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Current Topics in Microbiology and... 2017Various bacterial toxins have potent insecticidal activity. Recently, the Toxin complexes (Tc's) of Photorhabdus and Xenorhabdus species have become an increased focus...
Various bacterial toxins have potent insecticidal activity. Recently, the Toxin complexes (Tc's) of Photorhabdus and Xenorhabdus species have become an increased focus of current research. These large tripartite toxins with molecular masses >1.4 megadaltons consist of three components termed A, B, and C (or TcA, TcB, and TcC). While TcA is involved in receptor binding and toxin translocation, TcC possesses the specific toxin enzyme activity and TcB is a linker between components TcA and TcC. Here, a structure function analysis of the toxins is described and the application of Tc toxins as potential insecticides is discussed.
Topics: Bacterial Toxins; Insecticides; Photorhabdus
PubMed: 28233068
DOI: 10.1007/82_2016_55 -
Nature Reviews. Microbiology Dec 2003The genomes described this month reflect the overall historical bias of microbial genomics towards pathogenic bacteria. Although the balance is now being redressed to...
The genomes described this month reflect the overall historical bias of microbial genomics towards pathogenic bacteria. Although the balance is now being redressed to some extent, especially through the study of extremophiles, it is still the case that the opportunities provided by genomic studies are primarily taken up by those who study bacterial pathogenicity. This part of the field is, however, being broadened by including the study of pathogens of animals, insects and plants alongside those that afflict humans.
Topics: Actinomycetales; Animals; Bacterial Proteins; Epsilonproteobacteria; Genome, Bacterial; Genomics; Humans; Nematoda; Photorhabdus; Virulence
PubMed: 15035020
DOI: 10.1038/nrmicro778 -
Current Microbiology Feb 2011Association between bacteria Photorhabdus and their nematode hosts Heterorhabditis represents one of the emerging models in symbiosis studies. In this study, we isolated...
Association between bacteria Photorhabdus and their nematode hosts Heterorhabditis represents one of the emerging models in symbiosis studies. In this study, we isolated the bacterial symbionts of the nematode Heterorhabditis georgiana. Using gyrB sequences for phylogenetic analysis, these strains were shown to be part of the species of Photorhbdus luminescens but with clear separation from currently recognized subspecies. Physiological properties and DNA-DNA hybridization profiles also supported the phylogenetic relationship of these strains. Therefore, a new subspecies, Photorhabdus luminescens subsp. kleinii subsp. nov., is proposed with the type strain KMD37(T) (=DSM 23513 =ATCC =NRRL B-59419).
Topics: Animals; Bacterial Proteins; Bacterial Typing Techniques; Cluster Analysis; DNA Gyrase; DNA, Bacterial; Molecular Sequence Data; Nucleic Acid Hybridization; Photorhabdus; Phylogeny; Rhabditoidea; Sequence Analysis, DNA
PubMed: 20717672
DOI: 10.1007/s00284-010-9741-z -
Organic Letters Aug 2021Zwitterionic carbohydrate modifications, such as phosphoethanolamine (PEtN), govern host-pathogen interactions. Whereas it is recognized that these modifications...
Zwitterionic carbohydrate modifications, such as phosphoethanolamine (PEtN), govern host-pathogen interactions. Whereas it is recognized that these modifications stimulate the host immune system, the purpose of PEtN modification remains largely descriptive. As an enabling step toward studying this carbohydrate modification, we report a synthesis of the zwitterionic trisaccharide repeating unit. The 32-step synthesis was enabled by H-phosphonate chemistry to install the PEtN arm on a poorly reactive and sterically hindered C4-alcohol.
Topics: Ethanolamines; Molecular Structure; Photorhabdus; Trisaccharides
PubMed: 34314177
DOI: 10.1021/acs.orglett.1c02023 -
FEMS Microbiology Letters Jul 2014The binary toxin 'Photorhabdus insect-related' proteins (PirAB) produced by Photorhabdus luminescens have been reported to possess both injectable and oral activities...
