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Journal of Invertebrate Pathology Jul 2024Aedes-transmitted arboviral infections such as Dengue, Yellow Fever, Zika and Chikungunya are increasing public health problems. Xenorhabdus and Photorhabdus bacteria...
Aedes-transmitted arboviral infections such as Dengue, Yellow Fever, Zika and Chikungunya are increasing public health problems. Xenorhabdus and Photorhabdus bacteria are promising sources of effective compounds with important biological activities. This study investigated the effects of cell-free supernatants of X. szentirmaii, X. cabanillasii and P. kayaii against Ae. aegypti eggs and larvae and identified the bioactive larvicidal compound in X. szentirmaii using The EasyPACId method. Among the three tested bacterial species, X. cabanillasii exhibited the highest (96%) egg hatching inhibition and larvicidal activity (100% mortality), whereas P. kayaii was the least effective species in our study. EasyPACId method revealed that bioactive larvicidal compound in the bacterial supernatant was fabclavine. Fabclavines obtained from promoter exchange mutants of different bacterial species such as X. cabanillasii, X. budapestensis, X. indica, X. szentirmaii, X. hominckii and X. stockiae were effective against mosquito larvae. Results show that these bacterial metabolites have potential to be used in integrated pest management (IPM) programmes of mosquitoes.
Topics: Animals; Aedes; Photorhabdus; Larva; Xenorhabdus; Ovum; Mosquito Control; Mosquito Vectors; Pest Control, Biological; Insecticides
PubMed: 38734162
DOI: 10.1016/j.jip.2024.108126 -
Scientific Reports Nov 2023The discovery of novel bioactive compounds produced by microorganisms holds significant potential for the development of therapeutics and agrochemicals. In this study,...
The discovery of novel bioactive compounds produced by microorganisms holds significant potential for the development of therapeutics and agrochemicals. In this study, we conducted genome mining to explore the biosynthetic potential of entomopathogenic bacteria belonging to the genera Xenorhabdus and Photorhabdus. By utilizing next-generation sequencing and bioinformatics tools, we identified novel biosynthetic gene clusters (BGCs) in the genomes of the bacteria, specifically plu00736 and plu00747. These clusters were identified as unidentified non-ribosomal peptide synthetase (NRPS) and unidentified type I polyketide synthase (T1PKS) clusters. These BGCs exhibited unique genetic architecture and encoded several putative enzymes and regulatory elements, suggesting its involvement in the synthesis of bioactive secondary metabolites. Furthermore, comparative genome analysis revealed that these BGCs were distinct from previously characterized gene clusters, indicating the potential for the production of novel compounds. Our findings highlighted the importance of genome mining as a powerful approach for the discovery of biosynthetic gene clusters and the identification of novel bioactive compounds. Further investigations involving expression studies and functional characterization of the identified BGCs will provide valuable insights into the biosynthesis and potential applications of these bioactive compounds.
Topics: Genome, Bacterial; Bacteria; Computational Biology; Multigene Family; Biosynthetic Pathways
PubMed: 38007490
DOI: 10.1038/s41598-023-47121-9 -
Insect Biochemistry and Molecular... Nov 2023PirAB binary toxin from Photorhabdus is toxic to the larvae of dipteran and lepidopteran insect pests. However, the 3-D structures and their toxicity mechanism are not...
PirAB binary toxin from Photorhabdus is toxic to the larvae of dipteran and lepidopteran insect pests. However, the 3-D structures and their toxicity mechanism are not yet fully understood. Here we report the crystal structures of PirA and PirB proteins from Photorhabdus akhurstii subsp. akhurstii K-1 at 1.6 and 2.1 Å, respectively. PirA comprises of eight β-strands depicting jelly-roll topology while PirB folds into two distinct domains, an N-terminal domain (PirB-N) made up of seven α-helices and a C-terminal domain (PirB-C) consists of ten β-strands. Despite the low sequence identity, PirA adopts similar architecture as domain III and PirB shared similar architecture as domain I/II of the Cry δ-endotoxin of Bacillus thuringiensis, respectively. However, PirA shows significant structural variations as compared to domain III of lepidopteran and dipteran specific Cry toxins (Cry1Aa and Cry11Ba) suggesting its role in virulence among range of insect pests and hence, in receptor binding. High structural resemblance between PirB-N and domain I of Cry toxin raises the possibility that the putative PirAB binary toxin may mimic the toxicity mechanism of the Cry protein, particularly its ability to perform pore formation. The mixture of independently purified PirA and PirB proteins are not toxic to insects. However, PirA-PirB protein complex purified from expression of pir operon with non-coding Enterobacterial Repetitive Intergenic Consensus (ERIC) sequences found toxic to Galleria mellonella larvae with LD value of 1.62 μg/larva. This suggests that toxic conformation of PirA and PirB are achieved in-vivo with the help of ERIC sequences.
