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Eckstein S, Brehm J, Seidel M, Lechtenfeld M, Heermann R. Two novel XRE-like transcriptional regulators control phenotypic heterogeneity in Photorhabdus luminescens cell populations. BMC Microbiol 2021; 21:63. [PMID: 33627070 PMCID: PMC7905540 DOI: 10.1186/s12866-021-02116-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 01/25/2021] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND The insect pathogenic bacterium Photorhabdus luminescens exists in two phenotypically different forms, designated as primary (1°) and secondary (2°) cells. Upon yet unknown environmental stimuli up to 50% of the 1° cells convert to 2° cells. Among others, one important difference between the phenotypic forms is that 2° cells are unable to live in symbiosis with their partner nematodes, and therefore are not able to re-associate with them. As 100% switching of 1° to 2° cells of the population would lead to a break-down of the bacteria's life cycle the switching process must be tightly controlled. However, the regulation mechanism of phenotypic switching is still puzzling. RESULTS Here we describe two novel XRE family transcriptional regulators, XreR1 and XreR2, that play a major role in the phenotypic switching process of P. luminescens. Deletion of xreR1 in 1° or xreR2 in 2° cells as well as insertion of extra copies of xreR1 into 2° or xreR2 into 1° cells, respectively, induced the opposite phenotype in either 1° or 2° cells. Furthermore, both regulators specifically bind to different promoter regions putatively fulfilling a positive autoregulation. We found initial evidence that XreR1 and XreR2 constitute an epigenetic switch, whereby XreR1 represses xreR2 expression and XreR2 self-reinforces its own gene by binding to XreR1. CONCLUSION Regulation of gene expression by the two novel XRE-type regulators XreR1 and XreR2 as well as their interplay represents a major regulatory process in phenotypic switching of P. luminescens. A fine-tuning balance between both regulators might therefore define the fate of single cells to convert from the 1° to the 2° phenotype.
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Affiliation(s)
- Simone Eckstein
- Johannes-Gutenberg-Universität Mainz, Institut für Molekulare Physiologie, Biozentrum II, Mikrobiologie und Weinforschung, Hanns-Dieter-Hüsch-Weg 17, 55128, Mainz, Germany.,Ludwig-Maximilians-Universität München, Biozentrum, Bereich Mikrobiologie, Martinsried, Germany
| | - Jannis Brehm
- Johannes-Gutenberg-Universität Mainz, Institut für Molekulare Physiologie, Biozentrum II, Mikrobiologie und Weinforschung, Hanns-Dieter-Hüsch-Weg 17, 55128, Mainz, Germany
| | - Michael Seidel
- Ludwig-Maximilians-Universität München, Biozentrum, Bereich Mikrobiologie, Martinsried, Germany
| | - Mats Lechtenfeld
- Johannes-Gutenberg-Universität Mainz, Institut für Molekulare Physiologie, Biozentrum II, Mikrobiologie und Weinforschung, Hanns-Dieter-Hüsch-Weg 17, 55128, Mainz, Germany
| | - Ralf Heermann
- Johannes-Gutenberg-Universität Mainz, Institut für Molekulare Physiologie, Biozentrum II, Mikrobiologie und Weinforschung, Hanns-Dieter-Hüsch-Weg 17, 55128, Mainz, Germany.
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Glaeser A, Heermann R. A novel tool for stable genomic reporter gene integration to analyze heterogeneity in Photorhabdus luminescens at the single-cell level. Biotechniques 2015; 59:74-81. [PMID: 26260085 DOI: 10.2144/000114317] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 05/28/2015] [Indexed: 11/23/2022] Open
Abstract
Determination of reporter gene activity at the single-cell level is a prerequisite for analyzing heterogeneous gene expression in bacteria. The insect pathogenic enteric bacterium Photorhabdus luminescens is an excellent organism in which to study heterogeneity since it exists in two phenotypically different forms, called the primary and secondary variant. A tool for generating stable genomic integrations of reporter genes has been lacking for these bacteria, and this has hampered the acquisition of reliable data sets for promoter activities at the single-cell level. We therefore generated a plasmid tool named pPINT-mCherry for the easy and stable introduction of gene fragments upstream of an mCherry reporter gene followed by stable integration of the plasmid into the P. luminescens genome at the rpmE/glmS intergenic region. We demonstrate that the genomic integration of reporter genes for single-cell analysis is necessary in P. luminescens since plasmid-borne reporter genes mimic heterogeneity and are therefore not applicable in these bacteria, in contrast to their use in single-cell analysis in other bacteria like Escherichia coli.
