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Goyal RK, Schmidt MA, Hynes MF. Molecular Biology in the Improvement of Biological Nitrogen Fixation by Rhizobia and Extending the Scope to Cereals. Microorganisms 2021; 9:microorganisms9010125. [PMID: 33430332 PMCID: PMC7825764 DOI: 10.3390/microorganisms9010125] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 12/29/2020] [Accepted: 01/06/2021] [Indexed: 11/16/2022] Open
Abstract
The contribution of biological nitrogen fixation to the total N requirement of food and feed crops diminished in importance with the advent of synthetic N fertilizers, which fueled the “green revolution”. Despite being environmentally unfriendly, the synthetic versions gained prominence primarily due to their low cost, and the fact that most important staple crops never evolved symbiotic associations with bacteria. In the recent past, advances in our knowledge of symbiosis and nitrogen fixation and the development and application of recombinant DNA technology have created opportunities that could help increase the share of symbiotically-driven nitrogen in global consumption. With the availability of molecular biology tools, rapid improvements in symbiotic characteristics of rhizobial strains became possible. Further, the technology allowed probing the possibility of establishing a symbiotic dialogue between rhizobia and cereals. Because the evolutionary process did not forge a symbiotic relationship with the latter, the potential of molecular manipulations has been tested to incorporate a functional mechanism of nitrogen reduction independent of microbes. In this review, we discuss various strategies applied to improve rhizobial strains for higher nitrogen fixation efficiency, more competitiveness and enhanced fitness under unfavorable environments. The challenges and progress made towards nitrogen self-sufficiency of cereals are also reviewed. An approach to integrate the genetically modified elite rhizobia strains in crop production systems is highlighted.
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Affiliation(s)
- Ravinder K. Goyal
- Lacombe Research and Development Centre, Agriculture and Agri-Food Canada, Lacombe, AB T4L 1W1, Canada;
- Correspondence:
| | - Maria Augusta Schmidt
- Lacombe Research and Development Centre, Agriculture and Agri-Food Canada, Lacombe, AB T4L 1W1, Canada;
- Department of Biological Sciences, University of Calgary, 2500 University Dr NW, Calgary, AB T2N 1N4, Canada;
| | - Michael F. Hynes
- Department of Biological Sciences, University of Calgary, 2500 University Dr NW, Calgary, AB T2N 1N4, Canada;
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Jorrin B, Palacios JM, Peix Á, Imperial J. Rhizobium ruizarguesonis sp. nov., isolated from nodules of Pisum sativum L. Syst Appl Microbiol 2020; 43:126090. [PMID: 32690191 DOI: 10.1016/j.syapm.2020.126090] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 04/22/2020] [Accepted: 04/25/2020] [Indexed: 10/24/2022]
Abstract
Four strains, coded as UPM1132, UPM1133T, UPM1134 and UPM1135, and isolated from nodules of Pisum sativum plants grown on Ni-rich soils were characterised through a polyphasic taxonomy approach. Their 16S rRNA gene sequences were identical and showed 100% similarity with their closest phylogenetic neighbors, the species included in the 'R. leguminosarum group': R. laguerreae FB206T, R. leguminosarum USDA 2370T, R. anhuiense CCBAU 23252T, R. sophoreae CCBAU 03386T, R. acidisoli FH13T and R. hidalgonense FH14T, and 99.6% sequence similarity with R. esperanzae CNPSo 668T. The analysis of combined housekeeping genes recA, atpD and glnII sequences showed similarities of 92-95% with the closest relatives. Whole genome average nucleotide identity (ANI) values were 97.5-99.7% ANIb similarity among the four strains, and less than 92.4% with closely related species, while digital DNA-DNA hybridization average values (dDDH) were 82-85% within our strains and 34-52% with closely related species. Major fatty acids in strain UPM1133T were C18:1 ω7c / C18:1 ω6c in summed feature 8, C14:0 3OH/ C16:1 iso I in summed feature 2 and C18:0. Colonies were small to medium, pearl-white coloured in YMA at 28°C and growth was observed in the ranges 8-34°C, pH 5.5-7.5 and 0-0.7% (w/v) NaCl. The DNA G+C content was 60.8mol %. The combined genotypic, phenotypic and chemotaxonomic data support the classification of strains UPM1132, UPM1133T, UPM1134 and UPM1135 into a novel species of Rhizobium, for which the name Rhizobium ruizarguesonis sp. nov. is proposed. The type strain is UPM1133T (=CECT 9542T=LMG 30526T).
