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Chang G, Luo Z, Zhang Y, Xu X, Zhou T, Chen D, Li L, Wang X. Electron beam irradiation degrades the toxicity and alters the protein structure of Staphylococcus aureus alpha-hemolysin. Int J Biol Macromol 2023; 246:125608. [PMID: 37392914 DOI: 10.1016/j.ijbiomac.2023.125608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/25/2023] [Accepted: 06/27/2023] [Indexed: 07/03/2023]
Abstract
α-Hemolysin (Hla) is a potent pore-forming toxin (PFT) produced by Staphylococcus aureus that exacerbates the pathogenesis of S. aureus enterotoxicity and plays a role in population food poisoning. Hla lyses cells by binding to host cell membranes and oligomerizing to form heptameric structures, thereby disrupting the cell barrier. Although the broad bactericidal effect of electron beam irradiation (EBI) has been demonstrated whether it has a damaging or degrading effect on Hla's remains unknown. In this study, EBI was found to have the effect of altering the secondary structure of Hla proteins, verifying that the damaging effect of EBI-treated Hla on intestinal and skin epithelial cell barriers was significantly reduced. It was noted by hemolysis and protein interactions that EBI treatment significantly disrupted the binding of Hla to its high-affinity receptor, but did not affect the binding between Hla monomers to form heptamers. Thus, EBI can effectively reduce the threat of Hla to food safety.
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Affiliation(s)
- Guanhong Chang
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Zonghong Luo
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Yao Zhang
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xu Xu
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Ting Zhou
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - DiShi Chen
- Sichuan Animal Disease Prevention and Control Center, Chengdu 610041, China
| | - Li Li
- Sichuan Animal Disease Prevention and Control Center, Chengdu 610041, China
| | - Xin Wang
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China.
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2
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Wang C, Liu C, Zhu X, Peng Q, Ma Q. Catalytic site flexibility facilitates the substrate and catalytic promiscuity of Vibrio dual lipase/transferase. Nat Commun 2023; 14:4795. [PMID: 37558668 PMCID: PMC10412561 DOI: 10.1038/s41467-023-40455-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 07/27/2023] [Indexed: 08/11/2023] Open
Abstract
Although enzyme catalysis is typified by high specificity, enzymes can catalyze various substrates (substrate promiscuity) and/or different reaction types (catalytic promiscuity) using a single active site. This interesting phenomenon is widely distributed in enzyme catalysis, with both fundamental and applied importance. To date, the mechanistic understanding of enzyme promiscuity is very limited. Herein, we report the structural mechanism underlying the substrate and catalytic promiscuity of Vibrio dual lipase/transferase (VDLT). Crystal structures of the VDLT from Vibrio alginolyticus (ValDLT) and its fatty acid complexes were solved, revealing prominent structural flexibility. In particular, the "Ser-His-Asp" catalytic triad machinery of ValDLT contains an intrinsically flexible oxyanion hole. Analysis of ligand-bound structures and mutagenesis showed that the flexible oxyanion hole and other binding residues can undergo distinct conformational changes to facilitate substrate and catalytic promiscuity. Our study reveals a previously unknown flexible form of the famous catalytic triad machinery and proposes a "catalytic site tuning" mechanism to expand the mechanistic paradigm of enzyme promiscuity.
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Affiliation(s)
- Chongyang Wang
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Changshui Liu
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Xiaochuan Zhu
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
| | - Quancai Peng
- Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
| | - Qingjun Ma
- CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
- University of Chinese Academy of Sciences, Beijing, China.
- Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
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3
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Sakatoku A, Hatano K, Takada K, Shimizu R, Suzuki T, Seki M, Suzuki N, Tanaka D, Nakamura S, Isshiki T. Purification and Characterization of the Lecithin-Dependent Thermolabile Hemolysin Vhe1 from the Vibrio sp. Strain MA3 Associated with Mass Mortality of Pearl Oyster (Pinctada fucata). Curr Microbiol 2023; 80:288. [PMID: 37458864 DOI: 10.1007/s00284-023-03409-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 07/06/2023] [Indexed: 07/20/2023]
Abstract
In a previous study, we isolated a Vibrio sp. strain MA3 and its virulence factor, a hemolysin encoded by vhe1. This strain is associated with mass mortalities of the pearl oyster Pinctada fucata. In the present study, the vhe1 gene from strain MA3 was cloned and its encoded product was purified and characterized. Our results show that the vhe1 gene encodes a protein of 417 amino acids with an estimated molecular mass of 47.2 kDa and a pI of 5.14. The deduced protein, Vhe1, was found to contain the conserved amino acid sequence (GDSL motif) of the hydrolase/esterase superfamily and five conserved blocks characteristic of SGNH hydrolases. A BLAST homology search indicated that Vhe1 belongs the lecithin-dependent hemolysin/thermolabile hemolysin (LDH/TLH) family. In activity analyses, the optimal temperature for both the hemolytic and phospholipase activities of Vhe1 was 50 °C. Vhe1 hemolytic activity and phospholipase activity were highest at pH 8.5 and pH 8.0, respectively. However, both enzymatic activities sharply decreased at high temperature (> 50 °C) and pH < 7.0. Compared with previously reported hemolysins, Vhe1 appeared to be more thermal- and pH-labile. Both its hemolytic activity and phospholipase activity were significantly inhibited by CuCl2, CdCl2, ZnCl2, and NiCl2, and slightly inhibited by MnCl2 and CoCl2. Vhe1 showed higher phospholipase activity toward medium-chain fatty acids (C8-C12) than toward shorter- and longer-chain fatty acids. These results accumulate knowledge about the LDH/TLH of V. alginolyticus, which detailed characterization has not been reported, and contribute to solving of the mass mortality of pearl oyster.
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Affiliation(s)
- Akihiro Sakatoku
- School of Science, Academic Assembly, University of Toyama, Toyama, 930-8555, Japan.
| | - Kaito Hatano
- Noto Marine Laboratory, Institute of Nature and Environmental Technology, Kanazawa University, Ogi, Noto‑cho, Ishikawa, 927‑0553, Japan
| | - Kosei Takada
- School of Science, Academic Assembly, University of Toyama, Toyama, 930-8555, Japan
| | - Ryota Shimizu
- School of Science, Academic Assembly, University of Toyama, Toyama, 930-8555, Japan
| | - Takaya Suzuki
- School of Science, Academic Assembly, University of Toyama, Toyama, 930-8555, Japan
| | - Makoto Seki
- School of Science, Academic Assembly, University of Toyama, Toyama, 930-8555, Japan
| | - Nobuo Suzuki
- Noto Marine Laboratory, Institute of Nature and Environmental Technology, Kanazawa University, Ogi, Noto‑cho, Ishikawa, 927‑0553, Japan
| | - Daisuke Tanaka
- School of Science, Academic Assembly, University of Toyama, Toyama, 930-8555, Japan
| | - Shogo Nakamura
- School of Science, Academic Assembly, University of Toyama, Toyama, 930-8555, Japan
| | - Tadashi Isshiki
- Graduate School of Bioresources, Mie University, 1577 Kurimamachiya, Tsu, Mie, 514-8507, Japan
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4
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Vazquez-Morado LE, Robles-Zepeda RE, Ochoa-Leyva A, Arvizu-Flores AA, Garibay-Escobar A, Castillo-Yañez F, Lopez-Zavala AA. Biochemical characterization and inhibition of thermolabile hemolysin from Vibrio parahaemolyticus by phenolic compounds. PeerJ 2021; 9:e10506. [PMID: 33505784 PMCID: PMC7796666 DOI: 10.7717/peerj.10506] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 11/16/2020] [Indexed: 12/28/2022] Open
Abstract
Vibrio parahaemolyticus (Vp), a typical microorganism inhabiting marine ecosystems, uses pathogenic virulence molecules such as hemolysins to cause bacterial infections of both human and marine animals. The thermolabile hemolysin VpTLH lyses human erythrocytes by a phospholipase B/A2 enzymatic activity in egg-yolk lecithin. However, few studies have been characterized the biochemical properties and the use of VpTLH as a molecular target for natural compounds as an alternative to control Vp infection. Here, we evaluated the biochemical and inhibition parameters of the recombinant VpTLH using enzymatic and hemolytic assays and determined the molecular interactions by in silico docking analysis. The highest enzymatic activity was at pH 8 and 50 °C, and it was inactivated by 20 min at 60 °C with Tm = 50.9 °C. Additionally, the flavonoids quercetin, epigallocatechin gallate, and morin inhibited the VpTLH activity with IC50 values of 4.5 µM, 6.3 µM, and 9.9 µM, respectively; while phenolics acids were not effective inhibitors for this enzyme. Boltzmann and Arrhenius equation analysis indicate that VpTLH is a thermolabile enzyme. The inhibition of both enzymatic and hemolytic activities by flavonoids agrees with molecular docking, suggesting that flavonoids could interact with the active site’s amino acids. Future research is necessary to evaluate the antibacterial activity of flavonoids against Vp in vivo.
