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Lee T, Orvosova M, Batzenschlager M, Bueno Batista M, Bailey PC, Mohd-Radzman NA, Gurzadyan A, Stuer N, Mysore KS, Wen J, Ott T, Oldroyd GED, Schiessl K. Light-sensitive short hypocotyl genes confer symbiotic nodule identity in the legume Medicago truncatula. Curr Biol 2024; 34:825-840.e7. [PMID: 38301650 DOI: 10.1016/j.cub.2024.01.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 09/29/2023] [Accepted: 01/08/2024] [Indexed: 02/03/2024]
Abstract
Legumes produce specialized root nodules that are distinct from lateral roots in morphology and function, with nodules intracellularly hosting nitrogen-fixing bacteria. We have previously shown that a lateral root program underpins nodule initiation, but there must be additional developmental regulators that confer nodule identity. Here, we show two members of the LIGHT-SENSITIVE SHORT HYPOCOTYL (LSH) transcription factor family, predominantly known to define shoot meristem complexity and organ boundaries, function as regulators of nodule organ identity. In parallel to the root initiation program, LSH1/LSH2 recruit a program into the root cortex that mediates the divergence into nodules, in particular with cell divisions in the mid-cortex. This includes regulation of auxin and cytokinin, promotion of NODULE ROOT1/2 and Nuclear Factor YA1, and suppression of the lateral root program. A principal outcome of LSH1/LSH2 function is the production of cells able to accommodate nitrogen-fixing bacteria, a key feature unique to nodules.
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Affiliation(s)
- Tak Lee
- Sainsbury Laboratory, University of Cambridge, 47 Bateman Street, Cambridge CB2 1LR, UK; Crop Science Centre, Department of Plant Sciences, University of Cambridge, 93 Lawrence Weaver Road, Cambridge CB3 0LE, UK
| | - Martina Orvosova
- Sainsbury Laboratory, University of Cambridge, 47 Bateman Street, Cambridge CB2 1LR, UK; Crop Science Centre, Department of Plant Sciences, University of Cambridge, 93 Lawrence Weaver Road, Cambridge CB3 0LE, UK
| | | | - Marcelo Bueno Batista
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Paul C Bailey
- Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond TW9 3DS, UK
| | - Nadia A Mohd-Radzman
- Sainsbury Laboratory, University of Cambridge, 47 Bateman Street, Cambridge CB2 1LR, UK
| | - Aram Gurzadyan
- Sainsbury Laboratory, University of Cambridge, 47 Bateman Street, Cambridge CB2 1LR, UK
| | - Naomi Stuer
- Sainsbury Laboratory, University of Cambridge, 47 Bateman Street, Cambridge CB2 1LR, UK
| | - Kirankumar S Mysore
- Noble Research Institute, LLC, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Jiangqi Wen
- Noble Research Institute, LLC, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Thomas Ott
- University of Freiburg, Faculty of Biology, Schänzlestrasse, 79104 Freiburg, Germany; CIBSS - Centre of Integrative Biological Signalling Studies, University of Freiburg, Schänzlestrasse, 79104 Freiburg, Germany
| | - Giles E D Oldroyd
- Sainsbury Laboratory, University of Cambridge, 47 Bateman Street, Cambridge CB2 1LR, UK; Crop Science Centre, Department of Plant Sciences, University of Cambridge, 93 Lawrence Weaver Road, Cambridge CB3 0LE, UK.
| | - Katharina Schiessl
- Sainsbury Laboratory, University of Cambridge, 47 Bateman Street, Cambridge CB2 1LR, UK.
