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Ganesan R, Wierz JC, Kaltenpoth M, Flórez LV. How It All Begins: Bacterial Factors Mediating the Colonization of Invertebrate Hosts by Beneficial Symbionts. Microbiol Mol Biol Rev 2022; 86:e0012621. [PMID: 36301103 PMCID: PMC9769632 DOI: 10.1128/mmbr.00126-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Beneficial associations with bacteria are widespread across animals, spanning a range of symbiont localizations, transmission routes, and functions. While some of these associations have evolved into obligate relationships with permanent symbiont localization within the host, the majority require colonization of every host generation from the environment or via maternal provisions. Across the broad diversity of host species and tissue types that beneficial bacteria can colonize, there are some highly specialized strategies for establishment yet also some common patterns in the molecular basis of colonization. This review focuses on the mechanisms underlying the early stage of beneficial bacterium-invertebrate associations, from initial contact to the establishment of the symbionts in a specific location of the host's body. We first reflect on general selective pressures that can drive the transition from a free-living to a host-associated lifestyle in bacteria. We then cover bacterial molecular factors for colonization in symbioses from both model and nonmodel invertebrate systems where these have been studied, including terrestrial and aquatic host taxa. Finally, we discuss how interactions between multiple colonizing bacteria and priority effects can influence colonization. Taking the bacterial perspective, we emphasize the importance of developing new experimentally tractable systems to derive general insights into the ecological factors and molecular adaptations underlying the origin and establishment of beneficial symbioses in animals.
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Affiliation(s)
- Ramya Ganesan
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany
- Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Jürgen C. Wierz
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany
- Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Martin Kaltenpoth
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany
- Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Laura V. Flórez
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany
- Department of Plant and Environmental Sciences, Section for Organismal Biology, University of Copenhagen, Copenhagen, Denmark
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2
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Díez-Vives C, Koutsouveli V, Conejero M, Riesgo A. Global patterns in symbiont selection and transmission strategies in sponges. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1015592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Sponges host dense and diverse communities of microbes (known as the microbiome) beneficial for the host nutrition and defense. Symbionts in turn receive shelter and metabolites from the sponge host, making their relationship beneficial for both partners. Given that sponge-microbes associations are fundamental for the survival of both, especially the sponge, such relationship is maintained through their life and even passed on to the future generations. In many organisms, the microbiome has profound effects on the development of the host, but the influence of the microbiome on the reproductive and developmental pathways of the sponges are less understood. In sponges, microbes are passed on to oocytes, sperm, embryos, and larvae (known as vertical transmission), using a variety of methods that include direct uptake from the mesohyl through phagocytosis by oocytes to indirect transmission to the oocyte by nurse cells. Such microbes can remain in the reproductive elements untouched, for transfer to offspring, or can be digested to make the yolky nutrient reserves of oocytes and larvae. When and how those decisions are made are fundamentally unanswered questions in sponge reproduction. Here we review the diversity of vertical transmission modes existent in the entire phylum Porifera through detailed imaging using electron microscopy, available metabarcoding data from reproductive elements, and macroevolutionary patterns associated to phylogenetic constraints. Additionally, we examine the fidelity of this vertical transmission and possible reasons for the observed variability in some developmental stages. Our current understanding in marine sponges, however, is that the adult microbial community is established by a combination of both vertical and horizontal (acquisition from the surrounding environment in each new generation) transmission processes, although the extent in which each mode shapes the adult microbiome still remains to be determined. We also assessed the fundamental role of filtration, the cellular structures for acquiring external microbes, and the role of the host immune system, that ultimately shapes the stable communities of prokaryotes observed in adult sponges.
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3
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Upadhyay A, Mohan S. Bacillus subtilis and B. licheniformis Isolated from Heterorhabditis indica Infected Apple Root Borer (Dorysthenes huegelii) Suppresses Nematode Production in Galleria mellonella. Acta Parasitol 2021; 66:989-996. [PMID: 33768406 DOI: 10.1007/s11686-021-00366-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 03/01/2021] [Indexed: 10/21/2022]
Abstract
PURPOSE Heterorhabdits indica successfully controlled apple root borer Dorysthenes huegelii in the orchards, but nematode-infected cadavers revealed the presence of non-symbiotic bacterial B. subtilis and B. licheniformis, and no subsequent generations of H. indica were produced (hampered recycling phenomenon). Intrigued, we tested the effect of the two Bacillus species on symbiotic association of H. indica-Photorhabdus luminescens. METHODS One-to-one competitive parallel line in vitro assays were carried out between P. luminescens and the two Bacillus spp., while in vivo H. indica development was studied on the test insect Galleria mellonella which were fed with Bacillus mixed diet, followed by nematode exposure. RESULTS Where P. luminescens was flanked by either of the two Bacillus species, only B. subtilis significantly suppressed its growth, while in reversed assays both the Bacillus growth was unaffected. Heterorhabditis indica was able to kill Galleria larvae pre-fed with the two Bacillus spp.; these cadavers did not develop the characteristic evenly distributed brick red coloration. Besides P. luminesecns, both Bacillus spp. were found to coexist in these cadavers. Development of hermaphrodites was not affected, but second-generation females, and final nematode progeny was reduced significantly. Monozenic lawns of B. subtilis and B. licheniformis did not support H. indica development. CONCLUSION These results show the reduced development of H. indica by the presence of the non-symbiotic bacteria in G. mellonella is likely to affect their ability to recycle in other insect larvae. Reduced recycling caused by non-symbiotic bacteria will reduce the overall long-term pest control benefits and have implications in the development of application strategies using entomopathogenic nematodes (EPNs) as insect control agents.
