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BMC Genomics Jan 2008Photorhabdus luminescens and Yersinia enterocolitica are both enteric bacteria which are associated with insects. P. luminescens lives in symbiosis with soil nematodes... (Comparative Study)
Comparative Study Review
BACKGROUND
Photorhabdus luminescens and Yersinia enterocolitica are both enteric bacteria which are associated with insects. P. luminescens lives in symbiosis with soil nematodes and is highly pathogenic towards insects but not to humans. In contrast, Y. enterocolitica is widely found in the environment and mainly known to cause gastroenteritis in men, but has only recently been shown to be also toxic for insects. It is expected that both pathogens share an overlap of genetic determinants that play a role within the insect host.
RESULTS
A selective genome comparison was applied. Proteins belonging to the class of two-component regulatory systems, quorum sensing, universal stress proteins, and c-di-GMP signalling have been analysed. The interorganismic synopsis of selected regulatory systems uncovered common and distinct signalling mechanisms of both pathogens used for perception of signals within the insect host. Particularly, a new class of LuxR-like regulators was identified, which might be involved in detecting insect-specific molecules. In addition, the genetic overlap unravelled a two-component system that is unique for the genera Photorhabdus and Yersinia and is therefore suggested to play a major role in the pathogen-insect relationship. Our analysis also highlights factors of both pathogens that are expressed at low temperatures as encountered in insects in contrast to higher (body) temperature, providing evidence that temperature is a yet under-investigated environmental signal for bacterial adaptation to various hosts. Common degradative metabolic pathways are described that might be used to explore nutrients within the insect gut or hemolymph, thus enabling the proliferation of P. luminescens and Y. enterocolitica in their invertebrate hosts. A strikingly higher number of genes encoding insecticidal toxins and other virulence factors in P. luminescens compared to Y. enterocolitica correlates with the higher virulence of P. luminescens towards insects, and suggests a putative broader insect host spectrum of this pathogen.
CONCLUSION
A set of factors shared by the two pathogens was identified including those that are involved in the host infection process, in persistence within the insect, or in host exploitation. Some of them might have been selected during the association with insects and then adapted to pathogenesis in mammalian hosts.
Topics: Animals; Bacterial Proteins; Biological Evolution; Genes, Bacterial; Genome, Bacterial; Humans; Insecta; Photorhabdus; Signal Transduction; Species Specificity; Virulence; Yersinia enterocolitica
PubMed: 18221513
DOI: 10.1186/1471-2164-9-40 -
Applied and Environmental Microbiology Feb 1997Thirteen bacterial strains of Xenorhabdus and 14 strains of Photorhabdus originating from a wide range of geographical and nematode host sources were typed by analyzing... (Comparative Study)
Comparative Study
Thirteen bacterial strains of Xenorhabdus and 14 strains of Photorhabdus originating from a wide range of geographical and nematode host sources were typed by analyzing 16S rRNA gene (rDNA) restriction patterns obtained after digestion of PCR-amplified 16S rDNAs. Eight tetrameric restriction endonucleases were examined. A total of 17 genotypes were identified, forming two heterogeneous main clusters after analysis by the unweighted pair-group method using arithmetic averages: group I included all Xenorhabdus species and strains, symbionts of Steinernema, whereas group II encompassed the Photorhabdus strains, symbionts of Heterorhabditis. To identify the four valid species of Xenorhabdus and unclassified strains and all the genotypes of Photorhabdus luminescens, three restriction enzymes are required: CfoI, AluI, and HaeIII. Our results, in substantial agreement with DNA-DNA pairing and 16S rDNA sequence data, indicate that amplified 16S rDNA restriction analysis is a simple and accurate tool for identifying entomopathogenic nematode bacterial symbionts.
Topics: Animals; DNA, Ribosomal; Enterobacteriaceae; Genes, Bacterial; Genotype; Polymerase Chain Reaction; Polymorphism, Restriction Fragment Length; RNA, Ribosomal, 16S; Reproducibility of Results; Rhabditida; Rhabditoidea; Species Specificity; Symbiosis
PubMed: 9023937
DOI: 10.1128/aem.63.2.574-580.1997 -
Journal of Bacteriology Jul 2015The entomopathogenic nematode Heterorhabditis bacteriophora forms a specific mutualistic association with its bacterial partner Photorhabdus temperata. The microbial...
