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Wang HC, Lin SJ, Wang HC, Kumar R, Le PT, Leu JH. A bacterial binary toxin system that kills both insects and aquatic crustaceans: Photorhabdus insect-related toxins A and B. PLoS Pathog 2023; 19:e1011330. [PMID: 37141203 PMCID: PMC10159206 DOI: 10.1371/journal.ppat.1011330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023] Open
Abstract
Photorhabdus insect-related toxins A and B (PirA and PirB) were first recognized as insecticidal toxins from Photorhabdus luminescens. However, subsequent studies showed that their homologs from Vibrio parahaemolyticus also play critical roles in the pathogenesis of acute hepatopancreatic necrosis disease (AHPND) in shrimps. Based on the structural features of the PirA/PirB toxins, it was suggested that they might function in the same way as a Bacillus thuringiensis Cry pore-forming toxin. However, unlike Cry toxins, studies on the PirA/PirB toxins are still scarce, and their cytotoxic mechanism remains to be clarified. In this review, based on our studies of V. parahaemolyticus PirAvp/PirBvp, we summarize the current understanding of the gene locations, expression control, activation, and cytotoxic mechanism of this type of toxin. Given the important role these toxins play in aquatic disease and their potential use in pest control applications, we also suggest further topics for research. We hope the information presented here will be helpful for future PirA/PirB studies.
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Affiliation(s)
- Hao-Ching Wang
- Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan, Republic of China
- The PhD Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University and Academia Sinica, Taipei, Taiwan, Republic of China
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan, Republic of China
| | - Shin-Jen Lin
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan, Republic of China
| | - Han-Ching Wang
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan, Republic of China
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan, Republic of China
| | - Ramya Kumar
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan, Republic of China
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan, Republic of China
| | - Phuoc Thien Le
- Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan, Republic of China
| | - Jiann-Horng Leu
- Institute of Marine Biology, National Taiwan Ocean University, Keelung, Taiwan, Republic of China
- Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan, Republic of China
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Kinkar OU, Prashar A, Kumar A, Hadapad AB, Hire RS, Makde RD. Txp40, an insecticidal toxin protein from Xenorhabdus nematophila: Purification, toxicity assessment and biophysical characterization. Toxicon 2022; 218:40-46. [PMID: 36096207 DOI: 10.1016/j.toxicon.2022.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 08/12/2022] [Accepted: 09/06/2022] [Indexed: 10/14/2022]
Abstract
Txp40 is a ubiquitous toxin from Xenorhabdus and Photorhabdus bacteria, exhibits insecticidal activity against a wide range of insect pests belonging to Lepidoptera and Diptera orders. Initially, Txp40 affects midgut of the target insect and further damages some other tissues like fat bodies but the detailed mode of action is not known. Txp40 shares no significant sequence match to any proteins with known structure or function, suggesting that it is a novel type of insecticidal toxin. Here, we report purification, toxicity and biophysical characterization of the Txp40b toxin from X. nematophila (ATCC, 19061). The recombinant Txp40b was found toxic to Galleria mellonella larvae with LD50 of 30.42 ng larva-1. Circular dichroism spectroscopy revealed that purified Txp40b is an α-helix rich protein with a relatively lower melting temperature of 45 °C. In-silico model generated suggests two domain structure of Txp40b toxin. Detailed structural analysis of Txp40b will provide new insights about the mode of action and possibly it would illustrate a new domain and/or motif in the area of insecticidal proteins.
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Affiliation(s)
- Omkar U Kinkar
- Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, Maharashtra, India; Beamline Development and Application Section, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Arpit Prashar
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Ashwani Kumar
- Beamline Development and Application Section, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Ashok B Hadapad
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Ramesh S Hire
- Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, Maharashtra, India; Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Ravindra D Makde
- Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, Maharashtra, India; Beamline Development and Application Section, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
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Bubrig LT, Fierst JL. REVIEW OF THE DAUER HYPOTHESIS: WHAT NON-PARASITIC SPECIES CAN TELL US ABOUT THE EVOLUTION OF PARASITISM. J Parasitol 2021; 107:717-725. [PMID: 34525204 DOI: 10.1645/21-40] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Parasitic lineages have acquired suites of new traits compared to their nearest free-living relatives. When and why did these traits arise? We can envision lineages evolving through multiple stable intermediate steps such as a series of increasingly exploitative species interactions. This view allows us to use non-parasitic species that approximate those intermediate steps to uncover the timing and original function of parasitic traits, knowledge critical to understanding the evolution of parasitism. The dauer hypothesis proposes that free-living nematode lineages evolved into parasites through two intermediate steps, phoresy and necromeny. Here we delve into the proposed steps of the dauer hypothesis by collecting and organizing data from genetic, behavioral, and ecological studies in a range of nematode species. We argue that hypotheses on the evolution of parasites will be strengthened by complementing comparative genomic studies with ecological studies on non-parasites that approximate intermediate steps.
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Affiliation(s)
- Louis T Bubrig
- Department of Biology, University of Virginia, 485 McCormick Road, Charlottesville, Virginia 22904
| | - Janna L Fierst
- Department of Biological Sciences, University of Alabama, 300 Hackberry Lane, Tuscaloosa, Alabama 35487-0344
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Kumar V, Roy S, Behera BK, Bossier P, Das BK. Acute Hepatopancreatic Necrosis Disease (AHPND): Virulence, Pathogenesis and Mitigation Strategies in Shrimp Aquaculture. Toxins (Basel) 2021; 13:524. [PMID: 34437395 PMCID: PMC8402356 DOI: 10.3390/toxins13080524] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 07/20/2021] [Accepted: 07/22/2021] [Indexed: 02/06/2023] Open
Abstract
Shrimp, as a high-protein animal food commodity, are one of the fastest growing food producing sectors in the world. It has emerged as a highly traded seafood product, currently exceeding 8 MT of high value. However, disease outbreaks, which are considered as the primary cause of production loss in shrimp farming, have moved to the forefront in recent years and brought socio-economic and environmental unsustainability to the shrimp aquaculture industry. Acute hepatopancreatic necrosis disease (AHPND), caused by Vibrio spp., is a relatively new farmed penaeid shrimp bacterial disease. The shrimp production in AHPND affected regions has dropped to ~60%, and the disease has caused a global loss of USD 43 billion to the shrimp farming industry. The conventional approaches, such as antibiotics and disinfectants, often applied for the mitigation or cure of AHPND, have had limited success. Additionally, their usage has been associated with alteration of host gut microbiota and immunity and development of antibiotic resistance in bacterial pathogens. For example, the Mexico AHPND-causing V. parahaemolyticus strain (13-306D/4 and 13-511/A1) were reported to carry tetB gene coding for tetracycline resistance gene, and V. campbellii from China was found to carry multiple antibiotic resistance genes. As a consequence, there is an urgent need to thoroughly understand the virulence mechanism of AHPND-causing Vibrio spp. and develop novel management strategies to control AHPND in shrimp aquaculture, that will be crucially important to ensure food security in the future and offer economic stability to farmers. In this review, the most important findings of AHPND are highlighted, discussed and put in perspective, and some directions for future research are presented.
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Affiliation(s)
- Vikash Kumar
- Aquatic Environmental Biotechnology and Nanotechnology (AEBN) Division, ICAR-Central Inland Fisheries Research Institute (CIFRI), Barrackpore 700120, India; (S.R.); (B.K.B.); (B.K.D.)
- Laboratory of Aquaculture & Artemia Reference Center, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium;
| | - Suvra Roy
- Aquatic Environmental Biotechnology and Nanotechnology (AEBN) Division, ICAR-Central Inland Fisheries Research Institute (CIFRI), Barrackpore 700120, India; (S.R.); (B.K.B.); (B.K.D.)
- Laboratory of Aquaculture & Artemia Reference Center, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium;
| | - Bijay Kumar Behera
- Aquatic Environmental Biotechnology and Nanotechnology (AEBN) Division, ICAR-Central Inland Fisheries Research Institute (CIFRI), Barrackpore 700120, India; (S.R.); (B.K.B.); (B.K.D.)
| | - Peter Bossier
- Laboratory of Aquaculture & Artemia Reference Center, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium;
| | - Basanta Kumar Das
- Aquatic Environmental Biotechnology and Nanotechnology (AEBN) Division, ICAR-Central Inland Fisheries Research Institute (CIFRI), Barrackpore 700120, India; (S.R.); (B.K.B.); (B.K.D.)
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Dutta TK, Mathur C, Mandal A, Somvanshi VS. The differential strain virulence of the candidate toxins of Photorhabdus akhurstii can be correlated with their inter-strain gene sequence diversity. 3 Biotech 2020; 10:299. [PMID: 32550116 DOI: 10.1007/s13205-020-02288-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 06/01/2020] [Indexed: 02/06/2023] Open
Abstract
Photorhabdus akhurstii is an insect-parasitic bacterium that symbiotically associates with the nematode, Heterorhabditis indica. The bacterium possesses several pathogenicity islands that aids in conferring toxicity to different insects. Herein, we constructed the plasmid clones of coding sequences of four toxin genes (pirA, tcaA, tccA and tccC; each was isolated from four P. akhurstii strains IARI-SGMG3, IARI-SGGJ2, IARI-SGHR2 and IARI-SGMS1) in Escherichia coli and subsequently, their biological activity were investigated against the fourth-instar larvae of the model insect, Galleria mellonella via intra-hemocoel injection. Bioinformatics analyses indicated inter-strain amino acid sequence difference at several positions of the candidate toxins. In corroboration, differential insecticidal activity of the identical toxin protein (PirA, TcaA, TccA and TccC conferred 15-59, 27-100, 25-100 and 33-98% insect mortality, respectively, across the strains) derived from the different bacterial strains was observed, suggesting that the diverse gene pool in Indian strains of P. akhurstii leads to strain-specific virulence in this bacterium. These toxin candidates appear to be an attractive option to deploy them in biopesticide development for managing the insect pests globally.
