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Sana T, Khan M, Siddiqui BS, Baig TA, Jabeen A, Begum S, Hadda TB, Shah L. Anti-inflammatory and urease inhibitory iridoid glycosides from Nyctanthes arbor-tristis Linn. JOURNAL OF ETHNOPHARMACOLOGY 2024; 319:117368. [PMID: 38380570 DOI: 10.1016/j.jep.2023.117368] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 10/26/2023] [Accepted: 10/27/2023] [Indexed: 02/22/2024]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Nyctanthes arbor-tristis Linn. has been used by Ayruvedic physicians for the cure of different diseases including ulcers, gastric and inflammatory diseases. AIM OF THE STUDY To isolate and identify compounds from this source and investigate their therapeutic potential for the treatment of gastric ulcer and related disorders. MATERIAL AND METHODS The ethanol extract of fresh aerial parts of N. arbor-tristis was used in the present studies which was subjected to a bio-assay guided fractionation followed by chromatographic separations. The structures of pure compounds were elucidated using various spectroscopic techniques. The inhibition of urease enzyme was evaluated by weatherburn indophenol method. Molecular docking studies were determined by using Molecular Operating Environment (MOE) version 2020.0901 version. The intracellular ROS production from phagocytes was determined by chemiluminescence assay and NO generation was detected by Griess method. The proinflammatory cytokine TNF-α was quantified by ELISA. Cytotoxic activity was assessed by MTT assay. RESULTS One previously undescribed iridoid glycoside arborside F (1) and four known iridoid glycosides arborside A (2), arborside C (3), loganin (4) and 7-O-trans-cinnamoyl-6β-hydroxyloganin (5) were isolated and characterized in the present studies and their urease inhibitory activity was determined. Among these, 2 and 5 showed strong urease inhibition (IC50 = 12.1 ± 1.74 and 14.1 ± 0.59 μM respectively) (standard acetohydroxamic acid IC50 = 20.3 ± 0.42 μM), whereas rest of compounds showed moderate to low inhibition. Kinetic studies revealed that compounds 2 and 5 possess competitive type of inhibition. Molecular docking showed polar and non-polar interactions of compounds 2 and 5 with urease enzyme residues. Compounds 2 and 3 showed inhibition of ROS from whole blood (IC50 = 1.6 ± 0.3 and 2.5 ± 0.09 μg/mL respectively) and PMNs (IC50 = 1.5 ± 0.03 and 1.4 ± 0.0 μg/mL respectively). Compound 2 significantly inhibited nitric oxide and proinflammatory cytokine TNF-α (IC50 = 18.2 ± 3.0 and 73.8 ± 6.6 μg/mL respectively). Compounds 1, 4 and 5 were inactive on ROS. All isolated compounds were non-toxic on normal mouse fibroblasts (NIH-3T3) cells. CONCLUSIONS The ethno pharmacological repute of N. arbor-tristis in treating gastric and anti-inflammatory ailments is supported by present studies which resulted in isolation of a potent urease inhibitory and anti-inflammatory agent arborside A (2) a potential anti-ulcer and anti-inflammatory drug lead.
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Affiliation(s)
- Talea Sana
- H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan
| | - Majid Khan
- H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan
| | - Bina S Siddiqui
- H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan; Pakistan Academy of Sciences, 3-Constitution Avenue, G-5/2, Islamabad, Pakistan.
| | - Tariq Ahmad Baig
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan
| | - Almas Jabeen
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan
| | - Sabira Begum
- H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan
| | - Taibi B Hadda
- Laboratoire de Chimie des Matériaux, Facultédes Sciences, Université Mohammed Premier, 60000, Oujda, Morocco
| | - Luqman Shah
- Hazara University, Mansehra, 21300, Pakistan
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Taha M, Ismail S, Imran S, Almandil NB, Alomari M, Rahim F, Uddin N, Hayat S, Zaman K, Ibrahim M, Alghanem B, Islam I, Farooq RK, Boudjelal M, Khan KM. Synthesis of new urease enzyme inhibitors as antiulcer drug and computational study. J Biomol Struct Dyn 2021; 40:8232-8247. [PMID: 33860726 DOI: 10.1080/07391102.2021.1910072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
In search of potent urease inhibitor indole analogues (1-22) were synthesized and evaluated for their urease inhibitory potential. All analogues (1-22) showed a variable degree of inhibitory interaction potential having IC50 value ranging between 0.60 ± 0.05 to 30.90 ± 0.90 µM when compared with standard thiourea having IC50 value 21.86 ± 0.90 µM. Among the synthesized analogues, the compounds 1, 2, 3, 5, 6, 8, 12, 14, 18, 20 and 22 having IC50 value 3.10 ± 0.10, 1.20 ± 0.10, 4.60 ± 0.10, 0.60 ± 0.05, 5.30 ± 0.20, 2.50 ± 0.10, 7.50 ± 0.20, 3.90 ± 0.10, 3.90 ± 0.10, 2.30 ± 0.05 and 0.90 ± 0.05 µM respectively were found many fold better than the standard thiourea. All other analogues showed better urease interaction inhibition. Structure activity relationship (SAR) has been established for all analogues containing different substituents on the phenyl ring. To understand the binding interaction of most active analogues with enzyme active site docking study were performed.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Muhammad Taha
- Department of clinical pharmacy, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Sukinah Ismail
- Department of clinical pharmacy, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia.,College of clinical pharmacy, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Syahrul Imran
- Atta-ur-Rahman Institute for Natural Product Discovery, Universiti Teknologi MARA (UiTM), Bandar Puncak Alam, Selangor, Malaysia.,Faculty of Applied Science, UiTM Shah Alam, Shah Alam, Selangor, Malaysia
| | - Noor Barak Almandil
- Department of clinical pharmacy, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Munther Alomari
- Department of Stem Cell Biology, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Fazal Rahim
- Department of Chemistry, Hazara University, Mansehra, Khyber Pakhtunkhwa, Pakistan
| | - Nizam Uddin
- Department of Chemistry, University of Karachi, Karachi, Pakistan
| | - Shawkat Hayat
- Department of Chemistry, Hazara University, Mansehra, Khyber Pakhtunkhwa, Pakistan
| | - Khalid Zaman
- Department of Chemistry, Hazara University, Mansehra, Khyber Pakhtunkhwa, Pakistan
| | - Mohamad Ibrahim
- Department of clinical pharmacy, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Bandar Alghanem
- Medical Research Core Facility and Platforms (MRCFP, King Abdullah International Medical Research Center/King Saud bin Abdulaziz University for Health Sciences (KSAU-HS), King Abdulaziz Medical City (KAMC), NGHA, Riyadh, Saudi Arabia
| | - Imadul Islam
- Medical Research Core Facility and Platforms (MRCFP, King Abdullah International Medical Research Center/King Saud bin Abdulaziz University for Health Sciences (KSAU-HS), King Abdulaziz Medical City (KAMC), NGHA, Riyadh, Saudi Arabia
| | - Rai Khalid Farooq
- Department of Neuroscience Research, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Mohamed Boudjelal
- Medical Research Core Facility and Platforms (MRCFP, King Abdullah International Medical Research Center/King Saud bin Abdulaziz University for Health Sciences (KSAU-HS), King Abdulaziz Medical City (KAMC), NGHA, Riyadh, Saudi Arabia
| | - Khalid Mohammed Khan
- H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
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Kataria R, Khatkar A. Lead Molecules for Targeted Urease Inhibition: An Updated Review from 2010 -2018. Curr Protein Pept Sci 2020; 20:1158-1188. [PMID: 30894105 DOI: 10.2174/1389203720666190320170215] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/01/2019] [Accepted: 03/15/2019] [Indexed: 12/14/2022]
Abstract
The field of enzyme inhibition is a tremendous and quickly growing territory of research. Urease a nickel containing metalloenzyme found in bacteria, algae, fungi, and plants brings hydrolysis of urea and plays important role in environmental nitrogen cycle. Apart from this it was found to be responsible for many pathological conditions due to its presence in many microorganisms such as H. Pylori, a ureolytic bacteria having urease which elevates pH of gastric medium by hydrolyzing urea present in alimentary canal and help the bacteria to colonize and spread infection. Due to the infections caused by the various bacterial ureases such as Bacillus pasteurii, Brucella abortus, H. pylori, H. mustelae, Klebsiella aerogenes, Klebsiella tuberculosis, Mycobacterium tuberculosis, Pseudomonas putida, Sporosarcina pasteurii and Yersinia enterocolitica, it has been the current topic of today's research. About a wide range of compounds from the exhaustive literature survey has been discussed in this review which is enveloped into two expansive classes, as Inhibitors from synthetic origin and Inhibitors from natural origin. Moreover active site details of enzyme, mechanism of catalysis of substrate by enzyme, uses of plant urease and its pathogenic behavior has been included in the current review. So, overall, this review article diagrams the current landscape of the developments in the improvements in the thriving field of urease inhibitory movement in medicinal chemistry from year 2010 to 2018, with an emphasis on mechanism of action of inhibitors that may be used for more development of recent and strong urease inhibitors and open up new doors for assist examinations in a standout amongst the most lively and promising regions of research.
