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Bullones-Bolaños A, Bernal-Bayard J, Ramos-Morales F. The NEL Family of Bacterial E3 Ubiquitin Ligases. Int J Mol Sci 2022; 23:7725. [PMID: 35887072 PMCID: PMC9320238 DOI: 10.3390/ijms23147725] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 07/08/2022] [Accepted: 07/11/2022] [Indexed: 12/16/2022] Open
Abstract
Some pathogenic or symbiotic Gram-negative bacteria can manipulate the ubiquitination system of the eukaryotic host cell using a variety of strategies. Members of the genera Salmonella, Shigella, Sinorhizobium, and Ralstonia, among others, express E3 ubiquitin ligases that belong to the NEL family. These bacteria use type III secretion systems to translocate these proteins into host cells, where they will find their targets. In this review, we first introduce type III secretion systems and the ubiquitination process and consider the various ways bacteria use to alter the ubiquitin ligation machinery. We then focus on the members of the NEL family, their expression, translocation, and subcellular localization in the host cell, and we review what is known about the structure of these proteins, their function in virulence or symbiosis, and their specific targets.
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Affiliation(s)
| | | | - Francisco Ramos-Morales
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Sevilla, Spain; (A.B.-B.); (J.B.-B.)
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Nishat S, Hamim I, Khalil MI, Ali MA, Hossain MA, Meah MB, Islam MR. Genetic diversity of the bacterial wilt pathogen Ralstonia solanacearum using a RAPD marker. C R Biol 2015; 338:757-67. [PMID: 26302834 DOI: 10.1016/j.crvi.2015.06.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 06/06/2015] [Accepted: 06/09/2015] [Indexed: 11/27/2022]
Abstract
Bacterial wilt caused by Ralstonia solanacearum is a destructive disease of many economically important crop species. A significant variation in wilt incidence and severity in eggplant and potato was observed among the growing areas surveyed. R. solanacearum isolates obtained both from eggplant and potato belong to biovar III, while isolates from eggplant belong to race 1 and isolates obtained from potato belong to race 3. Random amplified polymorphic DNA (RAPD) technique was used as a tool for assessing genetic variation and relationship among seven isolate groups of R. solanacearum viz., RsB-1, RsB-2, RsB-3, RsP-1, RsP-2, RsP-3 and RsP-4, consisting in a total of 28 isolates. Out of the RAPD markers used, amplification with four decamer primers produced 70 bands with sizes ranging from 100 to 1400 bp. Out of 70 bands, 68 bands (97.06%) were polymorphic and two bands (2.94%) were monomorphic amongst the seven R. solanacearum isolates group. The Unweighted Pair Group Method of Arithmetic Means (UPGMA) dendrogram constructed from Nei's genetic distance produced two main clusters of the seven isolates of R. solanacearum. The isolates RsB-1, RsB-2, RsB-3 and R-4 grouped in cluster І, while RsP-2, RsP-3 and RsP-4 grouped in cluster ІІ. The highest intra-variety similarity index (Si) was found in RsB-1 isolate (86.35%) and the lowest one in RsP-2 (56.59%). The results indicated that relatively higher and lower levels of genetic variation were found in RsP-3 and RsB-3, respectively. The coefficient of gene differentiation (G(st)) was 0.5487, reflecting the existence of a high level of genetic variations among seven isolates of R. solanacearum. Comparatively higher genetic distance (0.4293) and lower genetic identity (0.6510) were observed between RsB-2 and RsP-4 combinations. The lowest genetic distance (0.0357) and highest genetic identity (0.9650) were found in RsB-1 vs. RsB-2 pair. Thus, RAPD offers a potentially simple, rapid and reliable method to evaluate genetic diversity analysis in R. solanacearum.
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Affiliation(s)
- Sayeda Nishat
- Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - Islam Hamim
- Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - M Ibrahim Khalil
- Plant Pathology Division, Bangladesh Institute of Nuclear Agriculture, Mymensingh, Bangladesh
| | - Md Ayub Ali
- Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - Muhammed Ali Hossain
- Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - M Bahadur Meah
- Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - Md Rashidul Islam
- Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh.
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Siri MI, Sanabria A, Boucher C, Pianzzola MJ. New type IV pili-related genes involved in early stages of Ralstonia solanacearum potato infection. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:712-24. [PMID: 24625029 DOI: 10.1094/mpmi-07-13-0210-r] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
This study provides insights into the pathogenesis of Ralstonia solanacearum, in particular with regards to strains belonging to phylotype IIB, sequevar 1 (IIB-1) and their interaction with potato, its natural host. We performed a comparative genomic analysis among IIB-1 R. solanacearum strains with different levels of virulence in order to identify candidate virulence genes. With this approach, we identified a 33.7-kb deletion in a strain showing reduced virulence on potato. This region contains a cluster of six genes putatively involved in type IV pili (Tfp) biogenesis. Functional analysis suggests that these proteins contribute to several Tfp-related functions such as twitching motility and biofilm formation. In addition, this genetic cluster was found to contribute to early bacterial wilt pathogenesis and colonization fitness of potato roots.
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Lefeuvre P, Cellier G, Remenant B, Chiroleu F, Prior P. Constraints on genome dynamics revealed from gene distribution among the Ralstonia solanacearum species. PLoS One 2013; 8:e63155. [PMID: 23723974 PMCID: PMC3665557 DOI: 10.1371/journal.pone.0063155] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 03/28/2013] [Indexed: 01/11/2023] Open
Abstract
Because it is suspected that gene content may partly explain host adaptation and ecology of pathogenic bacteria, it is important to study factors affecting genome composition and its evolution. While recent genomic advances have revealed extremely large pan-genomes for some bacterial species, it remains difficult to predict to what extent gene pool is accessible within or transferable between populations. As genomes bear imprints of the history of the organisms, gene distribution pattern analyses should provide insights into the forces and factors at play in the shaping and maintaining of bacterial genomes. In this study, we revisited the data obtained from a previous CGH microarrays analysis in order to assess the genomic plasticity of the R. solanacearum species complex. Gene distribution analyses demonstrated the remarkably dispersed genome of R. solanacearum with more than half of the genes being accessory. From the reconstruction of the ancestral genomes compositions, we were able to infer the number of gene gain and loss events along the phylogeny. Analyses of gene movement patterns reveal that factors associated with gene function, genomic localization and ecology delineate gene flow patterns. While the chromosome displayed lower rates of movement, the megaplasmid was clearly associated with hot-spots of gene gain and loss. Gene function was also confirmed to be an essential factor in gene gain and loss dynamics with significant differences in movement patterns between different COG categories. Finally, analyses of gene distribution highlighted possible highways of horizontal gene transfer. Due to sampling and design bias, we can only speculate on factors at play in this gene movement dynamic. Further studies examining precise conditions that favor gene transfer would provide invaluable insights in the fate of bacteria, species delineation and the emergence of successful pathogens.