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Affiliation(s)
- Tushar K Dutta
- Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Chetna Mathur
- Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Abhishek Mandal
- Division of Agricultural Chemicals, ICAR-Indian Agricultural Research Institute, New Delhi, 110012 India
| | - Vishal S Somvanshi
- Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, 110012 India
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PirAB VP Toxin Binds to Epithelial Cells of the Digestive Tract and Produce Pathognomonic AHPND Lesions in Germ-Free Brine Shrimp. Toxins (Basel) 2019; 11:toxins11120717. [PMID: 31835437 PMCID: PMC6950649 DOI: 10.3390/toxins11120717] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 11/28/2019] [Accepted: 12/06/2019] [Indexed: 01/22/2023] Open
Abstract
Acute hepatopancreatic necrosis disease (AHPND), a newly emergent farmed penaeid shrimp bacterial disease originally known as early mortality syndrome (EMS), is causing havoc in the shrimp industry. The causative agent of AHPND was found to be a specific strain of bacteria, e.g., Vibrio and Shewanella sps., that contains pVA1 plasmid (63–70 kb) encoding the binary PirAVP and PirBVP toxins. The PirABVP and toxins are the primary virulence factors of AHPND-causing bacteria that mediates AHPND and mortality in shrimp. Hence, in this study using a germ-free brine shrimp model system, we evaluated the PirABVP toxin-mediated infection process at cellular level, including toxin attachment and subsequent toxin-induced damage to the digestive tract. The results showed that, PirABVP toxin binds to epithelial cells of the digestive tract of brine shrimp larvae and produces characteristic symptoms of AHPND. In the PirABVP-challenged brine shrimp larvae, shedding or sloughing of enterocytes in the midgut and hindgut regions was regularly visualized, and the intestinal lumen was filled with moderately electron-dense cells of variable shapes and sizes. In addition, the observed cellular debris in the intestinal lumen of the digestive tract was found to be of epithelial cell origin. The detailed morphology of the digestive tract demonstrates further that the PirABVP toxin challenge produces focal to extensive necrosis and damages epithelial cells in the midgut and hindgut regions, resulting in pyknosis, cell vacuolisation, and mitochondrial and rough endoplasmic reticulum (RER) damage to different degrees. Taken together, our study provides substantial evidence that PirABVP toxins bind to the digestive tract of brine shrimp larvae and seem to be responsible for generating characteristic AHPND lesions and damaging enterocytes in the midgut and hindgut regions.
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Roderer D, Hofnagel O, Benz R, Raunser S. Structure of a Tc holotoxin pore provides insights into the translocation mechanism. Proc Natl Acad Sci U S A 2019; 116:23083-23090. [PMID: 31666324 PMCID: PMC6859359 DOI: 10.1073/pnas.1909821116] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Tc toxins are modular toxin systems of insect and human pathogenic bacteria. They are composed of a 1.4-MDa pentameric membrane translocator (TcA) and a 250-kDa cocoon (TcB and TcC) encapsulating the 30-kDa toxic enzyme (C terminus of TcC). Binding of Tc toxins to target cells and a pH shift trigger the conformational transition from the soluble prepore state to the membrane-embedded pore. Subsequently, the toxic enzyme is translocated and released into the cytoplasm. A high-resolution structure of a holotoxin embedded in membranes is missing, leaving open the question of whether TcB-TcC has an influence on the conformational transition of TcA. Here we show in atomic detail a fully assembled 1.7-MDa Tc holotoxin complex from Photorhabdus luminescens in the membrane. We find that the 5 TcA protomers conformationally adapt to fit around the cocoon during the prepore-to-pore transition. The architecture of the Tc toxin complex allows TcB-TcC to bind to an already membrane-embedded TcA pore to form a holotoxin. Importantly, assembly of the holotoxin at the membrane results in spontaneous translocation of the toxic enzyme, indicating that this process is not driven by a proton gradient or other energy source. Mammalian lipids with zwitterionic head groups are preferred over other lipids for the integration of Tc toxins. In a nontoxic Tc toxin variant, we can visualize part of the translocating toxic enzyme, which transiently interacts with alternating negative charges and hydrophobic stretches of the translocation channel, providing insights into the mechanism of action of Tc toxins.
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Affiliation(s)
- Daniel Roderer
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Oliver Hofnagel
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Roland Benz
- Department of Life Sciences and Chemistry, Jacobs University Bremen, 28759 Bremen, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany;
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Roderer D, Raunser S. Tc Toxin Complexes: Assembly, Membrane Permeation, and Protein Translocation. Annu Rev Microbiol 2019; 73:247-265. [DOI: 10.1146/annurev-micro-102215-095531] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Tc toxin complexes are virulence factors of many bacteria, including insect and human pathogens. Tc toxins are composed of three subunits that act together to perforate the host membrane, similar to a syringe, and translocate toxic enzymes into the host cell. The reactions of the toxic enzymes lead to deterioration and ultimately death of the cell. We review recent high-resolution structural and functional data that explain the mechanism of action of this type of bacterial toxin at an unprecedented level of molecular detail. We focus on the steps that are necessary for toxin activation and membrane permeation. This is where the largest conformational transitions appear. Furthermore, we compare the architecture and function of Tc toxins with those of anthrax toxin and vertebrate teneurin.
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Affiliation(s)
- Daniel Roderer
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany;,
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany;,
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Mathur C, Phani V, Kushwah J, Somvanshi VS, Dutta TK. TcaB, an insecticidal protein from Photorhabdus akhurstii causes cytotoxicity in the greater wax moth, Galleria mellonella. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2019; 157:219-229. [PMID: 31153472 DOI: 10.1016/j.pestbp.2019.03.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 03/22/2019] [Accepted: 03/31/2019] [Indexed: 06/09/2023]
Abstract
Photorhabdus akhurstii can produce a variety of proteins that aid this bacterium and its mutualistic nematode vector, Heterorhabditis indica to kill the insect host. Herein, we characterized (by heterologously expressing in E. coli) an open reading frame (1713 bp) of the toxin complex protein, TcaB from P. akhurstii strains IARI-SGHR2 and IARI-SGMS1 and assessed its toxic effect on G. mellonella larvae. The intra-hemocoel injection of purified TcaB (molecular weight-63 kDa) caused fourth instar larval bodies to blacken and die with LD50 values of 67.25 (IARI-SGHR2) and 52.08 (IARI-SGMS1) ng per larva at 12 h. Additionally, oral administration of the toxin caused larval mortality with LD50 values of 709.55 (IARI-SGHR2) and 598.44 (IARI-SGMS1) ng per g diet per larva at 7 days post feeding. Injection of purified TcaB caused loss of viability of fourth instar G. mellonella hemocytes at 6 h post incubation; cells displayed morphological changes typical of apoptosis, including cell shrinkage, membrane blebbing, nuclear condensation and disintegration. Injection of TcaB also elevated the phenoloxidase activity in insect hemolymph which triggers an extensive immune response that potentially leads to larval death. Similar to other bacterial toxins TcaB possesses potent biological activity which may enable it to be used as an efficient agent for pest management.
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Affiliation(s)
- Chetna Mathur
- Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, 110012, India
| | - Victor Phani
- Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, 110012, India
| | - Jyoti Kushwah
- Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, 110012, India
| | - Vishal S Somvanshi
- Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, 110012, India
| | - Tushar K Dutta
- Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, 110012, India.
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Perez CE, Crawford JM. Characterization of a Hybrid Nonribosomal Peptide–Carbohydrate Biosynthetic Pathway in Photorhabdus luminescens. Biochemistry 2019; 58:1131-1140. [DOI: 10.1021/acs.biochem.8b01120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Corey E. Perez
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
- Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, United States
| | - Jason M. Crawford
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
- Chemical Biology Institute, Yale University, West Haven, Connecticut 06516, United States
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut 06536, United States
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A 37 kDa Txp40 protein characterized from Photorhabdus luminescens sub sp. akhurstii conferred injectable and oral toxicity to greater wax moth, Galleria mellonella. Toxicon 2018; 154:69-73. [PMID: 30278182 DOI: 10.1016/j.toxicon.2018.09.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 09/15/2018] [Accepted: 09/25/2018] [Indexed: 11/22/2022]
Abstract
Photorhabdus luminescens is a gram-negative bacterium that symbiotically associates with insect-parasitic nematode, Heterorhabditis indica. Herein, we have characterized an insecticidal gene, Txp40 (1008 bp) from the indigenous isolates of P. luminescens, and tested its bioefficacy against Galleria mellonella via injectable and oral bioassay. The recombinant protein characterized from P. luminescens strain H3 exhibited comparatively greater insect toxicity than strain H1 in terms of LD50 and LT50 values. Txp40 holds great potential to replace Bt toxins in global agriculture.