UNLABELLED
The entomopathogenic nematode Heterorhabditis bacteriophora forms a specific mutualistic association with its bacterial partner Photorhabdus temperata. The microbial symbiont is required for nematode growth and development, and symbiont recognition is strain specific. The aim of this study was to sequence the genome of P. temperata and identify genes that plays a role in the pathogenesis of the Photorhabdus-Heterorhabditis symbiosis. A draft genome sequence of P. temperata strain NC19 was generated. The 5.2-Mb genome was organized into 17 scaffolds and contained 4,808 coding sequences (CDS). A genetic approach was also pursued to identify mutants with altered motility. A bank of 10,000 P. temperata transposon mutants was generated and screened for altered motility patterns. Five classes of motility mutants were identified: (i) nonmotile mutants, (ii) mutants with defective or aberrant swimming motility, (iii) mutant swimmers that do not require NaCl or KCl, (iv) hyperswimmer mutants that swim at an accelerated rate, and (v) hyperswarmer mutants that are able to swarm on the surface of 1.25% agar. The transposon insertion sites for these mutants were identified and used to investigate other physiological properties, including insect pathogenesis. The motility-defective mutant P13-7 had an insertion in the RNase II gene and showed reduced virulence and production of extracellular factors. Genetic complementation of this mutant restored wild-type activity. These results demonstrate a role for RNA turnover in insect pathogenesis and other physiological functions.
IMPORTANCE
The relationship between Photorhabdus and entomopathogenic nematode Heterorhabditis represents a well-known mutualistic system that has potential as a biological control agent. The elucidation of the genome of the bacterial partner and role that RNase II plays in its life cycle has provided a greater understanding of Photorhabdus as both an insect pathogen and a nematode symbiont.
Topics: Animals; DNA Transposable Elements; DNA, Bacterial; Gene Expression Regulation, Bacterial; Gene Library; Genome, Bacterial; Host-Parasite Interactions; Moths; Movement; Mutation; Nematoda; Photorhabdus; Symbiosis
PubMed: 25917908
DOI: 10.1128/JB.00197-15 -
Research in Microbiology 2021Understanding the mode of action of pathogenic bacteria through in vitro studies can provide additional insight into their infection strategies. Here we have...
Understanding the mode of action of pathogenic bacteria through in vitro studies can provide additional insight into their infection strategies. Here we have characterized the effect of Photorhabdus luminescens and Photorhabdus asymbiotica on two distinct insect cell lines. We report that insect cell survival and metabolism as well as bacterial proliferation differ between infection with two Photorhabdus species. These findings reinforce the notion that P. luminescens and P. asymbiotica deploy diverse tactics to infect insect cells. This knowledge might lead to better appreciation of the interaction between pathogenic bacteria and different types of insect cells.
Topics: Animals; Bacterial Proteins; Cell Line; In Vitro Techniques; Insecta; Photorhabdus; Virulence
PubMed: 33794299
DOI: 10.1016/j.resmic.2021.103832 -
Structure (London, England : 1993) May 2023Modification of the polyketide anthraquinone AQ-256 in the entomopathogenic Photorhabdus luminescens involves several O-methylations, but the biosynthetic gene cluster...
Modification of the polyketide anthraquinone AQ-256 in the entomopathogenic Photorhabdus luminescens involves several O-methylations, but the biosynthetic gene cluster antA-I lacks corresponding tailoring enzymes. We here describe the identification of five putative, highly homologous O-methyltransferases encoded in the genome of P. luminescens. Activity assays in vitro and deletion experiments in vivo revealed that three of them account for anthraquinone tailoring by producing three monomethylated and two dimethylated species of AQ-256. X-ray structures of all five enzymes indicate high structural and mechanistic similarity. As confirmed by structure-based mutagenesis, a conserved histidine at the active site likely functions as a general base for substrate deprotonation and subsequent methyl transfer in all enzymes. Eight complex structures with AQ-256 as well as mono- and dimethylated derivatives confirm the substrate specificity patterns found in vitro and visualize how single amino acid differences in the active-site pockets impact substrate orientation and govern site-specific methylation.
Topics: Methyltransferases; Methylation; Photorhabdus; Catalytic Domain; Anthraquinones
PubMed: 36963398
DOI: 10.1016/j.str.2023.03.001 -
Current Biology : CB Jan 2010Bacteria belonging to the genera Photorhabdus and Xenorhabdus participate in a trilateral symbiosis in which they enable their nematode hosts to parasitize insect...