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Affiliation(s)
- Pierre Lefeuvre
- CIRAD UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical, CIRAD-Université de la Réunion, Pôle de Protection des Plantes, Saint Pierre, La Réunion, France.
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González A, Plener L, Restrepo S, Boucher C, Genin S. Detection and functional characterization of a large genomic deletion resulting in decreased pathogenicity in Ralstonia solanacearum race 3 biovar 2 strains. Environ Microbiol 2011; 13:3172-85. [DOI: 10.1111/j.1462-2920.2011.02636.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Llop P, Barbé S, López MM. Functions and origin of plasmids in Erwinia species that are pathogenic to or epiphytically associated with pome fruit trees. TREES (BERLIN, GERMANY : WEST) 2011; 26:31-46. [PMID: 25983394 PMCID: PMC4425259 DOI: 10.1007/s00468-011-0630-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 09/17/2011] [Accepted: 09/21/2011] [Indexed: 05/29/2023]
Abstract
The genus Erwinia includes plant-associated pathogenic and non-pathogenic species. Among them, all species pathogenic to pome fruit trees (E. amylovora, E. pyrifoliae, E. piriflorinigrans, Erwinia sp. from Japan) cause similar symptoms, but differ in their degrees of aggressiveness, i.e. in symptoms, host range or both. The presence of plasmids of similar size, in the range of 30 kb, is a common characteristic that they possess. Besides, they share some genetic content with high homology in several genes associated with exopolysaccharide production and hence, with virulence, as well as in some other genes. Knowledge of the content of these plasmids and comparative genetic analyses may provide interesting new clues to understanding the origin and evolution of these pathogens and the level of symptoms they produce. Furthermore, genetic similarities observed among some of the plasmids (and genomes) from the above indicated pathogenic species and E. tasmaniensis or E. billingiae, which are epiphytic on the same hosts, may reveal associations that could expose the mechanisms of origin of pathogens. A summary of the current information on their plasmids and the relationships among them is presented here.
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Affiliation(s)
- Pablo Llop
- Instituto Valenciano de Investigaciones Agrarias (IVIA), Ctra. Moncada-Náquera Km 4.5, 46113 Moncada, Valencia Spain
| | - Silvia Barbé
- Instituto Valenciano de Investigaciones Agrarias (IVIA), Ctra. Moncada-Náquera Km 4.5, 46113 Moncada, Valencia Spain
| | - María M. López
- Instituto Valenciano de Investigaciones Agrarias (IVIA), Ctra. Moncada-Náquera Km 4.5, 46113 Moncada, Valencia Spain
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Coupat-Goutaland B, Bernillon D, Guidot A, Prior P, Nesme X, Bertolla F. Ralstonia solanacearum virulence increased following large interstrain gene transfers by natural transformation. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:497-505. [PMID: 21190441 DOI: 10.1094/mpmi-09-10-0197] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Horizontal gene transfer (HGT) is a major driving force of evolution and is also likely to play an important role in the threatening emergence of novel pathogens, especially if it involves distantly related strains with substantially different pathogenicity. In this study, the impact of natural transformation on pathogenicity in six strains belonging to the four phylotypes of the plant-pathogenic bacterium Ralstonia solanacearum was investigated. The study focused on genomic regions that vary between donor and recipient strains and that carry genes involved in pathogenicity such as type III effectors. First, strains from R. solanacearum species complex were naturally transformed with heterologous genomic DNA. Transferred DNA regions were then determined by comparative genomic hybridization and polymerase chain reaction sequencing. We identified three transformant strains that acquired large DNA regions of up to 80 kb. In one case, strain Psi07 (phylotype IV tomato isolate) acquired 39.4 kb from GMI1000 (phylotype I tomato isolate). Investigations revealed that i) 24.4 kb of the acquired region contained 20 new genes, ii) an allelic exchange of 12 genes occurred, and iii) 27 genes (33.4 kb) formerly present in Psi07 were lost. Virulence tests with the three transformants revealed a significant increase in the aggressiveness of BCG20 over its Psi07 parent on tomato. These findings demonstrate the potential importance of HGT in the pathogenic evolution of R. solanacearum strains and open new avenues for studying pathogen emergence.
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Affiliation(s)
- Bénédicte Coupat-Goutaland
- Université de Lyon, Université Lyon 1, CNRS, INRA, 16 rue Raphaël Dubois, Domaine Scientifique de La Doua, 69622 Villeurbanne cedex, France
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Guidot A, Coupat B, Fall S, Prior P, Bertolla F. Horizontal gene transfer between Ralstonia solanacearum strains detected by comparative genomic hybridization on microarrays. ISME JOURNAL 2009; 3:549-62. [PMID: 19242532 DOI: 10.1038/ismej.2009.14] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The plant pathogenic Betaproteobacterium Ralstonia solanacearum is a complex species in that most of the strains share the common characteristic of being naturally transformable. In this study, we used a new approach based on comparative genomic hybridization (CGH) on microarrays to investigate the extent of horizontal gene transfers (HGTs) between different strains of R. solanacearum. Recipient strains from phylotypes I, II and III were naturally transformed in vitro by genomic DNA from the GMI1000 reference strain (phylotype I) and the resulting DNAs were hybridized on a microarray representative of the 5120 predicted genes from the GMI1000 strain. In addition to transfer of the antibiotic resistance marker, in 8 of the 16 tested transformants, CGH on microarrays detected other transferred GMI1000 genes and revealed their number, category, function and localization along the genome. We showed that DNA blocks up to 30 kb and 33 genes could be integrated during a single event. Most of these blocks flanked the marker gene DNA but, interestingly, multiple DNA acquisitions along the genome also occurred in a single recombinant clone in one transformation experiment. The results were confirmed by PCR amplification, cloning and sequencing and Southern blot hybridization. This represents the first comprehensive identification of gene acquisitions and losses along the genome of the recipient bacterial strain during natural transformation experiments. In future studies, this strategy should help to answer many questions related to HGT mechanisms.