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Boyer NR, Tokmina-Lukaszewska M, Bueno Batista M, Mus F, Dixon R, Bothner B, Peters JW. Structural insights into redox signal transduction mechanisms in the control of nitrogen fixation by the NifLA system. Proc Natl Acad Sci U S A 2023; 120:e2302732120. [PMID: 37459513 PMCID: PMC10372690 DOI: 10.1073/pnas.2302732120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 06/15/2023] [Indexed: 07/20/2023] Open
Abstract
NifL is a conformationally dynamic flavoprotein responsible for regulating the activity of the σ54-dependent activator NifA to control the transcription of nitrogen fixation (nif) genes in response to intracellular oxygen, cellular energy, or nitrogen availability. The NifL-NifA two-component system is the master regulatory system for nitrogen fixation. NifL serves as a sensory protein, undergoing signal-dependent conformational changes that modulate its interaction with NifA, forming the NifL-NifA complex, which inhibits NifA activity in conditions unsuitable for nitrogen fixation. While NifL-NifA regulation is well understood, these conformationally flexible proteins have eluded previous attempts at structure determination. In work described here, we advance a structural model of the NifL dimer supported by a combination of scattering techniques and mass spectrometry (MS)-coupled structural analyses that report on the average structure in solution. Using a combination of small angle X-ray scattering-derived electron density maps and MS-coupled surface labeling, we investigate the conformational dynamics responsible for NifL oxygen and energy responses. Our results reveal conformational differences in the structure of NifL under reduced and oxidized conditions that provide the basis for a model for modulating NifLA complex formation in the regulation of nitrogen fixation in response to oxygen in the model diazotroph, Azotobacter vinelandii.
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Affiliation(s)
- Nathaniel R. Boyer
- Institute of Biological Chemistry, Washington State University, Pullman, WA99164
| | | | - Marcelo Bueno Batista
- Department of Molecular Microbiology, John Innes Centre, NorwichNR4 7UH, United Kingdom
| | - Florence Mus
- Institute of Biological Chemistry, Washington State University, Pullman, WA99164
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK73019
| | - Ray Dixon
- Department of Molecular Microbiology, John Innes Centre, NorwichNR4 7UH, United Kingdom
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT59717
| | - John W. Peters
- Institute of Biological Chemistry, Washington State University, Pullman, WA99164
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK73019
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Martin Del Campo JS, Rigsbee J, Bueno Batista M, Mus F, Rubio LM, Einsle O, Peters JW, Dixon R, Dean DR, Dos Santos PC. Overview of physiological, biochemical, and regulatory aspects of nitrogen fixation in Azotobacter vinelandii. Crit Rev Biochem Mol Biol 2023; 57:492-538. [PMID: 36877487 DOI: 10.1080/10409238.2023.2181309] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
Understanding how Nature accomplishes the reduction of inert nitrogen gas to form metabolically tractable ammonia at ambient temperature and pressure has challenged scientists for more than a century. Such an understanding is a key aspect toward accomplishing the transfer of the genetic determinants of biological nitrogen fixation to crop plants as well as for the development of improved synthetic catalysts based on the biological mechanism. Over the past 30 years, the free-living nitrogen-fixing bacterium Azotobacter vinelandii emerged as a preferred model organism for mechanistic, structural, genetic, and physiological studies aimed at understanding biological nitrogen fixation. This review provides a contemporary overview of these studies and places them within the context of their historical development.