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Affiliation(s)
- Beatriz Jorrin
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, 28223 Pozuelo de Alarcón, Madrid, Spain
| | - José Manuel Palacios
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, 28223 Pozuelo de Alarcón, Madrid, Spain; Departamento de Biotecnología y Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, 28040 Madrid, Spain
| | - Álvaro Peix
- Instituto de Recursos Naturales y Agrobiología, Consejo Superior de Investigaciones Científicas (IRNASA-CSIC), Salamanca, Spain; Unidad Asociada Grupo de Interacción Planta-Microorganismo Universidad de Salamanca-IRNASA (CSIC).
| | - Juan Imperial
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, 28223 Pozuelo de Alarcón, Madrid, Spain; Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Científicas (ICA-CSIC), 28006 Madrid, Spain.
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Hydrogen-uptake genes improve symbiotic efficiency in common beans (Phaseolus vulgaris L.). Antonie van Leeuwenhoek 2020; 113:687-696. [DOI: 10.1007/s10482-019-01381-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 12/26/2019] [Indexed: 01/20/2023]
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Cacho C, Brito B, Palacios J, Pérez-Conde C, Cámara C. Speciation of nickel by HPLC-UV/MS in pea nodules. Talanta 2010; 83:78-83. [PMID: 21035647 DOI: 10.1016/j.talanta.2010.08.044] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 08/20/2010] [Accepted: 08/26/2010] [Indexed: 11/15/2022]
Abstract
A new and sensitive methodology based on normal phase HPLC has been developed for the speciation of nickel in low-complexity plant extracts. The method combines a silica stationary phase column, a 9:1 (v/v) hexane:ethanol mixture as mobile phase, and the detection of nickel complexes by either UV or MS. The developed methodology was applied to the speciation of nickel complexes in the cytoplasm of pea root nodules. Results obtained indicate that nickel citrate and nickel malate accounts for 99% of nickel present in pea nodule cytoplasm fraction. The low detection limit of the method (<0.2 nM) enables nickel speciation in non-hyperaccumulator plants.
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Affiliation(s)
- C Cacho
- Department of Analytical Chemistry, Universidad Complutense de Madrid, 28040 Madrid, Spain
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Brito B, Prieto RI, Cabrera E, Mandrand-Berthelot MA, Imperial J, Ruiz-Argüeso T, Palacios JM. Rhizobium leguminosarum hupE encodes a nickel transporter required for hydrogenase activity. J Bacteriol 2010; 192:925-35. [PMID: 20023036 PMCID: PMC2812973 DOI: 10.1128/jb.01045-09] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 12/07/2009] [Indexed: 02/04/2023] Open
Abstract
Synthesis of the hydrogen uptake (Hup) system in Rhizobium leguminosarum bv. viciae requires the function of an 18-gene cluster (hupSLCDEFGHIJK-hypABFCDEX). Among them, the hupE gene encodes a protein showing six transmembrane domains for which a potential role as a nickel permease has been proposed. In this paper, we further characterize the nickel transport capacity of HupE and that of the translated product of hupE2, a hydrogenase-unlinked gene identified in the R. leguminosarum genome. HupE2 is a potential membrane protein that shows 48% amino acid sequence identity with HupE. Expression of both genes in the Escherichia coli nikABCDE mutant strain HYD723 restored hydrogenase activity and nickel transport. However, nickel transport assays revealed that HupE and HupE2 displayed different levels of nickel uptake. Site-directed mutagenesis of histidine residues in HupE revealed two motifs (HX(5)DH and FHGX[AV]HGXE) that are required for HupE functionality. An R. leguminosarum double mutant, SPF22A (hupE hupE2), exhibited reduced levels of hydrogenase activity in free-living cells, and this phenotype was complemented by nickel supplementation. Low levels of symbiotic hydrogenase activity were also observed in SPF22A bacteroid cells from lentil (Lens culinaris L.) root nodules but not in pea (Pisum sativum L.) bacteroids. Moreover, heterologous expression of the R. leguminosarum hup system in bacteroid cells of Rhizobium tropici and Mesorhizobium loti displayed reduced levels of hydrogen uptake in the absence of hupE. These data support the role of R. leguminosarum HupE as a nickel permease required for hydrogen uptake under both free-living and symbiotic conditions.