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Affiliation(s)
- Angela Glaeser
- Ludwig-Maximilians-Universität München, Biozentrum, Bereich Mikrobiologie, Martinsried/München, Germany
| | - Ralf Heermann
- Ludwig-Maximilians-Universität München, Biozentrum, Bereich Mikrobiologie, Martinsried/München, Germany
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Abebe-Akele F, Tisa LS, Cooper VS, Hatcher PJ, Abebe E, Thomas WK. Genome sequence and comparative analysis of a putative entomopathogenic Serratia isolated from Caenorhabditis briggsae. BMC Genomics 2015; 16:531. [PMID: 26187596 PMCID: PMC4506600 DOI: 10.1186/s12864-015-1697-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 06/12/2015] [Indexed: 12/21/2022] Open
Abstract
Background Entomopathogenic associations between nematodes in the genera Steinernema and Heterorhabdus with their cognate bacteria from the bacterial genera Xenorhabdus and Photorhabdus, respectively, are extensively studied for their potential as biological control agents against invasive insect species. These two highly coevolved associations were results of convergent evolution. Given the natural abundance of bacteria, nematodes and insects, it is surprising that only these two associations with no intermediate forms are widely studied in the entomopathogenic context. Discovering analogous systems involving novel bacterial and nematode species would shed light on the evolutionary processes involved in the transition from free living organisms to obligatory partners in entomopathogenicity. Results We report the complete genome sequence of a new member of the enterobacterial genus Serratia that forms a putative entomopathogenic complex with Caenorhabditis briggsae. Analysis of the 5.04 MB chromosomal genome predicts 4599 protein coding genes, seven sets of ribosomal RNA genes, 84 tRNA genes and a 64.8 KB plasmid encoding 74 genes. Comparative genomic analysis with three of the previously sequenced Serratia species, S. marcescens DB11 and S. proteamaculans 568, and Serratia sp. AS12, revealed that these four representatives of the genus share a core set of ~3100 genes and extensive structural conservation. The newly identified species shares a more recent common ancestor with S. marcescens with 99 % sequence identity in rDNA sequence and orthology across 85.6 % of predicted genes. Of the 39 genes/operons implicated in the virulence, symbiosis, recolonization, immune evasion and bioconversion, 21 (53.8 %) were present in Serratia while 33 (84.6 %) and 35 (89 %) were present in Xenorhabdus and Photorhabdus EPN bacteria respectively. Conclusion The majority of unique sequences in Serratia sp. SCBI (South African Caenorhabditis briggsae Isolate) are found in ~29 genomic islands of 5 to 65 genes and are enriched in putative functions that are biologically relevant to an entomopathogenic lifestyle, including non-ribosomal peptide synthetases, bacteriocins, fimbrial biogenesis, ushering proteins, toxins, secondary metabolite secretion and multiple drug resistance/efflux systems. By revealing the early stages of adaptation to this lifestyle, the Serratia sp. SCBI genome underscores the fact that in EPN formation the composite end result – killing, bioconversion, cadaver protection and recolonization- can be achieved by dissimilar mechanisms. This genome sequence will enable further study of the evolution of entomopathogenic nematode-bacteria complexes. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1697-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Feseha Abebe-Akele
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA. .,Hubbard Center for Genome Studies, 444 Gregg Hall, University of New Hampshire, 35 Colovos Road, Durham, NH, 03824, USA.
