-
Insects Jan 2020The fruit fly forms a magnificent model for interpreting conserved host innate immune signaling and functional processes in response to microbial assaults. In the broad... (Review)
Review
The fruit fly forms a magnificent model for interpreting conserved host innate immune signaling and functional processes in response to microbial assaults. In the broad research field of host-microbe interactions, model hosts are used in conjunction with a variety of pathogenic microorganisms to disentangle host immune system activities and microbial pathogenicity strategies. The pathogen is considered an established model for analyzing bacterial virulence and symbiosis due to its unique life cycle that extends between two invertebrate hosts: an insect and a parasitic nematode. In recent years, particular focus has been given to the mechanistic participation of the thioester-containing proteins (TEPs) in the overall immune capacity of the fly upon response against the pathogen alone or in combination with its specific nematode vector . The original role of certain TEPs in the insect innate immune machinery was linked to the antibacterial and antiparasite reaction of the mosquito malaria vector ; however, revamped interest in the immune competence of these molecules has recently emerged from the - infection system. Here, we review the latest findings on this topic with the expectation that such information will refine our understanding of the evolutionary immune role of TEPs in host immune surveillance.
PubMed: 32013030
DOI: 10.3390/insects11020085 -
Virulence Nov 2017
Topics: Animals; Immunity, Innate; Photorhabdus; Rhabditoidea
PubMed: 28704162
DOI: 10.1080/21505594.2017.1355662 -
ELife Sep 2019The proteins injected by bacteria into eukaryotic organisms can lead to fates as diverse as death and metamorphosis.
The proteins injected by bacteria into eukaryotic organisms can lead to fates as diverse as death and metamorphosis.
Topics: Bacterial Proteins; Eukaryotic Cells; Photorhabdus; Virulence
PubMed: 31526473
DOI: 10.7554/eLife.50815 -
Analytical Chemistry Dec 2019Whole-cell and cell-free transcription-translation biosensors have recently become favorable alternatives to conventional detection methods, as they are cost-effective,...
Whole-cell and cell-free transcription-translation biosensors have recently become favorable alternatives to conventional detection methods, as they are cost-effective, environmental friendly, and easy to use. Importantly, the biological responses from the biosensors need to be converted into a physicochemical signal for easy detection, and a variety of genetic reporters have been employed for this purpose. Reporter gene selection is vital to a sensor performance and application success. However, it was largely based on trial and error with very few systematic side-by-side investigations reported. To address this bottleneck, here we compared eight reporters from three reporter categories, i.e., fluorescent (, , , ), colorimetric (), and bioluminescent ( from and , ) reporters, under the control of two representative biosensors for mercury- and quorum-sensing molecules. Both whole-cell and cell-free formats were investigated to assess key sensing features including limit of detection (LOD), input and output dynamic ranges, response time, and output visibility. For both whole-cell biosensors, the lowest detectable concentration of analytes and the fastest responses were achieved with NanoLuc. Notably, we developed, to date, the most sensitive whole-cell mercury biosensor using NanoLuc as reporter, with an LOD ≤ 50.0 fM HgCl 30 min postinduction. For cell-free biosensors, overall, and led to shorter response time and lower LOD than the others. This comprehensive profile of diverse reporters in a single setting provides a new important benchmark for reporter selection, aiding the rapid development of whole-cell and cell-free biosensors for various applications in the environment and health.
Topics: Aliivibrio fischeri; Biosensing Techniques; Escherichia coli; Genes, Reporter; Mercury; Photorhabdus; Quorum Sensing
PubMed: 31690077
DOI: 10.1021/acs.analchem.9b04444 -
Current Microbiology Jun 2024One Gram-negative, rod-shaped bacterial strain, isolated from an undescribed Heterorhabditis entomopathogenic nematode species was characterized to determine its...
One Gram-negative, rod-shaped bacterial strain, isolated from an undescribed Heterorhabditis entomopathogenic nematode species was characterized to determine its taxonomic position. The 16S rRNA gene sequences indicate that it belongs to the class Gammaproteobacteria, to the family Morganellaceae, to the genus Photorhabdus, and likely represents a novel bacterial species. This strain, designated here as CRI-LC, was therefore molecularly, biochemically, and morphologically characterized to describe the novel bacterial species. Phylogenetic reconstructions using 16S rRNA gene sequences show that CRI-LC is closely related to P. laumondii subsp. laumondii TT01 and to P. laumondii subsp. clarkei BOJ-47. The 16rRNA gene sequences between CRI-LC and P. laumondii subsp. laumondii TT01 are 99.1% identical, and between CRI-LC and P. laumondii subsp. clarkei BOJ-47 are 99.2% identical. Phylogenetic reconstructions using whole genome sequences show that CRI-LC is closely related to P. laumondii subsp. laumondii TT01 and to P. laumondii subsp. clarkei BOJ-47. Moreover, digital DNA-DNA hybridization (dDDH) values between CRI-LC and its two relative species P. laumondii subsp. laumondii TT01 and P. laumondii subsp. clarkei BOJ-47 are 65% and 63%, respectively. In addition, we observed that average nucleotide identity (ANI) values between CRI-LC and its two relative species P. laumondii subsp. laumondii TT01 and P. laumondii subsp. clarkei BOJ-47 are 95.8% and 95.5%, respectively. These values are below the 70% dDDH and the 95-96% ANI divergence thresholds that delimits prokaryotic species. Based on these genomic divergence values, and the phylogenomic separation, we conclude that CRI-LC represents a novel bacterial species, for which we propose the name Photorhabdus africana sp. nov. with CRI-LC (= CCM 9390 = CCOS 2112) as the type strain. The following biochemical tests allow to differentiate P. africana sp. nov. CRI-LC from other species of the genus, including its more closely related taxa: β-Galactosidase, citrate utilization, urease and tryptophan deaminase activities, indole and acetoin production, and glucose and inositol oxidation. Our study contributes to a better understanding of the taxonomy and biodiversity of this important bacterial group with great biotechnological and agricultural potential.