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Affiliation(s)
- Alice Guidot
- CIRAD, UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical, Saint Pierre, La Réunion, France
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Barash I, Manulis-Sasson S. Recent evolution of bacterial pathogens: the gall-forming Pantoea agglomerans case. ANNUAL REVIEW OF PHYTOPATHOLOGY 2009; 47:133-52. [PMID: 19400643 DOI: 10.1146/annurev-phyto-080508-081803] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Pantoea agglomerans, a widespread epiphyte and commensal bacterium, has evolved into an Hrp-dependent and host-specific tumorigenic pathogen by acquiring a plasmid containing a pathogenicity island (PAI). The PAI was evolved on an iteron plasmid of the IncN family, which is distributed among genetically diverse populations of P. agglomerans. The structure of the PAI supports the premise of a recently evolved pathogen. This review offers insight into a unique model for emergence of new bacterial pathogens. It illustrates how horizontal gene transfer was the major driving force in the creation of the PAI, although a pathoadaptive mechanism might also be involved. It describes the crucial function of plant-produced indole-3-acetic acid (IAA) and cytokinines (CK) in gall initiation as opposed to the significant but secondary role of pathogen-secreted phytohormones. It also unveils the role of type III effectors in determination of host specificity and evolution of the pathogen into pathovars. Finally, it describes how interactions between the quorum sensing system, hrp regulatory genes, and bacterially secreted IAA or CKs affect gall formation and epiphytic fitness.
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Affiliation(s)
- Isaac Barash
- Department of Plant Sciences, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 61390, Israel.
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10
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Fall S, Mercier A, Bertolla F, Calteau A, Gueguen L, Perrière G, Vogel TM, Simonet P. Horizontal gene transfer regulation in bacteria as a "spandrel" of DNA repair mechanisms. PLoS One 2007; 2:e1055. [PMID: 17957239 PMCID: PMC2013936 DOI: 10.1371/journal.pone.0001055] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 10/02/2007] [Indexed: 12/01/2022] Open
Abstract
Horizontal gene transfer (HGT) is recognized as the major force for bacterial genome evolution. Yet, numerous questions remain about the transferred genes, their function, quantity and frequency. The extent to which genetic transformation by exogenous DNA has occurred over evolutionary time was initially addressed by an in silico approach using the complete genome sequence of the Ralstonia solanacearum GMI1000 strain. Methods based on phylogenetic reconstruction of prokaryote homologous genes families detected 151 genes (13.3%) of foreign origin in the R. solanacearum genome and tentatively identified their bacterial origin. These putative transfers were analyzed in comparison to experimental transformation tests involving 18 different genomic DNA positions in the genome as sites for homologous or homeologous recombination. Significant transformation frequency differences were observed among these positions tested regardless of the overall genomic divergence of the R. solanacearum strains tested as recipients. The genomic positions containing the putative exogenous DNA were not systematically transformed at the highest frequencies. The two genomic “hot spots”, which contain recA and mutS genes, exhibited transformation frequencies from 2 to more than 4 orders of magnitude higher than positions associated with other genes depending on the recipient strain. These results support the notion that the bacterial cell is equipped with active mechanisms to modulate acquisition of new DNA in different genomic positions. Bio-informatics study correlated recombination “hot-spots” to the presence of Chi-like signature sequences with which recombination might be preferentially initiated. The fundamental role of HGT is certainly not limited to the critical impact that the very rare foreign genes acquired mainly by chance can have on the bacterial adaptation potential. The frequency to which HGT with homologous and homeologous DNA happens in the environment might have led the bacteria to hijack DNA repair mechanisms in order to generate genetic diversity without losing too much genomic stability.
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Affiliation(s)
- Saliou Fall
- Environmental Microbial Genomics Group, Laboratoire AMPERE UMR CNRS 5005, Ecole Centrale de Lyon et Université de Lyon, Ecully, France
| | - Anne Mercier
- Ecologie Microbienne, UMR CNRS 5557, Université Claude Bernard–Lyon 1, Villeurbanne, France
| | - Franck Bertolla
- Ecologie Microbienne, UMR CNRS 5557, Université Claude Bernard–Lyon 1, Villeurbanne, France
| | - Alexandra Calteau
- Laboratoire de Biométrie et Biologie Évolutive, UMR CNRS 5558, Université Claude Bernard–Lyon 1, Villeurbanne, France
| | - Laurent Gueguen
- Laboratoire de Biométrie et Biologie Évolutive, UMR CNRS 5558, Université Claude Bernard–Lyon 1, Villeurbanne, France
| | - Guy Perrière
- Laboratoire de Biométrie et Biologie Évolutive, UMR CNRS 5558, Université Claude Bernard–Lyon 1, Villeurbanne, France
| | - Timothy M. Vogel
- Environmental Microbial Genomics Group, Laboratoire AMPERE UMR CNRS 5005, Ecole Centrale de Lyon et Université de Lyon, Ecully, France
| | - Pascal Simonet
- Environmental Microbial Genomics Group, Laboratoire AMPERE UMR CNRS 5005, Ecole Centrale de Lyon et Université de Lyon, Ecully, France
- * To whom correspondence should be addressed. E-mail:
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Grover A, Azmi W, Gadewar AV, Pattanayak D, Naik PS, Shekhawat GS, Chakrabarti SK. Genotypic diversity in a localized population of Ralstonia solanacearum as revealed by random amplified polymorphic DNA markers. J Appl Microbiol 2006; 101:798-806. [PMID: 16968291 DOI: 10.1111/j.1365-2672.2006.02974.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS To assess genotypic diversity within Ralstonia solanacearum isolates of a single field. METHODS AND RESULTS A total of 44 field isolates and 22 in vitro generated clones of R. solanacearum were studied for genotypic diversity by random amplified polymorphic DNA (RAPD) technique. Genomic DNA of these isolates and clones was extracted by proteinase-K-SDS lysis mini-prep method. RAPD analysis was done with 30 decamer primers. The data were analysed using NTSYSpc 2.02h software. Forty-two out of 44 field isolates and all the clonal isolates were identified as distinct genotypes at 70% similarity level. CONCLUSION Very high level of genome variability was observed within the field and clonal isolates of R. solanacearum. This might be a reason for the wide host range of this bacterium and for quick breakdown of wilt resistance in host plants. SIGNIFICANCE AND IMPACT OF THE STUDY The results suggest that it would be difficult to design specific diagnostic protocol for R. solanacearum even for a localized population and to breed cultivars with broad-spectrum resistance.