| | - Louis S Tisa
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA
| | - Vaughn S Cooper
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA
| | - Philip J Hatcher
- Department of Computer Science, University of New Hampshire, Durham, NH, USA
| | - Eyualem Abebe
- Department of Biology, Elizabeth City State University, 1704 Weeksville Road, Jenkins Science Center 421, Elizabeth City, NC, 27909, USA
| | - W Kelley Thomas
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA.,Hubbard Center for Genome Studies, 444 Gregg Hall, University of New Hampshire, 35 Colovos Road, Durham, NH, 03824, USA
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Lanois A, Pages S, Bourot S, Canoy AS, Givaudan A, Gaudriault S. Transcriptional analysis of a Photorhabdus sp. variant reveals transcriptional control of phenotypic variation and multifactorial pathogenicity in insects. Appl Environ Microbiol 2011; 77:1009-20. [PMID: 21131515 PMCID: PMC3028736 DOI: 10.1128/aem.01696-10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 11/20/2010] [Indexed: 11/20/2022] Open
Abstract
Photorhabdus luminescens lives in a mutualistic association with entomopathogenic nematodes and is pathogenic for insects. Variants of Photorhabdus frequently arise irreversibly and are studied because they have altered phenotypic traits that are potentially important for the host interaction. VAR* is a colonial and phenotypic variant displaying delayed pathogenicity when directly injected into the insect, Spodoptera littoralis. In this study, we evaluated the role of transcriptomic modulation in determining the phenotypic variation and delayed pathogenicity of VAR* with respect to the corresponding wild-type form, TT01α. A P. luminescens microarray identified 148 genes as differentially transcribed between VAR* and TT01α. The net regulator status of VAR* was found to be significantly modified. We also observed in VAR* a decrease in the transcription of genes supporting certain phenotypic traits, such as pigmentation, crystalline inclusion, antibiosis, and protease and lipase activities. Three genes encoding insecticidal toxins (pit and pirB) or putative insecticidal toxins (xnp2) were less transcribed in VAR* than in the TT01α. The overexpression of these genes was not sufficient to restore the virulence of VAR* to the levels of ΤΤ01α, which suggests that the lower virulence of VAR* does not result from impaired toxemia in insects. Three loci involved in oxidative stress responses (sodA, katE, and the hca operon) were found to be downregulated in VAR*. This is consistent with the greater sensitivity of VAR* to H(2)O(2) and may account for the impaired bacteremia in the hemolymph of S. littoralis larvae observed with VAR*. In conclusion, we demonstrate here that some phenotypic traits of VAR* are regulated transcriptionally and highlight the multifactorial nature of pathogenicity in insects.
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Affiliation(s)
- A. Lanois
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France, Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France, BioIM-BioAnalysis and Services, Bayer BioScience N.V., Technologiepark 38, B-9052 Zwijnaarde, Belgium, Equipe Transcriptome, Groupe de Recherche Génomique Amont, Biogemma, ZI du Brézet, 8 Rue des Frères Lumière, 63028 Clermont-Ferrand, Cedex 2, France
| | - S. Pages
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France, Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France, BioIM-BioAnalysis and Services, Bayer BioScience N.V., Technologiepark 38, B-9052 Zwijnaarde, Belgium, Equipe Transcriptome, Groupe de Recherche Génomique Amont, Biogemma, ZI du Brézet, 8 Rue des Frères Lumière, 63028 Clermont-Ferrand, Cedex 2, France
| | - S. Bourot
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France, Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France, BioIM-BioAnalysis and Services, Bayer BioScience N.V., Technologiepark 38, B-9052 Zwijnaarde, Belgium, Equipe Transcriptome, Groupe de Recherche Génomique Amont, Biogemma, ZI du Brézet, 8 Rue des Frères Lumière, 63028 Clermont-Ferrand, Cedex 2, France