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4
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Fujdiarová E, Houser J, Dobeš P, Paulíková G, Kondakov N, Kononov L, Hyršl P, Wimmerová M. Heptabladed β‐propeller lectins PLL2 and PHL from
Photorhabdus
spp. recognize
O
‐methylated sugars and influence the host immune system. FEBS J 2020; 288:1343-1365. [DOI: 10.1111/febs.15457] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 04/19/2020] [Accepted: 06/15/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Eva Fujdiarová
- Central European Institute of Technology (CEITEC) Masaryk University Brno Czech Republic
- National Centre for Biomolecular Research Faculty of Science Masaryk University Brno Czech Republic
| | - Josef Houser
- Central European Institute of Technology (CEITEC) Masaryk University Brno Czech Republic
- National Centre for Biomolecular Research Faculty of Science Masaryk University Brno Czech Republic
| | - Pavel Dobeš
- National Centre for Biomolecular Research Faculty of Science Masaryk University Brno Czech Republic
- Section of Animal Physiology and Immunology Department of Experimental Biology Faculty of Science Masaryk University Brno Czech Republic
| | - Gita Paulíková
- Central European Institute of Technology (CEITEC) Masaryk University Brno Czech Republic
- National Centre for Biomolecular Research Faculty of Science Masaryk University Brno Czech Republic
| | - Nikolay Kondakov
- N.D. Zelinsky Institute of Organic Chemistry Russian Academy of Sciences Moscow Russia
| | - Leonid Kononov
- N.D. Zelinsky Institute of Organic Chemistry Russian Academy of Sciences Moscow Russia
| | - Pavel Hyršl
- Section of Animal Physiology and Immunology Department of Experimental Biology Faculty of Science Masaryk University Brno Czech Republic
| | - Michaela Wimmerová
- Central European Institute of Technology (CEITEC) Masaryk University Brno Czech Republic
- National Centre for Biomolecular Research Faculty of Science Masaryk University Brno Czech Republic
- Department of Biochemistry Faculty of Science Masaryk University Brno Czech Republic
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5
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Erwinia carotovora Quorum Sensing System Regulates Host-Specific Virulence Factors and Development Delay in Drosophila melanogaster. mBio 2020; 11:mBio.01292-20. [PMID: 32576677 PMCID: PMC7315124 DOI: 10.1128/mbio.01292-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Integration of genetic networks allows bacteria to rapidly adapt to changing environments. This is particularly important in bacteria that interact with multiple hosts. Erwinia carotovora is a plant pathogen that uses Drosophila melanogaster as a vector. To interact with these two hosts, Ecc15 uses different sets of virulence factors: plant cell wall-degrading enzymes to infect plants and the Erwinia virulence factor (evf) to infect Drosophila. Our work shows that, despite the virulence factors being specific for each host, both sets are coactivated by homoserine lactone quorum sensing and by the two-component GacS/A system in infected plants. This regulation is essential for Ecc15 loads in the gut of Drosophila and minimizes the developmental delay caused by the bacteria with respect to the insect vector. Our findings provide evidence that coactivation of the host-specific factors in the plant may function as a predictive mechanism to maximize the probability of transit of the bacteria between hosts. Multihost bacteria have to rapidly adapt to drastic environmental changes, relying on a fine integration of multiple stimuli for an optimal genetic response. Erwinia carotovora spp. are phytopathogens that cause soft-rot disease. Strain Ecc15 in particular is a model for bacterial oral-route infection in Drosophila melanogaster as it harbors a unique gene, evf, that encodes the Erwinia virulence factor (Evf), which is a major determinant for infection of the D. melanogaster gut. However, the factors involved in the regulation of evf expression are poorly understood. We investigated whether evf could be controlled by quorum sensing as, in the Erwinia genus, quorum sensing regulates pectolytic enzymes, the major virulence factors needed to infect plants. Here, we show that transcription of evf is positively regulated by quorum sensing in Ecc15 via acyl-homoserine lactone (AHL) signal synthase ExpI and AHL receptors ExpR1 and ExpR2. We also show that the load of Ecc15 in the gut depends upon the quorum sensing-mediated regulation of evf. Furthermore, we demonstrate that larvae infected with Ecc15 suffer a developmental delay as a direct consequence of the regulation of evf via quorum sensing. Finally, we demonstrate that evf is coexpressed with plant cell wall-degrading enzymes (PCWDE) during plant infection in a quorum sensing-dependent manner. Overall, our results show that Ecc15 relies on quorum sensing to control production of both pectolytic enzymes and Evf. This regulation influences the interaction of Ecc15 with its two known hosts, indicating that quorum sensing signaling may impact bacterial dissemination via insect vectors that feed on rotting plants.