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Affiliation(s)
| | - Jack Rigsbee
- Department of Chemistry, Wake Forest University, Winston-Salem, NC, USA
| | | | - Florence Mus
- Institute of Biological Chemistry, Washington State University, Pullman, WA, USA
| | - Luis M Rubio
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA/CSIC), Pozuelo de Alarcón, Spain
| | - Oliver Einsle
- Department of Biochemistry, University of Freiburg, Freiburg, Germany
| | - John W Peters
- Institute of Biological Chemistry, Washington State University, Pullman, WA, USA
| | - Ray Dixon
- Department of Molecular Microbiology, John Innes Centre, Norwich, UK
| | - Dennis R Dean
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA
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Sayavedra L, Li T, Bueno Batista M, Seah BKB, Booth C, Zhai Q, Chen W, Narbad A. Desulfovibrio diazotrophicus sp. nov., a sulfate-reducing bacterium from the human gut capable of nitrogen fixation. Environ Microbiol 2022; 24:4971. [PMID: 36254869 DOI: 10.1111/1462-2920.16239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Appia-Ayme C, Little R, Chandra G, de Oliveira Martins C, Bueno Batista M, Dixon R. Interactions between paralogous bacterial enhancer-binding proteins enable metal-dependent regulation of alternative nitrogenases in Azotobacter vinelandii. Mol Microbiol 2022; 118:105-124. [PMID: 35718936 PMCID: PMC9542535 DOI: 10.1111/mmi.14955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/13/2022] [Accepted: 06/15/2022] [Indexed: 11/30/2022]
Abstract
All diazotrophic bacteria and archaea isolated so far utilise a nitrogenase enzyme‐containing molybdenum in the active site co‐factor to fix atmospheric dinitrogen to ammonia. However, in addition to the Mo‐dependent nitrogenase, some nitrogen‐fixing prokaryotes also express genetically distinct alternative nitrogenase isoenzymes, namely the V‐dependent and Fe‐only nitrogenases, respectively. Nitrogenase isoenzymes are expressed hierarchically according to metal availability and catalytic efficiency. In proteobacteria, this hierarchy is maintained via stringent transcriptional regulation of gene clusters by dedicated bacterial enhancer‐binding proteins (bEBPs). The model diazotroph Azotobacter vinelandii contains two paralogs of the vanadium nitrogenase activator VnfA (henceforth, VnfA1), designated VnfA2 and VnfA3, with unknown functions. Here we demonstrate that the VnfA1 and VnfA3 bEBPs bind to the same target promoters in the Azotobacter vinelandii genome and co‐activate a subset of genes in the absence of V, including the structural genes for the Fe‐only nitrogenase. Co‐activation is inhibited by the presence of V and is dependent on an accessory protein VnfZ that is co‐expressed with VnfA3. Our studies uncover a plethora of interactions between bEBPs required for nitrogen fixation, revealing the unprecedented potential for fine‐tuning the expression of alternative nitrogenases in response to metal availability.
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Affiliation(s)
| | - Richard Little
- Department of Molecular Microbiology, John Innes Centre, Norwich, UK
| | - Govind Chandra
- Department of Molecular Microbiology, John Innes Centre, Norwich, UK
| | | | | | - Ray Dixon
- Department of Molecular Microbiology, John Innes Centre, Norwich, UK
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Anderson AB, Assis J, Batista MB, Serrão EA, Guabiroba HC, Delfino SDT, Pinheiro HT, Pimentel CR, Gomes LEO, Vilar CC, Bernardino AF, Horta P, Ghisolfi RD, Joyeux JC. Global warming assessment suggests the endemic Brazilian kelp beds to be an endangered ecosystem. Mar Environ Res 2021; 168:105307. [PMID: 33984550 DOI: 10.1016/j.marenvres.2021.105307] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 03/01/2021] [Accepted: 03/11/2021] [Indexed: 06/12/2023]
Abstract
Kelps are canopy-forming brown seaweed sustaining critical ecosystem services in coastal habitats, including shelter, nursery grounds, and providing food resources to a myriad of associated species. This study modeled the fundamental niche of Laminaria abyssalis along the Brazilian continental margin, an endemic species of the South Atlantic, to anticipate potential distributional range shifts under two contrasting scenarios of future environmental changes (RCP2.6 and RCP8.5). The model for fundamental niche predictions considering the "present scenario" has shown a wider potential area than the realized niche (i.e., the area where the species actually occurs) along the Brazilian coast. In both future scenarios, the models have shown niche erosion on the northern portion of the Brazilian coast and niche gains towards the south. In both scenarios, L. abyssalis populations tend to shift to deeper regions of the reef. The restricted range of occurrence (33,000 km2), intense anthropic activities along these beds (e.g., trawling fisheries, oil/gas mining, or removal for agricultural purposes) acting synergically with global warming, may drive this ecosystem to collapse faster than kelp species' ability to adapt. We propose to classify L. abyssalis as Endangered - (EN) under IUCN criteria, and highlight that long-term monitoring of kelp beds is an urgent need to develop effective conservation initiatives to protect such rare and invaluable ecosystem.