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Affiliation(s)
- Ritu Kataria
- International Institute of Pharmaceutical Sciences, Sonepat, Haryana, India
| | - Anurag Khatkar
- Department of Pharmaceutical Sciences, Maharshi Dayanand University, Rohtak, Haryana, India
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Kataria R, Khatkar A. In-silico design, synthesis, ADMET studies and biological evaluation of novel derivatives of Chlorogenic acid against Urease protein and H. Pylori bacterium. BMC Chem 2019; 13:41. [PMID: 31384789 PMCID: PMC6661759 DOI: 10.1186/s13065-019-0556-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 03/15/2019] [Indexed: 12/26/2022] Open
Abstract
Background Plants have always played important role in treating human and animal diseases as a therapeutic agent for traditional medicine. Through extensive research throughout the world, potential of natural products have been identified to control the over activity of many enzymes. In-silico screening a library of chlorogenic acid derivatives highlighted some novel compounds which were found effective against urease enzyme and cancer causing H. Pylori bacterium. Selected top ligands possessing minimum binding energy and good docking score were synthesized in wet lab by suitable procedure and evaluated for urease enzyme inhibition and free radical scavenging property. Synthetic scheme includes three step reactions i. e protection of hydroxyl group of quinic acid part of chlorogenic acid with lactonisation process, anilide formation by reaction with substituted anilines followed by extraction with ethyl acetate under vacuum and deprotection of hydroxyl groups by treatment with hydrochloric acid. Results In-vitro results of the series concluded that compounds C4a, C4d and C4b (IC50 11.01 ± 0.013, 13.8 ± 0.041 and 15.86 ± 0.004 µM respectively in urease inhibition and 5.10 ± 0.018, 5.34 ± 0.007 and 6.01 ± 0.005 µM in antioxidant property against DPPH) were found to be significantly potent with excellent dock score − 10.091, − 10.603, − 9.833 and binding energy − 62.674, − 63.352, 56.267 kg/mol as compared to standard drugs thiourea and acetohydroxamic acid (− 3.459, − 3.049 and − 21.156 kJ/mol and − 17.454 kJ/mol) whereas compounds C4c, C4(e, h) exhibited moderate in vivo activity when compared to standard. Conclusions Selected candidates from the outcome of in vitro urease inhibitory were further examined for anti-H. Pylori activity by well diffusion method against H. pylori bacterium (DSM 4867). Compound C4a showed significant anti-H. Pylori activity with zone of inhibition 10.00 ± 0.00 mm and MIC value 500 μg/mL as compared to standard drug acetohydroxamic acid having zone of inhibition 9.00 ± 0.50 mm and MIC 1000 μg/mL. Molecular docking studies also showed that compounds show strong inhibition by forming strong hydrogen bonding interactions with residues of pocket site in target protein. Hence, the present investigation studies will provide a new vision for the discovery of potent agents against H. Pylori and urease associated diseases.
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Affiliation(s)
- Ritu Kataria
- International Institute of Pharmaceutical Sciences, Sonepat, Haryana India
| | - Anurag Khatkar
- 2Laboratory for Preservation Technology and Enzyme Inhibition Studies, Faculty of Pharmaceutical Sciences, Maharshi Dayanand University, Rohtak, Haryana India
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Isaac IO, al-Rashida M, Rahman SU, Alharthy RD, Asari A, Hameed A, Khan KM, Iqbal J. Acridine-based (thio)semicarbazones and hydrazones: Synthesis, in vitro urease inhibition, molecular docking and in-silico ADME evaluation. Bioorg Chem 2019; 82:6-16. [DOI: 10.1016/j.bioorg.2018.09.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 09/19/2018] [Accepted: 09/21/2018] [Indexed: 12/18/2022]
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Extracellular urease from Arthrobacter creatinolyticus MTCC 5604: scale up, purification and its cytotoxic effect thereof. Mol Biol Rep 2018; 46:133-141. [PMID: 30374769 DOI: 10.1007/s11033-018-4453-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 10/18/2018] [Indexed: 10/28/2022]
Abstract
Urease is a potent metalloenzyme with diverse applications. This paper describes the scale up and purification of an extracellular urease from Arthrobacter creatinolyticus MTCC 5604. The urease production was scaled-up in 3.7 L and 20 L fermentor. A maximum activity of 27 and 27.8 U/mL and a productivity of 0.90 and 0.99 U/mL/h were obtained at 30 h and 28 h in 3.7 and 20 L fermentor, respectively. Urease was purified to homogeneity with 49.85-fold purification by gel filtration and anion exchange chromatography with a yield of 36% and a specific activity of 1044.37 U/mg protein. The enzyme showed three protein bands with molecular mass of 72.6, 11.2 and 6.1 kDa on SDS-PAGE and ~ 270 kDa on native PAGE. The cytotoxic effect of urease was assessed in vitro using cancer cell lines (A549 and MG-63) and normal cell line (HEK 293). Urease showed its inhibitory effects on cancer cell lines through the generation of toxic ammonia, which in turn increased the pH of the surrounding medium. This increase in extracellular pH, enhanced the cytotoxic effect of weak base chemotherapeutic drugs, doxorubicin (50 µM) and vinblastine (100 µM) in the presence of urease (5 U/mL) and urea (0-4 mM) significantly.
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7
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Carrazoni T, Nguyen C, Maciel LF, Delgado-Cañedo A, Stewart BA, Lange AB, Dal Belo CA, Carlini CR, Orchard I. Jack bean urease modulates neurotransmitter release at insect neuromuscular junctions. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2018; 146:63-70. [PMID: 29626993 DOI: 10.1016/j.pestbp.2018.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 02/09/2018] [Accepted: 02/21/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Plants have developed a vast range of mechanisms to compete with phytophagous insects, including entomotoxic proteins such as ureases. The legume Canavalia ensiformis produces several urease isoforms, of which the more abundant is called Jack Bean Urease (JBU). Previews work has demonstrated the potential insecticidal effects of JBU, by mechanisms so far not entirely elucidated. In this work, we investigated the mechanisms involved in the JBU-induced activity upon neurotransmitter release on insect neuromuscular junctions. METHODS Electrophysiological recordings of nerve and muscle action potentials, and calcium imaging bioassays were employed. RESULTS AND CONCLUSION JBU (0.28 mg/animal/day) in Locusta migratoria 2nd instar through feeding and injection did not induce lethality, although it did result in a reduction of 20% in the weight gain at the end of 168 h (n = 9, p ≤ 0.05). JBU (0.014 and 0.14 mg) injected direct into the locust hind leg induced a dose and time-dependent decrease in the amplitude of muscle action potentials, with a maximum decrease of 70% in the amplitude at the highest dose (n = 5, p ≤ 0.05). At the same doses JBU did not alter the amplitude of action potentials evoked from motor neurons. Using Drosophila 3rd instar larvae neuromuscular preparations, JBU (10-7 M) increased the occurrence of miniature Excitatory Junctional Potentials (mEJPs) in the presence of 1 mM CaCl2 (n = 5, p ≤ 0.05). In low calcium (0.4 mM) assays, JBU (10-7 M) was not able to modulate the occurrence of the events. In Ca2+-free conditions, with EGTA or CoCl2, JBU induced a significant decrease in the occurrence of mEPJs (n = 5, p ≤ 0.05). Injected into the 3rd abdominal ganglion of Nauphoeta cinerea cockroaches, JBU (1 μM) induced a significant increase in Ca2+ influx (n = 7, p ≤ 0.01), similar to that seen for high KCl (35 mM) condition. Taken together the results confirm a direct action of JBU upon insect neuromuscular junctions and possibly central synapses, probably by disrupting the calcium machinery in the pre-synaptic region of the neurons.