The binary toxin 'Photorhabdus insect-related' proteins (PirAB) produced by Photorhabdus luminescens have been reported to possess both injectable and oral activities against a range of insects. Here, PirAB-fusion protein was constructed by linking pirA and pirB genes with the flexible linker (Gly4 Ser)3 DNA encoding sequence and then efficiently expressed in Escherichia coli. To better understand the role of PirAB toxin played in the process of invasion, its cytotoxicity against insect midgut CF-203 cells was investigated. Application of purified PirAB-fusion protein as well as PirA/PirB mixture caused loss of viability of CF-203 cells after 24 h incubation. CF-203 cells treated by PirAB-fusion protein displayed morphological changes typical of apoptosis, such as cell shrinkage, cell membrane blebbing, nuclear condensation and DNA fragmentation. Moreover, PirAB-fusion protein also exhibited injectable insecticidal activity against Spodoptera exigua larvae. The bodies of S. exigua fourth-instar larvae injected with PirAB-fusion protein turned completely black. Thus, we concluded that PirAB-fusion protein possessed similar biological activity (cytotoxicity and insecticidal activity) to PirA/PirB mixture, which would enable it to be used as an efficient agent for pest control.
Topics: Amino Acid Sequence; Animals; Apoptosis; Bacterial Proteins; Bacterial Toxins; Base Sequence; Cell Line; Cell Shape; Cell Survival; Escherichia coli; Insecticides; Larva; Molecular Sequence Data; Photorhabdus; Recombinant Fusion Proteins; Spodoptera
PubMed: 24840022
DOI: 10.1111/1574-6968.12474 -
Current Topics in Microbiology and... 2017Bacterial communication via small diffusible molecules to mediate group-coordinated behaviour is commonly referred to as 'quorum sensing'. The prototypical quorum...
Bacterial communication via small diffusible molecules to mediate group-coordinated behaviour is commonly referred to as 'quorum sensing'. The prototypical quorum sensing system of Gram-negative bacteria consists of a LuxI-type autoinducer synthase that produces acyl-homoserine lactones (AHLs) as signals and a LuxR-type receptor that detects the AHLs to control expression of specific genes. However, many bacteria possess LuxR homologs but lack a cognate LuxI-type AHL-synthase. Those LuxR-type receptors are designated as 'LuxR orphans' or 'solos'. Entomopathogenic bacteria of the genus Photorhabdus all harbour a large number of LuxR solos, more than any other bacteria examined so far. Two novel quorum sensing systems were found to regulate cell clumping in Photorhabdus and therefore affect pathogenicity. In Photorhabdus luminescens and Photorhabdus temperata the LuxR solo PluR senses α-pyrones named 'photopyrones' instead of AHLs, which are produced by the pyrone synthase PpyS. In contrast, Photorhabdus asymbiotica, a closely related insect and human pathogen, has the PluR homolog PauR, which senses dialkylresorcinols produced by the DarABC pathway to regulate pathogenicity. All three Photorhabdus species harbour at least one LuxR solo with an intact AHL-binding motif, which might also allow sensing of exogenous AHLs. However, the majority of the LuxR solos in all Photorhabdus species have a PAS4 signal-binding domain. These receptors are assumed to detect eukaryotic compounds and are proposed to be involved in host sensing. Overall, because of the large number of LuxR solos they encode, bacteria of the genus Photorhabdus are ideal candidates to study and to identify novel bacterial communication networks.
Topics: Acyl-Butyrolactones; Bacterial Proteins; Gene Expression Regulation, Bacterial; Humans; Photorhabdus; Quorum Sensing; Repressor Proteins; Trans-Activators
PubMed: 27848037
DOI: 10.1007/82_2016_28 -
The Journal of Biological Chemistry Dec 2017Lectins play important roles in infections by pathogenic bacteria, for example, in host colonization, persistence, and biofilm formation. The Gram-negative...
Lectins play important roles in infections by pathogenic bacteria, for example, in host colonization, persistence, and biofilm formation. The Gram-negative entomopathogenic bacterium symbiotically lives in insect-infecting nematodes and kills the insect host upon invasion by the nematode. The genome harbors the gene , coding for a novel lectin that we named PllA. We analyzed the binding properties of purified PllA with a glycan array and a binding assay in solution. Both assays revealed a strict specificity of PllA for α-galactoside-terminating glycoconjugates. The crystal structures of apo PllA and complexes with three different ligands revealed the molecular basis for the strict specificity of this lectin. Furthermore, we found that a 90° twist in subunit orientation leads to a peculiar quaternary structure compared with that of its ortholog LecA from We also investigated the utility of PllA as a probe for detecting α-galactosides. The α-Gal epitope is present on wild-type pig cells and is the main reason for hyperacute organ rejection in pig to primate xenotransplantation. We noted that PllA specifically recognizes this epitope on the glycan array and demonstrated that PllA can be used as a fluorescent probe to detect this epitope on primary porcine cells In summary, our biochemical and structural analyses of the lectin PllA have disclosed the structural basis for PllA's high specificity for α-galactoside-containing ligands, and we show that PllA can be used to visualize the α-Gal epitope on porcine tissues.