Topics: Phylogeny; Photorhabdus; Animals; RNA, Ribosomal, 16S; DNA, Bacterial; Rhabditoidea; Sequence Analysis, DNA; Bacterial Typing Techniques
PubMed: 38910178
DOI: 10.1007/s00284-024-03744-3 -
Cell Chemical Biology Apr 2022With the advent of genome sequencing and mining technologies, secondary metabolite biosynthetic gene clusters (BGCs) within bacterial genomes are becoming easier to...
With the advent of genome sequencing and mining technologies, secondary metabolite biosynthetic gene clusters (BGCs) within bacterial genomes are becoming easier to predict. For subsequent BGC characterization, clustered regularly interspaced short palindromic repeats (CRISPR) has contributed to knocking out target genes and/or modulating their expression; however, CRISPR is limited to strains for which robust genetic tools are available. Here we present a strategy that combines CRISPR with chassis-independent recombinase-assisted genome engineering (CRAGE), which enables CRISPR systems in diverse bacteria. To demonstrate CRAGE-CRISPR, we select 10 polyketide/non-ribosomal peptide BGCs in Photorhabdus luminescens as models and create their deletion and activation mutants. Subsequent loss- and gain-of-function studies confirm 22 secondary metabolites associated with the BGCs, including a metabolite from a previously uncharacterized BGC. These results demonstrate that the CRAGE-CRISPR system is a simple yet powerful approach to rapidly perturb expression of defined BGCs and to profile genotype-phenotype relationships in bacteria.
Topics: Bacteria; CRISPR-Cas Systems; Clustered Regularly Interspaced Short Palindromic Repeats; Gene Editing; Genome, Bacterial; Multigene Family; Recombinases
PubMed: 34508657
DOI: 10.1016/j.chembiol.2021.08.009 -
PloS One 2015Quorum sensing is a typical communication system among Gram-negative bacteria used to control group-coordinated behavior via small diffusible molecules dependent on cell...
Quorum sensing is a typical communication system among Gram-negative bacteria used to control group-coordinated behavior via small diffusible molecules dependent on cell number. The key components of a quorum sensing system are a LuxI-type synthase, producing acyl-homoserine lactones (AHLs) as signaling molecules, and a LuxR-type receptor that detects AHLs to control expression of specific target genes. Six conserved amino acids are present in the signal-binding domain of AHL-sensing LuxR-type proteins, which are important for ligand-binding and -specificity as well as shaping the ligand-binding pocket. However, many proteobacteria possess LuxR-type regulators without a cognate LuxI synthase, referred to as LuxR solos. The two LuxR solos PluR and PauR from Photorhabdus luminescens and Photorhabdus asymbiotica, respectively, do not sense AHLs. Instead PluR and PauR sense alpha-pyrones and dialkylresorcinols, respectively, and are part of cell-cell communication systems contributing to the overall virulence of these Photorhabdus species. However, PluR and PauR both harbor substitutions in the conserved amino acid motif compared to that in AHL sensors, which appeared to be important for binding the corresponding signaling molecules. Here we analyze the role of the conserved amino acids in the signal-binding domain of these two non-AHL LuxR-type receptors for their role in signal perception. Our studies reveal that the conserved amino acid motif alone is essential but not solely responsible for ligand-binding.
Topics: Acyl-Butyrolactones; Amino Acid Motifs; Bacterial Proteins; Conserved Sequence; Gene Expression Regulation, Bacterial; Ligands; Photorhabdus; Quorum Sensing; Repressor Proteins; Trans-Activators; Transcription Factors
PubMed: 25923884
DOI: 10.1371/journal.pone.0124093 -
The Journal of Antibiotics Aug 2016Photorhabdus luminescens is a bioluminescent entomopathogenic bacterium that undergoes phenotypic variation and lives in mutualistic association with nematodes of the...
