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Mollah MMI. Ligands of HMG-like dorsal switch protein 1 of Spodoptera exigua leads to mortality in diamondback moth, Plutellaxylostella. Heliyon 2024; 10:e27090. [PMID: 38509914 PMCID: PMC10950498 DOI: 10.1016/j.heliyon.2024.e27090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 03/22/2024] Open
Abstract
HMG-like dorsal switch protein 1 (DSP1) is the insect homolog of the high mobility group box 1 (HMGB1) protein of the vertebrates. Previous studies confirmed DSP1 in Spodoptera exigua, Tenebrio molitor, and Aedes albopictus, and were analyzed for their immune roles, survivability, and binding affinity with entomopathogenic bacterial metabolites. The present study aimed to predict, and confirm DSP1 in diamondback moth, Plutella xylostella along with the effect of Spodoptera exigua DSP1 ligands in the survivability of this insect. DSP1 of Plutella xylostella (Px-DSP1) consists of 465 amino acids (AA). Phylogeny analysis showed that Px-DSP1 clustered with other Lepidopteran insects where each insect order clustered separately. Domain analysis showed that like other insects, Px-DSP1 contains two HMG boxes (Box A and Box B), one coiled-coil (CC), five Q-rich low complexity (LC), and an acidic tail (AT). Px-DSP1 was expressed in each developmental stage and tissue. The highest expression was in L4 larvae and fat body tissues. Thermal shift assay (TSA) showed the binding affinity of 3-Ethoxy-4-Methoxyphenol (EMP), Phthalimide (PM), and o-Cyanobenzoic acid (CBA) to rDSP1 of Spodoptera exigua. Mortality bioassay showed that all these metabolites were toxic against P. xylostella larvae. Among these, EMP was more toxic providing more than 65% mortality at 500 ppm concentration. However, PM and CBA also showed more than 60 and 50% mortality, respectively at 500 ppm concentration. We assume that like Se-DSP1, these compounds also bind with Px-DSP1 which leads to the inhibition of DSP1-mediated immunity and impose the mortality of Plutella xylostella larvae.
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Affiliation(s)
- Md. Mahi Imam Mollah
- Department of Entomology, Patuakhali Science and Technology University, Dumki, 8602, Patuakhali, Bangladesh
- Department of Plant Medicals, College of Life Science, Andong National University, Andong, Republic of Korea
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Půža V, Nermuť J, Konopická J, Skoková Habuštová O. The effect of Xenorhabdus bacteria metabolites on Colorado potato beetle (Leptinotarsa decemlineata) adult feeding and larval survival. J Invertebr Pathol 2024; 203:108075. [PMID: 38350523 DOI: 10.1016/j.jip.2024.108075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 02/07/2024] [Accepted: 02/09/2024] [Indexed: 02/15/2024]
Abstract
Colorado Potato Beetle (CPB) is one of the most destructive potato pests that can quickly develop resistance to insecticides. Therefore, new safe and effective control strategies that are less susceptible to the development of resistance by CPB are urgently needed. Due to their complex mode of action, the likelihood of resistance development by target pests is generally low with antifeedants. In the present study, we assessed the effect of secondary metabolites of various Xenorhabdus bacteria species and strains on CPB adult feeding and on larval development. The metabolites were applied in the form of cell free supernatants (CFSs) from Xenorhabdus cultures. In bioassay 1, leaves treated with ten Xenorhabdus cultures were fed to CPB adults, and their feeding was assessed daily for one week. In bioassay 2, CPB egg masses were placed on the leaves treated with five bacterial cultures, and larval development to pupae was monitored. Out of the ten Xenorhabdus cultures tested, two strains exhibited a significant reduction in the feeding behavior of Colorado Potato Beetle adults, with reductions of up to 70% compared to the control. The effect of CFSs on larval development was variable, and when treated with X. khoisanae SGI 197, over 90% of larvae died in the first few days before reaching the 2nd instar, and complete mortality was achieved on the 8th day of the experiment. Our study is the first study to demonstrate the antifeedant effect of Xenorhabdus cultures towards herbivorous beetles, and the metabolites of these bacteria may have potential for CPB control. Clearly, the metabolites produced by X. khoisanae SGI-197 may be a promising tool for CPB larvae control with the potential to significantly decrease damage to potato plants.