| | - A.-S. Canoy
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France, Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France, BioIM-BioAnalysis and Services, Bayer BioScience N.V., Technologiepark 38, B-9052 Zwijnaarde, Belgium, Equipe Transcriptome, Groupe de Recherche Génomique Amont, Biogemma, ZI du Brézet, 8 Rue des Frères Lumière, 63028 Clermont-Ferrand, Cedex 2, France
| | - A. Givaudan
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France, Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France, BioIM-BioAnalysis and Services, Bayer BioScience N.V., Technologiepark 38, B-9052 Zwijnaarde, Belgium, Equipe Transcriptome, Groupe de Recherche Génomique Amont, Biogemma, ZI du Brézet, 8 Rue des Frères Lumière, 63028 Clermont-Ferrand, Cedex 2, France
| | - S. Gaudriault
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France, Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France, BioIM-BioAnalysis and Services, Bayer BioScience N.V., Technologiepark 38, B-9052 Zwijnaarde, Belgium, Equipe Transcriptome, Groupe de Recherche Génomique Amont, Biogemma, ZI du Brézet, 8 Rue des Frères Lumière, 63028 Clermont-Ferrand, Cedex 2, France
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Phase and antigenic variation mediated by genome modifications. Antonie van Leeuwenhoek 2008; 94:493-515. [DOI: 10.1007/s10482-008-9267-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2008] [Accepted: 07/09/2008] [Indexed: 11/26/2022]
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Gaudriault S, Pages S, Lanois A, Laroui C, Teyssier C, Jumas-Bilak E, Givaudan A. Plastic architecture of bacterial genome revealed by comparative genomics of Photorhabdus variants. Genome Biol 2008; 9:R117. [PMID: 18647395 PMCID: PMC2530875 DOI: 10.1186/gb-2008-9-7-r117] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Revised: 06/12/2008] [Accepted: 07/22/2008] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND The phenotypic consequences of large genomic architecture modifications within a clonal bacterial population are rarely evaluated because of the difficulties associated with using molecular approaches in a mixed population. Bacterial variants frequently arise among Photorhabdus luminescens, a nematode-symbiotic and insect-pathogenic bacterium. We therefore studied genome plasticity within Photorhabdus variants. RESULTS We used a combination of macrorestriction and DNA microarray experiments to perform a comparative genomic study of different P. luminescens TT01 variants. Prolonged culturing of TT01 strain and a genomic variant, collected from the laboratory-maintained symbiotic nematode, generated bacterial lineages composed of primary and secondary phenotypic variants and colonial variants. The primary phenotypic variants exhibit several characteristics that are absent from the secondary forms. We identify substantial plasticity of the genome architecture of some variants, mediated mainly by deletions in the 'flexible' gene pool of the TT01 reference genome and also by genomic amplification. We show that the primary or secondary phenotypic variant status is independent from global genomic architecture and that the bacterial lineages are genomic lineages. We focused on two unusual genomic changes: a deletion at a new recombination hotspot composed of long approximate repeats; and a 275 kilobase single block duplication belonging to a new class of genomic duplications. CONCLUSION Our findings demonstrate that major genomic variations occur in Photorhabdus clonal populations. The phenotypic consequences of these genomic changes are cryptic. This study provides insight into the field of bacterial genome architecture and further elucidates the role played by clonal genomic variation in bacterial genome evolution.