Photorhabdus luminescens is a bioluminescent entomopathogenic bacterium that undergoes phenotypic variation and lives in mutualistic association with nematodes of the family Heterorhabditidae. The pair infects and kills insects, and during their coordinated lifecycle, the bacteria produce an assortment of specialized metabolites to regulate its mutualistic and pathogenic roles. As part of our search for new specialized metabolites from the Photorhabdus genus, we examined organic extracts from P. luminescens grown in an amino-acid-rich medium based on the free amino-acid levels found in the circulatory fluid of its common insect prey, the Galleria mellonella larva. Reversed-phase HPLC/UV/MS-guided fractionation of the culture extracts led to the identification of two new pyrazinone metabolites, lumizinones A (1) and B (2), together with two N-acetyl dipeptides (3 and 4). The lumizinones were produced only in the phenotypic variant associated with nematode development and insect pathogenesis. Their chemical structures were elucidated by analysis of 1D and 2D NMR and high-resolution ESI-QTOF-MS spectral data. The absolute configurations of the amino acids in 3 and 4 were determined by Marfey's analysis. Compounds 1-4 were evaluated for their calpain protease inhibitory activity, and lumizinone A (1) showed inhibition with an IC50 (half-maximal inhibitory concentration) value of 3.9 μm.
Topics: Amino Acids; Animals; Chromatography, High Pressure Liquid; Inhibitory Concentration 50; Lepidoptera; Magnetic Resonance Spectroscopy; Mass Spectrometry; Photorhabdus; Protease Inhibitors; Pyrazines; Spectrometry, Mass, Electrospray Ionization
PubMed: 27353165
DOI: 10.1038/ja.2016.79 -
Insects Nov 2022The codling moth, (L.) (Lepidoptera: Tortricidae), is one of the major pests in pome fruit production worldwide. Heavy treatment of the larvae of with insecticides...
Identification and Biocontrol Potential of Entomopathogenic Nematodes and Their Endosymbiotic Bacteria in Apple Orchards against the Codling Moth, (L.) (Lepidoptera: Tortricidae).
The codling moth, (L.) (Lepidoptera: Tortricidae), is one of the major pests in pome fruit production worldwide. Heavy treatment of the larvae of with insecticides triggered the development of resistance to many groups of insecticides. In addition, the increasing concern about the adverse effects of synthetic insecticides on human health and the environment has led to the development of sustainable and eco-friendly control practices for . The entomopathogenic nematodes (EPNs) ( and spp.) and their endosymbionts ( and spp.) represent a newly emerging approach to controlling a wide range of insect pests. In the present study, field surveys were conducted in apple orchards to isolate and identify EPNs and their endosymbionts and evaluate their insecticidal efficacy on the larvae of . EPNs were isolated from 12 of 100 soil samples (12%). Seven samples were identified as (Filipjev, 1934) (Rhabditida: Steinernematidae), whereas five samples were assigned to (Poinar, 1976) (Rhabditida: Heterorhabditidae). The pathogenicity of the EPN species/isolates was screened on the last instar larvae of . The two most pathogenic isolates from each EPN species were tested against fifth instar larvae of under controlled conditions. The maximum mortality (100%) was achieved by all EPN species/isolates at a concentration of 100 IJs/larva 96 h after treatment. The endosymbionts of selected and species were identified as subsp. and , respectively. The mortality rates ranged between 25 and 62% when the fifth larval instar larvae of were exposed to the treatment of cell-free supernatants of symbiotic bacteria. In essence, the present survey indicated that EPNs and their symbiotic bacteria have good potential for biological control of .
PubMed: 36554995
DOI: 10.3390/insects13121085 -
Applied and Environmental Microbiology Aug 2020The number of sustainable agriculture techniques to improve pest management and environmental safety is rising, as biological control agents are used to enhance disease...
The number of sustainable agriculture techniques to improve pest management and environmental safety is rising, as biological control agents are used to enhance disease resistance and abiotic stress tolerance in crops. Here, we investigated the capacity of the secondary variant to react to plant root exudates and their behavior toward microorganisms in the rhizosphere. is known to live in symbiosis with entomopathogenic nematodes (EPNs) and to be highly pathogenic toward insects. The -EPN relationship has been widely studied, and this combination has been used as a biological control agent; however, not much attention has been paid to the putative lifestyle of in the rhizosphere. We performed transcriptome analysis to show how responds to plant root exudates. The analysis highlighted genes involved in chitin degradation, biofilm regulation, formation of flagella, and type VI secretion system. Furthermore, we provide evidence that can inhibit growth of phytopathogenic fungi. Finally, we demonstrated a specific interaction of with plant roots. Understanding the role and the function of this bacterium in the rhizosphere might accelerate the progress in biocontrol manipulation and elucidate the peculiar mechanisms adopted by plant growth-promoting rhizobacteria in plant root interactions. Insect-pathogenic bacteria are widely used in biocontrol strategies against pests. Very little is known about the life of these bacteria in the rhizosphere. Here, we show that can specifically react to and interact with plant roots. Understanding the adaptation of in the rhizosphere is highly important for the biotechnological application of entomopathogenic bacteria and could improve future sustainable pest management in agriculture.
Topics: Biological Control Agents; Chemotaxis; Exudates and Transudates; Fungi; Gene Expression Profiling; Genes, Bacterial; Photorhabdus; Plant Roots; RNA-Seq; Rhizosphere
PubMed: 32591378
DOI: 10.1128/AEM.00891-20