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Affiliation(s)
- Vladimír Půža
- Institute of Entomology, Biology centre, CAS, Branišovská 31, 37005 České Budějovice, Czech Republic.
| | - Jiří Nermuť
- Institute of Entomology, Biology centre, CAS, Branišovská 31, 37005 České Budějovice, Czech Republic
| | - Jana Konopická
- Institute of Entomology, Biology centre, CAS, Branišovská 31, 37005 České Budějovice, Czech Republic
| | - Oxana Skoková Habuštová
- Institute of Entomology, Biology centre, CAS, Branišovská 31, 37005 České Budějovice, Czech Republic
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Jin G, Kim IH, Kim Y. The Lrp transcriptional factor of an entomopathogenic bacterium, Xenorhabdus hominickii, activates non-ribosomal peptide synthetases to suppress insect immunity. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2024; 151:105101. [PMID: 38000489 DOI: 10.1016/j.dci.2023.105101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 11/11/2023] [Accepted: 11/17/2023] [Indexed: 11/26/2023]
Abstract
Two bacterial genera, Xenorhabdus and Photorhabdus, are mutually symbiotic to the entomopathogenic nematodes, Steinernema and Heterorhabditis, respectively. The infective juveniles deliver the symbiotic bacteria to the hemocoel of target insects, in which the bacteria proliferate and help the development of the host nematode. The successful parasitism of the nematode-bacterial complex depends on host immunosuppression by the bacteria via their secondary metabolites. Leucine-responsive regulatory protein (Lrp) is a global bacterial transcriptional factor that plays a crucial role in parasitism. However, its regulatory targets to suppress insect immunity are not clearly understood. This study investigated the bacterial genes regulated by Lrp and the subsequent production of secondary metabolites in Xenorhabdus hominickii. Lrp expression occurred at the early infection stage of the bacteria in a target insect, Spodoptera exigua. A preliminary in silico screening indicated that 3.7% genes among 4075 predicted genes encoded in X. hominickii had the Lrp-response element on their promoters, including two non-ribosomal peptide synthetases (NRPSs). Eight NRPS (NRPS1-NRPS8) genes were predicted in the bacterial genome, in which six NRPS (NRPS3-NRPS8) expressions were positively correlated with Lrp expression in the infected larvae of S. exigua. Exchange of the Lrp promoter with an inducible promoter altered the production of the secondary metabolites and the NRPS expression levels. The immunosuppressive activities of X. hominickii were dependent on the Lrp expression level. The metabolites produced by Lrp expression included the eicosanoid-biosynthesis inhibitors and hemolytic factors. A cyclic dipeptide (=cPF) was produced by the bacteria at high Lrp expression and inhibited the phospholipase A2 activity of S. exigua in a competitive inhibitory manner. These results suggest that Lrp is a global transcriptional factor of X. hominickii and plays a crucial role in insect immunosuppression by modulating NRPS expression.
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Affiliation(s)
- Gahyeon Jin
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea
| | - Il-Hwan Kim
- Korea Research Institute of Standards and Science, Daejeon, 34113, South Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, 36729, South Korea.