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12
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Structural Insights into the Cytotoxic Mechanism of Vibrio parahaemolyticus PirA vp and PirB vp Toxins. Mar Drugs 2017; 15:md15120373. [PMID: 29194352 PMCID: PMC5742833 DOI: 10.3390/md15120373] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 11/14/2017] [Accepted: 11/17/2017] [Indexed: 02/01/2023] Open
Abstract
In aquaculture, shrimp farming is a popular field. The benefits of shrimp farming include a relatively short grow-out time, high sale price, and good cost recovery. However, outbreaks of serious diseases inflict serious losses, and acute hepatopancreatic necrosis disease (AHPND) is an emerging challenge to this industry. In South American white shrimp (Penaeus vannamei) and grass shrimp (Penaeus monodon), this disease has a 70–100% mortality. The pathogenic agent of AHPND is a specific strain of Vibrio parahaemolyticus which contains PirAvp and PirBvp toxins encoded in the pVA1 plasmid. PirAvp and PirBvp have been shown to cause the typical histological symptoms of AHPND in infected shrimps, and in this review, we will focus on our structural understanding of these toxins. By analyzing their structures, a possible cytotoxic mechanism, as well as strategies for anti-AHPND drug design, is proposed.
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Abebe-Akele F, Tisa LS, Cooper VS, Hatcher PJ, Abebe E, Thomas WK. Genome sequence and comparative analysis of a putative entomopathogenic Serratia isolated from Caenorhabditis briggsae. BMC Genomics 2015; 16:531. [PMID: 26187596 PMCID: PMC4506600 DOI: 10.1186/s12864-015-1697-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 06/12/2015] [Indexed: 12/21/2022] Open
Abstract
Background Entomopathogenic associations between nematodes in the genera Steinernema and Heterorhabdus with their cognate bacteria from the bacterial genera Xenorhabdus and Photorhabdus, respectively, are extensively studied for their potential as biological control agents against invasive insect species. These two highly coevolved associations were results of convergent evolution. Given the natural abundance of bacteria, nematodes and insects, it is surprising that only these two associations with no intermediate forms are widely studied in the entomopathogenic context. Discovering analogous systems involving novel bacterial and nematode species would shed light on the evolutionary processes involved in the transition from free living organisms to obligatory partners in entomopathogenicity. Results We report the complete genome sequence of a new member of the enterobacterial genus Serratia that forms a putative entomopathogenic complex with Caenorhabditis briggsae. Analysis of the 5.04 MB chromosomal genome predicts 4599 protein coding genes, seven sets of ribosomal RNA genes, 84 tRNA genes and a 64.8 KB plasmid encoding 74 genes. Comparative genomic analysis with three of the previously sequenced Serratia species, S. marcescens DB11 and S. proteamaculans 568, and Serratia sp. AS12, revealed that these four representatives of the genus share a core set of ~3100 genes and extensive structural conservation. The newly identified species shares a more recent common ancestor with S. marcescens with 99 % sequence identity in rDNA sequence and orthology across 85.6 % of predicted genes. Of the 39 genes/operons implicated in the virulence, symbiosis, recolonization, immune evasion and bioconversion, 21 (53.8 %) were present in Serratia while 33 (84.6 %) and 35 (89 %) were present in Xenorhabdus and Photorhabdus EPN bacteria respectively. Conclusion The majority of unique sequences in Serratia sp. SCBI (South African Caenorhabditis briggsae Isolate) are found in ~29 genomic islands of 5 to 65 genes and are enriched in putative functions that are biologically relevant to an entomopathogenic lifestyle, including non-ribosomal peptide synthetases, bacteriocins, fimbrial biogenesis, ushering proteins, toxins, secondary metabolite secretion and multiple drug resistance/efflux systems. By revealing the early stages of adaptation to this lifestyle, the Serratia sp. SCBI genome underscores the fact that in EPN formation the composite end result – killing, bioconversion, cadaver protection and recolonization- can be achieved by dissimilar mechanisms. This genome sequence will enable further study of the evolution of entomopathogenic nematode-bacteria complexes. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1697-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Feseha Abebe-Akele
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA. .,Hubbard Center for Genome Studies, 444 Gregg Hall, University of New Hampshire, 35 Colovos Road, Durham, NH, 03824, USA.
| | - Louis S Tisa
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA
| | - Vaughn S Cooper
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA
| | - Philip J Hatcher
- Department of Computer Science, University of New Hampshire, Durham, NH, USA
| | - Eyualem Abebe
- Department of Biology, Elizabeth City State University, 1704 Weeksville Road, Jenkins Science Center 421, Elizabeth City, NC, 27909, USA
| | - W Kelley Thomas
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA.,Hubbard Center for Genome Studies, 444 Gregg Hall, University of New Hampshire, 35 Colovos Road, Durham, NH, 03824, USA
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Han JE, Tang KFJ, Tran LH, Lightner DV. Photorhabdus insect-related (Pir) toxin-like genes in a plasmid of Vibrio parahaemolyticus, the causative agent of acute hepatopancreatic necrosis disease (AHPND) of shrimp. DISEASES OF AQUATIC ORGANISMS 2015; 113:33-40. [PMID: 25667334 PMCID: PMC4785170 DOI: 10.3354/dao02830] [Citation(s) in RCA: 143] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The 69 kb plasmid pVPA3-1 was identified in Vibrio parahaemolyticus strain 13‑028/A3 that can cause acute hepatopancreatic necrosis disease (AHPND). This disease is responsible for mass mortalities in farmed penaeid shrimp and is referred to as early mortality syndrome (EMS). The plasmid has a GC content of 45.9% with a copy number of 37 per bacterial cell as determined by comparative quantitative PCR analyses. It consists of 92 open reading frames that encode mobilization proteins, replication enzymes, transposases, virulence-associated proteins, and proteins similar to Photorhabdus insect-related (Pir) toxins. In V. parahaemolyticus, these Pir toxin-like proteins are encoded by 2 genes (pirA- and pirB-like) located within a 3.5 kb fragment flanked with inverted repeats of a transposase-coding sequence (1 kb). The GC content of these 2 genes is only 38.2%, substantially lower than that of the rest of the plasmid, which suggests that these genes were recently acquired. Based on a proteomic analysis, the pirA-like (336 bp) and pirB-like (1317 bp) genes encode for 13 and 50 kDa proteins, respectively. In laboratory cultures of V. parahaemolyticus 13-028/A3, both proteins were secreted into the culture medium. We developed a duplex PCR diagnostic method, with a detection limit of 10(5) CFU ml(-1) and targeting pirA- and pirB-like genes in this strain of V. parahaemolyticus. This PCR protocol can reliably detect AHPND-causing strains of V. parahaemolyticus and does not cross react with non-pathogenic strains or with other species of Vibrio isolated from shrimp ponds.
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Affiliation(s)
- Jee Eun Han
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ 85721, USA
| | - Kathy F. J. Tang
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ 85721, USA
- Corresponding author:
| | - Loc H. Tran
- Department of Aquaculture Pathology, College of Fisheries, Nong Lam University, Ho Chi Minh City, Vietnam
| | - Donald V. Lightner
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ 85721, USA
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15
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Identification and characterization of the insecticidal toxin "makes caterpillars floppy" in Photorhabdus temperata M1021 using a cosmid library. Toxins (Basel) 2014; 6:2024-40. [PMID: 25014195 PMCID: PMC4113739 DOI: 10.3390/toxins6072024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Revised: 06/20/2014] [Accepted: 07/02/2014] [Indexed: 01/24/2023] Open
Abstract
Photorhabdus temperata is an entomopathogenic enterobacterium; it is a nematode symbiont that possesses pathogenicity islands involved in insect virulence. Herein, we constructed a P. temperata M1021 cosmid library in Escherichia coli XL1-Blue MRF` and obtained 7.14 × 105 clones. However, only 1020 physiologically active clones were screened for insect virulence factors by injection of each E. coli cosmid clone into Galleria mellonella and Tenebrio molitor larvae. A single cosmid clone, PtC1015, was consequently selected due to its characteristic virulent properties, e.g., loss of body turgor followed by death of larvae when the clone was injected into the hemocoel. The sequence alignment against the available sequences in Swiss-Prot and NCBI databases, confirmed the presence of the mcf gene homolog in the genome of P. temperata M1021 showing 85% homology and 98% query coverage with the P. luminescens counterpart. Furthermore, a 2932 amino acid long Mcf protein revealed limited similarity with three protein domains. The N-terminus of the Mcf encompassed consensus sequence for a BH3 domain, the central region revealed similarity to toxin B, and the C-terminus of Mcf revealed similarity to the bacterial export domain of ApxIVA, an RTX-like toxin. In short, the Mcf toxin is likely to play a role in the elimination of insect pests, making it a promising model for use in the agricultural field.