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Affiliation(s)
- Thiago Carrazoni
- Universidade Federal do Rio Grande do Sul, Graduate Program in Cell and Molecular Biology, Center of Biotechnology, Porto Alegre, RS, Brazil; University of Toronto Mississauga, Department of Biology, Mississauga, ON, Canada; Pontifícia Universidade Católica do Rio Grande de Sul, Brain Institute, Porto Alegre, RS, Brazil.
| | - Christine Nguyen
- University of Toronto Mississauga, Department of Biology, Mississauga, ON, Canada
| | - Lucas F Maciel
- Universidade Federal do Pampa, Campus São Gabriel, São Gabriel, RS, Brazil
| | | | - Bryan A Stewart
- University of Toronto Mississauga, Department of Biology, Mississauga, ON, Canada
| | - Angela B Lange
- University of Toronto Mississauga, Department of Biology, Mississauga, ON, Canada
| | | | - Celia R Carlini
- Universidade Federal do Rio Grande do Sul, Graduate Program in Cell and Molecular Biology, Center of Biotechnology, Porto Alegre, RS, Brazil; Pontifícia Universidade Católica do Rio Grande de Sul, Brain Institute, Porto Alegre, RS, Brazil.
| | - Ian Orchard
- University of Toronto Mississauga, Department of Biology, Mississauga, ON, Canada.
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Isaeva G, Valieva R. Biological characteristics and virulence of Helicobacter pylori. CLINICAL MICROBIOLOGY AND ANTIMICROBIAL CHEMOTHERAPY 2018. [DOI: 10.36488/cmac.2018.1.14-23] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2023]
Abstract
This review summarizes the most recent data on the biological characteristics of Helicobacter pylori (morphological, cultural, biochemical). H. pylori pathogenicity factors promoting colonization, adhesion, biofilm formation, aggression, and cytotoxicity, their contribution to the pathogenesis of diseases as well as the possible relationships with various clinical outcomes are described in detail. The genetic heterogeneity of H. pylori strains which can determine different clinical manifestations and have significance for conducting epidemiological studies is also considered.
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Affiliation(s)
- G.Sh. Isaeva
- Kazan Research Institute of Epidemiology and Microbiology; Kazan State Medical University (Kazan, Russia)
| | - R.I. Valieva
- Kazan Research Institute of Epidemiology and Microbiology; KazanState Medical University (Kazan, Russia)
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Scopel-Guerra A, Olivera-Severo D, Staniscuaski F, Uberti AF, Callai-Silva N, Jaeger N, Porto BN, Carlini CR. The Impact of Helicobacter pylori Urease upon Platelets and Consequent Contributions to Inflammation. Front Microbiol 2017; 8:2447. [PMID: 29312166 PMCID: PMC5733092 DOI: 10.3389/fmicb.2017.02447] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/24/2017] [Indexed: 12/22/2022] Open
Abstract
Gastric infection by Helicobacter pylori is considered a risk factor for gastric and duodenal cancer, and extragastric diseases. Previous data have shown that, in a non-enzymatic way, H. pylori urease (HPU) activates neutrophils to produce ROS and also induces platelet aggregation, requiring ADP secretion modulated by the 12-lipoxygenase pathway, a signaling cascade also triggered by the physiological agonist collagen. Here we investigated further the effects on platelets of recombinant versions of the holoenzyme HPU, and of its two subunits (HpUreA and HpUreB). Although HpUreA had no aggregating activity on platelets, it partially inhibited collagen-induced aggregation. HpUreB induced platelet aggregation in the nanomolar range, and also interfered dose-dependently on both collagen- and ADP-induced platelet aggregation. HPU-induced platelet aggregation was inhibited by antibodies against glycoprotein VI (GPVI), the main collagen receptor in platelets. Flow cytometry analysis revealed exposure of P-selectin in HPU-activated platelets. Anti-glycoprotein IIbIIIa (GPIIbIIIa) antibodies increased the binding of FITC-labeled HPU to activated platelets, whereas anti-GPVI did not. Evaluation of post-transcriptional events in HPU-activated platelets revealed modifications in the pre-mRNA processing of pro-inflammatory proteins, with increased levels of mRNAs encoding IL-1β and CD14. We concluded that HPU activates platelets probably through its HpUreB subunit. Activation of platelets by HPU turns these cells into a pro-inflammatory phenotype. Altogether, our data suggest that H. pylori urease, besides allowing bacterial survival within the gastric mucosa, may have an important, and so far overlooked, role in gastric inflammation mediated by urease-activated neutrophils and platelets.
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Affiliation(s)
- Adriele Scopel-Guerra
- Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Deiber Olivera-Severo
- Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Department of Biology, Universidade Regional Integrada do Alto Uruguai e das Missões, São Luiz Gonzaga, Brazil
| | - Fernanda Staniscuaski
- Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Department of Molecular Biology and Biotechnology, Institute of Biosciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Augusto F Uberti
- Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Institute of Biology, Universidade Federal de Pelotas, Pelotas, Brazil
| | - Natália Callai-Silva
- Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Natália Jaeger
- Institute of Biomedical Research, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Bárbara N Porto
- Institute of Biomedical Research, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Celia R Carlini
- Brain Institute (BRAINS-InsCer), Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
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Tan RJ, Sun HQ, Zhang W, Yuan HM, Li B, Yan HT, Lan CH, Yang J, Zhao Z, Wu JJ, Wu C. A 21-35 kDa Mixed Protein Component from Helicobacter pylori Activates Mast Cells Effectively in Chronic Spontaneous Urticaria. Helicobacter 2016; 21:565-574. [PMID: 27061753 DOI: 10.1111/hel.12312] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND Helicobacter pylori (H. pylori) seem to involve in the etiology of chronic spontaneous urticaria (CSU). But studies of the pathogenic mechanism are very little. METHODS In this study, we detected the serum-specific anti-H. pylori IgG and IgE antibodies in 211 CSU and 137 normal subjects by enzyme-linked immunosorbent assay (ELISA), evaluated the direct activation effects of H. pylori preparations and its protein components on human LAD2 mast cell line in vitro, and analyzed the specific protein ingredients and functions of the most effective H. pylori mixed protein component using liquid chromatography-mass spectrometry and ELISA assay. RESULTS In CSU patients, the positive rate of anti-H. pylori IgG positive rate was significantly higher than that in normal controls, and the anti-H. pylori IgE levels had no statistical difference between H. pylori-infected patients with and without CSU. Further studies suggested that H. pylori preparations can directly activate human LAD2 mast cell line in a dose-dependent manner and its most powerful protein component was a mixture of 21-35 kDa proteins. Moreover, the 21-35 kDa mixed protein component mainly contained 23 kinds of proteins, which can stimulate the release of histamine, TNF-a, IL-3, IFN-γ, and LTB4 by LAD2 cells in a dose-dependent or time-dependent manner. CONCLUSIONS A 21-35 kDa mixed protein component should be regarded as the most promising pathogenic factor contributing to the CSU associated with H. pylori infection.
