Eh), conditions under which Fe(2+) is stable. Fe(II) can thus be understood as a proxy for a broader environmental state; the cellular response to its detection may help rationalize the resistance of P. aeruginosa to clinically important cationic antibiotics. This finding demonstrates the importance of considering environmental chemistry when exploring mechanisms of microbial survival in habitats that include the human body.
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Vazquez DS, Agudelo WA, Yone A, Vizioli N, Arán M, González Flecha FL, González Lebrero MC, Santos J. A helix–coil transition induced by the metal ion interaction with a grafted iron-binding site of the CyaY protein family. Dalton Trans 2015; 44:2370-9. [DOI: 10.1039/c4dt02796e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An iron-binding motif EExxED from the first α-helical stretch of frataxin was grafted on a foreign peptide scaffold:KD= 1.9 ± 0.2 μM and 1 : 1 stoichiometry.
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Affiliation(s)
- Diego S. Vazquez
- Instituto de Química y Físico – Química Biológicas
- Universidad de Buenos Aires – CONICET
- Buenos Aires
- Argentina
| | - William A. Agudelo
- Instituto de Química y Físico – Química Biológicas
- Universidad de Buenos Aires – CONICET
- Buenos Aires
- Argentina
| | - Angel Yone
- Instituto de Química y Físico – Química Biológicas
- Universidad de Buenos Aires – CONICET
- Buenos Aires
- Argentina
| | - Nora Vizioli
- Instituto de Química y Físico – Química Biológicas
- Universidad de Buenos Aires – CONICET
- Buenos Aires
- Argentina
| | - Martín Arán
- Fundación Instituto Leloir and IIBBA – CONICET
- 1405 Buenos Aires
- Argentina
| | - F. Luis González Flecha
- Instituto de Química y Físico – Química Biológicas
- Universidad de Buenos Aires – CONICET
- Buenos Aires
- Argentina
| | - Mariano C. González Lebrero
- Instituto de Química y Físico – Química Biológicas
- Universidad de Buenos Aires – CONICET
- Buenos Aires
- Argentina
| | - Javier Santos
- Instituto de Química y Físico – Química Biológicas
- Universidad de Buenos Aires – CONICET
- Buenos Aires
- Argentina
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10
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Ortiz de Orué Lucana D, Fedosov SN, Wedderhoff I, Che EN, Torda AE. The extracellular heme-binding protein HbpS from the soil bacterium Streptomyces reticuli is an aquo-cobalamin binder. J Biol Chem 2014; 289:34214-28. [PMID: 25342754 PMCID: PMC4256353 DOI: 10.1074/jbc.m114.585489] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 10/22/2014] [Indexed: 11/06/2022] Open
Abstract
The extracellular protein HbpS from Streptomyces reticuli interacts with iron ions and heme. It also acts in concert with the two-component sensing system SenS-SenR in response to oxidative stress. Sequence comparisons suggested that the protein may bind a cobalamin. UV-visible spectroscopy confirmed binding (Kd = 34 μm) to aquo-cobalamin (H2OCbl(+)) but not to other cobalamins. Competition experiments with the H2OCbl(+)-coordinating ligand CN(-) and comparison of mutants identified a histidine residue (His-156) that coordinates the cobalt ion of H2OCbl(+) and substitutes for water. HbpS·Cobalamin lacks the Asp-X-His-X-X-Gly motif seen in some cobalamin binding enzymes. Preliminary tests showed that a related HbpS protein from a different species also binds H2OCbl(+). Furthermore, analyses of HbpS-heme binding kinetics are consistent with the role of HbpS as a heme-sensor and suggested a role in heme transport. Given the high occurrence of HbpS-like sequences among Gram-positive and Gram-negative bacteria, our findings suggest a great functional versatility among these proteins.
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Affiliation(s)
- Darío Ortiz de Orué Lucana
- From the Applied Genetics of Microorganisms, Department of Biology/Chemistry, University of Osnabrueck, 49067 Osnabrueck, Germany,
| | - Sergey N Fedosov
- Department of Engineering, Aarhus University, 8000 Aarhus, Denmark, and
| | - Ina Wedderhoff
- From the Applied Genetics of Microorganisms, Department of Biology/Chemistry, University of Osnabrueck, 49067 Osnabrueck, Germany
| | - Edith N Che
- From the Applied Genetics of Microorganisms, Department of Biology/Chemistry, University of Osnabrueck, 49067 Osnabrueck, Germany
| | - Andrew E Torda
- Centre for Bioinformatics, Hamburg University, 20146 Hamburg, Germany
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Ainsaar K, Mumm K, Ilves H, Hõrak R. The ColRS signal transduction system responds to the excess of external zinc, iron, manganese, and cadmium. BMC Microbiol 2014; 14:162. [PMID: 24946800 PMCID: PMC4074579 DOI: 10.1186/1471-2180-14-162] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 06/17/2014] [Indexed: 11/26/2022] Open
Abstract
Background The ColRS two-component system has been shown to contribute to the membrane functionality and stress tolerance of Pseudomonas putida as well as to the virulence of Pseudomonas aeruginosa and plant pathogenic Xanthomonas species. However, the conditions activating the ColRS pathway and the signal(s) sensed by ColS have remained unknown. Here we aimed to analyze the role of the ColRS system in metal tolerance of P. putida and to test whether ColS can respond to metal excess. Results We show that the ColRS system is necessary for P. putida to tolerate the excess of iron and zinc, and that it also contributes to manganese and cadmium tolerance. Excess of iron, zinc, manganese or cadmium activates ColRS signaling and as a result modifies the expression of ColR-regulated genes. Our data suggest that the genes in the ColR regulon are functionally redundant, as several loci have to be deleted to observe a significant decrease in metal tolerance. Site-directed mutagenesis of ColS revealed that excess of iron and, surprisingly, also zinc are sensed by a conserved ExxE motif in ColS’s periplasmic domain. While ColS is able to sense different metals, it still discriminates between the two oxidation states of iron, specifically responding to ferric and not ferrous iron. We propose a signal perception model involving a dimeric ColS, where each monomer donates one ExxE motif for metal binding. Conclusions Several transition metals are essential for living organisms in certain amounts, but toxic in excess. We show that ColRS is a sensor system which detects and responds to the excess of physiologically important metals such as zinc, iron and manganese. Thus, the ColRS system is an important factor for metal homeostasis and tolerance in P. putida.
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Affiliation(s)
| | | | | | - Rita Hõrak
- Institute of Molecular and Cell Biology, University of Tartu, 51010 Tartu, Estonia.
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