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Affiliation(s)
- Belén Brito
- Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, and Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M40, km 37.7, 28223 Pozuelo de Alarcón, Madrid, Spain, Université Lyon, F-69622 Lyon, Université Lyon 1, Villeurbanne, INSA de Lyon, F-69621 Villeurbanne, and CNRS UMR5240 Microbiologie, Adaptation et Pathogénie, Lyon, France, Consejo Superior de Investigaciones Científicas (CSIC), Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM), Madrid, Spain
| | - Rosa-Isabel Prieto
- Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, and Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M40, km 37.7, 28223 Pozuelo de Alarcón, Madrid, Spain, Université Lyon, F-69622 Lyon, Université Lyon 1, Villeurbanne, INSA de Lyon, F-69621 Villeurbanne, and CNRS UMR5240 Microbiologie, Adaptation et Pathogénie, Lyon, France, Consejo Superior de Investigaciones Científicas (CSIC), Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM), Madrid, Spain
| | - Ezequiel Cabrera
- Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, and Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M40, km 37.7, 28223 Pozuelo de Alarcón, Madrid, Spain, Université Lyon, F-69622 Lyon, Université Lyon 1, Villeurbanne, INSA de Lyon, F-69621 Villeurbanne, and CNRS UMR5240 Microbiologie, Adaptation et Pathogénie, Lyon, France, Consejo Superior de Investigaciones Científicas (CSIC), Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM), Madrid, Spain
| | - Marie-Andrée Mandrand-Berthelot
- Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, and Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M40, km 37.7, 28223 Pozuelo de Alarcón, Madrid, Spain, Université Lyon, F-69622 Lyon, Université Lyon 1, Villeurbanne, INSA de Lyon, F-69621 Villeurbanne, and CNRS UMR5240 Microbiologie, Adaptation et Pathogénie, Lyon, France, Consejo Superior de Investigaciones Científicas (CSIC), Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM), Madrid, Spain
| | - Juan Imperial
- Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, and Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M40, km 37.7, 28223 Pozuelo de Alarcón, Madrid, Spain, Université Lyon, F-69622 Lyon, Université Lyon 1, Villeurbanne, INSA de Lyon, F-69621 Villeurbanne, and CNRS UMR5240 Microbiologie, Adaptation et Pathogénie, Lyon, France, Consejo Superior de Investigaciones Científicas (CSIC), Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM), Madrid, Spain
| | - Tomás Ruiz-Argüeso
- Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, and Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M40, km 37.7, 28223 Pozuelo de Alarcón, Madrid, Spain, Université Lyon, F-69622 Lyon, Université Lyon 1, Villeurbanne, INSA de Lyon, F-69621 Villeurbanne, and CNRS UMR5240 Microbiologie, Adaptation et Pathogénie, Lyon, France, Consejo Superior de Investigaciones Científicas (CSIC), Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM), Madrid, Spain
| | - José-Manuel Palacios
- Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, and Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M40, km 37.7, 28223 Pozuelo de Alarcón, Madrid, Spain, Université Lyon, F-69622 Lyon, Université Lyon 1, Villeurbanne, INSA de Lyon, F-69621 Villeurbanne, and CNRS UMR5240 Microbiologie, Adaptation et Pathogénie, Lyon, France, Consejo Superior de Investigaciones Científicas (CSIC), Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid (UPM), Madrid, Spain
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Brito B, Toffanin A, Prieto RI, Imperial J, Ruiz-Argüeso T, Palacios JM. Host-dependent expression of Rhizobium leguminosarum bv. viciae hydrogenase is controlled at transcriptional and post-transcriptional levels in legume nodules. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:597-604. [PMID: 18393619 DOI: 10.1094/mpmi-21-5-0597] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The legume host affects the expression of Rhizobium leguminosarum hydrogenase activity in root nodules. High levels of symbiotic hydrogenase activity were detected in R. leguminosarum bacteroids from different hosts, with the exception of lentil (Lens culinaris). Transcription analysis showed that the NifA-regulated R. leguminosarum hydrogenase structural gene promoter (P(1)) is poorly induced in lentil root nodules. Replacement of the P(1) promoter by the FnrN-dependent promoter of the fixN gene restored transcription of hup genes in lentil bacteroids, but not hydrogenase activity. In the P(fixN)-hupSL strain, additional copies of the hup gene cluster and nickel supplementation to lentil plants increased bacteroid hydrogenase activity. However, the level of activity in lentil still was significantly lower than in pea bacteroids, indicating that an additional factor is impairing hydrogenase expression inside lentil nodules. Immunological analysis revealed that lentil bacteroids contain reduced levels of both hydrogenase structural subunit HupL and nickel-binding protein HypB. Altogether, results indicate that hydrogenase expression is affected by the legume host at the level of both transcription of hydrogenase structural genes and biosynthesis or stability of nickel-related proteins HypB and HupL, and suggest the existence of a plant-dependent mechanism that affects hydrogenase activity during the symbiosis by limiting nickel availability to the bacteroid.