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16
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Genomic versatility and functional variation between two dominant heterotrophic symbionts of deep-sea Osedax worms. ISME JOURNAL 2013; 8:908-24. [PMID: 24225886 DOI: 10.1038/ismej.2013.201] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Revised: 09/21/2013] [Accepted: 10/08/2013] [Indexed: 12/18/2022]
Abstract
An unusual symbiosis, first observed at ~3000 m depth in the Monterey Submarine Canyon, involves gutless marine polychaetes of the genus Osedax and intracellular endosymbionts belonging to the order Oceanospirillales. Ecologically, these worms and their microbial symbionts have a substantial role in the cycling of carbon from deep-sea whale fall carcasses. Microheterogeneity exists among the Osedax symbionts examined so far, and in the present study the genomes of the two dominant symbionts, Rs1 and Rs2, were sequenced. The genomes revealed heterotrophic versatility in carbon, phosphate and iron uptake, strategies for intracellular survival, evidence for an independent existence, and numerous potential virulence capabilities. The presence of specific permeases and peptidases (of glycine, proline and hydroxyproline), and numerous peptide transporters, suggests the use of degraded proteins, likely originating from collagenous bone matter, by the Osedax symbionts. (13)C tracer experiments confirmed the assimilation of glycine/proline, as well as monosaccharides, by Osedax. The Rs1 and Rs2 symbionts are genomically distinct in carbon and sulfur metabolism, respiration, and cell wall composition, among others. Differences between Rs1 and Rs2 and phylogenetic analysis of chemotaxis-related genes within individuals of symbiont Rs1 revealed the influence of the relative age of the whale fall environment and support possible local niche adaptation of 'free-living' lifestages. Future genomic examinations of other horizontally-propogated intracellular symbionts will likely enhance our understanding of the contribution of intraspecific symbiont diversity to the ecological diversification of the intact association, as well as the maintenance of host diversity.
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Baxt LA, Goldberg MB. Anaerobic environment of the intestine primes pathogenic Shigella for infection. Expert Rev Anti Infect Ther 2011; 8:1225-9. [PMID: 21073287 DOI: 10.1586/eri.10.123] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Marteyn et al. have investigated the role of oxygen and the regulator FNR in infection by the intracellular enteric pathogen Shigella flexneri. FNR is active under anaerobic conditions like those present in the lumen of the distal intestine. FNR causes elongation of a secretion apparatus required for bacterial entry into cells and represses secretion of proteins that trigger entry. Higher oxygen levels present at the intestinal cell surface are sufficient to inactivate FNR, thereby derepressing secretion. Thus, bacteria are 'primed' in the anaerobic environment of the lumen, and entry is triggered by the aerobic conditions at the intestinal cell surface. FNR is conserved among many enteric pathogens, suggesting that regulation of virulence in response to oxygen may be widely conserved.
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Affiliation(s)
- Leigh A Baxt
- Division of Infectious Diseases, Department of Medicine, Massachusetts General Hospital and Department of Microbiology and Molecular Genetics, Harvard Medical School, Cambridge, MA 02139, USA
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18
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Rodou A, Ankrah DO, Stathopoulos C. Toxins and secretion systems of Photorhabdus luminescens. Toxins (Basel) 2010; 2:1250-64. [PMID: 22069636 PMCID: PMC3153242 DOI: 10.3390/toxins2061250] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 05/22/2010] [Accepted: 05/28/2010] [Indexed: 12/31/2022] Open
Abstract
Photorhabdus luminescens is a nematode-symbiotic, gram negative, bioluminescent bacterium, belonging to the family of Enterobacteriaceae. Recent studies show the importance of this bacterium as an alternative source of insecticides, as well as an emerging human pathogen. Various toxins have been identified and characterized in this bacterium. These toxins are classified into four major groups: the toxin complexes (Tcs), the Photorhabdus insect related (Pir) proteins, the “makes caterpillars floppy” (Mcf) toxins and the Photorhabdus virulence cassettes (PVC); the mechanisms however of toxin secretion are not fully elucidated. Using bioinformatics analysis and comparison against the components of known secretion systems, multiple copies of components of all known secretion systems, except the ones composing a type IV secretion system, were identified throughout the entire genome of the bacterium. This indicates that Photorhabdus luminescens has all the necessary means for the secretion of virulence factors, thus it is capable of establishing a microbial infection.
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Affiliation(s)
- Athina Rodou
- Department of Biological Sciences, California State Polytechnic University, Pomona, CA 91768, USA.
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19
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Identification and characterization of hemolysin-like proteins similar to RTX toxin in Pasteurella pneumotropica. J Bacteriol 2009; 191:3698-705. [PMID: 19363112 DOI: 10.1128/jb.01527-08] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pasteurella pneumotropica is an opportunistic pathogen that causes lethal pneumonia in immunodeficient rodents. The virulence factors of this bacterium remain unknown. In this study, we identified the genes encoding two RTX toxins, designated as pnxI and pnxII, from the genomic DNA of P. pneumotropica ATCC 35149 and characterized with respect to hemolysis. The pnxI operon was organized according to the manner in which the genes encoded the structural RTX toxin (pnxIA), the type I secretion systems (pnxIB and pnxID), and the unknown orf. The pnxII gene was involved only with the pnxIIA that coded for a structural RTX toxin. Both the structural RTX toxins of deduced PnxIA and PnxIIA were involved in seven of the RTX repeat and repeat-like sequences. By quantitative PCR analysis of the structural RTX toxin-encoding genes in P. pneumotropica ATCC 35149, the gene expression of pnxIA was found to have increased from the early log phase, while that of pnxIIA increased from the late log to the early stationary phase. As expressed in Escherichia coli, both the recombinant proteins of PnxIA and PnxIIA showed weak hemolytic activity in both sheep and murine erythrocytes. On the basis of the results of the Southern blotting analysis, the pnxIA gene was detected in 82% of the isolates, while the pnxIIA gene was detected in 39%. These results indicate that the products of both pnxIA and pnxIIA were putative associations of virulence factors in the rodent pathogen P. pneumotropica.
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The emerging human pathogen Photorhabdus asymbiotica is a facultative intracellular bacterium and induces apoptosis of macrophage-like cells. Infect Immun 2008; 77:1022-30. [PMID: 19075024 DOI: 10.1128/iai.01064-08] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Photorhabdus species are gram-negative entomopathogenic bacteria of the family Enterobacteriaceae. Among the different members of the genus, one species, Photorhabdus asymbiotica, is a pathogen of both insects and humans. The pathogenicity mechanisms of this bacterium are unknown. Here we show that P. asymbiotica is a facultative intracellular pathogen that is able to replicate inside human macrophage-like cells. Furthermore, P. asymbiotica was shown for the first time in an intracellular location after insect infection. We also demonstrated that among Australian and American clinical isolates, only the Australian strains were able to invade nonphagocytic human cells. In cell culture infection experiments, Australian clinical isolates as well as cell-free bacterial culture supernatant induced strong apoptosis of a macrophage cell line at 6 h postinfection. American isolates also induced cellular death, but much later than that induced by Australian ones. Mammalian cultured cells analyzed for key features of apoptosis displayed apoptotic nuclear morphology, activation of the initiator caspases 8 and 9 and the executioner caspases 3 and 7, and poly(ADP-ribose) polymerase proteolysis, suggesting activation of both the intrinsic and extrinsic apoptotic pathways.
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Affiliation(s)
- David J Clarke
- Department of Microbiology, University College Cork, Cork, Ireland.
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22
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Abstract
Over the years it has been important for humans to control the populations of harmful insects and insecticides have been used for this purpose in agricultural and horticultural sectors. Synthetic insecticides, owing to their various side effects, have been widely replaced by biological insecticides. In this review we attempt to describe three bacterial species that are known to produce insecticidal toxins of tremendous biotechnological, agricultural, and economic importance. Bacillus thuringiensis (BT) accounts for 90% of the bioinsecticide market and it produces insecticidal toxins referred to as delta endotoxins. The other two bacteria belong to the genera Photorhabdus and Xenorhabdus, which are symbiotically associated with entomopathogenic nematodes of the families Heterorhabditidae and Steinernematidae respectively. Whereas, Xenorhabdus and Photorhabdus exist in a mutualistic association with the entomopathogenic nematodes, BT act alone. BT formulations are widely used in the field against insects; however, over the years there has been a gradual development of insect resistance against BT toxins. No resistance against Xenorhabdus or Photorhabdus has been reported to date. More recently BT transgenic crops have been prepared; however, there are growing concerns about the safety of these genetically modified crops. Nematodal formulations are also used in the field to curb harmful insect populations. Resistance development to entomopathogenic nematodes is unlikely due to the physical macroscopic nature of infection. Xenorhabdus and Photorhabdus transgenes have not yet been prepared; but are predicted to be available in the near future. In this review we start with an overview of the synthetic insecticides and then discuss Bacillus thuringiensis, Xenorhabdus nematophilus, and Photorhabdus luminescens in greater detail.
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Waterfield NR, Sanchez-Contreras M, Eleftherianos I, Dowling A, Yang G, Wilkinson P, Parkhill J, Thomson N, Reynolds SE, Bode HB, Dorus S, Ffrench-Constant RH. Rapid Virulence Annotation (RVA): identification of virulence factors using a bacterial genome library and multiple invertebrate hosts. Proc Natl Acad Sci U S A 2008; 105:15967-72. [PMID: 18838673 PMCID: PMC2572985 DOI: 10.1073/pnas.0711114105] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2007] [Indexed: 11/18/2022] Open
Abstract
Current sequence databases now contain numerous whole genome sequences of pathogenic bacteria. However, many of the predicted genes lack any functional annotation. We describe an assumption-free approach, Rapid Virulence Annotation (RVA), for the high-throughput parallel screening of genomic libraries against four different taxa: insects, nematodes, amoeba, and mammalian macrophages. These hosts represent different aspects of both the vertebrate and invertebrate immune system. Here, we apply RVA to the emerging human pathogen Photorhabdus asymbiotica using "gain of toxicity" assays of recombinant Escherichia coli clones. We describe a wealth of potential virulence loci and attribute biological function to several putative genomic islands, which may then be further characterized using conventional molecular techniques. The application of RVA to other pathogen genomes promises to ascribe biological function to otherwise uncharacterized virulence genes.