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Affiliation(s)
- A B Anderson
- Laboratory of Ichthyology, Department of Oceanography, Federal University of Espírito Santo, Vitória, ES, 29075-910, Brazil.
| | - J Assis
- Centre of Marine Sciences, CCMAR, University of Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
| | - M B Batista
- Laboratório de Ficologia, Departamento de Botânica, Universidade Federal de Santa Catarina, Florianópolis, SC, 88040-970, Brazil
| | - E A Serrão
- Centre of Marine Sciences, CCMAR, University of Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
| | - H C Guabiroba
- Laboratory of Ichthyology, Department of Oceanography, Federal University of Espírito Santo, Vitória, ES, 29075-910, Brazil
| | - S D T Delfino
- Laboratory of Ichthyology, Department of Oceanography, Federal University of Espírito Santo, Vitória, ES, 29075-910, Brazil
| | - H T Pinheiro
- Ichthyology Section, California Academy of Sciences, San Francisco, CA, 94118, USA
| | - C R Pimentel
- Laboratory of Ichthyology, Department of Oceanography, Federal University of Espírito Santo, Vitória, ES, 29075-910, Brazil
| | - L E O Gomes
- Benthic Ecology Group, Department of Oceanography, Federal University of Espírito Santo, Vitória, ES, 29075-910, Brazil
| | - C C Vilar
- Laboratory of Ichthyology, Department of Oceanography, Federal University of Espírito Santo, Vitória, ES, 29075-910, Brazil
| | - A F Bernardino
- Benthic Ecology Group, Department of Oceanography, Federal University of Espírito Santo, Vitória, ES, 29075-910, Brazil
| | - P Horta
- Laboratório de Ficologia, Departamento de Botânica, Universidade Federal de Santa Catarina, Florianópolis, SC, 88040-970, Brazil
| | - R D Ghisolfi
- Laboratory of Oceanography, Department of Oceanography, Federal University of Espírito Santo, Vitória, ES, 29075-910, Brazil
| | - J-C Joyeux
- Laboratory of Ichthyology, Department of Oceanography, Federal University of Espírito Santo, Vitória, ES, 29075-910, Brazil
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Bueno Batista M, Brett P, Appia-Ayme C, Wang YP, Dixon R. Disrupting hierarchical control of nitrogen fixation enables carbon-dependent regulation of ammonia excretion in soil diazotrophs. PLoS Genet 2021; 17:e1009617. [PMID: 34111137 PMCID: PMC8219145 DOI: 10.1371/journal.pgen.1009617] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/22/2021] [Accepted: 05/23/2021] [Indexed: 12/14/2022] Open
Abstract
The energetic requirements for biological nitrogen fixation necessitate stringent regulation of this process in response to diverse environmental constraints. To ensure that the nitrogen fixation machinery is expressed only under appropriate physiological conditions, the dedicated NifL-NifA regulatory system, prevalent in Proteobacteria, plays a crucial role in integrating signals of the oxygen, carbon and nitrogen status to control transcription of nitrogen fixation (nif) genes. Greater understanding of the intricate molecular mechanisms driving transcriptional control of nif genes may provide a blueprint for engineering diazotrophs that associate with cereals. In this study, we investigated the properties of a single amino acid substitution in NifA, (NifA-E356K) which disrupts the hierarchy of nif regulation in response to carbon and nitrogen status in Azotobacter vinelandii. The NifA-E356K substitution enabled overexpression of nitrogenase in the presence of excess fixed nitrogen and release of ammonia outside the cell. However, both of these properties were conditional upon the nature of the carbon source. Our studies reveal that the uncoupling of nitrogen fixation from its assimilation is likely to result from feedback regulation of glutamine synthetase, allowing surplus fixed nitrogen to be excreted. Reciprocal substitutions in NifA from other Proteobacteria yielded similar properties to the A. vinelandii counterpart, suggesting that this variant protein may facilitate engineering of carbon source-dependent ammonia excretion amongst diverse members of this family.