Bacteria belonging to the genera Photorhabdus and Xenorhabdus participate in a trilateral symbiosis in which they enable their nematode hosts to parasitize insect larvae. The bacteria switch from persisting peacefully in a nematode's digestive tract to a lifestyle in which pathways to produce insecticidal toxins, degrading enzymes to digest the insect for consumption, and antibiotics to ward off bacterial and fungal competitors are activated. This study addresses three questions: (1) What molecular signal triggers antibiotic production in the bacteria? (2) What small molecules are regulated by the signal? And (3), how do the bacteria recognize the signal? Differential metabolomic profiling in Photorhabdus luminescens TT01 and Xenorhabdus nematophila revealed that L-proline in the insect's hemolymph initiates a metabolic shift. Small molecules known to be crucial for virulence and antibiosis in addition to previously unknown metabolites are dramatically upregulated by L-proline, linking the recognition of host environment to bacterial metabolic regulation. To identify the L-proline-induced signaling pathway, we deleted the proline transporters putP and proU in P. luminescens TT01. Studies of these strains support a model in which acquisition of L-proline both regulates the metabolic shift and maintains the bacterial proton motive force that ultimately regulates the downstream bacterial pathways affecting virulence and antibiotic production.
Topics: Animals; Bacterial Toxins; Hemolymph; Host-Pathogen Interactions; Lepidoptera; Metabolomics; Mutagenesis; Nematoda; Photorhabdus; Proline; Proton-Motive Force; Virulence; Xenorhabdus
PubMed: 20022247
DOI: 10.1016/j.cub.2009.10.059 -
Scientific Reports Nov 2020The fungus, Sclerotinia sclerotiorum, causes white mold disease and infects a broad spectrum of host plants (> 500), including soybean with yield losses of up to 70%....
The fungus, Sclerotinia sclerotiorum, causes white mold disease and infects a broad spectrum of host plants (> 500), including soybean with yield losses of up to 70%. Biological control is a potential alternative for management of this severe plant pathogen, and relative to chemical fungicides, provides broad benefits to the environment, farmers and consumers. The symbiotic bacteria of entomopathogenic nematodes, Xenorhabdus spp. and Photorhabdus spp., are characterized by the production of antimicrobial compounds, which could serve as potential sources for new bio-fungicides. The objectives of this study were to assess cell-free supernatants (CFS) of 16 strains of these bacteria cultures on S. sclerotiorum mycelium growth; assess the volatiles of X. szentirmaii cultures on the fungus mycelium and sclerotium inhibition; and evaluate the X. szentirmaii cultures as well as their CFS on the protection of soybean seeds against the white mold disease. Among the 16 strains, the CFS of X. szentirmaii showed the highest fungicidal effect on growth of S. sclerotiorum. The CFS of X. szentirmaii inhibited > 98% of fungus growth from mycelium and sclerotia, whereas the volatiles generated by the bacterium culture inhibited to 100% of fungus growth and 100% of sclerotia production. The bacterial culture diluted to 33% in water and coated on soybean seeds inhibited S. sclerotiorum and protected soybean plants, allowing 78.3% of seed germination and 56.6% of plant development. Our findings indicate potential for a safe and novel control method for S. sclerotiorum in soybean. Moreover, this is the first study to indicate that volatile organic compounds from Xenorhabdus spp. can be used in plant disease suppression.
Topics: Animals; Antifungal Agents; Ascomycota; Germination; Mycelium; Nematoda; Photorhabdus; Plant Development; Plant Diseases; Seeds; Glycine max; Symbiosis; Volatile Organic Compounds; Xenorhabdus
PubMed: 33244079
DOI: 10.1038/s41598-020-77472-6 -
The FEBS Journal Dec 2011Various bacterial protein toxins and effectors target the actin cytoskeleton. At least three groups of toxins/effectors can be identified, which directly modify actin... (Review)
Review
Various bacterial protein toxins and effectors target the actin cytoskeleton. At least three groups of toxins/effectors can be identified, which directly modify actin molecules. One group of toxins/effectors causes ADP-ribosylation of actin at arginine-177, thereby inhibiting actin polymerization. Members of this group are numerous binary actin-ADP-ribosylating exotoxins (e.g. Clostridium botulinum C2 toxin) as well as several bacterial ADP-ribosyltransferases (e.g. Salmonella enterica SpvB) which are not binary in structure. The second group includes toxins that modify actin to promote actin polymerization and the formation of actin aggregates. To this group belongs a toxin from the Photorhabdus luminescens Tc toxin complex that ADP-ribosylates actin at threonine-148. A third group of bacterial toxins/effectors (e.g. Vibrio cholerae multifunctional, autoprocessing RTX toxin) catalyses a chemical crosslinking reaction of actin thereby forming oligomers, while blocking the polymerization of actin to functional filaments. Novel findings about members of these toxin groups are discussed in detail.