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Affiliation(s)
- Nicholas R Waterfield
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom.
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24
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Aslam SN, Newman MA, Erbs G, Morrissey KL, Chinchilla D, Boller T, Jensen TT, De Castro C, Ierano T, Molinaro A, Jackson RW, Knight MR, Cooper RM. Bacterial polysaccharides suppress induced innate immunity by calcium chelation. Curr Biol 2008; 18:1078-83. [PMID: 18639458 DOI: 10.1016/j.cub.2008.06.061] [Citation(s) in RCA: 151] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Revised: 06/18/2008] [Accepted: 06/19/2008] [Indexed: 10/21/2022]
Abstract
Bacterial pathogens and symbionts must suppress or negate host innate immunity. However, pathogens release conserved oligomeric and polymeric molecules or MAMPs (Microbial Associated Molecular Patterns), which elicit host defenses [1], [2] and [3]. Extracellular polysaccharides (EPSs) are key virulence factors in plant and animal pathogenesis, but their precise function in establishing basic compatibility remains unclear [4], [5], [6] and [7]. Here, we show that EPSs suppress MAMP-induced signaling in plants through their polyanionic nature [4] and consequent ability to chelate divalent calcium ions [8]. In plants, Ca2+ ion influx to the cytosol from the apoplast (where bacteria multiply [4], [5] and [9]) is a prerequisite for activation of myriad defenses by MAMPs [10]. We show that EPSs from diverse plant and animal pathogens and symbionts bind calcium. EPS-defective mutants or pure MAMPs, such as the flagellin peptide flg22, elicit calcium influx, expression of host defense genes, and downstream resistance. Furthermore, EPSs, produced by wild-type strains or purified, suppress induced responses but do not block flg22-receptor binding in Arabidopsis cells. EPS production was confirmed in planta, and the amounts in bacterial biofilms greatly exceed those required for binding of apoplastic calcium. These data reveal a novel, fundamental role for bacterial EPS in disease establishment, encouraging novel control strategies.
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Affiliation(s)
- Shazia N Aslam
- Department of Biology & Biochemistry, University of Bath, Bath BA2 7AY, UK
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25
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Gaudriault S, Pages S, Lanois A, Laroui C, Teyssier C, Jumas-Bilak E, Givaudan A. Plastic architecture of bacterial genome revealed by comparative genomics of Photorhabdus variants. Genome Biol 2008; 9:R117. [PMID: 18647395 PMCID: PMC2530875 DOI: 10.1186/gb-2008-9-7-r117] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Revised: 06/12/2008] [Accepted: 07/22/2008] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND The phenotypic consequences of large genomic architecture modifications within a clonal bacterial population are rarely evaluated because of the difficulties associated with using molecular approaches in a mixed population. Bacterial variants frequently arise among Photorhabdus luminescens, a nematode-symbiotic and insect-pathogenic bacterium. We therefore studied genome plasticity within Photorhabdus variants. RESULTS We used a combination of macrorestriction and DNA microarray experiments to perform a comparative genomic study of different P. luminescens TT01 variants. Prolonged culturing of TT01 strain and a genomic variant, collected from the laboratory-maintained symbiotic nematode, generated bacterial lineages composed of primary and secondary phenotypic variants and colonial variants. The primary phenotypic variants exhibit several characteristics that are absent from the secondary forms. We identify substantial plasticity of the genome architecture of some variants, mediated mainly by deletions in the 'flexible' gene pool of the TT01 reference genome and also by genomic amplification. We show that the primary or secondary phenotypic variant status is independent from global genomic architecture and that the bacterial lineages are genomic lineages. We focused on two unusual genomic changes: a deletion at a new recombination hotspot composed of long approximate repeats; and a 275 kilobase single block duplication belonging to a new class of genomic duplications. CONCLUSION Our findings demonstrate that major genomic variations occur in Photorhabdus clonal populations. The phenotypic consequences of these genomic changes are cryptic. This study provides insight into the field of bacterial genome architecture and further elucidates the role played by clonal genomic variation in bacterial genome evolution.
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Affiliation(s)
- Sophie Gaudriault
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
- Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
| | - Sylvie Pages
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
- Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
| | - Anne Lanois
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
- Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
| | - Christine Laroui
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
- Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
| | - Corinne Teyssier
- Université Montpellier 1, EA 3755, Laboratoire de Bactériologie-Virologie, 15, Avenue Charles Flahault, BP 14491, F-34060 Montpellier Cedex 5, France
| | - Estelle Jumas-Bilak
- Université Montpellier 1, EA 3755, Laboratoire de Bactériologie-Virologie, 15, Avenue Charles Flahault, BP 14491, F-34060 Montpellier Cedex 5, France
| | - Alain Givaudan
- INRA, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
- Université Montpellier 2, UMR 1133, Laboratoire EMIP, Place Eugène Bataillon, F-34095 Montpellier, France
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Comparative analysis of the Photorhabdus luminescens and the Yersinia enterocolitica genomes: uncovering candidate genes involved in insect pathogenicity. BMC Genomics 2008; 9:40. [PMID: 18221513 PMCID: PMC2266911 DOI: 10.1186/1471-2164-9-40] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Accepted: 01/25/2008] [Indexed: 11/24/2022] Open
Abstract
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.
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Abstract
Genomes from all of the crucial bacterial pathogens of humans, plants and animals have now been sequenced, as have genomes from many of the important commensal, symbiotic and environmental microorganisms. Analysis of these sequences has revealed the forces that shape pathogen evolution and has brought to light unexpected aspects of pathogen biology. The finding that horizontal gene transfer and genome decay have key roles in the evolution of bacterial pathogens was particularly surprising. It has also become evident that even the definitions for 'pathogen' and 'virulence factor' need to be re-evaluated.
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28
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Cloning and expression analysis of a predicted toxin gene fromPhotorhabdus sp. HB78. ANN MICROBIOL 2007. [DOI: 10.1007/bf03175066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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29
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Donadio S, Monciardini P, Sosio M. Polyketide synthases and nonribosomal peptide synthetases: the emerging view from bacterial genomics. Nat Prod Rep 2007; 24:1073-109. [PMID: 17898898 DOI: 10.1039/b514050c] [Citation(s) in RCA: 213] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A total of 223 complete bacterial genomes are analyzed, with 281 citations, for the presence of genes encoding modular polyketide synthases (PKS) and nonribosomal peptide synthetases (NRPS). We report on the distribution of these systems in different bacterial taxa and, whenever known, the metabolites they synthesize. We also highlight, in the different bacterial lineages, the PKS and NRPS genes and, whenever known, the corresponding products.
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30
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Tounsi S, Blight M, Jaoua S, de Lima Pimenta A. From insects to human hosts: Identification of major genomic differences between entomopathogenic strains of Photorhabdus and the emerging human pathogen Photorhabdus asymbiotica. Int J Med Microbiol 2006; 296:521-30. [PMID: 17029962 DOI: 10.1016/j.ijmm.2006.06.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Revised: 03/10/2006] [Accepted: 06/08/2006] [Indexed: 11/19/2022] Open
Abstract
Pathogenic bacteria of the genus Photorhabdus are naturally found in symbiotic association with soil entomopathogenic nematodes, and are of increasing economic interest in view of their potential for the development of novel biopesticides. This bipartite natural system is currently used for the biological control of crop pests in several countries. However, an increasing number of Photorhabdus strains have recently been isolated from human clinical specimens in both the United States and Australia, associated with locally invasive soft tissue infections and disseminated bacteraemia. In view of their growing use in biological control, which increases the potential rate of exposure of humans to these pathogens, we decided to undertake a comparative study of the genomic differences between insect and human pathogenic strains of Photorhabdus, in an attempt to understand the genetic mechanisms involved in the apparent change of host specificity, presumably responsible for their recently acquired capacity to infect humans. The data presented here demonstrates that major genomic differences exist between strains of Photorhabdus exhibiting virulence against insects or humans. Several individual genes, coding for virulence factors, were isolated and shown to be specific to the Photorhabdus asymbiotica human pathogens. One of these genes, sopB, encoding a host cell invasion factor translocated via the type III secretion system, has been cloned and the comparison of its genomic context in different pathogens strongly indicates that horizontal gene transfer is implicated in the acquisition of these virulence factors specific to the human pathogens. The precise role of this and other virulence factors identified here in the pathogenicity of P. asymbiotica towards humans is currently under investigation.