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Son DJ, Kim GG, Choo HY, Chung NJ, Choo YM. Functional Comparison of Three Chitinases from Symbiotic Bacteria of Entomopathogenic Nematodes. Toxins (Basel) 2024; 16:26. [PMID: 38251242 PMCID: PMC10821219 DOI: 10.3390/toxins16010026] [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] [Received: 11/20/2023] [Revised: 12/28/2023] [Accepted: 12/29/2023] [Indexed: 01/23/2024] Open
Abstract
Xenorhabdus and Photorhabdus, bacterial symbionts of entomopathogenic nematodes Steinernema and Heterorhabditis, respectively, have several biological activities including insecticidal and antimicrobial activities. Thus, XnChi, XhChi, and PtChi, chitinases of X. nematophila, X. hominickii, and P. temperata isolated from Korean indigenous EPNs S. carpocapsae GJ1-2, S. monticolum GJ11-1, and H. megidis GJ1-2 were cloned and expressed in Escherichia coli BL21 to compare their biological activities. Chitinase proteins of these bacterial symbionts purified using the Ni-NTA system showed different chitobiosidase and endochitinase activities, but N-acetylglucosamidinase activities were not shown in the measuring of chitinolytic activity through N-acetyl-D-glucosarmine oligomers. In addition, the proteins showed different insecticidal and antifungal activities. XnChi showed the highest insecticidal activity against Galleria mellonella, followed by PtChi and XhChi. In antifungal activity, XhChi showed the highest half-maximal inhibitory concentration (IC50) against Fusarium oxysporum with 0.031 mg/mL, followed by PtChi with 0.046 mg/mL, and XnChi with 0.072 mg/mL. XhChi also showed the highest IC50 against F. graminearum with 0.040 mg/mL, but XnChi was more toxic than PtChi with 0.055 mg/mL and 0.133 mg/mL, respectively. This study provides an innovative approach to the biological control of insect pests and fungal diseases of plants with the biological activity of symbiotic bacterial chitinases of entomopathogenic nematodes.
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Affiliation(s)
- Da-Jeong Son
- Department of Applied Bioscience, Dong-A University, Busan 49315, Republic of Korea;
- Division of Research and Development, Jinju Bioindustry Foundation, Jinju 52839, Republic of Korea
| | - Geun-Gon Kim
- Division of Research and Development, Nambo Co., Ltd., Jinju 52840, Republic of Korea; (G.-G.K.); (H.-Y.C.)
| | - Ho-Yul Choo
- Division of Research and Development, Nambo Co., Ltd., Jinju 52840, Republic of Korea; (G.-G.K.); (H.-Y.C.)
| | - Nam-Jun Chung
- Division of Research and Development, Nambo Co., Ltd., Jinju 52840, Republic of Korea; (G.-G.K.); (H.-Y.C.)
| | - Young-Moo Choo
- Division of Research and Development, Jinju Bioindustry Foundation, Jinju 52839, Republic of Korea
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Mollah MMI. Spätzle processing enzyme is required to activate dorsal switch protein 1 induced Toll immune signalling pathway in Tenebrio molitor. PLoS One 2023; 18:e0291976. [PMID: 37733725 PMCID: PMC10513244 DOI: 10.1371/journal.pone.0291976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 09/10/2023] [Indexed: 09/23/2023] Open
Abstract
Dorsal switch protein 1 (DSP1) acts as a damage-associated molecular pattern (DAMP) molecule to activate immune responses in Tenebrio molitor. From a previous study in Spodoptera exigua, we found that DSP1 activates Toll immune signalling pathway to induce immune responses by melanisation, PLA2 activity and AMP synthesis. However, the target site of DSP1 in this pathway remains unknown. The objective of this study was to determine the role of spätzle processing enzyme in the DSP1 induced toll immune signalling pathway. To address this, we analyzed spätzle processing enzyme (Tm-SPE) of the three-step serine protease cascade of T. molitor Toll pathway. Tm-SPE expressed in all developmental stages and larval tissues. Upon immune challenge, its expression levels were upregulated but significantly reduced after RNA interference (RNAi). In addition, the induction of immune responses upon immune challenge or recombinant DSP1 injection was significantly increased. Loss of function using RNA interference revealed that the Tm-SPE is involved in connecting DSP1 induced immune responses like hemocyte nodule formation, phenoloxidase (PO) activity, phospholipase A2 (PLA2) activity and antimicrobial peptide (AMP) synthesis. These suggest that Tm-SPE controls the DSP1 induced activation of Toll immune signalling pathway required for both cellular and humoral immune responses. However, to confirm the target molecule of DSP1 in three-step proteolytic cascade, we have to check other upstream serine proteases like Spatzle activating enzyme (SAE) or modular serine protease (MSP).
