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Chen X, Wang W, Hu H, Tang H, Liu Y, Xu P, Lin K, Cui C. Insights from comparative proteomic analysis into degradation of phenanthrene and salt tolerance by the halophilic Martelella strain AD-3. ECOTOXICOLOGY (LONDON, ENGLAND) 2021; 30:1499-1510. [PMID: 33244677 DOI: 10.1007/s10646-020-02310-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/30/2020] [Indexed: 06/11/2023]
Abstract
A halophilic PAHs-degrading strain, Martelella AD-3, was previously isolated from highly saline petroleum-contaminated soil. In this study, label-free proteomics were performed to identify differentially expressed proteins (DEPs) under Group P (phenanthrene +5% salinity) and Group G (glycerol +1% salinity), which would help to reveal the mechanism of phenanthrene degradation and salt tolerance. A total of 307 up-regulated DEPs were found in Group P, including 17 phenanthrene degradation proteins. Among these phenanthrene-degrading proteins, the ferredoxin of aromatic ring-hydroxylating dioxygenase (RHD) was up-regulated by 110-fold and gentisate 1,2-dioxygenases (GDOs) were only expressed in Group P. Besides, we also found nine high salt stress response proteins, including ectoine synthase and transport protein of compatible (osmoprotectant) solutes, were differentially up-regulated. These results indicate that strain AD-3 mainly relied on RHD and dihydrodiol dehydrogenase to degrade phenanthrene, and accumulated compatible solutes for resistance to salt stress. This study provides strong theoretical guidance for understanding the degradation of phenanthrene by strain AD-3 in high salt environments.
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Affiliation(s)
- Xin Chen
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, People's Republic of China
| | - Weiwei Wang
- State Key Laboratory of Microbial Metabolism, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Haiyang Hu
- State Key Laboratory of Microbial Metabolism, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Hongzhi Tang
- State Key Laboratory of Microbial Metabolism, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China.
| | - Yongdi Liu
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, People's Republic of China
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Kuangfei Lin
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, People's Republic of China
| | - Changzheng Cui
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, People's Republic of China.
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Aragón-Aranda B, Palacios-Chaves L, Salvador-Bescós M, de Miguel MJ, Muñoz PM, Vences-Guzmán MÁ, Zúñiga-Ripa A, Lázaro-Antón L, Sohlenkamp C, Moriyón I, Iriarte M, Conde-Álvarez R. The Phospholipid N-Methyltransferase and Phosphatidylcholine Synthase Pathways and the ChoXWV Choline Uptake System Involved in Phosphatidylcholine Synthesis Are Widely Conserved in Most, but Not All Brucella Species. Front Microbiol 2021; 12:614243. [PMID: 34421831 PMCID: PMC8371380 DOI: 10.3389/fmicb.2021.614243] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 07/09/2021] [Indexed: 11/13/2022] Open
Abstract
The brucellae are facultative intracellular bacteria with a cell envelope rich in phosphatidylcholine (PC). PC is abundant in eukaryotes but rare in prokaryotes, and it has been proposed that Brucella uses PC to mimic eukaryotic-like features and avoid innate immune responses in the host. Two PC synthesis pathways are known in prokaryotes: the PmtA-catalyzed trimethylation of phosphatidylethanolamine and the direct linkage of choline to CDP-diacylglycerol catalyzed by the PC synthase Pcs. Previous studies have reported that B. abortus and B. melitensis possess non-functional PmtAs and that PC is synthesized exclusively via Pcs in these strains. A putative choline transporter ChoXWV has also been linked to PC synthesis in B. abortus. Here, we report that Pcs and Pmt pathways are active in B. suis biovar 2 and that a bioinformatics analysis of Brucella genomes suggests that PmtA is only inactivated in B. abortus and B. melitensis strains. We also show that ChoXWV is active in B. suis biovar 2 and conserved in all brucellae except B. canis and B. inopinata. Unexpectedly, the experimentally verified ChoXWV dysfunction in B. canis did not abrogate PC synthesis in a PmtA-deficient mutant, which suggests the presence of an unknown mechanism for obtaining choline for the Pcs pathway in Brucella. We also found that ChoXWV dysfunction did not cause attenuation in B. suis biovar 2. The results of these studies are discussed with respect to the proposed role of PC in Brucella virulence and how differential use of the Pmt and Pcs pathways may influence the interactions of these bacteria with their mammalian hosts.