Topics: Animals; Photorhabdus; Bacterial Proteins; Endotoxins; Moths; Larva; Insecta; Hemolysin Proteins
PubMed: 37778713
DOI: 10.1016/j.ibmb.2023.104014 -
Pest Management Science Apr 2024In the perpetual struggle to manage mosquito populations, there has been increasing demand for the development of biopesticides to supplant/complement current products....
BACKGROUND
In the perpetual struggle to manage mosquito populations, there has been increasing demand for the development of biopesticides to supplant/complement current products. The insecticidal potential of Xenorhabdus and Photorhabdus has long been recognized and is of interest for the control of important mosquitoes like Aedes albopictus which vectors over 20 different arboviruses of global public health concern.
RESULTS
The larvicidal effects of cell-free supernatants, cell growth cultures and cell mass of an extensive list of Xenorhabdus and Photorhabdus spp. was investigated. They were quite effective against Ae. albopictus causing larval mortality ranging between 52-100%. Three Photorhabdus spp. and 13 Xenorhabdus spp. release larvicidal compounds in cell-free supernatants. Cell growth culture of all tested species exhibited larvicidal activity, except for Xenorhabdus sp. TS4. Twenty-one Xenorhabdus and Photorhabdus bacterial cells (pellet) exhibited oral toxicity (59-91%) against exposed larvae. The effect of bacterial supernatants on the mosquito eggs were also assessed. Bacterial supernatants inhibited the hatching of mosquito eggs; when unhatched eggs were transferred to clean water, they all hatched. Using the easyPACId approach, the larvicidal compounds in bacterial supernatant were identified as fabclavine from X. szentirmaii and xencoumacin from X. nematophila (causing 98 and 70% mortality, respectively, after 48 h). Xenorhabdus cabanillasii and X. hominickii fabclavines were as effective as commercial Bacillus thuringiensis subsp. israelensis and spinosad products within 5 days post-application (dpa).
CONCLUSION
Fabclavine and xenocoumacin can be developed into novel biolarvicides, can be used as a model to synthesize other compounds or/and can be combined with other commercial biolarvicides. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
PubMed: 38619291
DOI: 10.1002/ps.8127 -
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 -
Advanced Science (Weinheim,... Jun 2024Pigments such as anthraquinones (AQs) and melanins are antioxidants, protectants, or virulence factors. AQs from the entomopathogenic bacterium Photorhabdus laumondii...
Pigments such as anthraquinones (AQs) and melanins are antioxidants, protectants, or virulence factors. AQs from the entomopathogenic bacterium Photorhabdus laumondii are produced by a modular type II polyketide synthase system. A key enzyme involved in AQ biosynthesis is PlAntI, which catalyzes the hydrolysis of the bicyclic-intermediate-loaded acyl carrier protein, polyketide trimming, and assembly of the aromatic AQ scaffold. Here, multiple crystal structures of PlAntI in various conformations and with bound substrate surrogates or inhibitors are reported. Structure-based mutagenesis and activity assays provide experimental insights into the three sequential reaction steps to yield the natural product AQ-256. For comparison, a series of ligand-complex structures of two functionally related hydrolases involved in the biosynthesis of 1,8-dihydroxynaphthalene-melanin in pathogenic fungi is determined. These data provide fundamental insights into the mechanism of polyketide trimming that shapes pigments in pro- and eukaryotes.
Topics: Anthraquinones; Polyketides; Melanins; Polyketide Synthases; Photorhabdus; Naphthols; Pigments, Biological
PubMed: 38491909
DOI: 10.1002/advs.202400184 -
MicroPublication Biology 2023The fruit fly is an excellent model for dissecting the molecular and functional bases of bacterial pathogenicity and host antibacterial immune response. The...
The fruit fly is an excellent model for dissecting the molecular and functional bases of bacterial pathogenicity and host antibacterial immune response. The Gram-negative bacterium is an insect-specific pathogen that forms a mutualistic relationship with the entomopathogenic nematode . Here we find that oral infection of larvae with moderately reduces their survival ability while the bacteria replicate efficiently in the infected insects. This information will contribute towards understanding host gut immunity against potent bacterial pathogens.