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Affiliation(s)
- Slim Tounsi
- Laboratoire des Biopesticides, Centre de Biotechnologie de Sfax, 3038 Sfax, Tunisie
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31
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Waterfield N, Kamita SG, Hammock BD, ffrench-Constant R. The Photorhabdus Pir toxins are similar to a developmentally regulated insect protein but show no juvenile hormone esterase activity. FEMS Microbiol Lett 2005; 245:47-52. [PMID: 15796978 DOI: 10.1016/j.femsle.2005.02.018] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Revised: 01/18/2005] [Accepted: 02/14/2005] [Indexed: 10/25/2022] Open
Abstract
The genome of the insect pathogen Photorhabdus luminescens strain TT01 contains numerous genes predicting toxins and proteases. Within the P. luminescens TT01 genome, the products of two loci, plu 4093-plu 4092 and plu 4437-plu 4436, show oral insecticidal activity against both moth and mosquito larvae. The proteins encoded by these loci, here termed 'Photorhabdus insect related' (Pir) proteins A and B, show similarity both to delta-endotoxins from Bacillus thuringiensis (Bts) and a developmentally regulated protein from a beetle, Leptinotarsa decemlineata. The beetle protein has been inferred to possess juvenile hormone esterase (JHE) activity due to its developmentally regulated pattern of expression and the Photorhabdus proteins PirA and PirB have been proposed to be mimics of insect JHEs that can disrupt insect metamorphosis by metabolizing the insect growth regulator juvenile hormone (JH) [Nat. Biotechnol. 21 (2003) 1307-1313]. Here we confirm that, when injected together, PirA and PirB from two different Photorhabdus strains have insecticidal activity against caterpillars of the moth Galleria mellonella but show no oral activity against a second moth species Manduca sexta. Direct measurement of JHE activity, however, shows that the Pir proteins are not able to metabolise JH. These data show that the Pir proteins have no JHE activity, as suggested, but leave the mode of action of these interesting proteins uncertain.
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Affiliation(s)
- Nicholas Waterfield
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
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Pallen MJ, Beatson SA, Bailey CM. Bioinformatics, genomics and evolution of non-flagellar type-III secretion systems: a Darwinian perpective. FEMS Microbiol Rev 2005; 29:201-29. [PMID: 15808742 DOI: 10.1016/j.femsre.2005.01.001] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2004] [Revised: 12/22/2004] [Accepted: 01/06/2005] [Indexed: 12/17/2022] Open
Abstract
We review the biology of non-flagellar type-III secretion systems from a Darwinian perspective, highlighting the themes of evolution, conservation, variation and decay. The presence of these systems in environmental organisms such as Myxococcus, Desulfovibrio and Verrucomicrobium hints at roles beyond virulence. We review newly discovered sequence homologies (e.g., YopN/TyeA and SepL). We discuss synapomorphies that might be useful in formulating a taxonomy of type-III secretion. The problem of information overload is likely to be ameliorated by launch of a web site devoted to the comparative biology of type-III secretion ().
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Affiliation(s)
- Mark J Pallen
- Bacterial Pathogenesis and Genomics Unit, Division of Immunity and Infection, Medical School, University of Birmingham, Birmingham, West Midlands B15 2TT, UK.
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Bennett HPJ, Clarke DJ. The pbgPE operon in Photorhabdus luminescens is required for pathogenicity and symbiosis. J Bacteriol 2005; 187:77-84. [PMID: 15601690 PMCID: PMC538804 DOI: 10.1128/jb.187.1.77-84.2005] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Photorhabdus is a genus of gram-negative Enterobacteriaceae that is pathogenic to insect larvae while also maintaining a mutualistic relationship with nematodes from the family Heterorhabditis, where the bacteria occupy the gut of the infective juvenile (IJ) stage of the nematode. In this study we describe the identification and characterization of a mutation in the pbgE1 gene of Photorhabdus luminescens TT01, predicted to be the fifth gene in the pbgPE operon. We show that this mutant, BMM305, is strongly attenuated in virulence against larvae of the greater wax moth, Galleria mellonella, and we report that BMM305 is more sensitive to the cationic antimicrobial peptide, polymyxin B, and growth in mildly acidic pH than the parental strain of P. luminescens. Moreover, we also show that the lipopolysaccharide (LPS) present on the surface of BMM305 does not appear to contain any O antigen. Complementation studies reveal that the increased sensitivity to polymyxin B and growth in mildly acidic pH can be rescued by the in trans expression of pbgE1, while the defects in O-antigen assembly and pathogenicity require the in trans expression of pbgE1 and the downstream genes pbgE2 and pbgE3. Finally, we show that BMM305 is defective in symbiosis as this mutant is unable to colonize the gut of the IJ stage of the nematode. Therefore, we conclude that the pbgPE operon is required for both pathogenicity and symbiosis in P. luminescens.
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Affiliation(s)
- H P J Bennett
- Department of Biology and Biochemistry, Molecular Microbiology Laboratory, University of Bath, Bath BA2 7AY, United Kingdom
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34
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Abstract
The type III secretion system (TTSS) of gram-negative bacteria is responsible for delivering bacterial proteins, termed effectors, from the bacterial cytosol directly into the interior of host cells. The TTSS is expressed predominantly by pathogenic bacteria and is usually used to introduce deleterious effectors into host cells. While biochemical activities of effectors vary widely, the TTSS apparatus used to deliver these effectors is conserved and shows functional complementarity for secretion and translocation. This review focuses on proteins that constitute the TTSS apparatus and on mechanisms that guide effectors to the TTSS apparatus for transport. The TTSS apparatus includes predicted integral inner membrane proteins that are conserved widely across TTSSs and in the basal body of the bacterial flagellum. It also includes proteins that are specific to the TTSS and contribute to ring-like structures in the inner membrane and includes secretin family members that form ring-like structures in the outer membrane. Most prominently situated on these coaxial, membrane-embedded rings is a needle-like or pilus-like structure that is implicated as a conduit for effector translocation into host cells. A short region of mRNA sequence or protein sequence in effectors acts as a signal sequence, directing proteins for transport through the TTSS. Additionally, a number of effectors require the action of specific TTSS chaperones for efficient and physiologically meaningful translocation into host cells. Numerous models explaining how effectors are transported into host cells have been proposed, but understanding of this process is incomplete and this topic remains an active area of inquiry.
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Affiliation(s)
- Partho Ghosh
- Department of Chemistry & Biochemistry, University of California-San Diego, La Jolla, CA 92093-0314, USA.
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35
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Marokházi J, Lengyel K, Pekár S, Felföldi G, Patthy A, Gráf L, Fodor A, Venekei I. Comparison of proteolytic activities produced by entomopathogenic Photorhabdus bacteria: strain- and phase-dependent heterogeneity in composition and activity of four enzymes. Appl Environ Microbiol 2004; 70:7311-20. [PMID: 15574931 PMCID: PMC535150 DOI: 10.1128/aem.70.12.7311-7320.2004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2004] [Accepted: 08/01/2004] [Indexed: 11/20/2022] Open
Abstract
Twenty strains (including eight phase variant pairs) of nematode-symbiotic and insect-pathogenic Photorhabdus bacteria were examined for the production of proteolytic enzymes by using a combination of several methods, including gelatin liquefaction, zymography coupled to native and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and activity measurement with two chromogen substrate types. Four protease activities (approximately 74, approximately 55, approximately 54, and approximately 37 kDa) could be separated. The N-terminal sequences of three of the proteases were determined, and a comparison with sequences in databases allowed identification of these proteases as HEXXH metallopeptidases. Thus, the 74-kDa protease (described formerly as Php-B [J. Marokhazi, G. Koczan, F. Hudecz, L. Graf, A. Fodor, and I. Venekei, Biochem. J. 379:633-640, 2004) is an ortholog of OpdA, a member the thimet oligopeptidase family, and the 55-kDa protease is an ortholog of PrtA, a HEXXH+H peptidase in clan MB (metzincins), while the 37-kDa protease (Php-C) belongs to the HEXXH+E peptidases in clan MA. The 54-kDa protease (Php-D) is a nonmetalloenzyme. PrtA and Php-C were zymographically detected, and they occurred in several smaller forms as well. OpdA could not be detected by zymography. PrtA, Php-C, and Php-D were secreted proteases; OpdA, in contrast, was an intracellular enzyme. OpdA activity was found in every strain tested, while Php-D was detected only in the Brecon/1 strain. There was significant strain variation in the secretion of PrtA and Php-C activities, but reduced activity or a lack of activity was not specific to secondary-phase variants. The presence of PrtA, OpdA, and Php-C activities could be detected in the hemolymph of Galleria melonella larvae 20 to 40 h postinfection. These proteases appear not to be directly involved in the pathogenicity of Photorhabdus, since strains or phase variants lacking any of these proteases do not show reduced virulence when they are injected into G. melonella larvae.
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Affiliation(s)
- Judit Marokházi
- Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary
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36
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Abstract
The type III secretion system (TTSS) of gram-negative bacteria is responsible for delivering bacterial proteins, termed effectors, from the bacterial cytosol directly into the interior of host cells. The TTSS is expressed predominantly by pathogenic bacteria and is usually used to introduce deleterious effectors into host cells. While biochemical activities of effectors vary widely, the TTSS apparatus used to deliver these effectors is conserved and shows functional complementarity for secretion and translocation. This review focuses on proteins that constitute the TTSS apparatus and on mechanisms that guide effectors to the TTSS apparatus for transport. The TTSS apparatus includes predicted integral inner membrane proteins that are conserved widely across TTSSs and in the basal body of the bacterial flagellum. It also includes proteins that are specific to the TTSS and contribute to ring-like structures in the inner membrane and includes secretin family members that form ring-like structures in the outer membrane. Most prominently situated on these coaxial, membrane-embedded rings is a needle-like or pilus-like structure that is implicated as a conduit for effector translocation into host cells. A short region of mRNA sequence or protein sequence in effectors acts as a signal sequence, directing proteins for transport through the TTSS. Additionally, a number of effectors require the action of specific TTSS chaperones for efficient and physiologically meaningful translocation into host cells. Numerous models explaining how effectors are transported into host cells have been proposed, but understanding of this process is incomplete and this topic remains an active area of inquiry.