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Affiliation(s)
- Luis E Vazquez-Morado
- Departamento de Ciencias Quimico Biologicas, Universidad de Sonora, Hermosillo, Sonora, Mexico.,Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - Ramon E Robles-Zepeda
- Departamento de Ciencias Quimico Biologicas, Universidad de Sonora, Hermosillo, Sonora, Mexico
| | - Adrian Ochoa-Leyva
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - Aldo A Arvizu-Flores
- Departamento de Ciencias Quimico Biologicas, Universidad de Sonora, Hermosillo, Sonora, Mexico
| | - Adriana Garibay-Escobar
- Departamento de Ciencias Quimico Biologicas, Universidad de Sonora, Hermosillo, Sonora, Mexico
| | | | - Alonso A Lopez-Zavala
- Departamento de Ciencias Quimico Biologicas, Universidad de Sonora, Hermosillo, Sonora, Mexico
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5
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Spatiotemporal Regulation of Vibrio Exotoxins by HlyU and Other Transcriptional Regulators. Toxins (Basel) 2020; 12:toxins12090544. [PMID: 32842612 PMCID: PMC7551375 DOI: 10.3390/toxins12090544] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 08/17/2020] [Accepted: 08/19/2020] [Indexed: 02/06/2023] Open
Abstract
After invading a host, bacterial pathogens secrete diverse protein toxins to disrupt host defense systems. To ensure successful infection, however, pathogens must precisely regulate the expression of those exotoxins because uncontrolled toxin production squanders energy. Furthermore, inappropriate toxin secretion can trigger host immune responses that are detrimental to the invading pathogens. Therefore, bacterial pathogens use diverse transcriptional regulators to accurately regulate multiple exotoxin genes based on spatiotemporal conditions. This review covers three major exotoxins in pathogenic Vibrio species and their transcriptional regulation systems. When Vibrio encounters a host, genes encoding cytolysin/hemolysin, multifunctional-autoprocessing repeats-in-toxin (MARTX) toxin, and secreted phospholipases are coordinately regulated by the transcriptional regulator HlyU. At the same time, however, they are distinctly controlled by a variety of other transcriptional regulators. How this coordinated but distinct regulation of exotoxins makes Vibrio species successful pathogens? In addition, anti-virulence strategies that target the coordinating master regulator HlyU and related future research directions are discussed.
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6
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Wan Y, Liu C, Ma Q. Structural analysis of a Vibrio phospholipase reveals an unusual Ser-His-chloride catalytic triad. J Biol Chem 2019; 294:11391-11401. [PMID: 31073025 DOI: 10.1074/jbc.ra119.008280] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 04/30/2019] [Indexed: 12/22/2022] Open
Abstract
Phospholipases can disrupt host membranes and are important virulence factors in many pathogens. VvPlpA is a phospholipase A2 secreted by Vibrio vulnificus and essential for virulence. Its homologs, termed thermolabile hemolysins (TLHs), are widely distributed in Vibrio bacteria, but no structural information for this virulence factor class is available. Herein, we report the crystal structure of VvPlpA to 1.4-Å resolution, revealing that VvPlpA contains an N-terminal domain of unknown function and a C-terminal phospholipase domain and that these two domains are packed closely together. The phospholipase domain adopts a typical SGNH hydrolase fold, containing the four conserved catalytic residues Ser, Gly, Asn, and His. Interestingly, the structure also disclosed that the phospholipase domain accommodates a chloride ion near the catalytic His residue. The chloride is five-coordinated in a distorted bipyramid geometry, accepting hydrogen bonds from a water molecule and the amino groups of surrounding residues. This chloride substitutes for the most common Asp/Glu residue and forms an unusual Ser-His-chloride catalytic triad in VvPlpA. The chloride may orient the catalytic His and stabilize the charge on its imidazole ring during catalysis. Indeed, VvPlpA activity depended on chloride concentration, confirming the important role of chloride in catalysis. The VvPlpA structure also revealed a large hydrophobic substrate-binding pocket that is capable of accommodating a long-chain acyl group. Our results provide the first structure of the TLH family and uncover an unusual Ser-His-chloride catalytic triad, expanding our knowledge on the biological role of chloride.