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Affiliation(s)
- Ran-Jing Tan
- Department of Dermatology, Daping Hospital, The Third Military Medical University, Chongqing, 400042, China.,Department of Microbiology and Biochemical Pharmacy, National Engineering Research Center of Immunological Products, College of Pharmacy, The Third Military Medical University, Chongqing, 400038, China
| | - He-Qiang Sun
- Department of Microbiology and Biochemical Pharmacy, National Engineering Research Center of Immunological Products, College of Pharmacy, The Third Military Medical University, Chongqing, 400038, China
| | - Wei Zhang
- Department of Dermatology, Daping Hospital, The Third Military Medical University, Chongqing, 400042, China
| | - Han-Mei Yuan
- Department of Microbiology and Biochemical Pharmacy, National Engineering Research Center of Immunological Products, College of Pharmacy, The Third Military Medical University, Chongqing, 400038, China
| | - Bin Li
- Department of Microbiology and Biochemical Pharmacy, National Engineering Research Center of Immunological Products, College of Pharmacy, The Third Military Medical University, Chongqing, 400038, China
| | - Hong-Tao Yan
- Department of Dermatology, Daping Hospital, The Third Military Medical University, Chongqing, 400042, China
| | - Chun-Hui Lan
- Department of Gastroenterology, Daping Hospital, The Third Military Medical University, Chongqing, 400042, China
| | - Jun Yang
- Department of Gastroenterology, Daping Hospital, The Third Military Medical University, Chongqing, 400042, China
| | - Zhuo Zhao
- Department of Microbiology and Biochemical Pharmacy, National Engineering Research Center of Immunological Products, College of Pharmacy, The Third Military Medical University, Chongqing, 400038, China
| | - Jin-Jin Wu
- Department of Dermatology, Daping Hospital, The Third Military Medical University, Chongqing, 400042, China
| | - Chao Wu
- Department of Microbiology and Biochemical Pharmacy, National Engineering Research Center of Immunological Products, College of Pharmacy, The Third Military Medical University, Chongqing, 400038, China
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Micheletto YMS, Moro CF, Lopes FC, Ligabue-Braun R, Martinelli AHS, Marques CM, Schroder AP, Carlini CR, da Silveira NP. Interaction of jack bean (Canavalia ensiformis) urease and a derived peptide with lipid vesicles. Colloids Surf B Biointerfaces 2016; 145:576-585. [PMID: 27281243 DOI: 10.1016/j.colsurfb.2016.05.063] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 05/20/2016] [Accepted: 05/24/2016] [Indexed: 12/17/2022]
Abstract
Ureases are metalloenzymes that catalyze the hydrolysis of urea to ammonia and carbon dioxide. Jack bean (Canavalia ensiformis) produces three isoforms of urease (Canatoxin, JBU and JBURE-II). Canatoxin and JBU display several biological properties independent of their ureolytic activity, such as neurotoxicity, exocytosis-inducing and pro-inflammatory effects, blood platelets activation, insecticidal and antifungal activities. The Canatoxin entomotoxic activity is mostly due to an internal peptide, named pepcanatox, released upon the hydrolysis of the protein by insect cathepsin-like digestive enzymes. Based on pepcanatox sequence, Jaburetox-2Ec was produced in Escherichia coli. JBU and its peptides were shown to permeabilize membranes through an ion channel-based mechanism. Here we studied the JBU and Jaburetox-2Ec interaction with platelet-like multilamellar liposomes (PML) using Dynamic Light Scattering and Small Angle X-ray Scattering techniques. We also analyzed the interaction of JBU with giant unilamellar vesicles (GUVs) using Fluorescence Microscopy. The interaction of vesicles with JBU led to a slight reduction of hydrodynamic radius, and caused an increase in the lamellar repeat distance of PML, suggesting a membrane disordering effect. In contrast, Jaburetox-2Ec decreased the lamellar repeat distance of PML membranes, while also diminishing their hydrodynamic radius. Fluorescence microscopy showed that the interaction of GUVs with JBU caused membrane perturbation with formation of tethers. In conclusion, JBU can interact with PML, probably by inserting its Jaburetox "domain" into the PML external membrane. Additionally, the interaction of Jaburetox-2Ec affects the vesicle's internal bilayers and hence causes more drastic changes in the PML membrane organization in comparison with JBU.
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Affiliation(s)
| | - Carlo Frederico Moro
- Graduate Program in Cellular and Molecular Biology, Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Fernanda Cortez Lopes
- Instituto do Cérebro, Pontíficia Universidade Católicado Rio Grande do Sul, Porto Alegre, RS, Brazil; Department of Biophysics, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Rodrigo Ligabue-Braun
- Graduate Program in Cellular and Molecular Biology, Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | | | | | | | - Célia Regina Carlini
- Graduate Program in Cellular and Molecular Biology, Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil; Instituto do Cérebro, Pontíficia Universidade Católicado Rio Grande do Sul, Porto Alegre, RS, Brazil; Department of Biophysics, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
| | - Nádya Pesce da Silveira
- Graduate Program in Chemistry, Institute of Chemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
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Carlini CR, Ligabue-Braun R. Ureases as multifunctional toxic proteins: A review. Toxicon 2015; 110:90-109. [PMID: 26690979 DOI: 10.1016/j.toxicon.2015.11.020] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Revised: 11/09/2015] [Accepted: 11/26/2015] [Indexed: 12/21/2022]
Abstract
Ureases are metalloenzymes that hydrolyze urea into ammonia and carbon dioxide. They were the first enzymes to be crystallized and, with them, the notion that enzymes are proteins became accepted. Novel toxic properties of ureases that are independent of their enzyme activity have been discovered in the last three decades. Since our first description of the neurotoxic properties of canatoxin, an isoform of the jack bean urease, which appeared in Toxicon in 1981, about one hundred articles have been published on "new" properties of plant and microbial ureases. Here we review the present knowledge on the non-enzymatic properties of ureases. Plant ureases and microbial ureases are fungitoxic to filamentous fungi and yeasts by a mechanism involving fungal membrane permeabilization. Plant and at least some bacterial ureases have potent insecticidal effects. This entomotoxicity relies partly on an internal peptide released upon proteolysis of ingested urease by insect digestive enzymes. The intact protein and its derived peptide(s) are neurotoxic to insects and affect a number of other physiological functions, such as diuresis, muscle contraction and immunity. In mammal models some ureases are acutely neurotoxic upon injection, at least partially by enzyme-independent effects. For a long time bacterial ureases have been recognized as important virulence factors of diseases by urease-producing microorganisms. Ureases activate exocytosis in different mammalian cells recruiting eicosanoids and Ca(2+)-dependent pathways, even when their ureolytic activity is blocked by an irreversible inhibitor. Ureases are chemotactic factors recognized by neutrophils (and some bacteria), activating them and also platelets into a pro-inflammatory "status". Secretion-induction by ureases may play a role in fungal and bacterial diseases in humans and other animals. The now recognized "moonlighting" properties of these proteins have renewed interest in ureases for their biotechnological potential to improve plant defense against pests and as potential targets to ameliorate diseases due to pathogenic urease-producing microorganisms.
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Affiliation(s)
- Celia R Carlini
- Brain Institute (Instituto do Cérebro-INSCER), Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, Brazil; Center of Biotechnology, Universidade Federal do Rio Grande do Sul Porto Alegre, RS, Brazil.
| | - Rodrigo Ligabue-Braun
- Center of Biotechnology, Universidade Federal do Rio Grande do Sul Porto Alegre, RS, Brazil
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Feder V, Kmetzsch L, Staats CC, Vidal-Figueiredo N, Ligabue-Braun R, Carlini CR, Vainstein MH. Cryptococcus gattii urease as a virulence factor and the relevance of enzymatic activity in cryptococcosis pathogenesis. FEBS J 2015; 282:1406-18. [PMID: 25675897 DOI: 10.1111/febs.13229] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Revised: 01/19/2015] [Accepted: 02/05/2015] [Indexed: 11/26/2022]
Abstract
Ureases (EC 3.5.1.5) are Ni(2+) -dependent metalloenzymes produced by plants, fungi and bacteria that hydrolyze urea to produce ammonia and CO2 . The insertion of nickel atoms into the apo-urease is better characterized in bacteria, and requires at least three accessory proteins: UreD, UreF, and UreG. Our group has demonstrated that ureases possess ureolytic activity-independent biological properties that could contribute to the pathogenicity of urease-producing microorganisms. The presence of urease in pathogenic bacteria strongly correlates with pathogenesis in some human diseases. Some medically important fungi also produce urease, including Cryptococcus neoformans and Cryptococcus gattii. C. gattii is an etiological agent of cryptococcosis, most often affecting immunocompetent individuals. The cryptococcal urease might play an important role in pathogenesis. It has been proposed that ammonia produced via urease action might damage the host endothelium, which would enable yeast transmigration towards the central nervous system. To analyze the role of urease as a virulence factor in C. gattii, we constructed knockout mutants for the structural urease-coding gene URE1 and for genes that code the accessory proteins Ure4 and Ure6. All knockout mutants showed reduced multiplication within macrophages. In intranasally infected mice, the ure1Δ (lacking urease protein) and ure4Δ (enzymatically inactive apo-urease) mutants caused reduced blood burdens and a delayed time of death, whereas the ure6Δ (enzymatically inactive apo-urease) mutant showed time and dose dependency with regard to fungal burden. Our results suggest that C. gattii urease plays an important role in virulence, in part possibly through enzyme activity-independent mechanism(s).