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Affiliation(s)
- Sophie Gaudriault
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
- Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
| | - Sylvie Pages
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
- Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
| | - Anne Lanois
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
- Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
| | - Christine Laroui
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
- Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
| | - Corinne Teyssier
- Université Montpellier 1, EA 3755, Laboratoire de Bactériologie-Virologie, 15, Avenue Charles Flahault, BP 14491, F-34060 Montpellier Cedex 5, France
| | - Estelle Jumas-Bilak
- Université Montpellier 1, EA 3755, Laboratoire de Bactériologie-Virologie, 15, Avenue Charles Flahault, BP 14491, F-34060 Montpellier Cedex 5, France
| | - Alain Givaudan
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
- Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
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Münch A, Stingl L, Jung K, Heermann R. Photorhabdus luminescens genes induced upon insect infection. BMC Genomics 2008; 9:229. [PMID: 18489737 PMCID: PMC2422844 DOI: 10.1186/1471-2164-9-229] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Accepted: 05/19/2008] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Photorhabdus luminescens is a Gram-negative luminescent enterobacterium and a symbiote to soil nematodes belonging to the species Heterorhabditis bacteriophora. P.luminescens is simultaneously highly pathogenic to insects. This bacterium exhibits a complex life cycle, including one symbiotic stage characterized by colonization of the upper nematode gut, and a pathogenic stage, characterized by release from the nematode into the hemocoel of insect larvae, resulting in rapid insect death caused by bacterial toxins. P. luminescens appears to sense and adapt to the novel host environment upon changing hosts, which facilitates the production of factors involved in survival within the host, host-killing, and -exploitation. RESULTS A differential fluorescence induction (DFI) approach was applied to identify genes that are up-regulated in the bacterium after infection of the insect host Galleria mellonella. For this purpose, a P. luminescens promoter-trap library utilizing the mCherry fluorophore as a reporter was constructed, and approximately 13,000 clones were screened for fluorescence induction in the presence of a G. mellonella larvae homogenate. Since P. luminescens has a variety of regulators that potentially sense chemical molecules, like hormones, the screen for up-regulated genes or operons was performed in vitro, excluding physicochemical signals like oxygen, temperature or osmolarity as variables. Clones (18) were obtained exhibiting at least 2.5-fold induced fluorescence and regarded as specific responders to insect homogenate. In combination with a bioinformatics approach, sequence motifs were identified in these DNA-fragments that are similar to 29 different promoters within the P. luminescens genome. By cloning each of the predicted promoters upstream of the reporter gene, induction was verified for 27 promoters in vitro, and for 24 promoters in viable G. mellonella larvae. Among the validated promoters are some known to regulate the expression of toxin genes, including tccC1 (encoding an insecticidal toxin complex), and others encoding putative toxins. A comparably high number of metabolic genes or operons were observed to be induced upon infection; among these were eutABC, hutUH, and agaZSVCD, which encode proteins involved in ethanolamine, histidine and tagatose degradation, respectively. The results reflect rearrangements in metabolism and the use of other metabolites available from the insect. Furthermore, enhanced activity of promoters controlling the expression of genes encoding enzymes linked to antibiotic production and/or resistance was observed. Antibiotic production and resistance may influence competition with other bacteria, and thus might be important for a successful infection. Lastly, several genes of unknown function were identified that may represent novel pathogenicity factors. CONCLUSION We show that a DFI screen is useful for identifying genes or operons induced by chemical stimuli, such as diluted insect homogenate. A bioinformatics comparison of motifs similar to known promoters is a powerful tool for identifying regulated genes or operons. We conclude that signals for the regulation of those genes or operons induced in P. luminescens upon insect infection may represent a wide variety of compounds that make up the insect host. Our results provide insight into the complex response to the host that occurs in a bacterial pathogen, particularly reflecting the potential for metabolic shifts and other specific changes associated with virulence.