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Affiliation(s)
- Ye Wan
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Changshui Liu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Qingjun Ma
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China .,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China
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7
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The Probiotic Bacterium Phaeobacter inhibens Downregulates Virulence Factor Transcription in the Shellfish Pathogen Vibrio coralliilyticus by N-Acyl Homoserine Lactone Production. Appl Environ Microbiol 2019; 85:AEM.01545-18. [PMID: 30389771 DOI: 10.1128/aem.01545-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Accepted: 10/30/2018] [Indexed: 01/25/2023] Open
Abstract
Phaeobacter inhibens S4Sm acts as a probiotic bacterium against the oyster pathogen Vibrio coralliilyticus Here, we report that P. inhibens S4Sm secretes three molecules that downregulate the transcription of major virulence factors, metalloprotease genes, in V. coralliilyticus cultures. The effects of the S4Sm culture supernatant on the transcription of three genes involved in protease activity, namely, vcpA, vcpB, and vcpR (encoding metalloproteases A and B and their transcriptional regulator, respectively), were examined by reverse transcriptase quantitative PCR (qRT-PCR). The expression of vcpB and vcpR were reduced to 36% and 6.6%, respectively, compared to that in an untreated control. We constructed a V. coralliilyticus green fluorescent protein (GFP) reporter strain to detect the activity of inhibitory compounds. Using a bioassay-guided approach, the molecules responsible for V. coralliilyticus protease inhibition activity were isolated from S4Sm supernatant and identified as three N-acyl homoserine lactones (AHLs). The three AHLs are N-(3-hydroxydecanoyl)-l-homoserine lactone, N-(dodecanoyl-2,5-diene)-l-homoserine lactone, and N-(3-hydroxytetradecanoyl-7-ene)-l-homoserine lactone, and their half maximal inhibitory concentrations (IC50s) against V. coralliilyticus protease activity were 0.26 μM, 3.7 μM, and 2.9 μM, respectively. Our qRT-PCR data demonstrated that exposures to the individual AHLs reduced the transcription of vcpR and vcpB Combinations of the three AHLs (any two or all three AHLs) on V. coralliilyticus produced additive effects on protease inhibition activity. These AHL compounds may contribute to the host protective effects of S4Sm by disrupting the quorum sensing pathway that activates protease transcription of V. coralliilyticus IMPORTANCE Probiotics represent a promising alternative strategy to control infection and disease caused by marine pathogens of aquaculturally important species. Generally, the beneficial effects of probiotics include improved water quality, control of pathogenic bacteria and their virulence, stimulation of the immune system, and improved animal growth. Previously, we isolated a probiotic bacterium, Phaeobacter inhibens S4Sm, which protects oyster larvae from Vibrio coralliilyticus RE22Sm infection. We also demonstrated that both antibiotic secretion and biofilm formation play important roles in S4Sm probiotic activity. Here, we report that P. inhibens S4Sm, an alphaproteobacterium and member of the Roseobacter clade, also secretes secondary metabolites that hijack the quorum sensing ability of V. coralliilyticus RE22Sm, suppressing virulence gene expression. This finding demonstrates that probiotic bacteria can exert their host protection by using a multipronged array of behaviors that limit the ability of pathogens to become established and cause infection.