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Affiliation(s)
- Belén Brito
- Departamento de Biotecnología, Escuela Técnica Superior Ingenieros Agrónomos, Universidad Politécnica de Madrid (UPM), Spain
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7
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Vignais PM, Billoud B. Occurrence, Classification, and Biological Function of Hydrogenases: An Overview. Chem Rev 2007; 107:4206-72. [PMID: 17927159 DOI: 10.1021/cr050196r] [Citation(s) in RCA: 1025] [Impact Index Per Article: 60.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Paulette M. Vignais
- CEA Grenoble, Laboratoire de Biochimie et Biophysique des Systèmes Intégrés, UMR CEA/CNRS/UJF 5092, Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), 17 rue des Martyrs, 38054 Grenoble cedex 9, France, and Atelier de BioInformatique Université Pierre et Marie Curie (Paris 6), 12 rue Cuvier, 75005 Paris, France
| | - Bernard Billoud
- CEA Grenoble, Laboratoire de Biochimie et Biophysique des Systèmes Intégrés, UMR CEA/CNRS/UJF 5092, Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), 17 rue des Martyrs, 38054 Grenoble cedex 9, France, and Atelier de BioInformatique Université Pierre et Marie Curie (Paris 6), 12 rue Cuvier, 75005 Paris, France
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Baginsky C, Brito B, Imperial J, Ruiz-Argüeso T, Palacios JM. Symbiotic hydrogenase activity in Bradyrhizobium sp. (Vigna) increases nitrogen content in Vigna unguiculata plants. Appl Environ Microbiol 2005; 71:7536-8. [PMID: 16269797 PMCID: PMC1287714 DOI: 10.1128/aem.71.11.7536-7538.2005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bradyrhizobium sp. (Lupinus) and Bradyrhizobium sp. (Vigna) mutants in which hydrogenase (hup) activity was affected were constructed and analyzed. Vigna unguiculata plants inoculated with the Bradyrhizobium sp. (Vigna) hup mutant showed reduced nitrogenase activity and also a significant decrease in nitrogen content, suggesting a relevant contribution of hydrogenase activity to plant yield.
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Affiliation(s)
- Cecilia Baginsky
- Laboratory of Microbiology, Department of Biotechnology, E.T.S. Ingenieros Agrónomos, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
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9
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Ureta AC, Imperial J, Ruiz-Argüeso T, Palacios JM. Rhizobium leguminosarum biovar viciae symbiotic hydrogenase activity and processing are limited by the level of nickel in agricultural soils. Appl Environ Microbiol 2005; 71:7603-6. [PMID: 16269813 PMCID: PMC1287657 DOI: 10.1128/aem.71.11.7603-7606.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Accepted: 06/16/2005] [Indexed: 11/20/2022] Open
Abstract
Analysis of levels of hydrogenase processing and activity in Rhizobium leguminosarum biovar viciae bacteroids from pea (Pisum sativum) plants showed that the oxidation of nitrogenase-evolved hydrogen is limited by the availability of nickel in agricultural soils. This limitation was overcome by using an inoculant strain engineered for higher hydrogenase expression.
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Affiliation(s)
- Ana-Claudia Ureta
- Department of Biotechnology, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
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10
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Fernández D, Toffanin A, Palacios JM, Ruiz-Argüeso T, Imperial J. Hydrogenase genes are uncommon and highly conserved in Rhizobium leguminosarum bv. viciae. FEMS Microbiol Lett 2005; 253:83-8. [PMID: 16216440 DOI: 10.1016/j.femsle.2005.09.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2005] [Revised: 09/14/2005] [Accepted: 09/14/2005] [Indexed: 11/30/2022] Open
Abstract
A screening for hydrogen uptake (hup) genes in Rhizobium leguminosarum bv. viciae isolates from different locations within Spain identified no Hup+ strains, confirming the scarcity of the Hup trait in R. leguminosarum. However, five new Hup+ strains were isolated from Ni-rich soils from Italy and Germany. The hup gene variability was studied in these strains and in six available strains isolated from North America. Sequence analysis of three regions within the hup cluster showed an unusually high conservation among strains, with only 0.5-0.6% polymorphic sites, suggesting that R. leguminosarum acquired hup genes de novo in a very recent event.