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Affiliation(s)
- Beatriz Aragón-Aranda
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - Leyre Palacios-Chaves
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - Miriam Salvador-Bescós
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - María Jesús de Miguel
- Unidad de Producción y Sanidad Animal, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Zaragoza, Spain.,Instituto Agroalimentario de Aragón-IA2, CITA-Universidad de Zaragoza, Zaragoza, Spain
| | - Pilar M Muñoz
- Unidad de Producción y Sanidad Animal, Centro de Investigación y Tecnología Agroalimentaria de Aragón, Zaragoza, Spain.,Instituto Agroalimentario de Aragón-IA2, CITA-Universidad de Zaragoza, Zaragoza, Spain
| | | | - Amaia Zúñiga-Ripa
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - Leticia Lázaro-Antón
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - Christian Sohlenkamp
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Ignacio Moriyón
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - Maite Iriarte
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
| | - Raquel Conde-Álvarez
- Dpto. de Microbiología y Parasitología, Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra, Universidad de Navarra, Pamplona, Spain
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Ormeño-Orrillo E, Gomes DF, Del Cerro P, Vasconcelos ATR, Canchaya C, Almeida LGP, Mercante FM, Ollero FJ, Megías M, Hungria M. Genome of Rhizobium leucaenae strains CFN 299(T) and CPAO 29.8: searching for genes related to a successful symbiotic performance under stressful conditions. BMC Genomics 2016; 17:534. [PMID: 27485828 PMCID: PMC4971678 DOI: 10.1186/s12864-016-2859-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Accepted: 06/27/2016] [Indexed: 01/02/2023] Open
Abstract
Background Common bean (Phaseolus vulgaris L.) is the most important legume cropped worldwide for food production and its agronomic performance can be greatly improved if the benefits from symbiotic nitrogen fixation are maximized. The legume is known for its high promiscuity in nodulating with several Rhizobium species, but those belonging to the Rhizobium tropici “group” are the most successful and efficient in fixing nitrogen in tropical acid soils. Rhizobium leucaenae belongs to this group, which is abundant in the Brazilian “Cerrados” soils and frequently submitted to several environmental stresses. Here we present the first high-quality genome drafts of R. leucaenae, including the type strain CFN 299T and the very efficient strain CPAO 29.8. Our main objective was to identify features that explain the successful capacity of R. leucaenae in nodulating common bean under stressful environmental conditions. Results The genomes of R. leucaenae strains CFN 299T and CPAO 29.8 were estimated at 6.7–6.8 Mbp; 7015 and 6899 coding sequences (CDS) were predicted, respectively, 6264 of which are common to both strains. The genomes of both strains present a large number of CDS that may confer tolerance of high temperatures, acid soils, salinity and water deficiency. Types I, II, IV-pili, IV and V secretion systems were present in both strains and might help soil and host colonization as well as the symbiotic performance under stressful conditions. The symbiotic plasmid of CPAO 29.8 is highly similar to already described tropici pSyms, including five copies of nodD and three of nodA genes. R. leucaenae CFN 299T is capable of synthesizing Nod factors in the absence of flavonoids when submitted to osmotic stress, indicating that under abiotic stress the regulation of nod genes might be different. Conclusion A detailed study of the genes putatively related to stress tolerance in R. leucaenae highlighted an intricate pattern comprising a variety of mechanisms that are probably orchestrated to tolerate the stressful conditions to which the strains are submitted on a daily basis. The capacity to synthesize Nod factors under abiotic stress might follow the same regulatory pathways as in CIAT 899T and may help both to improve bacterial survival and to expand host range to guarantee the perpetuation of the symbiosis. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2859-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Douglas Fabiano Gomes
- Embrapa Soja, C.P. 231, 86001-970, Londrina, Paraná, Brazil.,CAPES, SBN, Quadra 2, Bloco L, Lote 06, Edifício Capes, 70.040-020, Brasília, Federal District, Brazil
| | - Pablo Del Cerro
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes, 6 Apdo Postal, 41012, Sevilla, Spain
| | - Ana Tereza Ribeiro Vasconcelos
- Laboratório Nacional de Computação Científica (LNCC), Labinfo, Rua Getúlio Vargas 333, 25651-071, Petrópolis, Rio de Janeiro, Brazil
| | - Carlos Canchaya