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Affiliation(s)
- Md. Mahi Imam Mollah
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Republic of Korea
- Department of Entomology, Faculty of Agriculture, Patuakhali Science and Technology University, Patuakhali, Bangladesh
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Alani OS, Cao M, Goodrich-Blair H, Heppert JK. Conjugation and transposon mutagenesis of Xenorhabdus griffiniae HGB2511, the bacterial symbiont of the nematode Steinernema hermaphroditum (India). MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.000772. [PMID: 37179970 PMCID: PMC10170317 DOI: 10.17912/micropub.biology.000772] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 04/05/2023] [Accepted: 04/19/2023] [Indexed: 05/15/2023]
Abstract
Symbiosis, the beneficial interactions between two organisms, is a ubiquitous feature of all life on Earth, including associations between animals and bacteria. However, the specific molecular and cellular mechanisms which underlie the diverse partnerships formed between animals and bacteria are still being explored. Entomopathogenic nematodes transport bacteria between insect hosts, together they kill the insect, and the bacteria consume the insect and serve as food source for the nematodes. These nematodes, including those in the Steinernema genus, are effective laboratory models for studying the molecular mechanisms of symbiosis because of the natural partnership they form with Xenorhabdus bacteria and their straightforward husbandry. Steinernema hermaphroditum nematodes and their Xenorhabdus griffiniae symbiotic bacteria are being developed as a genetic model pair for studying symbiosis. Our goal in this project was to begin to identify bacterial genes that may be important for symbiotic interactions with the nematode host. Towards this end, we adapted and optimized a protocol for delivery and insertion of a lacZ- promoter-probe transposon for use in the S. hermaphroditum symbiont, X. griffiniae HGB2511 (Cao et al., 2022). We assessed the frequencies at which we obtained exconjugants, metabolic auxotrophic mutants, and active promoter- lacZ fusions. Our data indicate that the Tn 10 transposon inserted relatively randomly based on the finding that 4.7% of the mutants exhibited an auxotrophic phenotype. Promoter-fusions with the transposon-encoded lacZ , which resulted in expression of β-galactosidase activity, occurred in 47% of the strains. To our knowledge, this is the first mutagenesis protocol generated for this bacterial species, and will facilitate the implementation of large scale screens for symbiosis and other phenotypes of interest in X. griffiniae .
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Affiliation(s)
- Omar S. Alani
- Department of Microbiology, University of Tennessee at Knoxville, Knoxville, Tennessee, United States
| | - Mengyi Cao
- California Institute of Technology, Pasadena, California, United States
| | - Heidi Goodrich-Blair
- Department of Microbiology, University of Tennessee at Knoxville, Knoxville, Tennessee, United States
| | - Jennifer K. Heppert
- Department of Microbiology, University of Tennessee at Knoxville, Knoxville, Tennessee, United States
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Fodor A, Gualtieri M, Zeller M, Tarasco E, Klein MG, Fodor AM, Haynes L, Lengyel K, Forst SA, Furgani GM, Karaffa L, Vellai T. Type Strains of Entomopathogenic Nematode-Symbiotic Bacterium Species, Xenorhabdus szentirmaii (EMC) and X. budapestensis (EMA), Are Exceptional Sources of Non-Ribosomal Templated, Large-Target-Spectral, Thermotolerant-Antimicrobial Peptides (by Both), and Iodinin (by EMC). Pathogens 2022; 11:pathogens11030342. [PMID: 35335666 PMCID: PMC8950435 DOI: 10.3390/pathogens11030342] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/18/2022] [Accepted: 02/23/2022] [Indexed: 01/26/2023] Open
Abstract
Antimicrobial multidrug resistance (MDR) is a global challenge, not only for public health, but also for sustainable agriculture. Antibiotics used in humans should be ruled out for use in veterinary or agricultural settings. Applying antimicrobial peptide (AMP) molecules, produced by soil-born organisms for protecting (soil-born) plants, seems a preferable alternative. The natural role of peptide-antimicrobials, produced by the prokaryotic partner of entomopathogenic-nematode/bacterium (EPN/EPB) symbiotic associations, is to sustain monoxenic conditions for the EPB in the gut of the semi-anabiotic infective dauer juvenile (IJ) EPN. They keep pathobiome conditions balanced for the EPN/EPB complex in polyxenic (soil, vanquished insect cadaver) niches. Xenorhabdus szentirmaii DSM16338(T) (EMC), and X. budapestensis DSM16342(T) (EMA), are the respective natural symbionts of EPN species Steinernema rarum and S. bicornutum. We identified and characterized both of these 15 years ago. The functional annotation of the draft genome of EMC revealed 71 genes encoding non-ribosomal peptide synthases, and polyketide synthases. The large spatial Xenorhabdus AMP (fabclavine), was discovered in EMA, and its biosynthetic pathway in EMC. The AMPs produced by EMA and EMC are promising candidates for controlling MDR prokaryotic and eukaryotic pathogens (bacteria, oomycetes, fungi, protozoa). EMC releases large quantity of iodinin (1,6-dihydroxyphenazine 5,10-dioxide) in a water-soluble form into the media, where it condenses to form spectacular water-insoluble, macroscopic crystals. This review evaluates the scientific impact of international research on EMA and EMC.