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8
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Ben Hamed S, Tavares Ranzani-Paiva MJ, Tachibana L, de Carla Dias D, Ishikawa CM, Esteban MA. Fish pathogen bacteria: Adhesion, parameters influencing virulence and interaction with host cells. FISH & SHELLFISH IMMUNOLOGY 2018; 80:550-562. [PMID: 29966687 DOI: 10.1016/j.fsi.2018.06.053] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 06/04/2018] [Accepted: 06/29/2018] [Indexed: 06/08/2023]
Abstract
Wild fisheries are declining due to over-fishing, climate change, pollution and marine habitat destructions among other factors, and, concomitantly, aquaculture is increasing significantly around the world. Fish infections caused by pathogenic bacteria are quite common in aquaculture, although their seriousness depends on the season. Drug-supplemented feeds are often used to keep farmed fish free from the diseases caused by such bacteria. However, given that bacteria can survive well in aquatic environments independently of their hosts, bacterial diseases have become major impediments to aquaculture development. On the other hand, the indiscriminate uses of antimicrobial agents has led to resistant strains and the need to switch to other antibiotics, although it seems that an integrated approach that considers not only the pathogen but also the host and the environment will be the most effective method in the long-term to improve aquatic animal health. This review covers the mechanisms of bacterial pathogenicity and details the foundations underlying the interactions occurring between pathogenic bacteria and the fish host in the aquatic environment, as well as the factors that influence virulence. Understanding and linking the different phenomena that occur from adhesion to colonization of the host will offer novel and useful means to help design suitable therapeutic strategies for disease prevention and treatment.
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Affiliation(s)
- Said Ben Hamed
- Fishery Institute-APTA - SAA, Research Center of Aquaculture, Av. Francisco Matarazzo, 455, CEP. 05001-900, Sao Paulo, SP, Brazil
| | - Maria José Tavares Ranzani-Paiva
- Fishery Institute-APTA - SAA, Research Center of Aquaculture, Av. Francisco Matarazzo, 455, CEP. 05001-900, Sao Paulo, SP, Brazil
| | - Leonardo Tachibana
- Fishery Institute-APTA - SAA, Research Center of Aquaculture, Av. Francisco Matarazzo, 455, CEP. 05001-900, Sao Paulo, SP, Brazil
| | - Danielle de Carla Dias
- Fishery Institute-APTA - SAA, Research Center of Aquaculture, Av. Francisco Matarazzo, 455, CEP. 05001-900, Sao Paulo, SP, Brazil
| | - Carlos Massatoshi Ishikawa
- Fishery Institute-APTA - SAA, Research Center of Aquaculture, Av. Francisco Matarazzo, 455, CEP. 05001-900, Sao Paulo, SP, Brazil
| | - María Angeles Esteban
- Fish Innate Immune System Group, Department of Cell Biology & Histology, Faculty of Biology, Regional Campus of International Excellence, ''Campus Mare Nostrum'', University of Murcia, 30100, Murcia, Spain.
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9
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Mou X, Spinard EJ, Hillman SL, Nelson DR. Isocitrate dehydrogenase mutation in Vibrio anguillarum results in virulence attenuation and immunoprotection in rainbow trout (Oncorhynchus mykiss). BMC Microbiol 2017; 17:217. [PMID: 29137620 PMCID: PMC5686843 DOI: 10.1186/s12866-017-1124-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 11/02/2017] [Indexed: 11/28/2022] Open
Abstract
Background Vibrio anguillarum is an extracellular bacterial pathogen that is a causative agent of vibriosis in finfish and crustaceans with mortality rates ranging from 30% to 100%. Mutations in central metabolism (glycolysis and the TCA cycle) of intracellular pathogens often result in attenuated virulence due to depletion of required metabolic intermediates; however, it was not known whether mutations in central metabolism would affect virulence in an extracellular pathogen such as V. anguillarum. Results Seven central metabolism mutants were created and characterized with regard to growth in minimal and complex media, expression of virulence genes, and virulence in juvenile rainbow trout (Oncorhynchus mykiss). Only the isocitrate dehydrogenase (icd) mutant was attenuated in virulence against rainbow trout challenged by either intraperitoneal injection or immersion. Further, the icd mutant was shown to be immunoprotective against wild type V. anguillarum infection. There was no significant decrease in the expression of the three hemolysin genes detected by qRT-PCR. Additionally, only the icd mutant exhibited a significantly decreased growth yield in complex media. Growth yield was directly related to the abundance of glutamate. A strain with a restored wild type icd gene was created and shown to restore growth to a wild type cell density in complex media and pathogenicity in rainbow trout. Conclusions The data strongly suggest that a decreased growth yield, resulting from the inability to synthesize α-ketoglutarate, caused the attenuation despite normal levels of expression of virulence genes. Therefore, the ability of an extracellular pathogen to cause disease is dependent upon the availability of host-supplied nutrients for growth. Additionally, a live vaccine strain could be created from an icd deletion strain. Electronic supplementary material The online version of this article (10.1186/s12866-017-1124-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xiangyu Mou
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, 02881, USA.,Present Address: Division of Infectious Diseases, Massachusetts General Hospital, 65 Landsdowne St, Cambridge, MA, 02139, USA
| | - Edward J Spinard
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, 02881, USA
| | - Shelby L Hillman
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, 02881, USA
| | - David R Nelson
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, 02881, USA.