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Affiliation(s)
- A Grover
- Central Potato Research Institute, Shimla, Himachal Pradesh, India
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12
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Genin S, Boucher C. Lessons learned from the genome analysis of ralstonia solanacearum. ANNUAL REVIEW OF PHYTOPATHOLOGY 2004; 42:107-134. [PMID: 15283662 DOI: 10.1146/annurev.phyto.42.011204.104301] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Ralstonia solanacearum is a devastating plant pathogen with a global distribution and an unusually wide host range. This bacterium can also be free-living as a saprophyte in water or in the soil in the absence of host plants. The availability of the complete genome sequence from strain GMI1000 provided the basis for an integrative analysis of the molecular traits determining the adaptation of the bacterium to various environmental niches and pathogenicity toward plants. This review summarizes current knowledge and speculates on some key bacterial functions, including metabolic versatility, resistance to metals, complex and extensive systems for motility and attachment to external surfaces, and multiple protein secretion systems. Genome sequence analysis provides clues about the evolution of essential virulence genes such as those encoding the Type III secretion system and related pathogenicity effectors. It also provided insights into possible mechanisms contributing to the rapid adaptation of the bacterium to its environment in general and to its interaction with plants in particular.
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Affiliation(s)
- Stéphane Genin
- Laboratoire Interactions Plantes-Microorganismes, CNRS-INRA, Castanet-Tolosan, France.
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13
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Salanoubat M, Genin S, Artiguenave F, Gouzy J, Mangenot S, Arlat M, Billault A, Brottier P, Camus JC, Cattolico L, Chandler M, Choisne N, Claudel-Renard C, Cunnac S, Demange N, Gaspin C, Lavie M, Moisan A, Robert C, Saurin W, Schiex T, Siguier P, Thébault P, Whalen M, Wincker P, Levy M, Weissenbach J, Boucher CA. Genome sequence of the plant pathogen Ralstonia solanacearum. Nature 2002; 415:497-502. [PMID: 11823852 DOI: 10.1038/415497a] [Citation(s) in RCA: 617] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ralstonia solanacearum is a devastating, soil-borne plant pathogen with a global distribution and an unusually wide host range. It is a model system for the dissection of molecular determinants governing pathogenicity. We present here the complete genome sequence and its analysis of strain GMI1000. The 5.8-megabase (Mb) genome is organized into two replicons: a 3.7-Mb chromosome and a 2.1-Mb megaplasmid. Both replicons have a mosaic structure providing evidence for the acquisition of genes through horizontal gene transfer. Regions containing genetically mobile elements associated with the percentage of G+C bias may have an important function in genome evolution. The genome encodes many proteins potentially associated with a role in pathogenicity. In particular, many putative attachment factors were identified. The complete repertoire of type III secreted effector proteins can be studied. Over 40 candidates were identified. Comparison with other genomes suggests that bacterial plant pathogens and animal pathogens harbour distinct arrays of specialized type III-dependent effectors.
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Affiliation(s)
- M Salanoubat
- Genoscope and CNRS UMR-8030, 2 rue Gaston Crémieux, CP5706, 91057 Evry Cedex, France
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14
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Vivian A, Murillo J, Jackson RW. The roles of plasmids in phytopathogenic bacteria: mobile arsenals? MICROBIOLOGY (READING, ENGLAND) 2001; 147:763-780. [PMID: 11283273 DOI: 10.1099/00221287-147-4-763] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Alan Vivian
- Centre for Research in Plant Science, Faculty of Applied Sciences, UWE-Bristol, Coldharbour Lane, Bristol BS16 1QY, UK1
| | - Jesús Murillo
- Centre for Research in Plant Science, Faculty of Applied Sciences, UWE-Bristol, Coldharbour Lane, Bristol BS16 1QY, UK1
| | - Robert W Jackson
- Centre for Research in Plant Science, Faculty of Applied Sciences, UWE-Bristol, Coldharbour Lane, Bristol BS16 1QY, UK1
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15
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Garg RP, Yindeeyoungyeon W, Gilis A, Denny TP, Van Der Lelie D, Schell MA. Evidence that Ralstonia eutropha (Alcaligenes eutrophus) contains a functional homologue of the Ralstonia solanacearum Phc cell density sensing system. Mol Microbiol 2000; 38:359-67. [PMID: 11069661 DOI: 10.1046/j.1365-2958.2000.02131.x] [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]
Abstract
In the phytopathogen Ralstonia (Pseudomonas) solanacearum, control of many virulence genes is partly mediated by the Phc cell density sensing system. Phc uses a novel self-produced signal molecule [3-hydroxypalmitic acid methyl ester (3-OH PAME)], an atypical two-component system (PhcS/PhcR), and a LysR-type activator (PhcA) to regulate a reversible switching between two different physiological states. While Phc is present in most R. solanacearum strains, it is apparently absent from other pseudomonad plant pathogens and prokaryotic genomes that have been sequenced. Here, we report discovery of a phcA orthologue in the non-pathogenic, facultative chemolithoautotroph Ralstonia eutropha (Alcaligenes eutrophus) that fully complements R. solanacearum phcA mutants. We also demonstrate that some R. eutropha produce an extracellular factor that complements R. solanacearum mutants deficient in production of the 3-OH PAME signal molecule that controls phcA. Additionally, Southern blot hybridization analysis suggested that R. eutropha harbours other Phc components, such as PhcB (a biosynthetic enzyme for 3-OH PAME) and PhcS (a 3-OH PAME-responsive sensor kinase). Analysis of a phcA-null mutant of R. eutropha showed that phcA (and probably Phc) positively activates motility, in contrast to R. solanacearum where it represses motility. Similarly, the R. eutropha phcA mutant was unaffected in siderophore production, whereas inactivation of phcA in R. solanacearum increases siderophore production. Although our data strongly suggest that R. eutropha has a functional Phc-like system and support the phylogeny of Ralstonia, it implies that Phc may have a different physiological and ecological function in R. eutropha.