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Affiliation(s)
| | - Paul Brett
- Department of Metabolic Biology, John Innes Centre, Norwich, United Kingdom
| | - Corinne Appia-Ayme
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
| | - Yi-Ping Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences & School of Advanced Agricultural Sciences, Peking University, Beijing, China
| | - Ray Dixon
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
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Sayavedra L, Li T, Bueno Batista M, Seah BKB, Booth C, Zhai Q, Chen W, Narbad A. Desulfovibrio diazotrophicus sp. nov., a sulfate-reducing bacterium from the human gut capable of nitrogen fixation. Environ Microbiol 2021; 23:3164-3181. [PMID: 33876566 DOI: 10.1111/1462-2920.15538] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 03/24/2021] [Accepted: 04/16/2021] [Indexed: 12/13/2022]
Abstract
Sulfate-reducing bacteria (SRB) are widespread in human guts, yet their expansion has been linked to colonic diseases. We report the isolation, sequencing and physiological characterization of strain QI0027T , a novel SRB species belonging to the class Desulfovibrionia. Metagenomic sequencing of stool samples from 45 Chinese individuals, and comparison with 1690 Desulfovibrionaceae metagenome-assembled genomes recovered from humans of diverse geographic locations, revealed the presence of QI0027T in 22 further individuals. QI0027T encoded nitrogen fixation genes and based on the acetylene reduction assay, actively fixed nitrogen. Transcriptomics revealed that QI0027T overexpressed 42 genes in nitrogen-limiting conditions compared to cultures supplemented with ammonia, including genes encoding nitrogenases, a urea uptake system and the urease complex. Reanalyses of 835 public stool metatranscriptomes showed that nitrogenase genes from Desulfovibrio bacteria were expressed in six samples suggesting that nitrogen fixation might be active in the gut environment. Although frequently thought of as a nutrient-rich environment, nitrogen fixation can occur in the human gut. Animals are often nitrogen limited and have evolved diverse strategies to capture biologically active nitrogen, ranging from amino acid transporters to stable associations with beneficial microbes that provide fixed nitrogen. QI0027T is the first Desulfovibrio human isolate for which nitrogen fixation has been demonstrated, suggesting that some sulfate-reducing bacteria could also play a role in the availability of nitrogen in the gut.
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Affiliation(s)
- Lizbeth Sayavedra
- Gut Health and Microbes, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
| | - Tianqi Li
- Gut Health and Microbes, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK.,State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Marcelo Bueno Batista
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, UK
| | - Brandon K B Seah
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Catherine Booth
- Gut Health and Microbes, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
| | - Qixiao Zhai
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Wei Chen
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China
| | - Arjan Narbad
- Gut Health and Microbes, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
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Batista MB, Chandra G, Monteiro RA, de Souza EM, Dixon R. Hierarchical interactions between Fnr orthologs allows fine-tuning of transcription in response to oxygen in Herbaspirillum seropedicae. Nucleic Acids Res 2019. [PMID: 29529262 PMCID: PMC5934665 DOI: 10.1093/nar/gky142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Bacteria adjust the composition of their electron transport chain (ETC) to efficiently adapt to oxygen gradients. This involves differential expression of various ETC components to optimize energy generation. In Herbaspirillum seropedicae, reprogramming of gene expression in response to oxygen availability is controlled at the transcriptional level by three Fnr orthologs. Here, we characterised Fnr regulons using a combination of RNA-Seq and ChIP-Seq analysis. We found that Fnr1 and Fnr3 directly regulate discrete groups of promoters (Groups I and II, respectively), and that a third group (Group III) is co-regulated by both transcription factors. Comparison of DNA binding motifs between the three promoter groups suggests Group III promoters are potentially co-activated by Fnr3–Fnr1 heterodimers. Specific interaction between Fnr1 and Fnr3, detected in two-hybrid assays, was dependent on conserved residues in their dimerization interfaces, indicative of heterodimer formation in vivo. The requirements for co-activation of the fnr1 promoter, belonging to Group III, suggest either sequential activation by Fnr3 and Fnr1 homodimers or the involvement of Fnr3–Fnr1 heterodimers. Analysis of Fnr proteins with swapped activation domains provides evidence that co-activation by Fnr1 and Fnr3 at Group III promoters optimises interactions with RNA polymerase to fine-tune transcription in response to prevailing oxygen concentrations.