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10
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Jang KK, Lee ZW, Kim B, Jung YH, Han HJ, Kim MH, Kim BS, Choi SH. Identification and characterization of Vibrio vulnificus plpA encoding a phospholipase A 2 essential for pathogenesis. J Biol Chem 2017; 292:17129-17143. [PMID: 28855258 DOI: 10.1074/jbc.m117.791657] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 08/28/2017] [Indexed: 12/23/2022] Open
Abstract
The marine bacterium Vibrio vulnificus causes food-borne diseases, which may lead to life-threatening septicemia in some individuals. Therefore, identifying virulence factors in V. vulnificus is of high priority. We performed a transcriptome analysis on V. vulnificus after infection of human intestinal HT29-methotrexate cells and found induction of plpA, encoding a putative phospholipase, VvPlpA. Bioinformatics, biochemical, and genetic analyses demonstrated that VvPlpA is a phospholipase A2 secreted in a type II secretion system-dependent manner. Compared with the wild type, the plpA mutant exhibited reduced mortality, systemic infection, and inflammation in mice as well as low cytotoxicity toward the human epithelial INT-407 cells. Moreover, plpA mutation attenuated the release of actin and cytosolic cyclophilin A from INT-407 cells, indicating that VvPlpA is a virulence factor essential for causing lysis and necrotic death of the epithelial cells. plpA transcription was growth phase-dependent, reaching maximum levels during the early stationary phase. Also, transcription factor HlyU and cAMP receptor protein (CRP) mediate additive activation and host-dependent induction of plpA Molecular biological analyses revealed that plpA expression is controlled via the promoter, P plpA , and that HlyU and CRP directly bind to P plpA upstream sequences. Taken together, this study demonstrated that VvPlpA is a type II secretion system-dependent secretory phospholipase A2 regulated by HlyU and CRP and is essential for the pathogenicity of V. vulnificus.
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Affiliation(s)
- Kyung Ku Jang
- From the National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, and
| | - Zee-Won Lee
- From the National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, and
| | - Bityeoul Kim
- From the National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, and
| | - Young Hyun Jung
- the Department of Veterinary Physiology, College of Veterinary Medicine, Research Institute for Veterinary Medicine, BK21 PLUS Creative Veterinary Research Center, Seoul National University, Seoul 08826, South Korea and
| | - Ho Jae Han
- the Department of Veterinary Physiology, College of Veterinary Medicine, Research Institute for Veterinary Medicine, BK21 PLUS Creative Veterinary Research Center, Seoul National University, Seoul 08826, South Korea and
| | - Myung Hee Kim
- the Infection and Immunity Research Laboratory, Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, South Korea
| | - Byoung Sik Kim
- the Infection and Immunity Research Laboratory, Metabolic Regulation Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, South Korea
| | - Sang Ho Choi
- From the National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, and
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11
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Li Y, Ma Q. Iron Acquisition Strategies of Vibrio anguillarum. Front Cell Infect Microbiol 2017; 7:342. [PMID: 28791260 PMCID: PMC5524678 DOI: 10.3389/fcimb.2017.00342] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 07/11/2017] [Indexed: 12/03/2022] Open
Abstract
The hemorrhagic septicemic disease vibriosis caused by Vibrio anguillarum shows noticeable similarities to invasive septicemia in humans, and in this case, the V. anguillarum–host system has the potential to serve as a model for understanding native eukaryotic host–pathogen interactions. Iron acquisition, as a fierce battle occurring between pathogenic V. anguillarum and the fish host, is a pivotal step for virulence. In this article, advances in defining the roles of iron uptake pathways in growth and virulence of V. anguillarum have been summarized, divided into five aspects, including siderophore biosynthesis and secretion, iron uptake, iron release, and regulation of iron uptake. Understanding the molecular mechanisms of iron acquisition will have important implications for the pathogenicity of this organism.