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Affiliation(s)
- Vanessa Feder
- Programa de Pós Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Universidade Federal do Rio Grande, Porto Alegre, Brazil
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Konieczna I, Zarnowiec P, Kwinkowski M, Kolesinska B, Fraczyk J, Kaminski Z, Kaca W. Bacterial urease and its role in long-lasting human diseases. Curr Protein Pept Sci 2013; 13:789-806. [PMID: 23305365 PMCID: PMC3816311 DOI: 10.2174/138920312804871094] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 07/15/2012] [Accepted: 09/03/2012] [Indexed: 02/07/2023]
Abstract
Urease is a virulence factor found in various pathogenic bacteria. It is essential in colonization of a host organism and in maintenance of bacterial cells in tissues. Due to its enzymatic activity, urease has a toxic effect on human cells. The presence of ureolytic activity is an important marker of a number of bacterial infections. Urease is also an immunogenic protein and is recognized by antibodies present in human sera. The presence of such antibodies is connected with progress of several long-lasting diseases, like rheumatoid arthritis, atherosclerosis or urinary tract infections. In bacterial ureases, motives with a sequence and/or structure similar to human proteins may occur. This phenomenon, known as molecular mimicry, leads to the appearance of autoantibodies, which take part in host molecules destruction. Detection of antibodies-binding motives (epitopes) in bacterial proteins is a complex process. However, organic chemistry tools, such as synthetic peptide libraries, are helpful in both, epitope mapping as well as in serologic investigations. In this review, we present a synthetic report on a molecular organization of bacterial ureases - genetic as well as structural. We characterize methods used in detecting urease and ureolytic activity, including techniques applied in disease diagnostic processes and in chemical synthesis of urease epitopes. The review also provides a summary of knowledge about a toxic effect of bacterial ureases on human body and about occurrence of anti-urease antibodies in long-lasting diseases.
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Affiliation(s)
- Iwona Konieczna
- Department of Microbiology, Institute of Biology, The Jan Kochanowski University, ul. Swietokrzyska 15, 25-406 Kielce, Poland.
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Arayne MS, Sultana N, Gul S, Khan A. Novel derivatives of 5-amino-1-cyclopropyl-7-[(3R,5S)3,5-dimethylpiperazine-1-yl]-6,8-difluoro-4-oxo-quinoline-3-carboxylic acid: their synthesis, antimicrobial, antifungal, and urease inhibitory studies. Med Chem Res 2013. [DOI: 10.1007/s00044-013-0699-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Uberti AF, Olivera-Severo D, Wassermann GE, Scopel-Guerra A, Moraes JA, Barcellos-de-Souza P, Barja-Fidalgo C, Carlini CR. Pro-inflammatory properties and neutrophil activation by Helicobacter pylori urease. Toxicon 2013; 69:240-9. [PMID: 23466444 DOI: 10.1016/j.toxicon.2013.02.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 12/25/2012] [Accepted: 02/05/2013] [Indexed: 01/25/2023]
Abstract
The gastric pathogen Helicobacter pylori produces large amounts of urease, whose enzyme activity enables the bacterium to survive in the stomach. We have previously shown that ureases display enzyme-independent effects in mammalian models, most through lipoxygenases-mediated pathways. Here, we evaluated potential pro-inflammatory properties of H. pylori urease (HPU). Mouse paw edema and activation of human neutrophils were tested using a purified, cell-free, recombinant HPU. rHPU induced paw edema with intense neutrophil infiltration. In vitro 100 nM rHPU was chemotactic to human neutrophils, inducing production of reactive oxygen species. rHPU-activated neutrophils showed increased lifespan, with inhibition of apoptosis accompanied by alterations of Bcl-XL and Bad contents. These effects of rHPU persisted in the absence of enzyme activity. rHPU-induced paw edema, neutrophil chemotaxis and apoptosis inhibition reverted in the presence of the lipoxygenase inhibitors esculetin or AA861. Neutrophils exposed to rHPU showed increased content of lipoxygenase(s) and no alteration of cyclooxygenase(s). Altogether, our data indicate that HPU, besides allowing the bacterial survival in the stomach, could play an important role in the pathogenesis of the gastrointestinal inflammatory disease caused by H. pylori.
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Affiliation(s)
- Augusto F Uberti
- Graduate Program in Cellular and Molecular Biology, Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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Paluzzi JPV, Young P, Defferrari MS, Orchard I, Carlini CR, O'Donnell MJ. Investigation of the potential involvement of eicosanoid metabolites in anti-diuretic hormone signaling in Rhodnius prolixus. Peptides 2012; 34:127-34. [PMID: 22079222 DOI: 10.1016/j.peptides.2011.10.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 10/21/2011] [Accepted: 10/23/2011] [Indexed: 11/21/2022]
Abstract
The use of naturally occurring plant-derived compounds for controlling insect pests remains an attractive alternative to potentially dangerous synthetic chemical compounds. One prospective plant-based compound, isoforms of the so-called jack bean urease (JBU) from the jack bean, Canavalia ensiformis, as well a derived peptide, Jaburetox-2Ec, have insecticidal effects on an array of insect species. In the Chagas' disease vector, Rhodnius prolixus, some of the physiological effects attributed to these urease isoforms include inhibition of serotonin (5-HT)-stimulated fluid secretion by the Malpighian tubules (MTs). Here, we investigated whether the effects of these exogenous urease isoforms were targeting the neuroendocrine network involved in the anti-diuretic hormone (RhoprCAPA-2) signaling cascade. We show that pharmacological agents known to interfere with eicosanoid metabolite biosynthesis do not affect RhoprCAPA-2 inhibition of 5-HT-stimulated fluid secretion by MTs. In addition, we demonstrate that RhoprCAPA-2 inhibition of MTs is independent of extracellular or intracellular calcium. Using a heterologous system for analysis of receptor activation, we show that neither JBU nor Jaburetox-2Ec are agonists of the anti-diuretic hormone receptor, RhoprCAPAr1. Finally, activation of the receptor using sub-maximal doses of the natural ligand, RhoprCAPA-2, was not influenced by the presence of either JBU or Jaburetox-2Ec indicating that the urease isoforms do not compete with RhoprCAPA-2 for binding and activation of RhoprCAPAr1. Taken together, these results suggest that at least two distinct mechanisms leading to inhibition of fluid secretion by MTs exist in R. prolixus and, unlike the urease-related effects, the eicosanoid metabolite pathway is not involved in RhoprCAPA-2 mediated anti-diuresis.
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Plant ureases and related peptides: understanding their entomotoxic properties. Toxins (Basel) 2012; 4:55-67. [PMID: 22474566 PMCID: PMC3317107 DOI: 10.3390/toxins4020055] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 01/05/2012] [Accepted: 01/11/2012] [Indexed: 01/08/2023] Open
Abstract
Recently, ureases were included in the arsenal of plant defense proteins, alongside many other proteins with biotechnological potential such as insecticides. Isoforms of Canavalia ensiformis urease (canatoxin—CNTX and jack bean urease—JBURE-I) are toxic to insects of different orders. This toxicity is due in part to the release of a 10 kDa peptide from the native protein, by cathepsin-like enzymes present in the insect digestive tract. The entomotoxic peptide, Jaburetox-2Ec, exhibits potent insecticidal activity against several insects, including many resistant to the native ureases. JBURE-I and Jaburetox-2Ec cause major alterations of post-feeding physiological processes in insects, which contribute to, or can be the cause of, their entomotoxic effect. An overview of the current knowledge on plant urease processing and mechanisms of action in insects is presented in this review.