Topics: Amino Acid Sequence; Animals; Galactosides; Glycoconjugates; Hemagglutination Tests; Lectins; Molecular Probes; Photorhabdus; Protein Binding; Protein Conformation; Sequence Homology, Amino Acid; Swine
PubMed: 28972138
DOI: 10.1074/jbc.M117.812792 -
The Journal of Parasitology Jan 2023The entomopathogenic nematode (EPN) Heterorhabditis bacteriophora infects a wide range of insect hosts with the aid of its mutualistic bacteria Photorhabdus luminescens....
The entomopathogenic nematode (EPN) Heterorhabditis bacteriophora infects a wide range of insect hosts with the aid of its mutualistic bacteria Photorhabdus luminescens. While the mutualistic relationship between H. bacteriophora and P. luminescens and the infectivity of the nematode-bacteria complex have been characterized, how nematode fitness is affected by entomopathogenic bacteria existing in association with other EPN species remains poorly understood. In this study, the survival of H. bacteriophora infective juveniles containing or lacking P. luminescens was tested against the entomopathogenic bacteria Xenorhabdus nematophila and Photorhabdus asymbiotica as well as the non-pathogenic Escherichia coli. While X. nematophila and E. coli did not significantly affect the survival of H. bacteriophora, P. asymbiotica exerted a significant effect on nematode survival, particularly on those lacking P. luminescens. These results imply that P. asymbiotica encodes factors that are pathogenic to EPNs. Future efforts will focus on the identification of the bacterial molecular components that induce these effects. This study makes an important contribution to a growing body of research aimed at exploiting the full potential of nematode-bacterial complexes for eliminating noxious insect pests and treating infectious diseases caused by parasitic nematodes.
Topics: Animals; Photorhabdus; Escherichia coli; Nematoda; Symbiosis
PubMed: 36805240
DOI: 10.1645/22-55 -
PloS One 2020Xenorhabdus and Photorhabdus, symbiotically associated with entomopathogenic nematodes (EPNs), produce a range of antimicrobial compounds. The objective of this study is...
Xenorhabdus and Photorhabdus, symbiotically associated with entomopathogenic nematodes (EPNs), produce a range of antimicrobial compounds. The objective of this study is to identify Xenorhabdus and Photorhabdus and their EPNs hosts, which were isolated from soil samples from Saraburi province, and study their antibacterial activity against 15 strains of drug-resistant bacteria. Fourteen isolates (6.1%), consisting of six Xenorhabdus isolates and eight Photorhabdus isolates, were obtained from 230 soil samples. Based on the BLASTN search incorporating the phylogenetic analysis of a partial recA gene, all six isolates of Xenorhabdus were found to be identical and closely related to X. stockiae. Five isolates of Photorhabdus were found to be identical and closely related to P. luminescens subsp. akhurstii. Two isolates of Photorhabdus were found to be identical and closely related to P. luminescens subsp. hainanensis. The remaining isolate of Photorhabdus was found to be identical to P. asymbiotica subsp. australis. The bacterial extracts from P. luminescens subsp. akhurstii showed strong inhibition the growth of S. aureus strain PB36 (MSRA) by disk diffusion, minimal inhibitory concentration, and minimal bactericidal concentration assay. The combination between each extract from Xenorhabdus/Photorhabdus and oxacillin or vancomycin against S. aureus strain PB36 (MRSA) exhibited no interaction on checkerboard assay. Moreover, killing curve assay of P. luminescens subsp. akhurstii extracts against S. aureus strain PB36 exhibited a steady reduction of 105 CFU/ml to 103 CFU/ml within 30 min. This study demonstrates that Xenorhabdus and Photorhabdus, showed antibacterial activity. This finding may be useful for further research on antibiotic production.
Topics: Animals; Anti-Bacterial Agents; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Nematoda; Oxacillin; Photorhabdus; Phylogeny; Soil; Vancomycin; Xenorhabdus
PubMed: 32502188
DOI: 10.1371/journal.pone.0234129 -
PloS One 2019Photorhabdus luminescens is an entomopathogenic bacterium found in symbiosis with the nematode Heterorhabditis. Dam DNA methylation is involved in the pathogenicity of...
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.
Topics: Animals; Bacterial Proteins; Insecta; Nematoda; Photorhabdus; Site-Specific DNA-Methyltransferase (Adenine-Specific); Symbiosis
PubMed: 31596856
DOI: 10.1371/journal.pone.0212655