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Affiliation(s)
- Anna Münch
- Ludwig-Maximilians-Universität München, Adolf-Butenandt-Institut, Bereich Biochemie, Schillerstr. 44, 80336 München, Germany
| | - Lavinia Stingl
- Universitätsklinikum Würzburg, Klinik und Poliklinik für Strahlentherapie, Josef-Schneider-Str. 11, 97080 Würzburg, Germany
| | - Kirsten Jung
- Ludwig-Maximilians-Universität München, Department Biologie I, Bereich Mikrobiologie, Maria-Ward-Str. 1a, D-80638 München, Germany
- Munich Center for Integrated Protein Science (CIPSM), Ludwig-Maximilians-Universität München, München, Germany
| | - Ralf Heermann
- Ludwig-Maximilians-Universität München, Department Biologie I, Bereich Mikrobiologie, Maria-Ward-Str. 1a, D-80638 München, Germany
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Cowles KN, Cowles CE, Richards GR, Martens EC, Goodrich-Blair H. The global regulator Lrp contributes to mutualism, pathogenesis and phenotypic variation in the bacterium Xenorhabdus nematophila. Cell Microbiol 2007; 9:1311-23. [PMID: 17223926 DOI: 10.1111/j.1462-5822.2006.00873.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Xenorhabdus nematophila is a Gram-negative bacterium that leads both pathogenic and mutualistic lifestyles. In this study, we examine the role of Lrp, the leucine-responsive regulatory protein, in regulating both of these lifestyles. lrp mutants have attenuated virulence towards Manduca sexta insects and are defective in suppression of both cellular and humoral insect immunity. In addition, an lrp mutant is deficient in initiating colonization of and growth within mutualistic host nematodes. Furthermore, nematodes reared on lrp mutant lawns exhibit decreased overall numbers of nematode progeny. To our knowledge, this is the first demonstration of virulence attenuation associated with an lrp mutation in any bacterium, as well as the first report of a factor involved in both X. nematophila symbioses. Protein profiles of wild-type and mutant cells indicate that Lrp is a global regulator of expression in X. nematophila, affecting approximately 65% of 290 proteins. We show that Lrp binds to the promoter regions of genes known to be involved in basic metabolism, mutualism and pathogenesis, demonstrating that the regulation of at least some host interaction factors is likely direct. Finally, we demonstrate that Lrp influences aspects of X. nematophila phenotypic variation, a spontaneous process that occurs during prolonged growth in stationary phase.
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Affiliation(s)
- Kimberly N Cowles
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
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McGillivary G, Tomaras AP, Rhodes ER, Actis LA. Cloning and sequencing of a genomic island found in the Brazilian purpuric fever clone of Haemophilus influenzae biogroup aegyptius. Infect Immun 2005; 73:1927-38. [PMID: 15784532 PMCID: PMC1087403 DOI: 10.1128/iai.73.4.1927-1938.2005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
A genomic island was identified in the Haemophilus influenzae biogroup aegyptius Brazilian purpuric fever (BPF) strain F3031. This island, which was also found in other BPF isolates, could not be detected in non-BPF biogroup aegyptius strains or in nontypeable or typeable H. influenzae strains, with the exception of a region present in the type b Eagan strain. This 34,378-bp island is inserted, in reference to H. influenzae Rd KW20, within a choline transport gene and contains a mosaic structure of Mu-like prophage genes, several hypothetical genes, and genes potentially encoding an Erwinia carotovora carotovoricin Er-like bacteriocin. The product of the tail fiber ORF in the bacteriocin-like region shows a hybrid structure where the C terminus is similar to an H. influenzae phage HP1 tail protein implicating this open reading frame in altering host specificity for a putative bacteriocin. Significant synteny is seen in the entire genomic island with genomic regions from Salmonella enterica subsp. enterica serovar Typhi CT18, Photorhabdus luminescens subsp. laumondii TT01, Chromobacterium violaceum, and to a lesser extent Haemophilus ducreyi 35000HP. In a previous work, we isolated several BPF-specific DNA fragments through a genome subtraction procedure, and we have found that a majority of these fragments map to this locus. In addition, several subtracted fragments generated from an independent laboratory by using different but related strains also map to this island. These findings underscore the importance of this BPF-specific chromosomal region in explaining some of the genomic differences between highly invasive BPF strains and non-BPF isolates of biogroup aegyptius.