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6
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Abstract
Different model systems have, over the years, contributed to our current understanding of the molecular mechanisms underpinning the various types of interaction between bacteria and their animal hosts. The genus
Photorhabdus
comprises Gram-negative insect pathogenic bacteria that are normally found as symbionts that colonize the gut of the infective juvenile stage of soil-dwelling nematodes from the family Heterorhabditis. The nematodes infect susceptible insects and release the bacteria into the insect haemolymph where the bacteria grow, resulting in the death of the insect. At this stage the nematodes feed on the bacterial biomass and, following several rounds of reproduction, the nematodes develop into infective juveniles that leave the insect cadaver in search of new hosts. Therefore
Photorhabdus
has three distinct and obligate roles to play during this life-cycle: (1)
Photorhabdus
must kill the insect host; (2)
Photorhabdus
must be capable of supporting nematode growth and development; and (3)
Photorhabdus
must be able to colonize the gut of the next generation of infective juveniles before they leave the insect cadaver. In this review I will discuss how genetic analysis has identified key genes involved in mediating, and regulating, the interaction between
Photorhabdus
and each of its invertebrate hosts. These studies have resulted in the characterization of several new families of toxins and a novel inter-kingdom signalling molecule and have also uncovered an important role for phase variation in the regulation of these different roles.
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Affiliation(s)
- David J Clarke
- School of Microbiology and APC Microbiome Ireland, University College Cork, Cork, Ireland
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7
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Payelleville A, Blackburn D, Lanois A, Pagès S, Cambon MC, Ginibre N, Clarke DJ, Givaudan A, Brillard J. Role of the Photorhabdus Dam methyltransferase during interactions with its invertebrate hosts. PLoS One 2019; 14:e0212655. [PMID: 31596856 PMCID: PMC6785176 DOI: 10.1371/journal.pone.0212655] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 09/20/2019] [Indexed: 11/19/2022] Open
Abstract
Photorhabdus luminescens is an entomopathogenic bacterium found in symbiosis with the nematode Heterorhabditis. Dam DNA methylation is involved in the pathogenicity of many bacteria, including P. luminescens, whereas studies about the role of bacterial DNA methylation during symbiosis are scarce. The aim of this study was to determine the role of Dam DNA methylation in P. luminescens during the whole bacterial life cycle including during symbiosis with H. bacteriophora. We constructed a strain overexpressing dam by inserting an additional copy of the dam gene under the control of a constitutive promoter in the chromosome of P. luminescens and then achieved association between this recombinant strain and nematodes. The dam overexpressing strain was able to feed the nematode in vitro and in vivo similarly as a control strain, and to re-associate with Infective Juvenile (IJ) stages in the insect. No difference in the amount of emerging IJs from the cadaver was observed between the two strains. Compared to the nematode in symbiosis with the control strain, a significant increase in LT50 was observed during insect infestation with the nematode associated with the dam overexpressing strain. These results suggest that during the life cycle of P. luminescens, Dam is not involved the bacterial symbiosis with the nematode H. bacteriophora, but it contributes to the pathogenicity of the nemato-bacterial complex.
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Affiliation(s)
| | - Dana Blackburn
- Department of Microbiology, University College Cork, Cork, Ireland
| | - Anne Lanois
- DGIMI, INRA, Univ. Montpellier, Montpellier, France
| | - Sylvie Pagès
- DGIMI, INRA, Univ. Montpellier, Montpellier, France
| | - Marine C. Cambon
- DGIMI, INRA, Univ. Montpellier, Montpellier, France
- Évolution et Diversité Biologique, CNRS, UPS Université Paul Sabatier, Toulouse, France
| | | | - David J. Clarke
- Department of Microbiology, University College Cork, Cork, Ireland
| | | | - Julien Brillard
- DGIMI, INRA, Univ. Montpellier, Montpellier, France
- * E-mail: (JB); (AP)
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8
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Skjerning RB, Senissar M, Winther KS, Gerdes K, Brodersen DE. The RES domain toxins of RES-Xre toxin-antitoxin modules induce cell stasis by degrading NAD+. Mol Microbiol 2018; 111:221-236. [PMID: 30315706 DOI: 10.1111/mmi.14150] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2018] [Indexed: 12/18/2022]
Abstract
Type II toxin-antitoxin (TA) modules, which are important cellular regulators in prokaryotes, usually encode two proteins, a toxin that inhibits cell growth and a nontoxic and labile inhibitor (antitoxin) that binds to and neutralizes the toxin. Here, we demonstrate that the res-xre locus from Photorhabdus luminescens and other bacterial species function as bona fide TA modules in Escherichia coli. The 2.2 Å crystal structure of the intact Pseudomonas putida RES-Xre TA complex reveals an unusual 2:4 stoichiometry in which a central RES toxin dimer binds two Xre antitoxin dimers. The antitoxin dimers each expose two helix-turn-helix DNA-binding domains of the Cro repressor type, suggesting the TA complex is capable of binding the upstream promoter sequence on DNA. The toxin core domain shows structural similarity to ADP-ribosylating enzymes such as diphtheria toxin but has an atypical NAD+ -binding pocket suggesting an alternative function. We show that activation of the toxin in vivo causes a depletion of intracellular NAD+ levels eventually leading to inhibition of cell growth in E. coli and inhibition of global macromolecular biosynthesis. Both structure and activity are unprecedented among bacterial TA systems, suggesting the functional scope of bacterial TA toxins is much wider than previously appreciated.