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Murphy TF, Brauer AL. Expression of urease by Haemophilus influenzae during human respiratory tract infection and role in survival in an acid environment. BMC Microbiol 2011; 11:183. [PMID: 21843372 PMCID: PMC3166929 DOI: 10.1186/1471-2180-11-183] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2011] [Accepted: 08/16/2011] [Indexed: 12/21/2022] Open
Abstract
Background Nontypeable Haemophilus influenzae is a common cause of otitis media in children and lower respiratory tract infection in adults with chronic obstructive pulmonary disease (COPD). Prior studies have shown that H. influenzae expresses abundant urease during growth in the middle ear of the chinchilla and in pooled human sputum, suggesting that expression of urease is important for colonization and infection in the hostile environments of the middle ear and in the airways in adults. Virtually nothing else is known about the urease of H. influenzae, which was characterized in the present study. Results Analysis by reverse transcriptase PCR revealed that the ure gene cluster is expressed as a single transcript. Knockout mutants of a urease structural gene (ureC) and of the entire ure operon demonstrated no detectable urease activity indicating that this operon is the only one encoding an active urease. The ure operon is present in all strains tested, including clinical isolates from otitis media and COPD. Urease activity decreased as nitrogen availability increased. To test the hypothesis that urease is expressed during human infection, purified recombinant urease C was used in ELISA with pre acquisition and post infection serum from adults with COPD who experienced infections caused by H. influenzae. A total of 28% of patients developed new antibodies following infection indicating that H. influenzae expresses urease during airway infection. Bacterial viability assays performed at varying pH indicate that urease mediates survival of H. influenzae in an acid environment. Conclusions The H. influenzae genome contains a single urease operon that mediates urease expression and that is present in all clinical isolates tested. Nitrogen availability is a determinant of urease expression. H. influenzae expresses urease during human respiratory tract infection and urease is a target of the human antibody response. Expression of urease enhances viability in an acid environment. Taken together, these observations suggest that urease is important for survival and replication of H. influenzae in the human respiratory tract.
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Affiliation(s)
- Timothy F Murphy
- Division of Infectious Diseases, Department of Medicine, University at Buffalo, State University of New York, Buffalo, NY 14203, USA.
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Demartini DR, Carlini CR, Thelen JJ. Global and targeted proteomics in developing jack bean (Canavalia ensiformis) seedlings: an investigation of urease isoforms mobilization in early stages of development. PLANT MOLECULAR BIOLOGY 2011; 75:53-65. [PMID: 20978823 DOI: 10.1007/s11103-010-9707-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2010] [Accepted: 10/12/2010] [Indexed: 05/30/2023]
Abstract
Jack bean (Canavalia ensiformis) seeds are toxic for insects and the toxicity is due in part to an entomotoxic peptide enzymatically released from ureases in the midgut of susceptible insects. To characterize expression of urease isoforms in jack bean seed, particularly the more abundant urease isoform (JBU), quantitative proteomics was performed. Quiescent through 5-day germinating seeds were analyzed at 1-day intervals using a total proteomics approach (TPA) and also after co-immunoprecipitation (co-IP) with anti-JBU monoclonal antibodies. Jack bean proteins for TPA and co-IP were pre-fractionated by SDS-PAGE, segmented for in-gel trypsin digestion, and analyzed by liquid chromatography coupled to nanospray ionization tandem mass spectrometry (LC-MS/MS). Acquired MS(2) data were searched against a comprehensive plant database and the MEROPS peptidase database, in the absence of a jack bean EST database. Proteins detected in TPA were quantified by label-free spectral counting. A total of 234 and 106 non-redundant proteins were detected in TPA and co-IP, respectively. Mobilization of JBU was observed beginning 3-days after imbibition indicating that the entomotoxic peptide was not formed before this stage. A predicted urease isoform, JBURE-IIb, was detected in the co-IP study. Additionally, 46 plastid proteins, including RuBisCO and plastid ATPase were pulled down with JBU antibodies. These data shed new light on the behavior of urease isoforms during the early stages of plant development.
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Affiliation(s)
- Diogo Ribeiro Demartini
- Department of Biophysics and Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500 Prédio 43422. Sala 204, Porto Alegre, RS, 91501-970, Brazil.
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Functional and phylogenetic analysis of ureD in Shiga toxin-producing Escherichia coli. J Bacteriol 2010; 193:875-86. [PMID: 21148732 DOI: 10.1128/jb.00922-10] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) is a food-borne pathogen that can cause severe health complications and utilizes a much lower infectious dose than other E. coli pathotypes. Despite having an intact ure locus, ureDABCEFG, the majority of EHEC strains are phenotypically urease negative under tested conditions. Urease activity potentially assists with survival fitness by enhancing acid tolerance during passage through the stomach or by aiding with colonization in either human or animal reservoirs. Previously, in the EHEC O157:H7 Sakai strain, a point mutation in ureD, encoding a urease chaperone protein, was identified, resulting in a substitution of an amber stop codon for glutamine. This single nucleotide polymorphism (SNP) is observed in the majority of EHEC O157:H7 isolates and correlates with a negative urease phenotype in vitro. We demonstrate that the lack of urease activity in vitro is not solely due to the amber codon in ureD. Our analysis has identified two additional SNPs in ureD affecting amino acid positions 38 and 205, in both cases determining whether the encoded amino acid is leucine or proline. Phylogenetic analysis based on Ure protein sequences from a variety of urease-encoding bacteria demonstrates that the proline at position 38 is highly conserved among Gram-negative bacteria. Experiments reveal that the L38P substitution enhances urease enzyme activity; however, the L205P substitution does not. Multilocus sequence typing analysis for a variety of Shiga toxin-producing E. coli isolates combined with the ureD sequence reveals that except for a subset of the O157:H7 strains, neither the in vitro urease-positive phenotype nor the ureD sequence is phylogenetically restricted.
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Stanisçuaski F, Te Brugge V, Carlini CR, Orchard I. Jack bean urease alters serotonin-induced effects on Rhodnius prolixus anterior midgut. JOURNAL OF INSECT PHYSIOLOGY 2010; 56:1078-1086. [PMID: 20223243 DOI: 10.1016/j.jinsphys.2010.03.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 03/01/2010] [Accepted: 03/01/2010] [Indexed: 05/28/2023]
Abstract
Urease isoforms from jack bean seeds are toxic to insects, and this entomotoxic effect is mostly due to the release of a peptide by insect digestive enzymes. We previously demonstrated that jack bean urease (JBU) has antidiuretic effects on Rhodnius prolixus Malpighian tubules, decreasing the serotonin-stimulated secretion of fluid. Now, we evaluate the toxicity of the intact JBU and its effect on R. prolixus anterior midgut, to further elucidate the mechanism of action of JBU in insects. JBU decreases the serotonin-induced fluid transport by the anterior midgut in vitro when injected into the lumen. A decrease in the levels of cAMP is observed in tissues treated with JBU (in the presence of serotonin). JBU also causes a dose-dependent increase in the frequency of serotonin-induced contractions in the anterior midgut, but does not alter the frequency of spontaneous contractions. The cyclooxygenase inhibitor indomethacin and the prostaglandin antagonist AH6809 block JBU's potentiation of serotonin-induced contractions, indicating that prostaglandins might act as second messengers for JBU action. Prostaglandin E(2) (PGE(2)) increases the frequency of serotonin-induced contractions, again supporting the role of prostaglandins as second messengers for JBU action. JBU and PGE(2) increase cGMP levels in the anterior midgut, indicating that this molecule might also be part of the JBU pathway.