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Affiliation(s)
- Glen McGillivary
- Department of Microbiology, Miami University, 40 Pearson Hall, Oxford, OH 45056, USA
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Derzelle S, Ngo S, Turlin É, Duchaud É, Namane A, Kunst F, Danchin A, Bertin P, Charles JF. AstR-AstS, a new two-component signal transduction system, mediates swarming, adaptation to stationary phase and phenotypic variation in Photorhabdus luminescens. MICROBIOLOGY-SGM 2004; 150:897-910. [PMID: 15073299 DOI: 10.1099/mic.0.26563-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Photorhabdus luminescens is an insect-pathogenic bacterium that forms a symbiosis with specific entomopathogenic nematodes. In this bacterium, a symbiosis-'deficient' phenotypic variant (known as the secondary variant or form II) arises at a low frequency during prolonged incubation. A knock-out mutant was generated of the regulator of a newly identified two-component regulatory system, designated AstR-AstS. Interestingly, this mutation altered the timing of phenotypic switching. Variant cells arose in the mutant strain several days before they did in the wild-type population, suggesting that AstRS is directly or indirectly involved in the genetic mechanism underlying variant cell formation. This mutation also affected motility and antibiotic synthesis. To identify AstRS-regulated genes, a comparative analysis using two-dimensional gel electrophoresis was performed. Seventeen proteins with modified synthesis in stationary phase were identified by mass spectrometry and shown to be involved in electron-transport systems, energy metabolism, iron acquisition and stress responses. The results imply that AstRS is involved in the adaptation of cells to the stationary phase, whilst negatively affecting the competitive advantage of form I cells. The link between AstRS-dependent stationary-phase adaptation and phenotypic variation is discussed.
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Affiliation(s)
- Sylviane Derzelle
- Unité de Génétique des Génomes Bactériens, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Saravuth Ngo
- Unité de Génétique des Génomes Bactériens, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Évelyne Turlin
- Unité de Génétique des Génomes Bactériens, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Éric Duchaud
- Laboratoire de Génomique des Micro-organismes Pathogènes, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Abdelkader Namane
- Plate-forme Technologique Protéomique, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Frank Kunst
- Laboratoire de Génomique des Micro-organismes Pathogènes, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Antoine Danchin
- Unité de Génétique des Génomes Bactériens, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Philippe Bertin
- Unité de Génétique des Génomes Bactériens, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Jean-François Charles
- Unité de Génétique des Génomes Bactériens, Département de Structure et Dynamique des Génomes, Institut Pasteur, 75724 Paris Cedex 15, France
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11
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Salaün L, Snyder LA, Saunders NJ. Adaptation by phase variation in pathogenic bacteria. ADVANCES IN APPLIED MICROBIOLOGY 2003; 52:263-301. [PMID: 12964248 DOI: 10.1016/s0065-2164(03)01011-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Laurence Salaün
- Bacterial Pathogenesis and Functional Genomics Group, Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
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12
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Duchaud E, Rusniok C, Frangeul L, Buchrieser C, Givaudan A, Taourit S, Bocs S, Boursaux-Eude C, Chandler M, Charles JF, Dassa E, Derose R, Derzelle S, Freyssinet G, Gaudriault S, Médigue C, Lanois A, Powell K, Siguier P, Vincent R, Wingate V, Zouine M, Glaser P, Boemare N, Danchin A, Kunst F. The genome sequence of the entomopathogenic bacterium Photorhabdus luminescens. Nat Biotechnol 2003; 21:1307-13. [PMID: 14528314 DOI: 10.1038/nbt886] [Citation(s) in RCA: 410] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2003] [Accepted: 08/18/2003] [Indexed: 11/09/2022]
Abstract
Photorhabdus luminescens is a symbiont of nematodes and a broad-spectrum insect pathogen. The complete genome sequence of strain TT01 is 5,688,987 base pairs (bp) long and contains 4,839 predicted protein-coding genes. Strikingly, it encodes a large number of adhesins, toxins, hemolysins, proteases and lipases, and contains a wide array of antibiotic synthesizing genes. These proteins are likely to play a role in the elimination of competitors, host colonization, invasion and bioconversion of the insect cadaver, making P. luminescens a promising model for the study of symbiosis and host-pathogen interactions. Comparison with the genomes of related bacteria reveals the acquisition of virulence factors by extensive horizontal transfer and provides clues about the evolution of an insect pathogen. Moreover, newly identified insecticidal proteins may be effective alternatives for the control of insect pests.