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Affiliation(s)
- R P Garg
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
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Schell MA. Control of Virulence and Pathogenicity Genes of Ralstonia Solanacearum by an Elaborate Sensory Network. ANNUAL REVIEW OF PHYTOPATHOLOGY 2000; 38:263-292. [PMID: 11701844 DOI: 10.1146/annurev.phyto.38.1.263] [Citation(s) in RCA: 188] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Ralstonia solanacearum causes a lethal bacterial wilt disease of diverse plants. It invades the xylem vessels of roots and disseminates into the stem where it multiplies and wilts by excessive exopolysaccharide production. Many of its key extracytoplasmic virulence and pathogenicity factors are transcriptionally controlled by an extensive network of distinct, interacting signal transduction pathways. The core of this sensory network is the five-gene Phc system that regulates exopolysaccharide, cell-wall-degrading exoenzymes, and other factors in response to a self-produced signal molecule that monitors the pathogen's growth status and environment. Four additional environmentally responsive two-component systems work independently and with the Phc system to fine-tune virulence gene expression. Another critical system is Prh which transduces plant cell-derived signals through a six-gene cascade to activate deployment of the Type III secretion pathway encoded by the hrp pathogenicity genes. Here I summarize knowledge about the regulated targets, signal transduction mechanisms, and crosstalk between Phc, Prh, and other systems. I also provide insight into why R. solanacearum has evolved such a sophisticated sensory apparatus, and how it functions in disease.
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Affiliation(s)
- Mark A Schell
- Department of Microbiology and Department of Plant Pathology, University of Georgia, Athens, Georgia 30602; e-mail:
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He SY. Type III protein secretion systems in plant and animal pathogenic bacteria. ANNUAL REVIEW OF PHYTOPATHOLOGY 1998; 36:363-92. [PMID: 15012505 DOI: 10.1146/annurev.phyto.36.1.363] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Among many interesting and sophisticated mechanisms used by bacterial pathogens to subvert eukaryotic hosts is a class of specialized protein secretion systems (known as type III protein secretion systems) that deliver bacterial virulence proteins directly into the host cell. Recent studies have revealed four important features of these secretion systems. First, they are widespread among plant and animal bacterial pathogens, and mutations affecting type III protein secretion often eliminate bacterial virulence completely. Second, at least eight type III secretion components share sequence similarities with those of the flagellar assembly machinery and flagellum-like structures are associated with type III secretion, raising the possibility that these secretion systems are derived from the presumably more ancient flagellar assembly apparatus. Third, type III secretion is activated in vivo upon contact with host cells. Fourth, the type III secretion mechanism is Sec-independent and the effector proteins may possess mRNA-based targeting signals. This review highlights the similarities and differences among type III secretion systems of selected model plant and animal pathogenic bacteria.
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Affiliation(s)
- S Y He
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA.
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Baudouin E, Charpenteau M, Roby D, Marco Y, Ranjeva R, Ranty B. Functional expression of a tobacco gene related to the serine hydrolase family -- esterase activity towards short-chain dinitrophenyl acylesters. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 248:700-6. [PMID: 9342220 DOI: 10.1111/j.1432-1033.1997.t01-1-00700.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have recently reported the isolation of a tobacco gene, hsr 203J, whose transcripts accumulate during the hypersensitive reaction, a plant response associated with resistance to pathogens. We present and discuss here some structural and biochemical properties of the gene product. Nucleotide sequence analysis has shown that the hsr 203J gene contains an open reading frame coding for a polypeptide of 335 amino acids. The predicted amino acid sequence contains the GXSXG motif characteristic of serine hydrolases, and displays limited but significant similarity to lipases and esterases of prokaryotic origin. The hsr 203J gene was expressed in Escherichia coli, and the recombinant protein, purified to near homogeneity, was able to degrade p-nitrophenylbutyrate, a general substrate for carboxylesterases. The enzyme was unable to hydrolyze lipids, and was active on short-chain acyl esters only. The hydrolytic activity was abolished by diisopropyl fluorophosphate and a derivative of isocoumarin, as expected for a member of the serine hydrolase family. Sequence similarities between the tobacco esterase and expressed sequence tags in databases suggest the existence of members of this enzyme family in various plant species.
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Affiliation(s)
- E Baudouin
- Laboratoire Signaux et Messages Cellulaires chez les Végétaux, UMR 5546 CNRS, Université Paul Sabatier, Toulouse, France
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Alfano JR, Collmer A. The type III (Hrp) secretion pathway of plant pathogenic bacteria: trafficking harpins, Avr proteins, and death. J Bacteriol 1997; 179:5655-62. [PMID: 9294418 PMCID: PMC179450 DOI: 10.1128/jb.179.18.5655-5662.1997] [Citation(s) in RCA: 367] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- J R Alfano
- Department of Plant Pathology, Cornell University, Ithaca, New York 14853-4203, USA
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Lindgren PB. The role of hrp genes during plant-bacterial interactions. ANNUAL REVIEW OF PHYTOPATHOLOGY 1997; 35:129-52. [PMID: 15012518 DOI: 10.1146/annurev.phyto.35.1.129] [Citation(s) in RCA: 145] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
hrp genes control the ability of phytopathogenic bacteria to cause disease and to elicit hypersensitive reactions on resistant plants. Genetic and biochemical studies have demonstrated that Hrp proteins are components of Type III secretion systems, regulatory proteins, proteinaceous elicitors of the hypersensitive reaction, and enzymes needed for synthesis of periplasmic glucans. Significantly, Type III secretion systems are involved with the secretion of pathogenicity proteins in bacterial pathogens of animals. The transcriptional activation of a number of bacterial avirulence (avr) genes is controlled by Hrp regulatory proteins, and recent experimental evidence suggests that Avr proteins may be transported by Hrp secretion systems. It has also been hypothesized that pathogenicity and/or virulence gene products exit bacterial phytopathogens via Hrp pathways. Thus, hrp genes may be one of the most important groups of genes found in phytopathogenic bacteria in relationship to pathogenicity and host range.
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Affiliation(s)
- P B Lindgren
- Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695-7616, USA.