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Affiliation(s)
- F Stanisçuaski
- Department of Biophysics, Institute of Biosciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
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Crystal structure of the first plant urease from jack bean: 83 years of journey from its first crystal to molecular structure. J Mol Biol 2010; 400:274-83. [PMID: 20471401 DOI: 10.1016/j.jmb.2010.05.009] [Citation(s) in RCA: 206] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 05/03/2010] [Accepted: 05/06/2010] [Indexed: 11/23/2022]
Abstract
Urease, a nickel-dependent metalloenzyme, is synthesized by plants, some bacteria, and fungi. It catalyzes the hydrolysis of urea into ammonia and carbon dioxide. Although the amino acid sequences of plant and bacterial ureases are closely related, some biological activities differ significantly. Plant ureases but not bacterial ureases possess insecticidal properties independent of its ureolytic activity. To date, the structural information is available only for bacterial ureases although the jack bean urease (Canavalia ensiformis; JBU), the best-studied plant urease, was the first enzyme to be crystallized in 1926. To better understand the biological properties of plant ureases including the mechanism of insecticidal activity, we initiated the structural studies on some of them. Here, we report the crystal structure of JBU, the first plant urease structure, at 2.05 A resolution. The active-site architecture of JBU is similar to that of bacterial ureases containing a bi-nickel center. JBU has a bound phosphate and covalently modified residue (Cys592) by beta-mercaptoethanol at its active site, and the concomitant binding of multiple inhibitors (phosphate and beta-mercaptoethanol) is not observed so far in bacterial ureases. By correlating the structural information of JBU with the available biophysical and biochemical data on insecticidal properties of plant ureases, we hypothesize that the amphipathic beta-hairpin located in the entomotoxic peptide region of plant ureases might form a membrane insertion beta-barrel as found in beta-pore-forming toxins.
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Wassermann GE, Olivera-Severo D, Uberti AF, Carlini CR. Helicobacter pylori urease activates blood platelets through a lipoxygenase-mediated pathway. J Cell Mol Med 2009; 14:2025-34. [PMID: 19754669 PMCID: PMC3823284 DOI: 10.1111/j.1582-4934.2009.00901.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The bacterium Helicobacter pylori causes peptic ulcers and gastric cancer in human beings by mechanisms yet not fully understood. H. pylori produces urease which neutralizes the acidic medium permitting its survival in the stomach. We have previously shown that ureases from jackbean, soybean or Bacillus pasteurii induce blood platelet aggregation independently of their enzyme activity by a pathway requiring platelet secretion, activation of calcium channels and lipoxygenase-derived eicosanoids. We investigated whether H. pylori urease displays platelet-activating properties and defined biochemical pathways involved in this phenomenon. For that the effects of purified recombinant H. pylori urease (HPU) added to rabbit platelets were assessed turbidimetrically. ATP secretion and production of lipoxygenase metabolites by activated platelets were measured. Fluorescein-labelled HPU bound to platelets but not to erythrocytes. HPU induced aggregation of rabbit platelets (ED(50) 0.28 microM) accompanied by ATP secretion. No correlation was found between platelet activation and ureolytic activity of HPU. Platelet aggregation was blocked by esculetin (12-lipoxygenase inhibitor) and enhanced approximately 3-fold by indomethacin (cyclooxygenase inhibitor). A metabolite of 12-lipoxygenase was produced by platelets exposed to HPU. Platelet responses to HPU did not involve platelet-activating factor, but required activation of verapamil-inhibitable calcium channels. Our data show that purified H. pylori urease activates blood platelets at submicromolar concentrations. This property seems to be common to ureases regardless of their source (plant or bacteria) or quaternary structure (single, di- or tri-chain proteins). These properties of HPU could play an important role in pathogenesis of gastrointestinal and associated cardiovascular diseases caused by H. pylori.
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Affiliation(s)
- German E Wassermann
- Graduate Program in Cellular and Molecular Biology, Center of Biotechnology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
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Stanisçuaski F, Te Brugge V, Carlini CR, Orchard I. Invitro effect of Canavalia ensiformis urease and the derived peptide Jaburetox-2Ec on Rhodnius prolixus Malpighian tubules. JOURNAL OF INSECT PHYSIOLOGY 2009; 55:255-263. [PMID: 19121321 DOI: 10.1016/j.jinsphys.2008.12.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Revised: 12/02/2008] [Accepted: 12/04/2008] [Indexed: 05/27/2023]
Abstract
Ureases are metalloenzymes that are widespread among plants, fungi and bacteria. Urease isoforms (jack bean urease-JBU and canatoxin) from Canavalia ensiformis seeds are toxic to insects and fungi, suggesting a role in plant defense. The entomotoxic effect is due to the release of a 10-kDa peptide by cathepsin-like enzymes in the insect's midgut. Urease causes a decrease in post-feeding weight loss in Rhodnius prolixus, suggesting an effect on water balance. To investigate how this impairment occurs, we have evaluated the action of JBU and the urease-derivated peptide Jaburetox-2Ec on R. prolixus Malpighian tubules and also investigated the involvement of second messengers. JBU and Jaburetox-2Ec affect serotonin-induced secretion from Malpighian tubules. This effect is not cAMP-dependent, but the Jaburetox-2Ec effect is cGMP-dependent. Eicosanoid metabolites and calcium ions appear to be involved in JBU effect on diuresis, but are not involved in the action of Jaburetox-2Ec. Jaburetox-2Ec, but not JBU, causes a change in the transepithelial potential of the tubules. Canatoxin has a similar effect on tubules secretion, decreasing the secretion rate, but the urease from Helicobacter pylori has no significant effect. These data are helpful in our understanding of the actions of ureases and derived peptides on insects, and also reinforces the potential use of these proteins as biopesticides.
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Affiliation(s)
- Fernanda Stanisçuaski
- Department of Biophysics, Institute of Biosciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, 91501-970, Brazil.
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26
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Tobin NP, Henehan GT, Murphy RP, Atherton JC, Guinan AF, Kerrigan SW, Cox D, Cahill PA, Cummins PM. Helicobacter pylori-induced inhibition of vascular endothelial cell functions: a role for VacA-dependent nitric oxide reduction. Am J Physiol Heart Circ Physiol 2008; 295:H1403-13. [PMID: 18660451 DOI: 10.1152/ajpheart.00240.2008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Epidemiological and clinical studies provide compelling support for a causal relationship between Helicobacter pylori infection and endothelial dysfunction, leading to vascular diseases. However, clear biochemical evidence for this association is limited. In the present study, we have conducted a comprehensive investigation of endothelial injury in bovine aortic endothelial cells (BAECs) induced by H. pylori-conditioned medium (HPCM) prepared from H. pylori 60190 [vacuolating cytotoxin A (Vac(+))]. BAECs were treated with either unconditioned media, HPCM (0-25% vol/vol), or Escherichia coli-conditioned media for 24 h, and cell functions were monitored. Vac(+) HPCM significantly decreased BAEC proliferation, tube formation, and migration (by up to 44%, 65%, and 28%, respectively). Posttreatment, we also observed sporadic zonnula occludens-1 immunolocalization along the cell-cell border, and increased BAEC permeability to FD40 Dextran, indicating barrier reduction. These effects were blocked by 5-nitro-2-(3-phenylpropylamino)benzoic acid (VacA inhibitor) and were not observed with conditioned media prepared from either VacA-deleted H. pylori or E. coli. The cellular mechanism mediating these events was also considered. Vac(+) HPCM (but not Vac(-)) reduced nitric oxide (NO) by >50%, whereas S-nitroso-N-acetylpenicillamine, an NO donor, recovered all Vac(+) HPCM-dependent effects on cell functions. We further demonstrated that laminar shear stress, an endothelial NO synthase/NO stimulus in vivo, could also recover the Vac(+) HPCM-induced decreases in BAEC functions. This study shows, for the first time, a significant proatherogenic effect of H. pylori-secreted factors on a range of vascular endothelial dysfunction markers. Specifically, the VacA-dependent reduction in endothelial NO is indicated in these events. The atheroprotective impact of laminar shear stress in this context is also evident.