- Department Biochemistry, Genetics and Immunology, Faculty of Biology, University of Vigo, 36310, Vigo, Spain
| | - Luiz Gonzaga Paula Almeida
- Laboratório Nacional de Computação Científica (LNCC), Labinfo, Rua Getúlio Vargas 333, 25651-071, Petrópolis, Rio de Janeiro, Brazil
| | | | - Francisco Javier Ollero
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes, 6 Apdo Postal, 41012, Sevilla, Spain
| | - Manuel Megías
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes, 6 Apdo Postal, 41012, Sevilla, Spain
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Involvement of Agrobacterium tumefaciens Galacturonate Tripartite ATP-Independent Periplasmic (TRAP) Transporter GaaPQM in Virulence Gene Expression. Appl Environ Microbiol 2015; 82:1136-1146. [PMID: 26637603 DOI: 10.1128/aem.02891-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 12/01/2015] [Indexed: 11/20/2022] Open
Abstract
Monosaccharides capable of serving as nutrients for the soil bacterium Agrobacterium tumefaciens are also inducers of the vir regulon present in the tumor-inducing (Ti) plasmid of this plant pathogen. One such monosaccharide is galacturonate, the predominant monomer of pectin found in plant cell walls. This ligand is recognized by the periplasmic sugar binding protein ChvE, which interacts with the VirA histidine kinase that controls vir gene expression. Although ChvE is also a member of the ChvE-MmsAB ABC transporter involved in the utilization of many neutral sugars, it is not involved in galacturonate utilization. In this study, a putative tripartite ATP-independent periplasmic (TRAP) transporter, GaaPQM, is shown to be essential for the utilization of galacturonic acid; we show that residue R169 in the predicted sugar binding site of the GaaP is required for activity. The gene upstream of gaaPQM (gaaR) encodes a member of the GntR family of regulators. GaaR is shown to repress the expression of gaaPQM, and the repression is relieved in the presence of the substrate for GaaPQM. Moreover, GaaR is shown to bind putative promoter regions in the sequences required for galacturonic acid utilization. Finally, A. tumefaciens strains carrying a deletion of gaaPQM are more sensitive to galacturonate as an inducer of vir gene expression, while the overexpression of gaaPQM results in strains being less sensitive to this vir inducer. This supports a model in which transporter activity is crucial in ensuring that vir gene expression occurs only at sites of high ligand concentration, such as those at a plant wound site.
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Enzymatic properties and substrate specificity of a bacterial phosphatidylcholine synthase. FEBS J 2014; 281:3523-41. [DOI: 10.1111/febs.12877] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 06/11/2014] [Accepted: 06/11/2014] [Indexed: 11/26/2022]
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Rudder S, Doohan F, Creevey CJ, Wendt T, Mullins E. Genome sequence of Ensifer adhaerens OV14 provides insights into its ability as a novel vector for the genetic transformation of plant genomes. BMC Genomics 2014; 15:268. [PMID: 24708309 PMCID: PMC4051167 DOI: 10.1186/1471-2164-15-268] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 03/19/2014] [Indexed: 02/19/2023] Open
Abstract
BACKGROUND Recently it has been shown that Ensifer adhaerens can be used as a plant transformation technology, transferring genes into several plant genomes when equipped with a Ti plasmid. For this study, we have sequenced the genome of Ensifer adhaerens OV14 (OV14) and compared it with those of Agrobacterium tumefaciens C58 (C58) and Sinorhizobium meliloti 1021 (1021); the latter of which has also demonstrated a capacity to genetically transform crop genomes, albeit at significantly reduced frequencies. RESULTS The 7.7 Mb OV14 genome comprises two chromosomes and two plasmids. All protein coding regions in the OV14 genome were functionally grouped based on an eggNOG database. No genes homologous to the A. tumefaciens Ti plasmid vir genes appeared to be present in the OV14 genome. Unexpectedly, OV14 and 1021 were found to possess homologs to chromosomal based genes cited as essential to A. tumefaciens T-DNA transfer. Of significance, genes that are non-essential but exert a positive influence on virulence and the ability to genetically transform host genomes were identified in OV14 but were absent from the 1021 genome. CONCLUSIONS This study reveals the presence of homologs to chromosomally based Agrobacterium genes that support T-DNA transfer within the genome of OV14 and other alphaproteobacteria. The sequencing and analysis of the OV14 genome increases our understanding of T-DNA transfer by non-Agrobacterium species and creates a platform for the continued improvement of Ensifer-mediated transformation (EMT).