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Van Gijsegem F, Gough C, Zischek C, Niqueux E, Arlat M, Genin S, Barberis P, German S, Castello P, Boucher C. The hrp gene locus of Pseudomonas solanacearum, which controls the production of a type III secretion system, encodes eight proteins related to components of the bacterial flagellar biogenesis complex. Mol Microbiol 1995; 15:1095-114. [PMID: 7623665 DOI: 10.1111/j.1365-2958.1995.tb02284.x] [Citation(s) in RCA: 171] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Five transcription units of the Pseudomonas solanacearum hrp gene cluster are required for the secretion of the HR-inducing PopA1 protein. The nucleotide sequences of two of these, units 1 and 3, have been reported. Here, we present the nucleotide sequence of the three other transcription units, units 2, 4 and 7, which are together predicted to code for 15 hrp genes. This brings the total number of Hrp proteins encoded by these five transcription units to 20, including HrpB, the positive regulatory protein, and HpaP, which is apparently not required for plant interactions. Among the 18 other proteins, eight belong to protein families regrouping proteins involved in type III secretion pathways in animal and plant bacterial pathogens and in flagellum biogenesis, while two are related solely to proteins involved in secretion systems. For the various proteins found to be related to P. solanacearum Hrp proteins, those in plant-pathogenic bacteria include proteins encoded by hrp genes. For Hrp-related proteins of animal pathogens, those encoded by the spa and mxi genes of Shigella flexneri and of Salmonella typhimurium and by the ysc genes of Yersinia are involved in type III secretion pathways. Proteins involved in flagellum biogenesis, which are related to Hrp proteins of P. solancearum, include proteins encoded by fli and flh genes of S. typhimurium, Bacillus subtilis and Escherichia coli and by mop genes of Erwinia carotovora. P. solanacearum Hrp proteins were also found to be related to proteins of Rhizobium fredii involved in nodulation specificity.
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Affiliation(s)
- F Van Gijsegem
- Laboratoire de Biologie Moléculaire des Relations Plantes Microorganismes, INRA-CNRS, Castanet Tolosan, France
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Genes governing the secretion of factors involved in host-bacteria interactions are conserved among animal and plant pathogenic bacteria. ACTA ACUST UNITED AC 1994. [DOI: 10.1007/978-94-011-0746-4_45] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
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Gough CL, Genin S, Lopes V, Boucher CA. Homology between the HrpO protein of Pseudomonas solanacearum and bacterial proteins implicated in a signal peptide-independent secretion mechanism. MOLECULAR & GENERAL GENETICS : MGG 1993; 239:378-92. [PMID: 8316211 DOI: 10.1007/bf00276936] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A region of approximately 22 kb of DNA defines the large hrp gene cluster of strain GMI1000 of Pseudomonas solanacearum. The majority of mutants that map to this region have lost the ability to induce disease symptoms on tomato plants and are no longer able to elicit a hypersensitive reaction (HR) on tobacco, a non-host plant. In this study we present the complementation analysis and nucleotide sequence of a 4772 bp region of this hrp gene cluster. Three complete open reading frames (ORFs) are predicted within this region. The corresponding putative proteins, HrpN, HrpO and HpaP, have predicted sizes of 357, 690 and 197 amino acids, respectively, and predicted molecular weights of 38,607, 73,990 and 21,959 dalton, respectively. HrpN and HrpO are both predicted to be hydrophobic proteins with potential membrane-spanning domains and HpaP is rich in proline residues. A mutation in hpaP (for hrp associated) does not affect the HR on tobacco or the disease on tomato plants. None of the proteins is predicted to have an N-terminal signal sequence, which would have indicated that the proteins are exported. Considerable sequence similarities were found between HrpO and eight known or predicted prokaryotic proteins: LcrD of Yersinia pestis and Y. enterocolitica, FlbF of Caulobacter crescentus, FlhA of Bacillus subtilis, MxiA and VirH of Shigella flexneri, InvA of Salmonella typhimurium and HrpC2 of Xanthomonas campestris pv. vesicatoria. These homologies suggest that certain hrp genes of phytopathogenic bacteria code for components of a secretory system, which is related to the systems for secretion of flagellar proteins, Ipa proteins of Shigella flexneri and the Yersinia Yop proteins. Furthermore, these homologous proteins have the common feature of being implicated in a distinct secretory mechanism, which does not require the cleavage of a signal peptide. The sequence similarity between HrpO and HrpC2 is particularly high (66% identity and 81% similarity) and the amino acid sequence comparison between these two proteins presented here reveals the first such sequence similarity to be shown between Hrp proteins of P. solanacearum and X. campestris. An efflux of plant electrolytes was found to be associated with the interactions between P. solanacearum and both tomato and tobacco leaves. This phenomenon may be part of the mechanism by which hrp gene products control and determine plant-bacterial interactions, since hrpO mutants induced levels of leakage which were significantly lower than those induced by the wild type on each plant.
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Affiliation(s)
- C L Gough
- Laboratoire de Biologie Moléculaire des Relations Plantes Microorganismes, INRA-CNRS, Castanet-Tolosan, France
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25
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Genin S, Gough CL, Zischek C, Boucher CA. Evidence that the hrpB gene encodes a positive regulator of pathogenicity genes from Pseudomonas solanacearum. Mol Microbiol 1992; 6:3065-76. [PMID: 1479894 DOI: 10.1111/j.1365-2958.1992.tb01764.x] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The hrp gene cluster of Pseudomonas solanacearum GMI1000 strain encodes functions that are essential for pathogenicity on tomato and for the elicitation of the hypersensitive response on tobacco. In this study, we present the nucleotide sequence of one of the hrp genes (hrpB) located at the left-hand end of the cluster and we show that hrpB encodes a positive regulator controlling the expression of hrp genes. hrpB has a coding capacity for a 477-amino-acid polypeptide, which shows significant similarity to several prokaryotic transcriptional activators including the AraC protein of Escherichia coli, the XylS protein of Pseudomonas putida and the VirF protein of Yersinia enterocolitica. The predicted hrpB gene product belongs to a family of bacterial regulators different from the previously described HrpS protein of the hrp gene cluster of Pseudomonas syringae pv. phaseolicola. Genetic evidence demonstrates that the hrpB gene product acts as a positive regulator of the expression in minimal medium of all but one of the putative transcription units of the hrp gene cluster and also controls the expression of genes located outside this cluster. We also show in this paper that the transcription of hrpB is induced in minimal medium and is partly autoregulated.