Topics: ADP Ribose Transferases; Actin Cytoskeleton; Adenosine Diphosphate Ribose; Animals; Arginine; Bacterial Toxins; Humans; Models, Molecular; Polymerization; Protein Conformation; Threonine
PubMed: 21466657
DOI: 10.1111/j.1742-4658.2011.08113.x -
The Science of the Total Environment Jun 2023Larvae of the greater wax moth Galleria mellonella are common pests of beehives and commercial apiaries, and in more applied settings, these insects act as alternative...
Larvae of the greater wax moth Galleria mellonella are common pests of beehives and commercial apiaries, and in more applied settings, these insects act as alternative in vivo bioassays to rodents for studying microbial virulence, antibiotic development, and toxicology. In the current study, our aim was to assess the putative adverse effects of background gamma radiation levels on G. mellonella. To achieve this, we exposed larvae to low (0.014 mGy/h), medium (0.056 mGy/h), and high (1.33 mGy/h) doses of caesium-137 and measured larval pupation events, weight, faecal discharge, susceptibility to bacterial and fungal challenges, immune cell counts, activity, and viability (i.e., haemocyte encapsulation) and melanisation levels. The effects of low and medium levels of radiation were distinguishable from the highest dose rates used - the latter insects weighed the least and pupated earlier. In general, radiation exposure modulated cellular and humoral immunity over time, with larvae showing heightened encapsulation/melanisation levels at the higher dose rates but were more susceptible to bacterial (Photorhabdus luminescens) infection. There were few signs of radiation impacts after 7 days exposure, whereas marked changes were recorded between 14 and 28 days. Our data suggest that G. mellonella demonstrates plasticity at the whole organism and cellular levels when irradiated and offers insight into how such animals may cope in radiologically contaminated environments (e.g. Chornobyl Exclusion Zone).
Topics: Animals; Moths; Larva; Gamma Rays; Anti-Bacterial Agents; Virulence
PubMed: 36906041
DOI: 10.1016/j.scitotenv.2023.162742 -
Experimental Parasitology Sep 2019Only two drugs are currently available for the treatment of Chagas disease and their effectiveness are unsatisfactory. Photorhabdus luminescens and Xenorhabdus...
Only two drugs are currently available for the treatment of Chagas disease and their effectiveness are unsatisfactory. Photorhabdus luminescens and Xenorhabdus nematophila, two enteric bacteria highly pathogenic to a broad range of insects, have been studied as potential source for bioactive metabolites against protozoa causing neglected tropical diseases. Therefore, we tested the in vitro anti-Trypanosoma cruzi activity of secreted metabolites from these bacteria. The conditioned medium of X. nematophila and P. luminescens showed significant parasiticidal activity in a concentration-dependent manner (ICXN = 0.34 mg/mL, ICPL = 1.0 mg/mL). The parasiticidal compound was identified as a small molecule stable to heating and pH changes ranging from 2 to 12. Moreover, anti-Trypanosoma molecules secreted by both bacteria stimulate the trypanocidal activity of macrophages by a mechanism independent of nitric oxide. Summarizing, our studies reveal that P. luminescens and X. nematophila are potential sources of putative novel drugs against Chagas disease.
Topics: Analysis of Variance; Animals; Bacterial Proteins; Biological Assay; Chagas Disease; Culture Media, Conditioned; Endopeptidase K; Humans; Hydrogen-Ion Concentration; Inhibitory Concentration 50; Photorhabdus; Temperature; Trypanocidal Agents; Trypanosoma cruzi; Xenorhabdus
PubMed: 31279930
DOI: 10.1016/j.exppara.2019.107724