PubMed: 37711508
DOI: 10.17912/micropub.biology.000938 -
Nature Communications Dec 2023The bacterial Makes caterpillars floppy 1 (Mcf1) toxin promotes apoptosis in insects, leading to loss of body turgor and death. The molecular mechanism underlying Mcf1...
The bacterial Makes caterpillars floppy 1 (Mcf1) toxin promotes apoptosis in insects, leading to loss of body turgor and death. The molecular mechanism underlying Mcf1 intoxication is poorly understood. Here, we present the cryo-EM structure of Mcf1 from Photorhabdus luminescens, revealing a seahorse-like shape with a head and tail. While the three head domains contain two effectors, as well as an activator-binding domain (ABD) and an autoprotease, the tail consists of two putative translocation and three putative receptor-binding domains. Rearrangement of the tail moves the C-terminus away from the ABD and allows binding of the host cell ADP-ribosylation factor 3, inducing conformational changes that position the cleavage site closer to the protease. This distinct activation mechanism that is based on a hook-loop interaction results in three autocleavage reactions and the release of two toxic effectors. Unexpectedly, the BH3-like domain containing ABD is not an active effector. Our findings allow us to understand key steps of Mcf1 intoxication at the molecular level.
Topics: Animals; Bacterial Toxins; Lepidoptera; Apoptosis; Peptide Hydrolases
PubMed: 38086871
DOI: 10.1038/s41467-023-44069-2 -
Plant Disease Nov 2023Root-knot nematodes (RKNs) cause significant economic damage to crop plants, spurring demand for safe, affordable, and sustainable nematicides. A previous study by our...
Root-knot nematodes (RKNs) cause significant economic damage to crop plants, spurring demand for safe, affordable, and sustainable nematicides. A previous study by our research team showed that the combination of two nematicidal secondary metabolites (SMs) derived from bacteria, -cinnamic acid (-CA), and (4)-5-phenylpent-4-enoic acid (PPA) have a synergistic effect against RKNs in vitro. In this study, we considered in planta assays to assess the effects of this SM mixture on the virulence and reproductive fitness of the RKN in a cowpea. Factorial combinations of five -CA + PPA concentrations (0, 9.0, 22.9, 57.8, and 91.0 μg/ml) and two nematode inoculation conditions (presence or absence) were evaluated in 6-week growth chamber experiments. Results from this study showed that a single root application of the -CA + PPA mixture significantly reduced the penetration of infective juveniles (J2s) into the cowpea roots. The potential toxicity of -CA + PPA on RKN-susceptible cowpea seedlings was also investigated. The effect of -CA + PPA × nematode inoculation interactions and the -CA + PPA mixture did not show significant phytotoxic effects, nor did it adversely affect plant growth parameters or alter leaf chlorophyll content. Total leaf chlorophyll and chlorophyll content were significantly reduced (by 15 and 22%, respectively) only by the nematode inoculum and not by any of the SM treatments. Our results suggest that a single root application of a mixture of -CA and PPA reduces J2's ability to infect the roots without impairing plant growth or chlorophyll content.
Topics: Animals; Tylenchoidea; Vigna; Photorhabdus; Antinematodal Agents; Chlorophyll
PubMed: 37330631
DOI: 10.1094/PDIS-11-22-2574-SC -
Archives of Biochemistry and Biophysics May 2024Recent research into membrane interactions has uncovered a diverse range of therapeutic opportunities through the bioengineering of human and non-human macromolecules....
Recent research into membrane interactions has uncovered a diverse range of therapeutic opportunities through the bioengineering of human and non-human macromolecules. Although the majority of this research is focussed on fundamental developments, emerging studies are showcasing promising new technologies to combat conditions such as cancer, Alzheimer's and inflammatory and immune-based disease, utilising the alteration of bacteriophage, adenovirus, bacterial toxins, type 6 secretion systems, annexins, mitochondrial antiviral signalling proteins and bacterial nano-syringes. To advance the field further, each of these opportunities need to be better understood, and the therapeutic models need to be further optimised. Here, we summarise the knowledge and insights into several membrane interactions and detail their current and potential uses therapeutically.
PubMed: 38387829
DOI: 10.1016/j.abb.2024.109939