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Affiliation(s)
- Marcelo Bueno Batista
- Department of Molecular Microbiology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
| | - Govind Chandra
- Department of Molecular Microbiology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
| | - Rose Adele Monteiro
- Department of Biochemistry and Molecular Biology, Universidade Federal do Parana, P.O. Box 19046, Curitiba, PR 81531-990, Brazil
| | - Emanuel Maltempi de Souza
- Department of Biochemistry and Molecular Biology, Universidade Federal do Parana, P.O. Box 19046, Curitiba, PR 81531-990, Brazil
| | - Ray Dixon
- Department of Molecular Microbiology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
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Batista MB, Wassem R, Pedrosa FDO, de Souza EM, Dixon R, Monteiro RA. Enhanced oxygen consumption in Herbaspirillum seropedicae fnr mutants leads to increased NifA mediated transcriptional activation. BMC Microbiol 2015; 15:95. [PMID: 25947294 PMCID: PMC4422417 DOI: 10.1186/s12866-015-0432-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 04/24/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Orthologous proteins of the Crp/Fnr family have been previously implicated in controlling expression and/or activity of the NifA transcriptional activator in some diazotrophs. This study aimed to address the role of three Fnr-like proteins from H. seropedicae SmR1 in controlling NifA activity and consequent NifA-mediated transcription activation. RESULTS The activity of NifA-dependent transcriptional fusions (nifA::lacZ and nifB::lacZ) was analysed in a series of H. seropedicae fnr deletion mutant backgrounds. We found that combined deletions in both the fnr1 and fnr3 genes lead to higher expression of both the nifA and nifB genes and also an increased level of nifH transcripts. Expression profiles of nifB under different oxygen concentrations, together with oxygen consumption measurements suggest that the triple fnr mutant has higher respiratory activity when compared to the wild type, which we believe to be responsible for greater stability of the oxygen sensitive NifA protein. This conclusion was further substantiated by measuring the levels of NifA protein and its activity in fnr deletion strains in comparison with the wild-type. CONCLUSIONS Fnr proteins are indirectly involved in controlling the activity of NifA in H. seropedicae, probably as a consequence of their influence on respiratory activity in relation to oxygen availability. Additionally we can suggest that there is some redundancy in the physiological function of the three Fnr paralogs in this organism, since altered respiration and effects on NifA activity are only observed in deletion strains lacking both fnr1 and fnr3.
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Affiliation(s)
- Marcelo Bueno Batista
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, P.O. Box 19046, Curitiba, PR, 81531-990, Brazil.
| | - Roseli Wassem
- Department of Genetics, Universidade Federal do Paraná, P.O. Box 19071, Curitiba, PR, 81531-990, Brazil.
| | - Fábio de Oliveira Pedrosa
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, P.O. Box 19046, Curitiba, PR, 81531-990, Brazil.
| | - Emanuel Maltempi de Souza
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, P.O. Box 19046, Curitiba, PR, 81531-990, Brazil.
| | - Ray Dixon
- Department of Molecular Microbiology, John Innes Centre, Colney Lane, Norwich, NR4 7UH, UK.
| | - Rose Adele Monteiro
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, P.O. Box 19046, Curitiba, PR, 81531-990, Brazil.