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Affiliation(s)
- András Fodor
- Department of Genetics, Eötvös University, Pázmány Péter Sétány 1/C, H-1117 Budapest, Hungary; (A.M.F.); (K.L.); or (G.M.F.); or (T.V.)
- Department of Genetics, University of Szeged, Középfasor 52, H-6726 Szeged, Hungary
- Correspondence: ; Tel.: +36-(30)-490-9294
| | - Maxime Gualtieri
- Nosopharm, 110 Allée Charles Babbage, Espace Innovation 2, 30000 Nîmes, France;
| | - Matthias Zeller
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47906, USA;
| | - Eustachio Tarasco
- Department of Soil, Plant and Food Sciences, University of Bari “Aldo Moro”, Via Amendola 165/A, 70126 Bari, Italy;
- Institute for Sustainable Plant Protection of CNR, Via Amendola 122/D, 70126 Bari, Italy
| | - Michael G. Klein
- USDA-ARS & Department of Entomology, The Ohio State University, 13416 Claremont Ave, Cleveland, OH 44130, USA;
| | - Andrea M. Fodor
- Department of Genetics, Eötvös University, Pázmány Péter Sétány 1/C, H-1117 Budapest, Hungary; (A.M.F.); (K.L.); or (G.M.F.); or (T.V.)
| | - Leroy Haynes
- Department of Chemistry, The College of Wooster, Wooster, OH 44691, USA;
| | - Katalin Lengyel
- Department of Genetics, Eötvös University, Pázmány Péter Sétány 1/C, H-1117 Budapest, Hungary; (A.M.F.); (K.L.); or (G.M.F.); or (T.V.)
- National Institute of Pharmacy and Nutrition (NIPN), Zrinyi utca 3, H-1051 Budapest, Hungary
| | - Steven A. Forst
- Department of Biological Sciences, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201, USA;
| | - Ghazala M. Furgani
- Department of Genetics, Eötvös University, Pázmány Péter Sétány 1/C, H-1117 Budapest, Hungary; (A.M.F.); (K.L.); or (G.M.F.); or (T.V.)
- Department of Plant Protection, Faculty of Agriculture, University of Tripoli, Tripoli P.O. Box 13793, Libya
| | - Levente Karaffa
- Department of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, Egyetem Tér 1, H-4032 Debrecen, Hungary;
- Institute of Metagenomics, University of Debrecen, Egyetem tér 1, H-4032 Debrecen, Hungary
| | - Tibor Vellai
- Department of Genetics, Eötvös University, Pázmány Péter Sétány 1/C, H-1117 Budapest, Hungary; (A.M.F.); (K.L.); or (G.M.F.); or (T.V.)