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Affiliation(s)
- Ragnhild Bager Skjerning
- Department of Biology, Centre for Bacterial Stress Response and Persistence (BASP), University of Copenhagen, Copenhagen, Denmark
| | - Meriem Senissar
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
| | - Kristoffer S Winther
- Department of Biology, Centre for Bacterial Stress Response and Persistence (BASP), University of Copenhagen, Copenhagen, Denmark
| | - Kenn Gerdes
- Department of Biology, Centre for Bacterial Stress Response and Persistence (BASP), University of Copenhagen, Copenhagen, Denmark
| | - Ditlev E Brodersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
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9
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Expression of Heterorhabditis bacteriophora C-type lectins, Hb-clec-1 and Hb-clec-78, in context of symbiosis with Photorhabdus bacteria. Symbiosis 2018. [DOI: 10.1007/s13199-018-0569-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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10
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Hoinville ME, Wollenberg AC. Changes in Caenorhabditis elegans gene expression following exposure to Photorhabdus luminescens strain TT01. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 82:165-176. [PMID: 29203330 DOI: 10.1016/j.dci.2017.09.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 09/05/2017] [Accepted: 09/08/2017] [Indexed: 06/07/2023]
Abstract
Photorhabdus bacteria enter into a mutualistic symbiosis with Heterorhabditis nematodes to infect insect larvae. However, they rapidly kill the model nematode Caenorhabditis elegans. One hypothesis for these divergent outcomes is that the nematode defense responses differ. To begin testing this hypothesis, we have systematically analyzed available data on the transcriptional response of C. elegans to P. luminescens strain Hb. From a starting pool of over 7000 differentially expressed genes, we carefully chose 21 Heterorhabditis-conserved genes to develop as comparative markers. Using newly designed and validated qRT-PCR primers, we measured expression of these genes in C. elegans exposed to the sequenced TT01 strain of P. luminescens, on two different media types. Almost all (18/21) of the genes showed a significant response to P. luminescens strain TT01. One response is dependent on media type, and a subset of genes may respond differentially to distinct strains. Overall, we have established useful resources and generated new hypotheses regarding how C. elegans responds to P. luminescens infection.
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Affiliation(s)
- Megan E Hoinville
- Biology Department, Kalamazoo College, 1200 Academy St., Kalamazoo, MI 49006, USA
| | - Amanda C Wollenberg
- Biology Department, Kalamazoo College, 1200 Academy St., Kalamazoo, MI 49006, USA.
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11
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Perez CE, Park HB, Crawford JM. Functional Characterization of a Condensation Domain That Links Nonribosomal Peptide and Pteridine Biosynthetic Machineries in Photorhabdus luminescens. Biochemistry 2018; 57:354-361. [PMID: 29111689 DOI: 10.1021/acs.biochem.7b00863] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Nonribosomal peptide synthetases (NRPSs) produce a wide variety of biologically important small molecules. NRPSs can interface with other enzymes to form hybrid biosynthetic systems that expand the structural and functional diversity of their products. The pepteridines are metabolites encoded by an unprecedented pteridine-NRPS-type hybrid biosynthetic gene cluster in Photorhabdus luminescens, but how the distinct enzymatic systems interface to produce these molecules has not been examined at the biochemical level. By an unknown mechanism, the genetic locus can also affect the regulation of other enzymes involved in autoinducer and secondary metabolite biosynthesis. Here, through in vitro protein biochemical assays, we demonstrate that an atypical NRPS condensation (C) domain present in the pathway condenses acyl units derived from α-keto acids onto a free 5,6,7,8-tetrahydropterin core, producing the tertiary cis-amide-containing pepteridines. Solution studies of the chemically synthesized molecules led to the same amide regiochemistries that were observed in the natural products. The biochemical transformations mediated by the C domain destroy the radical scavenging activity of its redox active tetrahydropterin substrate. Secondary metabolite analyses revealed that the pepteridine locus affects select metabolic pathways associated with quorum sensing, antibiosis, and symbiosis. Taken together, the results suggest that the pathway likely regulates cellular redox and specialized metabolic pathways through engagement with the citric acid cycle.