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Affiliation(s)
- Steven Rudder
- Department of Crop Science, Teagasc Crops Research Centre, Oak Park, Carlow, Ireland
- UCD Earth Institute and UCD School of Biology and Environmental Sciences, University College Dublin, Belfield, Dublin 4, Ireland
| | - Fiona Doohan
- UCD Earth Institute and UCD School of Biology and Environmental Sciences, University College Dublin, Belfield, Dublin 4, Ireland
| | - Christopher J Creevey
- Animal and Bioscience Research Department, Animal and Grassland Research and Innovation Centre, Teagasc, Grange, Dunsany, Co. Meath, Ireland
- Current address: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, Ceredigion SY23 3FL, UK
| | - Toni Wendt
- Department of Crop Science, Teagasc Crops Research Centre, Oak Park, Carlow, Ireland
- UCD Earth Institute and UCD School of Biology and Environmental Sciences, University College Dublin, Belfield, Dublin 4, Ireland
- Current address: Carlsberg Research Centre, Gamle Carlsberg Vej 4-10, 1799 Copenhagen V, Denmark
| | - Ewen Mullins
- Department of Crop Science, Teagasc Crops Research Centre, Oak Park, Carlow, Ireland
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Aktas M, Danne L, Möller P, Narberhaus F. Membrane lipids in Agrobacterium tumefaciens: biosynthetic pathways and importance for pathogenesis. FRONTIERS IN PLANT SCIENCE 2014; 5:109. [PMID: 24723930 PMCID: PMC3972451 DOI: 10.3389/fpls.2014.00109] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 03/07/2014] [Indexed: 05/25/2023]
Abstract
Many cellular processes critically depend on the membrane composition. In this review, we focus on the biosynthesis and physiological roles of membrane lipids in the plant pathogen Agrobacterium tumefaciens. The major components of A. tumefaciens membranes are the phospholipids (PLs), phosphatidylethanolamine (PE), phosphatidylglycerol, phosphatidylcholine (PC) and cardiolipin, and ornithine lipids (OLs). Under phosphate-limited conditions, the membrane composition shifts to phosphate-free lipids like glycolipids, OLs and a betaine lipid. Remarkably, PC and OLs have opposing effects on virulence of A. tumefaciens. OL-lacking A. tumefaciens mutants form tumors on the host plant earlier than the wild type suggesting a reduced host defense response in the absence of OLs. In contrast, A. tumefaciens is compromised in tumor formation in the absence of PC. In general, PC is a rare component of bacterial membranes but amount to ~22% of all PLs in A. tumefaciens. PC biosynthesis occurs via two pathways. The phospholipid N-methyltransferase PmtA methylates PE via the intermediates monomethyl-PE and dimethyl-PE to PC. In the second pathway, the membrane-integral enzyme PC synthase (Pcs) condenses choline with CDP-diacylglycerol to PC. Apart from the virulence defect, PC-deficient A. tumefaciens pmtA and pcs double mutants show reduced motility, enhanced biofilm formation and increased sensitivity towards detergent and thermal stress. In summary, there is cumulative evidence that the membrane lipid composition of A. tumefaciens is critical for agrobacterial physiology and tumor formation.