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Affiliation(s)
- Eric Duchaud
- Laboratoire de Génomique des Microorganismes Pathogènes, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 15, France
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13
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Joyce SA, Clarke DJ. A hexA homologue from Photorhabdus regulates pathogenicity, symbiosis and phenotypic variation. Mol Microbiol 2003; 47:1445-57. [PMID: 12603747 DOI: 10.1046/j.1365-2958.2003.03389.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Photorhabdus is a genus of entomopathogenic Gram-negative bacteria that belong to the family Enterobactericeae. Remarkably, at the same time as being pathogenic to insect larvae, Photorhabdus also have a mutualistic relationship with entomophagous nematodes of the family Heterorhabditiae. Photorhabdus can be isolated in two phenotypically distinct forms, termed the primary and secondary variant. Both variants grow equally well and are equally virulent when injected into insect larvae. However, only the primary variant can colonize the intestinal tract of the IJ stage of the nematode and support nematode growth and development. The primary variant expresses several phenotypes that are absent from the secondary variant, including the production of extracellular enzymes, pigments, antibiotics and light. In this study, we use Photorhabdus temperata strain K122 to show that these primary-specific products are symbiosis factors, i.e. factors that are required for nematode growth and development. We also show that, in P. temperata K122, the production of these symbiosis factors is repressed in the secondary variant by the protein encoded by a gene with homology to hexA from Erwinia. Moreover, the derepression of the symbiosis factors in the secondary variant results in a significant attenuation of virulence to larvae of the greater wax moth, Galleria mellonella. This suggests that, during a normal infection, pathogenicity and symbiosis must be temporally separated and that HexA is involved in the regulation of this pathogen-symbiont transition.
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Affiliation(s)
- Susan A Joyce
- Molecular Microbiology Laboratory, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
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14
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ffrench-Constant R, Waterfield N, Daborn P, Joyce S, Bennett H, Au C, Dowling A, Boundy S, Reynolds S, Clarke D. Photorhabdus: towards a functional genomic analysis of a symbiont and pathogen. FEMS Microbiol Rev 2003; 26:433-56. [PMID: 12586390 DOI: 10.1111/j.1574-6976.2003.tb00625.x] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Pathogenicity and symbiosis are central to bacteria-host interactions. Although several human pathogens have been subjected to functional genomic analysis, we still understand little about bacteria-invertebrate interactions despite their ecological prevalence. Advances in our knowledge of this area are often hindered by the difficulty of isolating and working with invertebrate pathogenic bacteria and their hosts. Here we review studies on pathogenicity and symbiosis in an insect pathogenic bacterium Photorhabdus and its entomopathogenic nematode vector and model insect hosts. Whilst switching between these hosts, Photorhabdus changes from a state of symbiosis with its nematode vector to one of pathogenicity towards its new insect host and both the bacteria and the nematode then cooperatively exploit the dying insect. We examine candidate genes involved in symbiosis and pathogenicity, their secretion and expression patterns in culture and in the host, and begin to dissect the extent of their genetic coregulation. We describe the presence of several large genomic islands, putatively involved in pathogenicity or symbiosis, within the otherwise Yersinia-like backbone of the Photorhabdus genome. Finally, we examine the emerging comparative genomics of the Photorhabdus group and begin to describe the interrelationship between anti-invertebrate virulence factors and those used against vertebrates.
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Affiliation(s)
- Richard ffrench-Constant
- Centre for Molecular Microbiology, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.
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15
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Abstract
Genomic islands are responsible for unique aspects of bacterial behavior such as symbiosis and pathogenicity. Photorhabdus luminescens is a pathogen of insects that spends part of its lifecycle in symbiosis with a nematode. Here, we describe novel genomic islands from Photorhabdus that are involved in symbiosis and pathogenicity, and discuss the inter-relationship between virulence factors used against invertebrates and vertebrates.
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