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Affiliation(s)
- Corey E Perez
- Department of Chemistry, Yale University , New Haven, Connecticut 06520, United States.,Chemical Biology Institute, Yale University , West Haven, Connecticut 06516, United States
| | - Hyun Bong Park
- Department of Chemistry, Yale University , New Haven, Connecticut 06520, United States.,Chemical Biology Institute, Yale University , West Haven, Connecticut 06516, United States
| | - Jason M Crawford
- Department of Chemistry, Yale University , New Haven, Connecticut 06520, United States.,Chemical Biology Institute, Yale University , West Haven, Connecticut 06516, United States.,Department of Microbial Pathogenesis, Yale School of Medicine , New Haven, Connecticut 06510, United States
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12
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Park HB, Perez CE, Barber KW, Rinehart J, Crawford JM. Genome mining unearths a hybrid nonribosomal peptide synthetase-like-pteridine synthase biosynthetic gene cluster. eLife 2017; 6. [PMID: 28431213 PMCID: PMC5384830 DOI: 10.7554/elife.25229] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 02/28/2017] [Indexed: 01/03/2023] Open
Abstract
Nonribosomal peptides represent a large class of metabolites with pharmaceutical relevance. Pteridines, such as pterins, folates, and flavins, are heterocyclic metabolites that often serve as redox-active cofactors. The biosynthetic machineries for construction of these distinct classes of small molecules operate independently in the cell. Here, we discovered an unprecedented nonribosomal peptide synthetase-like-pteridine synthase hybrid biosynthetic gene cluster in Photorhabdus luminescens using genome synteny analysis. P. luminescens is a Gammaproteobacterium that undergoes phenotypic variation and can have both pathogenic and mutualistic roles. Through extensive gene deletion, pathway-targeted molecular networking, quantitative proteomic analysis, and NMR, we show that the genetic locus affects the regulation of quorum sensing and secondary metabolic enzymes and encodes new pteridine metabolites functionalized with cis-amide acyl-side chains, termed pepteridine A (1) and B (2). The pepteridines are produced in the pathogenic phenotypic variant and represent the first reported metabolites to be synthesized by a hybrid NRPS-pteridine pathway. These studies expand our view of the combinatorial biosynthetic potential available in bacteria.
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Affiliation(s)
- Hyun Bong Park
- Department of Chemistry, Yale University, New Haven, United States.,Chemical Biology Institute, Yale University, West Haven, United States
| | - Corey E Perez
- Department of Chemistry, Yale University, New Haven, United States.,Chemical Biology Institute, Yale University, West Haven, United States
| | - Karl W Barber
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, United States.,Systems Biology Institute, Yale University, West Haven, United States
| | - Jesse Rinehart
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, United States.,Systems Biology Institute, Yale University, West Haven, United States
| | - Jason M Crawford
- Department of Chemistry, Yale University, New Haven, United States.,Chemical Biology Institute, Yale University, West Haven, United States.,Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, United States
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13
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Mouammine A, Pages S, Lanois A, Gaudriault S, Jubelin G, Bonabaud M, Cruveiller S, Dubois E, Roche D, Legrand L, Brillard J, Givaudan A. An antimicrobial peptide-resistant minor subpopulation of Photorhabdus luminescens is responsible for virulence. Sci Rep 2017; 7:43670. [PMID: 28252016 PMCID: PMC5333078 DOI: 10.1038/srep43670] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 01/27/2017] [Indexed: 11/09/2022] Open
Abstract
Some of the bacterial cells in isogenic populations behave differently from others. We describe here how a new type of phenotypic heterogeneity relating to resistance to cationic antimicrobial peptides (CAMPs) is determinant for the pathogenic infection process of the entomopathogenic bacterium Photorhabdus luminescens. We demonstrate that the resistant subpopulation, which accounts for only 0.5% of the wild-type population, causes septicemia in insects. Bacterial heterogeneity is driven by the PhoPQ two-component regulatory system and expression of pbgPE, an operon encoding proteins involved in lipopolysaccharide (LPS) modifications. We also report the characterization of a core regulon controlled by the DNA-binding PhoP protein, which governs virulence in P. luminescens. Comparative RNAseq analysis revealed an upregulation of marker genes for resistance, virulence and bacterial antagonism in the pre-existing resistant subpopulation, suggesting a greater ability to infect insect prey and to survive in cadavers. Finally, we suggest that the infection process of P. luminescens is based on a bet-hedging strategy to cope with the diverse environmental conditions experienced during the lifecycle.