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Affiliation(s)
| | | | | | - Franz Narberhaus
- *Correspondence: Franz Narberhaus, Microbial Biology, Department for Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, NDEF 06/783, 44780 Bochum, Germany e-mail:
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Moser R, Aktas M, Narberhaus F. Phosphatidylcholine biosynthesis inXanthomonas campestrisvia a yeast-like acylation pathway. Mol Microbiol 2014; 91:736-50. [DOI: 10.1111/mmi.12492] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/10/2013] [Indexed: 12/01/2022]
Affiliation(s)
- Roman Moser
- Microbial Biology; Ruhr University Bochum; Bochum Germany
| | - Meriyem Aktas
- Microbial Biology; Ruhr University Bochum; Bochum Germany
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Chen C, Li S, McKeever DR, Beattie GA. The widespread plant-colonizing bacterial species Pseudomonas syringae detects and exploits an extracellular pool of choline in hosts. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:891-902. [PMID: 23763788 DOI: 10.1111/tpj.12262] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 06/07/2013] [Accepted: 06/10/2013] [Indexed: 06/02/2023]
Abstract
The quaternary ammonium compound (QAC) choline is a major component of membrane lipids in eukaryotes and, if available to microbial colonists of plants, could provide benefits for growth and protection from stress. Free choline is found in homogenized plant tissues, but its subcellular location and availability to plant microbes are not known. Whole-cell bacterial bioreporters of the phytopathogen Pseudomonas syringae were constructed that couple a QAC-responsive transcriptional fusion with well-characterized bacterial QAC transporters. These bioreporters demonstrated the presence of abundant free choline compounds released from germinating seeds and seedlings of the bean Phaseolus vulgaris, and a smaller but consistently detectable amount of QACs, probably choline, from leaves. The localization of P. syringae bioreporter cells to the surface and intercellular sites of plant tissues demonstrated the extracellular location of these QAC pools. Moreover, P. syringae mutants that were deficient in the uptake of choline compounds exhibited reduced fitness on leaves, highlighting the importance of extracellular choline to P. syringae on leaves. Our data support a model in which this choline pool is derived from the phospholipid phosphatidylcholine through plant-encoded phospholipases that release choline into the intercellular spaces of plant tissues, such as for membrane lipid recycling. The consequent extracellular release of choline compounds enables their interception and exploitation by plant-associated microbes, and thus provides a selective advantage for microbes such as P. syringae that are adapted to maximally exploit choline.
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Affiliation(s)
- Chiliang Chen
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA 50011, USA
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10
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Ormeño-Orrillo E, Menna P, Almeida LGP, Ollero FJ, Nicolás MF, Pains Rodrigues E, Shigueyoshi Nakatani A, Silva Batista JS, Oliveira Chueire LM, Souza RC, Ribeiro Vasconcelos AT, Megías M, Hungria M, Martínez-Romero E. Genomic basis of broad host range and environmental adaptability of Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 which are used in inoculants for common bean (Phaseolus vulgaris L.). BMC Genomics 2012; 13:735. [PMID: 23270491 PMCID: PMC3557214 DOI: 10.1186/1471-2164-13-735] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 12/15/2012] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 are α-Proteobacteria that establish nitrogen-fixing symbioses with a range of legume hosts. These strains are broadly used in commercial inoculants for application to common bean (Phaseolus vulgaris) in South America and Africa. Both strains display intrinsic resistance to several abiotic stressful conditions such as low soil pH and high temperatures, which are common in tropical environments, and to several antimicrobials, including pesticides. The genetic determinants of these interesting characteristics remain largely unknown. RESULTS Genome sequencing revealed that CIAT 899 and PRF 81 share a highly-conserved symbiotic plasmid (pSym) that is present also in Rhizobium leucaenae CFN 299, a rhizobium displaying a similar host range. This pSym seems to have arisen by a co-integration event between two replicons. Remarkably, three distinct nodA genes were found in the pSym, a characteristic that may contribute to the broad host range of these rhizobia. Genes for biosynthesis and modulation of plant-hormone levels were also identified in the pSym. Analysis of genes involved in stress response showed that CIAT 899 and PRF 81 are well equipped to cope with low pH, high temperatures and also with oxidative and osmotic stresses. Interestingly, the genomes of CIAT 899 and PRF 81 had large numbers of genes encoding drug-efflux systems, which may explain their high resistance to antimicrobials. Genome analysis also revealed a wide array of traits that may allow these strains to be successful rhizosphere colonizers, including surface polysaccharides, uptake transporters and catabolic enzymes for nutrients, diverse iron-acquisition systems, cell wall-degrading enzymes, type I and IV pili, and novel T1SS and T5SS secreted adhesins. CONCLUSIONS Availability of the complete genome sequences of CIAT 899 and PRF 81 may be exploited in further efforts to understand the interaction of tropical rhizobia with common bean and other legume hosts.