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Affiliation(s)
- Nicholas P Tobin
- School of Biotechnology, Dublin City University, Dublin, Ireland
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27
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Menegassi A, Wassermann GE, Olivera-Severo D, Becker-Ritt AB, Martinelli AHS, Feder V, Carlini CR. Urease from cotton (Gossypium hirsutum) seeds: isolation, physicochemical characterization, and antifungal properties of the protein. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2008; 56:4399-405. [PMID: 18494485 DOI: 10.1021/jf0735275] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Ureases (EC 3.5.1.5) are metalloenzymes that hydrolyze urea to produce ammonia and carbon dioxide These enzymes, which are found in fungi, bacteria, and plants, show very similar structures. Despite an abundance of urease in vegetal tissues, the physiological role of this enzyme in plants is still poorly understood. It has been previously described that ureases from the legumes jackbean ( Canavalia ensiformis) and soybean ( Glycine max) have insecticidal activity and antifungal properties. This work presents the physicochemical purification and characterization of a urease from cotton ( Gossypium hirsutum) seeds, the first description of this enzyme in Malvaceae. The urease content varied among different cotton cultivars. Cotton seed urease (98.3 kDa) displayed low ureolytic activity but exhibited potent antifungal properties at sub-micromolar concentrations against different phytopathogenic fungi. As described for other ureases, the antifungal effect of cotton urease persisted after treatment with an irreversible inhibitor of its enzyme activity. The data suggest an important role of these proteins in plant defense.
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Affiliation(s)
- Angela Menegassi
- Graduate Program in Molecular and Cellular Biology-Center of Biotechnology and Department of Biophysics, Universidade Federal do Rio Grande do Sul-UFRGS, Porto Alegre, RS CEP 91501-970, Brazil
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28
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Follmer C. Insights into the role and structure of plant ureases. PHYTOCHEMISTRY 2008; 69:18-28. [PMID: 17706733 DOI: 10.1016/j.phytochem.2007.06.034] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Revised: 06/11/2007] [Accepted: 06/28/2007] [Indexed: 05/11/2023]
Abstract
The broad distribution of ureases in leguminous seeds, as well as the accumulation pattern of the protein during seed maturation, are suggestive of an important physiological role for this enzyme. Since the isolation and characterization of jack bean urease by Sumner in 1926, many investigations have been dedicated to the structural and biological features of this enzyme; nevertheless, many questions still remain. It has been reported that ureases from plants (jack bean and soybean seeds) display biological properties unrelated to their ureolytic activity, notably a high insecticidal activity against Coleoptera (beetles) and Hemiptera (bugs), suggesting that ureases might be involved in plant defense. Besides the insecticidal activity, canatoxin, a jack bean urease isoform, causes convulsions and death in mice and rats, induces indirect hemagglutination (hemilectin activity) and promotes exocytosis in several cell types. Not only plant ureases but also some microbial ureases (found in Bacillus pasteurii and Helicobacter pylori) are able to induce activation of platelets in a process mediated by lipoxygenase-derived metabolites. This review summarizes the biological and structural properties of plant ureases, compares them with those displayed by bacterial ureases, and discusses the significance of these findings.
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Affiliation(s)
- Cristian Follmer
- Departamento de Físico-Química, Instituto de Química, Universidade Federal do Rio de Janeiro, CT, Bloco A S410, Rio de Janeiro 21941-909, Brazil.
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29
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Becker-Ritt AB, Martinelli AHS, Mitidieri S, Feder V, Wassermann GE, Santi L, Vainstein MH, Oliveira JTA, Fiuza LM, Pasquali G, Carlini CR. Antifungal activity of plant and bacterial ureases. Toxicon 2007; 50:971-83. [PMID: 17825863 DOI: 10.1016/j.toxicon.2007.07.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Revised: 07/10/2007] [Accepted: 07/11/2007] [Indexed: 10/23/2022]
Abstract
Ureases (EC 3.5.1.5) are nickel-dependent metalloenzymes that catalyze the hydrolysis of urea to ammonia and carbon dioxide. Produced by plants, fungi and bacteria, but not by animals, ureases share significant homology and similar mechanisms of catalysis, although differing in quaternary structures. While fungal and plant ureases are homo-oligomeric proteins of 90 kDa subunits, bacterial ureases are multimers of two (e.g. Helicobacter pylori) or three subunit complexes. It has been proposed that in plants these enzymes are involved in nitrogen bioavailability and in protection against pathogens. Previous studies by our group have shown that plant ureases, but not a bacterial (Bacillus pasteurii) urease, display insecticidal activity. Herein we demonstrate that (Glycine max) embryo-specific soybean urease, jackbean (Canavalia ensiformis) major urease and a recombinant H. pylori urease impair growth of selected phytopathogenic fungi at sub-micromolar concentrations. This antifungal property of ureases is not affected by treatment of the proteins with an irreversible inhibitor of the ureolytic activity. Scanning electron microscopy of urease-treated fungi suggests plasmolysis and cell wall injuries. Altogether, our data indicate that ureases probably contribute to the plant arsenal of defense compounds against predators and phytopathogens and that the urease defense mechanism is independent of ammonia release from urea.
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Affiliation(s)
- A B Becker-Ritt
- Graduate Program in Molecular and Cellular Biology, Center of Biotechnology, Universidade Federal do Rio Grande do Sul-UFRGS, Brazil
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30
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Smith MG, Gianoulis TA, Pukatzki S, Mekalanos JJ, Ornston LN, Gerstein M, Snyder M. New insights into Acinetobacter baumannii pathogenesis revealed by high-density pyrosequencing and transposon mutagenesis. Genes Dev 2007; 21:601-14. [PMID: 17344419 PMCID: PMC1820901 DOI: 10.1101/gad.1510307] [Citation(s) in RCA: 374] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Acinetobacter baumannii has emerged as an important and problematic human pathogen as it is the causative agent of several types of infections including pneumonia, meningitis, septicemia, and urinary tract infections. We explored the pathogenic content of this harmful pathogen using a combination of DNA sequencing and insertional mutagenesis. The genome of this organism was sequenced using a strategy involving high-density pyrosequencing, a novel, rapid method of high-throughput sequencing. Excluding the rDNA repeats, the assembled genome is 3,976,746 base pairs (bp) and has 3830 ORFs. A significant fraction of ORFs (17.2%) are located in 28 putative alien islands, indicating that the genome has acquired a large amount of foreign DNA. Consistent with its role in pathogenesis, a remarkable number of the islands (16) contain genes implicated in virulence, indicating the organism devotes a considerable portion of its genes to pathogenesis. The largest island contains elements homologous to the Legionella/Coxiella Type IV secretion apparatus. Type IV secretion systems have been demonstrated to be important for virulence in other organisms and thus are likely to help mediate pathogenesis of A. baumannii. Insertional mutagenesis generated avirulent isolates of A. baumannii and verified that six of the islands contain virulence genes, including two novel islands containing genes that lacked homology with others in the databases. The DNA sequencing approach described in this study allows the rapid elucidation of the DNA sequence of any microbe and, when combined with genetic screens, can identify many novel genes important for microbial pathogenesis.
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Affiliation(s)
- Michael G. Smith
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA
| | - Tara A. Gianoulis
- Department of Molecular Biochemistry and Biophysics, Yale University, New Haven, Connecticut 06520, USA
- Program in Computational Biology and Bioinformatics, Yale University, New Haven, Connecticut 06520, USA
| | - Stefan Pukatzki
- Harvard Medical School, Department of Microbiology and Molecular Genetics, Boston, Massachusetts 02115, USA
| | - John J. Mekalanos
- Harvard Medical School, Department of Microbiology and Molecular Genetics, Boston, Massachusetts 02115, USA
| | - L. Nicholas Ornston
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA
| | - Mark Gerstein
- Department of Molecular Biochemistry and Biophysics, Yale University, New Haven, Connecticut 06520, USA
- Program in Computational Biology and Bioinformatics, Yale University, New Haven, Connecticut 06520, USA
| | - Michael Snyder
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA
- Department of Molecular Biochemistry and Biophysics, Yale University, New Haven, Connecticut 06520, USA
- Corresponding author.E-MAIL ; FAX (203) 432-6161
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