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Affiliation(s)
- Partho Ghosh
- Department of Chemistry & Biochemistry, University of California-San Diego, La Jolla, CA 92093-0314, USA.
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37
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Waterfield NR, Wren BW, Ffrench-Constant RH. Invertebrates as a source of emerging human pathogens. Nat Rev Microbiol 2004; 2:833-41. [PMID: 15378047 DOI: 10.1038/nrmicro1008] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Despite their importance, little is known about the origins of many emerging human pathogens. However, given the age and current predominance of invertebrates, it is likely that bacteria-invertebrate interactions are not only a present source of human pathogens but have also shaped their evolution. Pathogens of invertebrate and unicellular organisms represent an extensive reservoir of bacterial strains equipped with virulence factors that evolved to overcome the innate immune responses of their hosts. This reservoir might represent a source of new human pathogenic strains and might also foster the spread of novel virulence factors into existing human commensal or pathogenic bacteria. This article examines the available evidence for this concept by examining pairs of closely related bacteria, one of which is benign, but insect associated, and one of which is a human pathogen.
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Affiliation(s)
- Nicholas R Waterfield
- Centre for Molecular Microbiology, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
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Gerrard J, Waterfield N, Vohra R, ffrench-Constant R. Human infection with Photorhabdus asymbiotica: an emerging bacterial pathogen. Microbes Infect 2004; 6:229-37. [PMID: 15049334 DOI: 10.1016/j.micinf.2003.10.018] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The three currently recognised Photorhabdus species are bioluminescent bacteria that are pathogenic to insects. P. luminescens and P. temperata form a symbiotic relationship with nematodes that infect insects. P. asymbiotica, on the other hand, has only been isolated from human clinical specimens from the USA and Australia. The bacterium has been associated with locally invasive soft tissue and disseminated bacteraemic infections. An invertebrate vector for P. asymbiotica has not yet been identified.
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Affiliation(s)
- John Gerrard
- Department of Medicine, Gold Coast Hospital, Southport, Australia.
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39
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Ren CP, Chaudhuri RR, Fivian A, Bailey CM, Antonio M, Barnes WM, Pallen MJ. The ETT2 gene cluster, encoding a second type III secretion system from Escherichia coli, is present in the majority of strains but has undergone widespread mutational attrition. J Bacteriol 2004; 186:3547-60. [PMID: 15150243 PMCID: PMC415751 DOI: 10.1128/jb.186.11.3547-3560.2004] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2003] [Accepted: 02/12/2004] [Indexed: 11/20/2022] Open
Abstract
ETT2 is a second cryptic type III secretion system in Escherichia coli which was first discovered through the analysis of genome sequences of enterohemorrhagic E. coli O157:H7. Comparative analyses of Escherichia and Shigella genome sequences revealed that the ETT2 gene cluster is larger than was previously thought, encompassing homologues of genes from the Spi-1, Spi-2, and Spi-3 Salmonella pathogenicity islands. ETT2-associated genes, including regulators and chaperones, were found at the same chromosomal location in the majority of genome-sequenced strains, including the laboratory strain K-12. Using a PCR-based approach, we constructed a complete tiling path through the ETT2 gene cluster for 79 strains, including the well-characterized E. coli reference collection supplemented with additional pathotypes. The ETT2 gene cluster was found to be present in whole or in part in the majority of E. coli strains, whether pathogenic or commensal, with patterns of distribution and deletion mirroring the known phylogenetic structure of the species. In almost all strains, including enterohemorrhagic E. coli O157:H7, ETT2 has been subjected to varying degrees of mutational attrition that render it unable to encode a functioning secretion system. A second type III secretion system-associated locus that likely encodes the ETT2 translocation apparatus was found in some E. coli strains. Intact versions of both ETT2-related clusters are apparently present in enteroaggregative E. coli strain O42.
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Affiliation(s)
- Chuan-Peng Ren
- Bacterial Pathogenesis and Genomics Unit, Division of Immunity and Infection, Medical School, University of Birmingham, Birmingham B15 2TT, United Kingdom
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40
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Dobrindt U, Hochhut B, Hentschel U, Hacker J. Genomic islands in pathogenic and environmental microorganisms. Nat Rev Microbiol 2004; 2:414-24. [PMID: 15100694 DOI: 10.1038/nrmicro884] [Citation(s) in RCA: 755] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Ulrich Dobrindt
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, Röntgenring 11, 97070 Wuerzburg, Germany
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41
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Brown SE, Cao AT, Hines ER, Akhurst RJ, East PD. A Novel Secreted Protein Toxin from the Insect Pathogenic Bacterium Xenorhabdus nematophila. J Biol Chem 2004; 279:14595-601. [PMID: 14707137 DOI: 10.1074/jbc.m309859200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The bacterium Xenorhabdus nematophila is an insect pathogen that produces several proteins that enable it to kill insects. Screening of a cosmid library constructed from X. nematophila strain A24 identified a gene that encoded a novel protein that was toxic to insects. The 42-kDa protein encoded by the toxin gene was expressed and purified from a recombinant system, and was shown to kill the larvae of insects such as Galleria mellonella and Helicoverpa armigera when injected at doses of around 30-40 ng/g larvae. Sequencing and bioinformatic analysis suggested that the toxin was a novel protein, and that it was likely to be part of a genomic island involved in pathogenicity. When the native bacteria were grown under laboratory conditions, a soluble form of the 42-kDa toxin was secreted only by bacteria in the phase II state. Preliminary histological analysis of larvae injected with recombinant protein suggested that the toxin primarily acted on the midgut of the insect. Finally, some of the common strategies used by the bacterial pathogens of insects, animals, and plants are discussed.
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Affiliation(s)
- Susan E Brown
- CSIRO Entomology, GPO Box 1700, Acton, Australian Capital Territory 2601, Australia.
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42
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Abstract
Secretion of proteins into the extracellular environment is important to almost all bacteria, and in particular mediates interactions between pathogenic or symbiotic bacteria with their eukaryotic hosts. The accumulation of bacterial genome sequence data in the past few years has provided great insights into the distribution and function of these secretion systems. Three systems are responsible for secretion of proteins across the bacterial cytoplasmic membrane: Sec, SRP and Tat. Many novel examples of systems for transport across the Gram-negative bacterial cell envelope have been discovered through genome sequencing and surveys, including many novel type III secretion systems and autotransporters. Similarly, genomic data mining has revealed many new potential secretion substrates and identified unsuspected domains in secretion-associated proteins. Interestingly, genomic analyses have also hinted at the existence of a dedicated protein secretion system in Gram-positive bacteria, targeting members of the WXG100/ESAT-6 family of proteins, and have revealed an unexpectedly wide distribution of sortase-driven protein-targeting systems.
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Affiliation(s)
- Mark J Pallen
- Bacterial Pathogenesis and Genomics Unit, Division of Immunity and Infection, The Medical School, University of Birmingham, Vincent Drive, B15 2TT, Birmingham, UK.
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Duchaud E, Rusniok C, Frangeul L, Buchrieser C, Givaudan A, Taourit S, Bocs S, Boursaux-Eude C, Chandler M, Charles JF, Dassa E, Derose R, Derzelle S, Freyssinet G, Gaudriault S, Médigue C, Lanois A, Powell K, Siguier P, Vincent R, Wingate V, Zouine M, Glaser P, Boemare N, Danchin A, Kunst F. The genome sequence of the entomopathogenic bacterium Photorhabdus luminescens. Nat Biotechnol 2003; 21:1307-13. [PMID: 14528314 DOI: 10.1038/nbt886] [Citation(s) in RCA: 410] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2003] [Accepted: 08/18/2003] [Indexed: 11/09/2022]
Abstract
Photorhabdus luminescens is a symbiont of nematodes and a broad-spectrum insect pathogen. The complete genome sequence of strain TT01 is 5,688,987 base pairs (bp) long and contains 4,839 predicted protein-coding genes. Strikingly, it encodes a large number of adhesins, toxins, hemolysins, proteases and lipases, and contains a wide array of antibiotic synthesizing genes. These proteins are likely to play a role in the elimination of competitors, host colonization, invasion and bioconversion of the insect cadaver, making P. luminescens a promising model for the study of symbiosis and host-pathogen interactions. Comparison with the genomes of related bacteria reveals the acquisition of virulence factors by extensive horizontal transfer and provides clues about the evolution of an insect pathogen. Moreover, newly identified insecticidal proteins may be effective alternatives for the control of insect pests.
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Affiliation(s)
- Eric Duchaud
- Laboratoire de Génomique des Microorganismes Pathogènes, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 15, France
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44
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Marokhazi J, Waterfield N, LeGoff G, Feil E, Stabler R, Hinds J, Fodor A, ffrench-Constant RH. Using a DNA microarray to investigate the distribution of insect virulence factors in strains of photorhabdus bacteria. J Bacteriol 2003; 185:4648-56. [PMID: 12867479 PMCID: PMC165762 DOI: 10.1128/jb.185.15.4648-4656.2003] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Photorhabdus is an insect-pathogenic bacterium in which oral toxicity to insects is found in two distinct taxonomic groups. Using a DNA microarray and comparative genomics, we show that oral toxicity is associated with toxin complex genes tcaABC and that this locus can be mobilized or deleted within different strains.