- MTA-ELTE Genetics Research Group, Pázmány Péter Sétány 1/C, H-1117 Budapest, Hungary
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Mollah MMI, Choi HW, Yeam I, Lee JM, Kim Y. Salicylic Acid, a Plant Hormone, Suppresses Phytophagous Insect Immune Response by Interrupting HMG-Like DSP1. Front Physiol 2021; 12:744272. [PMID: 34671276 PMCID: PMC8521015 DOI: 10.3389/fphys.2021.744272] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 09/06/2021] [Indexed: 12/23/2022] Open
Abstract
Salicylic acid is a plant hormone that can mediate various plant physiological processes. Salicylic acid can bind to human high mobility group box 1 (HMGB1) and interrupt its role in mediating immune responses. Dorsal switch protein 1 (DSP1) is an insect homolog of HMGB1. In this study, a DSP1 (Se-DSP1) encoded in Spodoptera exigua, a phytophagous insect, was characterized, and its potential role in immune response was explored. Upon bacterial challenge, Se-DSP1 was localized in the nucleus and released into the hemolymph. The released Se-DSP1 could mediate both cellular and humoral immune responses by activating eicosanoid biosynthesis. Salicylic acid could bind to Se-DSP1 with a high affinity. The immune responses of S. exigua were significantly interrupted by SA feeding. Larvae reared on tomatoes with high endogenous SA levels became more susceptible to entomopathogens. Taken together, these results suggest a tritrophic defensive role of plant SA against phytophagous insects.
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Affiliation(s)
- Md Mahi Imam Mollah
- Department of Plant Medicals, Andong National University, Andong, South Korea
| | - Hyong Woo Choi
- Department of Plant Medicals, Andong National University, Andong, South Korea
| | - Inhwa Yeam
- Department of Horticulture and Breeding, Andong National University, Andong, South Korea
| | - Je Min Lee
- Department of Horticultural Science, Kyungpook National University, Daegu, South Korea
| | - Yonggyun Kim
- Department of Plant Medicals, Andong National University, Andong, South Korea
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Chalivendra S. Microbial Toxins in Insect and Nematode Pest Biocontrol. Int J Mol Sci 2021; 22:ijms22147657. [PMID: 34299280 PMCID: PMC8303606 DOI: 10.3390/ijms22147657] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 07/09/2021] [Accepted: 07/15/2021] [Indexed: 12/24/2022] Open
Abstract
Invertebrate pests, such as insects and nematodes, not only cause or transmit human and livestock diseases but also impose serious crop losses by direct injury as well as vectoring pathogenic microbes. The damage is global but greater in developing countries, where human health and food security are more at risk. Although synthetic pesticides have been in use, biological control measures offer advantages via their biodegradability, environmental safety and precise targeting. This is amply demonstrated by the successful and widespread use of Bacillusthuringiensis to control mosquitos and many plant pests, the latter by the transgenic expression of insecticidal proteins from B. thuringiensis in crop plants. Here, I discuss the prospects of using bacterial and fungal toxins for pest control, including the molecular basis of their biocidal activity.
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Evaluation of the Physicochemical, Antioxidant, and Antibacterial Properties of Tunichrome Released from Phallusia nigra Persian Gulf Marine Tunicate. J FOOD QUALITY 2021. [DOI: 10.1155/2021/5513717] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The aim of this study was to evaluate the physicochemical, nutraceutical, antioxidant, and antibacterial properties of tunichrome released from Persian Gulf tunicate (Phallusia nigra). For this purpose, molecular weight (SDS-PAGE), amino acid profile, chemical composition (GC-MS), mineral composition, functional groups (FTIR), total phenol content (TPC), total flavonoid content (TFC), antioxidant activity, and antimicrobial properties were investigated. The results showed that tunichrome contained a high amount of essential amino acids (i.e., Lys = 32.24 mg/100 g) and essential minerals. According to GC-MS results, tunichrome had different antioxidant and antimicrobial components. The TPC and TFC of tunichrome were 0.55 mg GA/g and 0.21 mg quercetin/100 g, respectively. Tunichrome showed higher antioxidant activity than ascorbic acid, and its radical scavenging activity values were increased from 30.28 to 82.08% by increasing concentration from 50 to 200 ppm. Inhibition zones of Staphylococcus aureus, Bacillus cereus, Salmonella enterica, and Escherichia coli O157:H7 were 14, 18, 17, and 15 mm, respectively. Moreover, the minimum inhibitory concentration values of tunichrome for S. aureus, Bacillus cereus, S. enterica, and E. coli O157:H7 were 1.17, 0.59, 0.59, and 1.17 mg/ml, respectively. The minimum bacterial concentrations were 2.34, 1.17, 1.17, and 2.34 mg/ml for S. aureus, Bacillus cereus, S. enterica, and E. coli O157:H7, respectively. These results showed that tunichrome of Phallusia nigra has excellent biological effects as a bioactive compound for food fortification.