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Affiliation(s)
| | - Sylvie Pages
- DGIMI, INRA, Univ. Montpellier, Montpellier, France
| | - Anne Lanois
- DGIMI, INRA, Univ. Montpellier, Montpellier, France
| | | | | | | | - Stéphane Cruveiller
- Laboratoire d'Analyse Bioinformatique en Génomique et Métabolisme, CEA, Genoscope &CNRS, Evry, France
| | - Emeric Dubois
- MGX-Montpellier GenomiX, c/o IGF, Montpellier, France
| | - David Roche
- Laboratoire d'Analyse Bioinformatique en Génomique et Métabolisme, CEA, Genoscope &CNRS, Evry, France
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14
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Park HB, Sampathkumar P, Perez CE, Lee JH, Tran J, Bonanno JB, Hallem EA, Almo SC, Crawford JM. Stilbene epoxidation and detoxification in a Photorhabdus luminescens-nematode symbiosis. J Biol Chem 2017; 292:6680-6694. [PMID: 28246174 DOI: 10.1074/jbc.m116.762542] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 02/16/2017] [Indexed: 11/06/2022] Open
Abstract
Members of the gammaproteobacterial Photorhabdus genus share mutualistic relationships with Heterorhabditis nematodes, and the pairs infect a wide swath of insect larvae. Photorhabdus species produce a family of stilbenes, with two major components being 3,5-dihydroxy-4-isopropyl-trans-stilbene (compound 1) and its stilbene epoxide (compound 2). This family of molecules harbors antimicrobial and immunosuppressive activities, and its pathway is responsible for producing a nematode "food signal" involved in nematode development. However, stilbene epoxidation biosynthesis and its biological roles remain unknown. Here, we identified an orphan protein (Plu2236) from Photorhabdus luminescens that catalyzes stilbene epoxidation. Structural, mutational, and biochemical analyses confirmed the enzyme adopts a fold common to FAD-dependent monooxygenases, contains a tightly bound FAD prosthetic group, and is required for the stereoselective epoxidation of compounds 1 and 2. The epoxidase gene was dispensable in a nematode-infective juvenile recovery assay, indicating the oxidized compound is not required for the food signal. The epoxide exhibited reduced cytotoxicity toward its producer, suggesting this may be a natural route for intracellular detoxification. In an insect infection model, we also observed two stilbene-derived metabolites that were dependent on the epoxidase. NMR, computational, and chemical degradation studies established their structures as new stilbene-l-proline conjugates, prolbenes A (compound 3) and B (compound 4). The prolbenes lacked immunosuppressive and antimicrobial activities compared with their stilbene substrates, suggesting a metabolite attenuation mechanism in the animal model. Collectively, our studies provide a structural view for stereoselective stilbene epoxidation and functionalization in an invertebrate animal infection model and provide new insights into stilbene cellular detoxification.
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Affiliation(s)
- Hyun Bong Park
- From the Department of Chemistry, Yale University, New Haven, Connecticut 06520.,the Chemical Biology Institute, Yale University, West Haven, Connecticut 06516
| | | | - Corey E Perez
- From the Department of Chemistry, Yale University, New Haven, Connecticut 06520.,the Chemical Biology Institute, Yale University, West Haven, Connecticut 06516
| | - Joon Ha Lee
- the Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, California 90095, and
| | - Jeannie Tran
- the Chemical Biology Institute, Yale University, West Haven, Connecticut 06516
| | - Jeffrey B Bonanno
- the Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Elissa A Hallem
- the Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, California 90095, and
| | - Steven C Almo
- the Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Jason M Crawford
- From the Department of Chemistry, Yale University, New Haven, Connecticut 06520, .,the Chemical Biology Institute, Yale University, West Haven, Connecticut 06516.,the Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut 06510
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15
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Valverde C. Who's the boss here? The post‐transcriptional global regulator
H
fq takes over control of secondary metabolite production in the nematode symbiont
P
hotorhabdus luminiscens. Environ Microbiol 2017; 19:21-24. [DOI: 10.1111/1462-2920.13635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Claudio Valverde
- Departamento de Ciencia y Tecnología, LBMIBSUniversidad Nacional de Quilmes – CONICETBernalB1876BXD Argentina
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16
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Death Becomes Them: Bacterial Community Dynamics and Stilbene Antibiotic Production in Cadavers of Galleria mellonella Killed by Heterorhabditis and Photorhabdus spp. Appl Environ Microbiol 2016; 82:5824-37. [PMID: 27451445 DOI: 10.1128/aem.01211-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 07/14/2016] [Indexed: 12/19/2022] Open
Abstract
UNLABELLED Insect larvae killed by entomopathogenic nematodes are thought to contain bacterial communities dominated by a single bacterial genus, that of the nematode's bacterial symbiont. In this study, we used next-generation sequencing to profile bacterial community dynamics in greater wax moth (Galleria mellonella) larvae cadavers killed by Heterorhabditis nematodes and their Photorhabdus symbionts. We found that, although Photorhabdus strains did initially displace an Enterococcus-dominated community present in uninfected G. mellonella insect larvae, the cadaver community was not static. Twelve days postinfection, Photorhabdus shared the cadaver with Stenotrophomonas species. Consistent with this result, Stenotrophomonas strains isolated from infected cadavers were resistant to Photorhabdus-mediated toxicity in solid coculture assays. We isolated and characterized a Photorhabdus-produced antibiotic from G. mellonella cadavers, produced it synthetically, and demonstrated that both the natural and synthetic compounds decreased G. mellonella-associated Enterococcus growth, but not Stenotrophomonas growth, in vitro Finally, we showed that the Stenotrophomonas strains described here negatively affected Photorhabdus growth in vitro Our results add an important dimension to a broader understanding of Heterorhabditis-Photorhabdus biology and also demonstrate that interspecific bacterial competition likely characterizes even a theoretically monoxenic environment, such as a Heterorhabditis-Photorhabdus-parasitized insect cadaver. IMPORTANCE Understanding, and eventually manipulating, both human and environmental health depends on a complete accounting of the forces that act on and shape microbial communities. One of these underlying forces is hypothesized to be resource competition. A resource that has received little attention in the general microbiological literature, but likely has ecological and evolutionary importance, is dead/decaying multicellular organisms. Metazoan cadavers, including those of insects, are ephemeral and nutrient-rich environments, where resource competition might shape interspecific macrobiotic and microbiotic interactions. This study is the first to use a next-generation sequencing approach to study the community dynamics of bacteria within a model insect cadaver system: insect larvae parasitized by entomopathogenic nematodes and their bacterial symbionts. By integrating bioinformatic, biochemical, and classic in vitro microbiological approaches, we have provided mechanistic insight into how antibiotic-mediated bacterial interactions may shape community dynamics within insect cadavers.