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Affiliation(s)
- Ernesto Ormeño-Orrillo
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - Pâmela Menna
- Embrapa Soja, C. P. 231, Londrina, Paraná, 86001-970, Brazil
| | - Luiz Gonzaga P Almeida
- Laboratório Nacional de Computação Científica (LNCC), Avenida Getúlio Vargas 333, Petrópolis, Rio de Janeiro, Brazil
| | | | - Marisa Fabiana Nicolás
- Laboratório Nacional de Computação Científica (LNCC), Avenida Getúlio Vargas 333, Petrópolis, Rio de Janeiro, Brazil
| | | | | | | | | | - Rangel Celso Souza
- Laboratório Nacional de Computação Científica (LNCC), Avenida Getúlio Vargas 333, Petrópolis, Rio de Janeiro, Brazil
| | | | - Manuel Megías
- Universidad de Sevilla, Apdo Postal 874, Sevilla, 41080, Spain
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Identification and characterization of a high-affinity choline uptake system of Brucella abortus. J Bacteriol 2012; 195:493-501. [PMID: 23161032 DOI: 10.1128/jb.01929-12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phosphatidylcholine (PC), a common phospholipid of the eukaryotic cell membrane, is present in the cell envelope of the intracellular pathogen Brucella abortus, the etiological agent of bovine brucellosis. In this pathogen, the biosynthesis of PC proceeds mainly through the phosphatidylcholine synthase pathway; hence, it relies on the presence of choline in the milieu. These observations imply that B. abortus encodes an as-yet-unknown choline uptake system. Taking advantage of the requirement of choline uptake for PC synthesis, we devised a method that allowed us to identify a homologue of ChoX, the high-affinity periplasmic binding protein of the ABC transporter ChoXWV. Disruption of the choX gene completely abrogated PC synthesis at low choline concentrations in the medium, thus indicating that it is a high-affinity transporter needed for PC synthesis via the PC synthase (PCS) pathway. However, the synthesis of PC was restored when the mutant was incubated in media with higher choline concentrations, suggesting the presence of an alternative low-affinity choline uptake activity. By means of a fluorescence-based equilibrium-binding assay and using the kinetics of radiolabeled choline uptake, we show that ChoX binds choline with an extremely high affinity, and we also demonstrate that its activity is inhibited by increasing choline concentrations. Cell infection assays indicate that ChoX activity is required during the first phase of B. abortus intracellular traffic, suggesting that choline concentrations in the early and intermediate Brucella-containing vacuoles are limited. Altogether, these results suggest that choline transport and PC synthesis are strictly regulated in B. abortus.
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Nau-Wagner G, Opper D, Rolbetzki A, Boch J, Kempf B, Hoffmann T, Bremer E. Genetic control of osmoadaptive glycine betaine synthesis in Bacillus subtilis through the choline-sensing and glycine betaine-responsive GbsR repressor. J Bacteriol 2012; 194:2703-14. [PMID: 22408163 PMCID: PMC3347207 DOI: 10.1128/jb.06642-11] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Accepted: 02/27/2012] [Indexed: 11/20/2022] Open
Abstract
Synthesis of the compatible solute glycine betaine confers a considerable degree of osmotic stress tolerance to Bacillus subtilis. This osmoprotectant is produced through the uptake of the precursor choline via the osmotically inducible OpuB and OpuC ABC transporters and a subsequent two-step oxidation process by the GbsB and GbsA enzymes. We characterized a regulatory protein, GbsR, controlling the transcription of both the structural genes for the glycine betaine biosynthetic enzymes (gbsAB) and those for the choline-specific OpuB transporter (opuB) but not of that for the promiscuous OpuC transporter. GbsR acts genetically as a repressor and functions as an intracellular choline sensor. Spectroscopic analysis of the purified GbsR protein showed that it binds the inducer choline with an apparent K(D) (equilibrium dissociation constant) of approximately 165 μM. Based on the X-ray structure of a protein (Mj223) from Methanococcus jannaschii, a homology model for GbsR was derived. Inspection of this GbsR in silico model revealed a possible ligand-binding pocket for choline resembling those of known choline-binding sites present in solute receptors of microbial ABC transporters, e.g., that of the OpuBC ligand-binding protein of the OpuB ABC transporter. GbsR was not only needed to control gbsAB and opuB expression in response to choline availability but also required to genetically tune down glycine betaine production once cellular adjustment to high osmolarity has been achieved. The GbsR regulatory protein from B. subtilis thus records and integrates cellular and environmental signals for both the onset and the repression of the synthesis of the osmoprotectant glycine betaine.
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Affiliation(s)
- Gabriele Nau-Wagner
- Philipps-University Marburg, Department of Biology, Laboratory for Microbiology, Marburg, Germany
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