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Affiliation(s)
- Yingjie Li
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of SciencesQingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and TechnologyQingdao, China
| | - Qingjun Ma
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of SciencesQingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and TechnologyQingdao, China
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Chromosome-Encoded Hemolysin, Phospholipase, and Collagenase in Plasmidless Isolates of Photobacterium damselae subsp. damselae Contribute to Virulence for Fish. Appl Environ Microbiol 2017; 83:AEM.00401-17. [PMID: 28341681 DOI: 10.1128/aem.00401-17] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 03/18/2017] [Indexed: 11/20/2022] Open
Abstract
Photobacterium damselae subsp. damselae is a pathogen of marine animals, including fish of importance in aquaculture. The virulence plasmid pPHDD1, characteristic of highly hemolytic isolates, encodes the hemolysins damselysin (Dly) and phobalysin (PhlyP). Strains lacking pPHDD1 constitute the vast majority of the isolates from fish outbreaks, but genetic studies to identify virulence factors in plasmidless strains are scarce. Here, we show that the chromosome I-encoded hemolysin PhlyC plays roles in virulence and cell toxicity in pPHDD1-negative isolates of this pathogen. By combining the analyses of whole genomes and of gene deletion mutants, we identified two hitherto uncharacterized chromosomal loci encoding a phospholipase (PlpV) and a collagenase (ColP). PlpV was ubiquitous in the subspecies and exerted hemolytic activity against fish erythrocytes, which was enhanced in the presence of lecithin. ColP was restricted to a fraction of the isolates and was responsible for the collagen-degrading activity in this subspecies. Consistent with the presence of signal peptides in PlpV and ColP sequences, mutants for the type II secretion system (T2SS) genes epsL and pilD exhibited impairments in phospholipase and collagenase activities. Sea bass virulence experiments and cell culture assays demonstrated major contributions of PhlyC and PlpV to virulence and toxicity.IMPORTANCE This study constitutes genetic and genomic analyses of plasmidless strains of an emerging pathogen in marine aquaculture, Photobacterium damselae subsp. damselae To date, studies on the genetic basis of virulence were restricted to the pPHDD1 plasmid-encoded toxins Dly and PhlyP. However, the vast majority of the recent isolates of this pathogen from fish farm outbreaks lack this plasmid. Here we demonstrate that the plasmidless strains produce two hitherto uncharacterized ubiquitous toxins encoded in chromosome I, namely, the hemolysin PhlyC and the phospholipase PlpV. We report the main roles of these two toxins in fish virulence and in cell toxicity. Our results constitute the basis for a better understanding of the virulence of a widespread marine pathogen.
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Draft Genome Sequence of the Emerging Bivalve Pathogen Vibrio tubiashii subsp. europaeus. GENOME ANNOUNCEMENTS 2016; 4:4/4/e00625-16. [PMID: 27469949 PMCID: PMC4966453 DOI: 10.1128/genomea.00625-16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Vibrio tubiashii subsp. europaeus is a bivalve pathogen isolated during episodes of mortality affecting larval cultures in different shellfish hatcheries. Here, we announce the draft genome sequence of the type strain PP-638 and describe potential virulence factors, which may provide insight into the mechanism of pathogenicity.
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Draft Genome Sequence of the Marine Pathogen Vibrio coralliilyticus RE22. GENOME ANNOUNCEMENTS 2015; 3:3/6/e01432-15. [PMID: 26634766 PMCID: PMC4669407 DOI: 10.1128/genomea.01432-15] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Vibrio coralliilyticus RE22 is a causative agent of vibriosis in larval bivalves. We report here the draft genome sequence of V. coralliilyticus RE22 and describe additional virulence factors that may provide insight into its mechanism of pathogenicity.
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15
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Luna-Castro S, Aguilar-Romero F, Samaniego-Barrón L, Godínez-Vargas D, de la Garza M. Effect of bovine apo-lactoferrin on the growth and virulence of Actinobacillus pleuropneumoniae. Biometals 2014; 27:891-903. [DOI: 10.1007/s10534-014-9752-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 05/15/2014] [Indexed: 01/01/2023]
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