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Affiliation(s)
- Judit Marokhazi
- Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, United Kingdom
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45
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ffrench-Constant R, Waterfield N, Daborn P, Joyce S, Bennett H, Au C, Dowling A, Boundy S, Reynolds S, Clarke D. Photorhabdus: towards a functional genomic analysis of a symbiont and pathogen. FEMS Microbiol Rev 2003; 26:433-56. [PMID: 12586390 DOI: 10.1111/j.1574-6976.2003.tb00625.x] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Pathogenicity and symbiosis are central to bacteria-host interactions. Although several human pathogens have been subjected to functional genomic analysis, we still understand little about bacteria-invertebrate interactions despite their ecological prevalence. Advances in our knowledge of this area are often hindered by the difficulty of isolating and working with invertebrate pathogenic bacteria and their hosts. Here we review studies on pathogenicity and symbiosis in an insect pathogenic bacterium Photorhabdus and its entomopathogenic nematode vector and model insect hosts. Whilst switching between these hosts, Photorhabdus changes from a state of symbiosis with its nematode vector to one of pathogenicity towards its new insect host and both the bacteria and the nematode then cooperatively exploit the dying insect. We examine candidate genes involved in symbiosis and pathogenicity, their secretion and expression patterns in culture and in the host, and begin to dissect the extent of their genetic coregulation. We describe the presence of several large genomic islands, putatively involved in pathogenicity or symbiosis, within the otherwise Yersinia-like backbone of the Photorhabdus genome. Finally, we examine the emerging comparative genomics of the Photorhabdus group and begin to describe the interrelationship between anti-invertebrate virulence factors and those used against vertebrates.
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Affiliation(s)
- Richard ffrench-Constant
- Centre for Molecular Microbiology, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.
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46
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Roche DM, Dowds BCA. Identification and sequence of an unstable DNA element in the entomopathogenic bacteria Photorhabdus temperata strain K122. Lett Appl Microbiol 2002; 35:131-5. [PMID: 12100588 DOI: 10.1046/j.1472-765x.2002.01158.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS A search was conducted for a difference in genome composition between phenotypic variants of the insect pathogenic bacteria, Photorhabdus temperata. METHODS An unstable 300 bp fragment of DNA was identified by amplified fragment length polymorphism (AFLP) analysis, which was not, however, associated with phenotypic variation. RESULTS During prolonged culturing of the bacteria, one copy of the repeated fragment was deleted and a restriction site linked to one of the copies was lost or gained. The sequence did not show substantial identity to any in the database, but a 16-bp region was identical to part of the marR gene of Escherichia coli. SIGNIFICANCE AND IMPACT OF THE STUDY The work has implications for the understanding of genetic instability in this and other pathogenic species of bacteria. In addition, the complete unstable element may be useful as a genetic tool in Photorhabdus spp.
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Affiliation(s)
- D M Roche
- Department of Biology and Institute for Bioengineering and Agroecology, National University of Ireland, Maynooth, Co. Kildare, Ireland
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47
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Abstract
Genomic islands are responsible for unique aspects of bacterial behavior such as symbiosis and pathogenicity. Photorhabdus luminescens is a pathogen of insects that spends part of its lifecycle in symbiosis with a nematode. Here, we describe novel genomic islands from Photorhabdus that are involved in symbiosis and pathogenicity, and discuss the inter-relationship between virulence factors used against invertebrates and vertebrates.
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48
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Sharma S, Waterfield N, Bowen D, Rocheleau T, Holland L, James R, ffrench-Constant R. The lumicins: novel bacteriocins from Photorhabdus luminescens with similarity to the uropathogenic-specific protein (USP) from uropathogenic Escherichia coli. FEMS Microbiol Lett 2002; 214:241-9. [PMID: 12351238 DOI: 10.1111/j.1574-6968.2002.tb11354.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Bacteriocins are proteins produced by bacteria to destroy other bacteria occupying their ecological niche. Photorhabdus luminescens is an insect pathogenic bacterium carried by an entomopathogenic nematode and occupies several different niches in its life cycle. The nematode enters the insect and releases a single strain of P. luminescens. The bacteria then kill the host and the bacteria and nematodes replicate within the cadaver. Strikingly, at the end of the infection the cadaver is still occupied by a single strain of bacterium, suggesting that P. luminescens can destroy other bacteria entering, or present within, the insect. Here we describe four loci encoding 'lumicins' in P. luminescens subsp. akhurstii strain W14. The lumicins are novel bacteriocins capable of killing other strains of Photorhabdus and Escherichia coli. These loci predict killer proteins and multiple dual type immunity proteins with domains similar to pyocins and colicins. The killer proteins are chimeric in nature with multiple domains, one of which is similar to the uropathogenic-specific protein (USP) described from uropathogenic E. coli. The implications of these novel bacteriocins for the lifestyle of Photorhabdus and the potential role of USP as a bacteriocin in E. coli are discussed.
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Affiliation(s)
- Sadhana Sharma
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
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49
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Daborn PJ, Waterfield N, Silva CP, Au CPY, Sharma S, Ffrench-Constant RH. A single Photorhabdus gene, makes caterpillars floppy (mcf), allows Escherichia coli to persist within and kill insects. Proc Natl Acad Sci U S A 2002; 99:10742-7. [PMID: 12136122 PMCID: PMC125031 DOI: 10.1073/pnas.102068099] [Citation(s) in RCA: 171] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2002] [Indexed: 11/18/2022] Open
Abstract
Photorhabdus luminescens, a bacterium with alternate pathogenic and symbiotic phases of its lifestyle, represents a source of novel genes associated with both virulence and symbiosis. This entomopathogen lives in a "symbiosis of pathogens" with nematodes that invade insects. Thus the bacteria are symbiotic with entomopathogenic nematodes but become pathogenic on release from the nematode into the insect blood system. Within the insect, the bacteria need to both avoid the peptide- and cellular- (hemocyte) mediated immune response and also to kill the host, which then acts as a reservoir for bacterial and nematode reproduction. However, the mechanisms whereby Photorhabdus evades the insect immune system and kills the host are unclear. Here we show that a single large Photorhabdus gene, makes caterpillars floppy (mcf), is sufficient to allow Esherichia coli both to persist within and kill an insect. The predicted high molecular weight Mcf toxin has little similarity to other known protein sequences but carries a BH3 domain and triggers apoptosis in both insect hemocytes and the midgut epithelium.
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Affiliation(s)
- P J Daborn
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom
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Brillard J, Duchaud E, Boemare N, Kunst F, Givaudan A. The PhlA hemolysin from the entomopathogenic bacterium Photorhabdus luminescens belongs to the two-partner secretion family of hemolysins. J Bacteriol 2002; 184:3871-8. [PMID: 12081958 PMCID: PMC135187 DOI: 10.1128/jb.184.14.3871-3878.2002] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Photorhabdus is an entomopathogenic bacterium symbiotically associated with nematodes of the family Heterorhabditidae. Bacterial hemolysins found in numerous pathogenic bacteria are often virulence factors. We describe here the nucleotide sequence and the molecular characterization of the Photorhabdus luminescens phlBA operon, a locus encoding a hemolysin which shows similarities to the Serratia type of hemolysins. It belongs to the two-partner secretion (TPS) family of proteins. In low-iron conditions, a transcriptional induction of the phlBA operon was observed by using the chloramphenicol acetyltransferase reporter gene, causing an increase in PhlA hemolytic activity compared to iron-rich media. A spontaneous phase variant of P. luminescens was deregulated in phlBA transcription. The phlA mutant constructed by allelic exchange remained highly pathogenic after injection in the lepidopteran Spodoptera littoralis, indicating that PhlA hemolysin is not a major virulence determinant. Using the gene encoding green fluorescent protein as a reporter, phlBA transcription was observed in hemolymph before insect death. We therefore discuss the possible role of PhlA hemolytic activity in the bacterium-nematode-insect interactions.
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Affiliation(s)
- Julien Brillard
- Laboratoire EMIP, Université Montpellier II, IFR56, Institut National de la Recherche Agronomique (UMR 1133), 34095 Montpellier Cedex 5, Laboratoire de Génomique des Microorganismes Pathogènes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Eric Duchaud
- Laboratoire EMIP, Université Montpellier II, IFR56, Institut National de la Recherche Agronomique (UMR 1133), 34095 Montpellier Cedex 5, Laboratoire de Génomique des Microorganismes Pathogènes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Noël Boemare
- Laboratoire EMIP, Université Montpellier II, IFR56, Institut National de la Recherche Agronomique (UMR 1133), 34095 Montpellier Cedex 5, Laboratoire de Génomique des Microorganismes Pathogènes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Frank Kunst
- Laboratoire EMIP, Université Montpellier II, IFR56, Institut National de la Recherche Agronomique (UMR 1133), 34095 Montpellier Cedex 5, Laboratoire de Génomique des Microorganismes Pathogènes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Alain Givaudan
- Laboratoire EMIP, Université Montpellier II, IFR56, Institut National de la Recherche Agronomique (UMR 1133), 34095 Montpellier Cedex 5, Laboratoire de Génomique des Microorganismes Pathogènes, Institut Pasteur, 75724 Paris Cedex 15, France
- Corresponding author. Mailing address: Laboratoire EMIP, CC101, INRA-Université Montpellier II (UMR 1133), Place E. Bataillon, 34095 Montpellier Cedex 5, France. Phone: 33-4-67144812. Fax: 33-4-67144679. E-mail:
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