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17
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Hoang KL, Morran LT, Gerardo NM. Experimental Evolution as an Underutilized Tool for Studying Beneficial Animal-Microbe Interactions. Front Microbiol 2016; 7:1444. [PMID: 27679620 PMCID: PMC5020044 DOI: 10.3389/fmicb.2016.01444] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Accepted: 08/30/2016] [Indexed: 11/29/2022] Open
Abstract
Microorganisms play a significant role in the evolution and functioning of the eukaryotes with which they interact. Much of our understanding of beneficial host–microbe interactions stems from studying already established associations; we often infer the genotypic and environmental conditions that led to the existing host–microbe relationships. However, several outstanding questions remain, including understanding how host and microbial (internal) traits, and ecological and evolutionary (external) processes, influence the origin of beneficial host–microbe associations. Experimental evolution has helped address a range of evolutionary and ecological questions across different model systems; however, it has been greatly underutilized as a tool to study beneficial host–microbe associations. In this review, we suggest ways in which experimental evolution can further our understanding of the proximate and ultimate mechanisms shaping mutualistic interactions between eukaryotic hosts and microbes. By tracking beneficial interactions under defined conditions or evolving novel associations among hosts and microbes with little prior evolutionary interaction, we can link specific genotypes to phenotypes that can be directly measured. Moreover, this approach will help address existing puzzles in beneficial symbiosis research: how symbioses evolve, how symbioses are maintained, and how both host and microbe influence their partner’s evolutionary trajectories. By bridging theoretical predictions and empirical tests, experimental evolution provides us with another approach to test hypotheses regarding the evolution of beneficial host–microbe associations.
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Affiliation(s)
- Kim L Hoang
- Department of Biology, O. Wayne Rollins Research Center, Emory University Atlanta, GA, USA
| | - Levi T Morran
- Department of Biology, O. Wayne Rollins Research Center, Emory University Atlanta, GA, USA
| | - Nicole M Gerardo
- Department of Biology, O. Wayne Rollins Research Center, Emory University Atlanta, GA, USA
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18
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Bager R, Roghanian M, Gerdes K, Clarke DJ. Alarmone (p)ppGpp regulates the transition from pathogenicity to mutualism in Photorhabdus luminescens. Mol Microbiol 2016; 100:735-47. [PMID: 26845750 DOI: 10.1111/mmi.13345] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2016] [Indexed: 01/21/2023]
Abstract
The enteric gamma-proteobacterium Photorhabdus luminescens kills a wide range of insects, whilst also maintaining a mutualistic relationship with soil nematodes from the family Heterorhabditis. Pathogenicity is associated with bacterial exponential growth, whilst mutualism is associated with post-exponential (stationary) phase. During post-exponential growth, P. luminescens also elaborates an extensive secondary metabolism, including production of bioluminescence, antibiotics and pigment. However, the regulatory network that controls the expression of this secondary metabolism is not well understood. The stringent response is a well-described global regulatory system in bacteria and mediated by the alarmone (p)ppGpp. In this study, we disrupted the genes relA and spoT, encoding the two predicted (p)ppGpp synthases of P. luminescens TTO1, and we showed that (p)ppGpp is required for secondary metabolism. Moreover, we found the (p)ppGpp is not required for pathogenicity of P. luminescens, but is required for bacterial survival within the insect cadaver. Finally, we showed that (p)ppGpp is required for P. luminescens to support normal nematode growth and development. Therefore, the regulatory network that controls the transition from pathogenicity to mutualism in P. luminescens requires (p)ppGpp. This is the first report outlining a role for (p)ppGpp in controlling the outcome of an interaction between a bacteria and its host.
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Affiliation(s)
- Ragnhild Bager
- Department of Biology, University of Copenhagen, DK-2200, Copenhagen, Denmark.,School of Microbiology and APC Microbiome Institute, University College Cork, Cork, Ireland
| | - Mohammad Roghanian
- Department of Biology, University of Copenhagen, DK-2200, Copenhagen, Denmark
| | - Kenn Gerdes
- Department of Biology, University of Copenhagen, DK-2200, Copenhagen, Denmark
| | - David J Clarke
- School of Microbiology and APC Microbiome Institute, University College Cork, Cork, Ireland
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19
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20
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Yadav S, Shokal U, Forst S, Eleftherianos I. An improved method for generating axenic entomopathogenic nematodes. BMC Res Notes 2015; 8:461. [PMID: 26386557 PMCID: PMC4575472 DOI: 10.1186/s13104-015-1443-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Accepted: 09/11/2015] [Indexed: 12/19/2022] Open
Abstract
Background Steinernema carpocapsae are parasitic nematodes that invade and kill insects. The nematodes are mutualistically associated with the bacteria Xenorhabdus nematophila and together form an excellent model to study pathogen infection processes and host anti-nematode/antibacterial immune responses. To determine the contribution of S. carpocapsae and their associated X. nematophila to the successful infection of insects as well as to investigate the interaction of each mutualistic partner with the insect immune system, it is important to develop and establish robust methods for generating nematodes devoid of their bacteria. Findings To produce S. carpocapsae nematodes without their associated X. nematophila bacteria, we have modified a previous method, which involves the use of a X. nematophilarpoS mutant strain that fails to colonize the intestine of the worms. We confirmed the absence of bacteria in the nematodes using a molecular diagnostic and two rounds of an axenicity assay involving appropriate antibiotics and nematode surface sterilization. We used axenic and symbiotic S. carpocapsae to infect Drosophila melanogaster larvae and found that both types of nematodes were able to cause insect death at similar rates. Conclusion Generation of entomopathogenic nematodes lacking their mutualistic bacteria provides an excellent tool to dissect the molecular and genetic basis of nematode parasitism and to identify the insect host immune factors that participate in the immune response against nematode infections.