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Affiliation(s)
- Domingo Fernández
- Laboratorio de Microbiología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Ciudad Universitaria, s/n, 28040 Madrid, Spain
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11
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Palacios JM, Manyani H, Martínez M, Ureta AC, Brito B, Báscones E, Rey L, Imperial J, Ruiz-Argüeso T. Genetics and biotechnology of the H(2)-uptake [NiFe] hydrogenase from Rhizobium leguminosarum bv. viciae, a legume endosymbiotic bacterium. Biochem Soc Trans 2005; 33:94-6. [PMID: 15667275 DOI: 10.1042/bst0330094] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A limited number of strains belonging to several genera of Rhizobiaceae are capable of expressing a hydrogenase system that allows partial or full recycling of hydrogen evolved by nitrogenase, thus increasing the energy efficiency of the nitrogen fixation process. This review is focused on the genetics and biotechnology of the hydrogenase system from Rhizobium leguminosarum bv. viciae, a frequent inhabitant of European soils capable of establishing symbiotic association with peas, lentils, vetches and other legumes.
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Affiliation(s)
- J M Palacios
- Laboratorio de Microbiología, Department of Biotechnology, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain.
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13
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Abstract
Nickel is an essential nutrient for selected microorganisms where it participates in a variety of cellular processes. Many microbes are capable of sensing cellular nickel ion concentrations and taking up this nutrient via nickel-specific permeases or ATP-binding cassette-type transport systems. The metal ion is specifically incorporated into nickel-dependent enzymes, often via complex assembly processes requiring accessory proteins and additional non-protein components, in some cases accompanied by nucleotide triphosphate hydrolysis. To date, nine nickel-containing enzymes are known: urease, NiFe-hydrogenase, carbon monoxide dehydrogenase, acetyl-CoA decarbonylase/synthase, methyl coenzyme M reductase, certain superoxide dismutases, some glyoxylases, aci-reductone dioxygenase, and methylenediurease. Seven of these enzymes have been structurally characterized, revealing distinct metallocenter environments in each case.
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Affiliation(s)
- Scott B Mulrooney
- Department of Microbiology and Molecular Genetics, 6193 Biomedical Physical Sciences, Michigan State University, East Lansing, MI 48824, USA
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Baginsky C, Brito B, Imperial J, Palacios JM, Ruiz-Argüeso T. Diversity and evolution of hydrogenase systems in rhizobia. Appl Environ Microbiol 2002; 68:4915-24. [PMID: 12324339 PMCID: PMC126442 DOI: 10.1128/aem.68.10.4915-4924.2002] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Uptake hydrogenases allow rhizobia to recycle the hydrogen generated in the nitrogen fixation process within the legume nodule. Hydrogenase (hup) systems in Bradyrhizobium japonicum and Rhizobium leguminosarum bv. viciae show highly conserved sequence and gene organization, but important differences exist in regulation and in the presence of specific genes. We have undertaken the characterization of hup gene clusters from Bradyrhizobium sp. (Lupinus), Bradyrhizobium sp. (Vigna), and Rhizobium tropici and Azorhizobium caulinodans strains with the aim of defining the extent of diversity in hup gene composition and regulation in endosymbiotic bacteria. Genomic DNA hybridizations using hupS, hupE, hupUV, hypB, and hoxA probes showed a diversity of intraspecific hup profiles within Bradyrhizobium sp. (Lupinus) and Bradyrhizobium sp. (Vigna) strains and homogeneous intraspecific patterns within R. tropici and A. caulinodans strains. The analysis also revealed differences regarding the possession of hydrogenase regulatory genes. Phylogenetic analyses using partial sequences of hupS and hupL clustered R. leguminosarum and R. tropici hup sequences together with those from B. japonicum and Bradyrhizobium sp. (Lupinus) strains, suggesting a common origin. In contrast, Bradyrhizobium sp. (Vigna) hup sequences diverged from the rest of rhizobial sequences, which might indicate that those organisms have evolved independently and possibly have acquired the sequences by horizontal transfer from an unidentified source.