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Kowalski LP, Batista MB, Santos CR, Scopel A, Salvajolli JV, Torloni H. Prognostic factors in T3,N0-1 glottic and transglottic carcinoma. A multifactorial study of 221 cases treated by surgery or radiotherapy. Arch Otolaryngol Head Neck Surg 1996; 122:77-82. [PMID: 8554750 DOI: 10.1001/archotol.1996.01890130069011] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVE To evaluate prognostic factors in patients with T3,N0-1 glottic and transglottic carcinoma treated in a single institution. DESIGN Retrospective, nonrandomized case series. SETTING Tertiary case referral centers, ambulatory or hospitalized care. PATIENTS Two hundred twenty-one consecutive cases of stage III glottic or transglottic squamous cell carcinoma. Tumor stage was T3,N0,M0 in 167 cases and T3,N1,M0 in 54 cases. INTERVENTIONS Surgery in 176 cases and radiotherapy in 45 cases. MAIN OUTCOME MEASURES Recurrences and survival (multivariate). RESULTS Almost 7% of the patients who underwent surgery and 39.6% who had radiotherapy had local recurrences. Recurrences in the neck were seen in 16.4% of the patients who underwent surgery and in 10.5% of those who had radiotherapy. Distant metastases were diagnosed only in patients who underwent surgery (4.6%). The 5-year actuarial overall survival rates were 56.3% in the surgical group and 35.2% in the radiotherapy group (P = .007). Age involvement of pyriform sinus, N stage, and history of tracheostomy were independent prognostic factors for risk of death. CONCLUSIONS The presence of metastatic lymph nodes, age, and involvement of the pyriform sinus were the important prognostic factors in patients who underwent surgery. A small group of patients with T3,N0,M0 tumors could benefit from radiotherapy, with surgery reserved for recurrence.
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Affiliation(s)
- L P Kowalski
- Department of Head and Neck Surgery, Hospital A C Camargo, São Paulo, Brazil
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Kowalski LP, Batista MB, Santos CR, Scopel AA, Salvajoli JV, Novaes PE, Trippe N. Prognostic factors in glottic carcinoma clinical stage I and II treated by surgery or radiotherapy. Am J Otolaryngol 1993; 14:122-7. [PMID: 8484477 DOI: 10.1016/0196-0709(93)90051-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
INTRODUCTION Decision making regarding selection of treatment for early glottic carcinoma remains controversial. This study was undertaken to assess the impact of such factors as patient age, stage of tumor, site and size of characteristic of the lesion, and other characteristics relative to disease free and overall survival rates. PATIENTS AND METHODS The records of 145 consecutive patients with stage I and II glottic carcinomas treated between 1954 and 1990 were reviewed retrospectively. Surgery was performed on 50 patients (34.5%), and irradiation therapy was performed on 95 (65.5%). Cox's regression model was used to estimate the hazard ratios of recurrence and death. RESULTS Median follow-up was 69.3 months. Death due to cancer or treatment complications occurred in 29 patients, whereas 25 patients died due to causes not related to cancer. Five-year rates for overall survival and disease-free intervals were 94.6% and 70.8%, respectively. Tumor control was achieved by initial surgery or irradiation in 78% and 69.5%, respectively. T stage and vocal cord mobility in this series were not associated with prognosis. Arytenoid involvement intended to indicate a worse prognosis. Other site involvement such as anterior commissure had no prognostic impact. DISCUSSION Although stage I and II glottic cancers represent a heterogenous group, survival rates after surgery or radiotherapy vary relatively little. Death due to occurred in 17.9% of patients included in this series, whereas 17.2% died due to causes not related to cancer. Local recurrence following irradiation (29.5%) occurred more frequently than following surgery (10%). The choice of treatment modality for stage I and II glottic cancer should be justified by patient preference, involvement of anterior commissure, and impairment of vocal cord mobility and should not be a contraindication to radiotherapy.
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Affiliation(s)
- L P Kowalski
- Head and Neck Surgery Department, A. C. Camargo Hospital, Sao Paulo, Brazil
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Ferreira LA, Henriques OB, Lebrun I, Batista MB, Prezoto BC, Andreoni AS, Zelnik R, Habermehl G. A new bradykinin-potentiating peptide (peptide P) isolated from the venom of Bothrops jararacussu (jararacuçu tapete, urutu dourado). Toxicon 1992; 30:33-40. [PMID: 1595077 DOI: 10.1016/0041-0101(92)90499-u] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Several bradykinin potentiators were identified in the venom of Bothrops jararacussu by chromatographic techniques and biological assays. One of them which was isolated inhibited the angiotensin-converting enzyme in vitro and potentiated the bradykinin-induced lowering of the arterial pressure in the rat.
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Affiliation(s)
- L A Ferreira
- Serviço de Bioquímica-Lab, Cininas, Instituto Butantan, São Paulo, Brazil
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