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Affiliation(s)
- S Genin
- Laboratoire de Biologie Moléculaires des Relations Plantes Microorganismes, INRA-CNRS, Castanet-Tolosan, France
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26
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Godiard L, Froissard D, Fournier J, Axelos M, Marco Y. Differential regulation in tobacco cell suspensions of genes involved in plant-bacteria interactions by pathogen-related signals. PLANT MOLECULAR BIOLOGY 1991; 17:409-13. [PMID: 1715785 DOI: 10.1007/bf00040635] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Six cDNA clones whose corresponding mRNAs accumulate early during the hypersensitive reaction in tobacco leaves have been classified into 2 groups according to their maximum levels of accumulation in an incompatible versus a compatible interaction with Pseudomonas solanacearum. We present evidence that, at least in the first stages of the interaction, tobacco cell suspensions retain the ability to respond differentially to compatible and incompatible isolates of P. solanacearum. In addition, studies on the effect of a fungal elicitor on the accumulation of the mRNAs corresponding to the cDNA clones in cell suspensions indicate that only one group of genes responds to this treatment.
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Affiliation(s)
- L Godiard
- Laboratoire de Biologie Moléculaire, Relations Plantes-Microorganismes, CNRS-INRA, UMR 05, Castanet-Tolosan, France
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Steinberger EM, Cheng GY, Beer SV. Characterization of a 56-kb plasmid of Erwinia amylovora Ea322: its noninvolvement in pathogenicity. Plasmid 1990; 24:12-24. [PMID: 2270226 DOI: 10.1016/0147-619x(90)90021-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A plasmid from Erwinia amylovora strain Ea322, pCPP60, was studied for its involvement in the phytopathogenicity of this strain. Eviction through incompatibility and curing with acridine orange did not affect the pathogenic capability of Ea322. The plasmid was characterized as self-transmissible with a narrow host range. Hybridization of its origin of replication with plasmids of different incompatibility groups revealed affiliation with IncF. The exact subgroup was not determined, although it does not belong to IncFI, IncFII, IncFIV, or IncFV. A sequence of 800 bp, required for conjugation in cis, was cloned in pUC9. A "miniplasmid" containing the origin of replication in a 1.2-kb sequence was constructed. Its high copy number was in contrast with the stringently controlled copy number of the native plasmid of one to three copies per chromosome equivalent.
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Affiliation(s)
- E M Steinberger
- Department of Plant Pathology, Cornell University, Ithaca, New York 14853
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28
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Marco YJ, Ragueh F, Godiard L, Froissard D. Transcriptional activation of 2 classes of genes during the hypersensitive reaction of tobacco leaves infiltrated with an incompatible isolate of the phytopathogenic bacterium Pseudomonas solanacearum. PLANT MOLECULAR BIOLOGY 1990; 15:145-54. [PMID: 2103428 DOI: 10.1007/bf00017732] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Fourteen cDNA clones whose corresponding mRNAs accumulate during the hypersensitive reaction (HR) of tobacco leaves infiltrated with an incompatible strain of the bacterial pathogen Pseudomonas solanacearum have been subdivided by sequence homologies into 6 families. Studies on the accumulation of the mRNAs encoded by these genes in compatible and incompatible plant-bacterial interactions have been carried out and indicate that the 6 cDNA clones can be subdivided into 2 groups. In one group corresponding to 3 cDNA clones, the maximal level of mRNA accumulation is similar in both types of interaction, whereas in the other group, maximal mRNA accumulation in leaves undergoing an HR is 3- to 7-fold higher than in leaves infiltrated with the compatible strain. Within each group, the timing and kinetics of accumulation of the corresponding mRNAs differ for each individual cDNA clone. Run-on experiments indicate that transcriptional activation of these genes plays a major role in the control of their expression. Genomic hybridizations have been performed and indicate that the mRNAs corresponding to the cDNA clones are encoded by multigene families (6 to 20 genes).
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Affiliation(s)
- Y J Marco
- Laboratoire de Biologie Moléculaire des Relations Plantes-Microorganismes, CNRS-INRA, Castanet-Tolosan, France
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Barny MA, Guinebretière MH, Marçais B, Coissac E, Paulin JP, Laurent J. Cloning of a large gene cluster involved in Erwinia amylovora CFBP1430 virulence. Mol Microbiol 1990; 4:777-86. [PMID: 2117695 DOI: 10.1111/j.1365-2958.1990.tb00648.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Phage MudIIPR13 insertional mutagenesis of Erwinia amylovora CFBP1430 allowed us to isolate 6900 independent CmR mutants. The frequencies of different auxotrophs in this population indicated that MudIIPR13 had inserted randomly in E. amylovora. Screening of 3500 CmR mutants on (i) apple calli and (ii) pear and apple seedlings led to the isolation of 19 non-pathogenic prototrophic single mutants, four of which expressed a LacZ+ hybrid protein. Expression of the fusion proteins was temperature sensitive. The 19 mutants could be separated into two classes according to their behaviour on tobacco: 13 were unable to elicit the hypersensitive response on tobacco (Hrp-) while six still could (Dsp-). The 19 MudIIPR13 insertions all mapped in the same virulence region. The MudIIPR13 insertions of Hrp- mutants were all clustered on the left part of this region, while the MudIIPR13 insertions of Dsp- mutants were located on the right part. All of the mutants except one, which proved to have a large deletion of the entire virulence region, could be complemented functionally by cosmids from an E. amylovora CFBP1430 genomic library. No hybridization was observed between the cosmid pPV130, which complemented 12 hrp::MudIIPR13 mutations, and the hrp genes from Pseudomonas syringae pv. phaseolicola (Lindgren et al., 1986), P. syringae pv. tomato (N.J. Panopoulos, unpublished data) or P. solanacearum (Boucher et al., 1987). Further analysis of the large virulence region will allow mapping of the border of the virulence region and facilitate the study of the function and regulation of the hrp and dsp genes.