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Affiliation(s)
- Cecilia Baginsky
- Laboratorio de Microbiología, E.T.S. Ingenieros Agrónomos, Universidad Politécnica de Madrid, Spain
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Brito B, Palacios JM, Imperial J, Ruiz-Argüeso T. Engineering the Rhizobium leguminosarum bv. viciae hydrogenase system for expression in free-living microaerobic cells and increased symbiotic hydrogenase activity. Appl Environ Microbiol 2002; 68:2461-7. [PMID: 11976122 PMCID: PMC127565 DOI: 10.1128/aem.68.5.2461-2467.2002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rhizobium leguminosarum bv. viciae UPM791 induces hydrogenase activity in pea (Pisum sativum L.) bacteroids but not in free-living cells. The symbiotic induction of hydrogenase structural genes (hupSL) is mediated by NifA, the general regulator of the nitrogen fixation process. So far, no culture conditions have been found to induce NifA-dependent promoters in vegetative cells of this bacterium. This hampers the study of the R. leguminosarum hydrogenase system. We have replaced the native NifA-dependent hupSL promoter with the FnrN-dependent fixN promoter, generating strain SPF25, which expresses the hup system in microaerobic free-living cells. SPF25 reaches levels of hydrogenase activity in microaerobiosis similar to those induced in UPM791 bacteroids. A sixfold increase in hydrogenase activity was detected in merodiploid strain SPF25(pALPF1). A time course induction of hydrogenase activity in microaerobic free-living cells of SPF25(pALPF1) shows that hydrogenase activity is detected after 3 h of microaerobic incubation. Maximal hydrogen uptake activity was observed after 10 h of microaerobiosis. Immunoblot analysis of microaerobically induced SPF25(pALPF1) cell fractions indicated that the HupL active form is located in the membrane, whereas the unprocessed protein remains in the soluble fraction. Symbiotic hydrogenase activity of strain SPF25 was not impaired by the promoter replacement. Moreover, bacteroids from pea plants grown in low-nickel concentrations induced higher levels of hydrogenase activity than the wild-type strain and were able to recycle all hydrogen evolved by nodules. This constitutes a new strategy to improve hydrogenase activity in symbiosis.
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Affiliation(s)
- B Brito
- Laboratorio de Microbiología, E. T. S. Ingenieros Agrónomos, Universidad Politécnica de Madrid, 28040 Madrid, Spain
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Báscones E, Imperial J, Ruiz-Argüeso T, Palacios JM. Generation of new hydrogen-recycling Rhizobiaceae strains by introduction of a novel hup minitransposon. Appl Environ Microbiol 2000; 66:4292-9. [PMID: 11010872 PMCID: PMC92298 DOI: 10.1128/aem.66.10.4292-4299.2000] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hydrogen evolution by nitrogenase is a source of inefficiency for the nitrogen fixation process by the Rhizobium-legume symbiosis. To develop a strategy to generate rhizobial strains with H(2)-recycling ability, we have constructed a Tn5 derivative minitransposon (TnHB100) that contains the ca. 18-kb H(2) uptake (hup) gene cluster from Rhizobium leguminosarum bv. viciae UPM791. Bacteroids from TnHB100-containing strains of R. leguminosarum bv. viciae PRE, Bradyrhizobium japonicum, R. etli, and Mesorhizobium loti expressed high levels of hydrogenase activity that resulted in full recycling of the hydrogen evolved by nitrogenase in nodules. Efficient processing of the hydrogenase large subunit (HupL) in these strains was shown by immunoblot analysis of bacteroid extracts. In contrast, Sinorhizobium meliloti, M. ciceri, and R. leguminosarum bv. viciae UML2 strains showed poor expression of the hup system that resulted in H(2)-evolving nodules. For the latter group of strains, no immunoreactive material was detected in bacteroid extracts using anti-HupL antiserum, suggesting a low level of transcription of hup genes or HupL instability. A general procedure for the characterization of the minitransposon insertion site and removal of antibiotic resistance gene included in TnHB100 has been developed and used to generate engineered strains suitable for field release.
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Affiliation(s)
- E Báscones
- Laboratorio de Microbiología, Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
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