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Mollah MMI, Ahmed S, Kim Y. Immune mediation of HMG-like DSP1 via Toll-Spätzle pathway and its specific inhibition by salicylic acid analogs. PLoS Pathog 2021; 17:e1009467. [PMID: 33765093 PMCID: PMC8023496 DOI: 10.1371/journal.ppat.1009467] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 04/06/2021] [Accepted: 03/11/2021] [Indexed: 12/22/2022] Open
Abstract
Xenorhabdus hominickii, an entomopathogenic bacterium, inhibits eicosanoid biosynthesis of target insects to suppress their immune responses by inhibiting phospholipase A2 (PLA2) through binding to a damage-associated molecular pattern (DAMP) molecule called dorsal switch protein 1 (DSP1) from Spodoptera exigua, a lepidopteran insect. However, the signalling pathway between DSP1 and PLA2 remains unknown. The objective of this study was to determine whether DSP1 could activate Toll immune signalling pathway to activate PLA2 activation and whether X. hominickii metabolites could inhibit DSP1 to shutdown eicosanoid biosynthesis. Toll-Spätzle (Spz) signalling pathway includes two Spz (SeSpz1 and SeSpz2) and 10 Toll receptors (SeToll1-10) in S. exigua. Loss-of-function approach using RNA interference showed that SeSpz1 and SeToll9 played crucial roles in connecting DSP1 mediation to activate PLA2. Furthermore, a deletion mutant against SeToll9 using CRISPR/Cas9 abolished DSP1 mediation and induced significant immunosuppression. Organic extracts of X. hominickii culture broth could bind to DSP1 at a low micromolar range. Subsequent sequential fractionations along with binding assays led to the identification of seven potent compounds including 3-ethoxy-4-methoxyphenol (EMP). EMP could bind to DSP1 and prevent its translocation to plasma in response to bacterial challenge and suppress the up-regulation of PLA2 activity. These results suggest that X. hominickii inhibits DSP1 and prevents its DAMP role in activating Toll immune signalling pathway including PLA2 activation, leading to significant immunosuppression of target insects. Immune responses of insects are highly effective in defending various entomopathogens. Xenorhabdus hominickii is an entomopathogenic bacterium that uses a pathogenic strategy of suppressing host insect immunity by inhibiting phospholipase A2 (PLA2) which catalyzes the committed step for eicosanoid biosynthesis. Eicosanoids mediate both cellular and humoral immune responses in insects. This study discovers an upstream signalling pathway to activate PLA2 in response to bacterial challenge. Se-DSP1 is an insect homolog of vertebrate HMGB1 that acts as a damage-associated molecular pattern. Upon bacterial infection, Se-DSP1 is released to the circulatory system to activate Spätzle, an insect cytokine that can bind to Toll receptor. Toll immune signalling pathway can activate antimicrobial peptide gene expression and PLA2. A deletion mutant against a Toll gene abolished immune responses mediated by Se-DSP1. Indeed, X. hominickii can produce and secrete secondary metabolites including salicylic acid analogs that can strongly bind to Se-DSP1. These bacterial metabolites prevented the release of Se-DSP1, which impaired the activation of PLA2 and resulted in a significant immunosuppression of target insects against bacterial infection.
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Affiliation(s)
- Md. Mahi Imam Mollah
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Korea
| | - Shabbir Ahmed
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Korea
| | - Yonggyun Kim
- Department of Plant Medicals, College of Life Sciences, Andong National University, Andong, Korea
- * E-mail:
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