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Affiliation(s)
- Shruti Yadav
- Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, Washington DC, USA.
| | - Upasana Shokal
- Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, Washington DC, USA.
| | - Steven Forst
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA.
| | - Ioannis Eleftherianos
- Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, Washington DC, USA.
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21
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Mouammine A, Lanois A, Pagès S, Lafay B, Molle V, Canova M, Girard PA, Duvic B, Givaudan A, Gaudriault S. Ail and PagC-related proteins in the entomopathogenic bacteria of Photorhabdus genus. PLoS One 2014; 9:e110060. [PMID: 25333642 PMCID: PMC4198210 DOI: 10.1371/journal.pone.0110060] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 09/07/2014] [Indexed: 01/14/2023] Open
Abstract
Among pathogenic Enterobacteriaceae, the proteins of the Ail/OmpX/PagC family form a steadily growing family of outer membrane proteins with diverse biological properties, potentially involved in virulence such as human serum resistance, adhesion and entry into eukaryotic culture cells. We studied the proteins Ail/OmpX/PagC in the bacterial Photorhabdus genus. The Photorhabdus bacteria form symbiotic complexes with nematodes of Heterorhabditis species, associations which are pathogenic to insect larvae. Our phylogenetic analysis indicated that in Photorhabdus asymbiotica and Photorhabdus luminescens only Ail and PagC proteins are encoded. The genomic analysis revealed that the Photorhabdus ail and pagC genes were present in a unique copy, except two ail paralogs from P. luminescens. These genes, referred to as ail1Pl and ail2Pl, probably resulted from a recent tandem duplication. Surprisingly, only ail1Pl expression was directly controlled by PhoPQ and low external Mg2+ conditions. In P. luminescens, the magnesium-sensing two-component regulatory system PhoPQ regulates the outer membrane barrier and is required for pathogenicity against insects. In order to characterize Ail functions in Photorhabdus, we showed that only ail2Pl and pagCPl had the ability, when expressed into Escherichia coli, to confer resistance to complement in human serum. However no effect in resistance to antimicrobial peptides was found. Thus, the role of Ail and PagC proteins in Photorhabdus life cycle is discussed.
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Affiliation(s)
- Annabelle Mouammine
- INRA, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
- Université Montpellier 2, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
| | - Anne Lanois
- INRA, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
- Université Montpellier 2, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
| | - Sylvie Pagès
- INRA, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
- Université Montpellier 2, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
| | - Bénédicte Lafay
- Université de Lyon, Écully, France
- CNRS, UMR5005 - Laboratoire Ampère, École Centrale de Lyon, Écully, France
| | - Virginie Molle
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités de Montpellier 2 et 1, CNRS, UMR 5235, Montpellier, France
| | - Marc Canova
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Universités de Montpellier 2 et 1, CNRS, UMR 5235, Montpellier, France
| | - Pierre-Alain Girard
- INRA, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
- Université Montpellier 2, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
| | - Bernard Duvic
- INRA, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
- Université Montpellier 2, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
| | - Alain Givaudan
- INRA, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
- Université Montpellier 2, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
| | - Sophie Gaudriault
- INRA, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
- Université Montpellier 2, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), Montpellier, France
- * E-mail:
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22
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Klassen JL. Microbial secondary metabolites and their impacts on insect symbioses. CURRENT OPINION IN INSECT SCIENCE 2014; 4:15-22. [PMID: 28043403 DOI: 10.1016/j.cois.2014.08.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/01/2014] [Accepted: 08/05/2014] [Indexed: 06/06/2023]
Abstract
All insects host communities of microbes that interact both with the insect and each other. Secondary metabolites are understood to mediate many of these interactions, although examples having robust genetic, chemical and/or ecological evidence are relatively rare. Here, I review secondary metabolites mediating community interactions in the beewolf, entomopathogenic nematode and fungus-growing ant symbioses, using the logic of Koch's postulates to emphasize well-validated symbiotic functions mediated by these metabolites. I especially highlight how these interaction networks are structured by both ecological and evolutionary processes, and how selection acting on secondary metabolite production can be multidimensional.
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Affiliation(s)
- Jonathan L Klassen
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269-3125, USA.
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