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Affiliation(s)
- M A Barny
- Laboratoire de Pathologie Végétale, I.N.R.A., Paris, France
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Abstract
A circular linkage map of the Rhizobium meliloti megaplasmid pRmeSU47b was constructed. The map consists of transposon insertions carrying alternating antibiotic resistance markers linked by phi M12 transduction. Data from conjugation experiments utilizing donor strains carrying Tn5-oriT insertions in the megaplasmid supported the proposed genetic map. In addition, the positions of previously identified Fix, exopolysaccharide synthetic, thiamine synthetic, and C4-dicarboxylate transport loci on the megaplasmid map were determined. By converting cotransduction frequencies to physical distance, we calculated the replicon to be 1,600 kilobases in size, which compares favorably with previous physical estimates.
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Affiliation(s)
- T C Charles
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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Roberts DP, Denny TP, Schell MA. Cloning of the egl gene of Pseudomonas solanacearum and analysis of its role in phytopathogenicity. J Bacteriol 1988; 170:1445-51. [PMID: 2832363 PMCID: PMC210987 DOI: 10.1128/jb.170.4.1445-1451.1988] [Citation(s) in RCA: 127] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The egl gene of Pseudomonas solanacearum was cloned on a cosmid and expressed in Escherichia coli. Restriction endonuclease mapping, transposon mutagenesis, and subclone analysis showed that the egl gene was located on a 2.7-kilobase XhoI-SalI P. solanacearum DNA fragment. Immunoabsorption experiments and sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis showed that the egl gene encodes the 43-kilodalton endoglucanase that is the major excreted endoglucanase of P. solanacearum. In E. coli, the egl gene appeared to be expressed from its own promoter, but its product was restricted to the cytoplasm. The cloned egl gene was mutagenized with Tn5 and used to specifically mutate the chromosomal egl gene of P. solanacearum by site-directed mutagenesis. The resultant mutant was identical to the wild-type strain in production of extracellular polysaccharide and extracellular polygalacturonase as well as several other excreted proteins but produced at least 200-fold less endoglucanase. This mutant strain was significantly less virulent on tomato than the wild-type strain in plant bioassay experiments. Virulence of the endoglucanase-deficient strain was restored to near wild-type levels by complementation in trans with the cloned egl gene, indicating that the egl gene is important but not absolutely required for pathogenesis.
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Affiliation(s)
- D P Roberts
- Department of Microbiology, University of Georgia, Athens 30602
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Piecq M, van Gijsegem F, Schoonejans E, Toussaint A. Chromosomal mapping of the pel and cel genes in Erwinia chrysanthemi strain B374. Mol Microbiol 1988; 2:297-302. [PMID: 2837618 DOI: 10.1111/j.1365-2958.1988.tb00032.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Using the RP4::mini-Mu in vivo cloning technique, van Gijsegem et al. (1985) isolated several pel and cel genes of Erwinia chrysanthemi (Ech) B374 strain. We have localized these genes on the Ech chromosome by co-transfer mapping of MudI1734 insertion mutants and refined the map by co-transposition analysis. This analysis has enabled us to identify another cel gene.
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Affiliation(s)
- M Piecq
- Département de Biologie Moléculaire, Université Libre de Bruxelles, Rhode-Saint-Genèse, Belgium
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Xu PL, Leong S, Sequeira L. Molecular cloning of genes that specify virulence in Pseudomonas solanacearum. J Bacteriol 1988; 170:617-22. [PMID: 2828316 PMCID: PMC210699 DOI: 10.1128/jb.170.2.617-622.1988] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The suicide plasmid pSUP2021 was used to introduce Tn5 into the Pseudomonas solanacearum wild-type strain K60. We isolated eight avirulent mutants after screening 6,000 kanamycin-resistant transconjugants by inoculating eggplant (Solanum melongena L. cv. Black Beauty) and tobacco (Nicotiana tabacum L. cv. Bottom Special) seedlings. The Tn5-containing EcoRI fragments from the eight mutants were unique, suggesting that numerous genes specify virulence in this species. These EcoRI fragments were cloned into pBR322 or pUC12, and one of the clones, pKD810, was transformed into K60. All of the kanamycin-resistant, ampicillin-sensitive transformants were avirulent. Three randomly selected avirulent transformants were shown to carry the Tn5-containing fragment in place of the wild-type fragment and to exhibit the same hybridization pattern as the original KD810 mutant did. With pKD810 as a probe, we identified cosmids carrying the wild-type virulence genes by using a genomic library of K60 prepared in pLAFR3. Two of the homologous cosmids, pL810A and pL810C, when introduced into KD810 by transformation, restored virulence and normal growth of this mutant in tobacco. Altogether, these data indicate that the gene(s) interrupted by Tn5 insertion in KD810 is essential for the virulence of P. solanacearum. Further characterization of this gene is now being completed by subcloning, transposon mutagenesis, and complementation analysis.
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Affiliation(s)
- P L Xu
- Department of Plant Pathology, University of Wisconsin-Madison 53706
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Boucher CA, Van Gijsegem F, Barberis PA, Arlat M, Zischek C. Pseudomonas solanacearum genes controlling both pathogenicity on tomato and hypersensitivity on tobacco are clustered. J Bacteriol 1987; 169:5626-32. [PMID: 2824440 PMCID: PMC214013 DOI: 10.1128/jb.169.12.5626-5632.1987] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
A pLAFR3 cosmid clone designated pVir2 containing a 25-kilobase (kb) DNA insert was isolated from a wild-type Pseudomonas solanacearum GMI1000 genomic library. This cosmid was shown to complement all but one of the nine Tn5-induced mutants which have been isolated after random mutagenesis and which have lost both pathogenicity toward tomato and ability to induce hypersensitive reaction (HR) on tobacco (hrp mutants). The insert is colinear with the genome and provides restoration of the HR-inducing ability when transferred into several Tn5-induced hrp mutants, but failed to complement deletion mutants extending on both sides of the pVir2 region. Localized mutagenesis demonstrated that the hrp genes are clustered within a 17.5-kb region of pVir2 and that this cluster probably extends on the genomic region adjacent to the pVir2 insert. A 3-kb region adjacent to the hrp cluster modulates aggressiveness toward tomato but does not control HR-inducing ability. Sequences within the hrp cluster of pVir2 have homology with the genomic DNA of Xanthomonas campestris strains representing eight different pathovars, suggesting that a set of common pathogenicity functions could be shared by P. solanacearum and X. campestris.
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Affiliation(s)
- C A Boucher
- Laboratoire de Biologie Moléculaire des Relations Plantes-Microorganismes, Institut National de la Recherche Agronomique, Castanet-Tolosan, France
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