1
|
Johnston EL, Guy-Von Stieglitz S, Zavan L, Cross J, Greening DW, Hill AF, Kaparakis-Liaskos M. The effect of altered pH growth conditions on the production, composition, and proteomes of Helicobacter pylori outer membrane vesicles. Proteomics 2023:e2300269. [PMID: 37991474 DOI: 10.1002/pmic.202300269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/03/2023] [Accepted: 10/16/2023] [Indexed: 11/23/2023]
Abstract
Gram-negative bacteria release outer membrane vesicles (OMVs) that contain cargo derived from their parent bacteria. Helicobacter pylori is a Gram-negative human pathogen that produces urease to increase the pH of the surrounding environment to facilitate colonization of the gastric mucosa. However, the effect of acidic growth conditions on the production and composition of H. pylori OMVs is unknown. In this study, we examined the production, composition, and proteome of H. pylori OMVs produced during acidic and neutral pH growth conditions. H. pylori growth in acidic conditions reduced the quantity and size of OMVs produced. Additionally, OMVs produced during acidic growth conditions had increased protein, DNA, and RNA cargo compared to OMVs produced during neutral conditions. Proteomic analysis comparing the proteomes of OMVs to their parent bacteria demonstrated significant differences in the enrichment of beta-lactamases and outer membrane proteins between bacteria and OMVs, supporting that differing growth conditions impacts OMV composition. We also identified differences in the enrichment of proteins between OMVs produced during different pH growth conditions. Overall, our findings reveal that growth of H. pylori at different pH levels is a factor that alters OMV proteomes, which may affect their subsequent functions.
Collapse
Affiliation(s)
- Ella L Johnston
- Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Bundoora, Australia
- Research Centre for Extracellular Vesicles, La Trobe University, Bundoora, Australia
| | - Sebastian Guy-Von Stieglitz
- Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Bundoora, Australia
- Research Centre for Extracellular Vesicles, La Trobe University, Bundoora, Australia
| | - Lauren Zavan
- Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Bundoora, Australia
- Research Centre for Extracellular Vesicles, La Trobe University, Bundoora, Australia
| | - Jonathon Cross
- Baker Heart and Diabetes Institute, Melbourne, Australia
- Baker Department of Cardiometabolic Health, University of Melbourne, Melbourne, Australia
| | - David W Greening
- Research Centre for Extracellular Vesicles, La Trobe University, Bundoora, Australia
- Baker Heart and Diabetes Institute, Melbourne, Australia
- Baker Department of Cardiometabolic Health, University of Melbourne, Melbourne, Australia
| | - Andrew F Hill
- Research Centre for Extracellular Vesicles, La Trobe University, Bundoora, Australia
- Department of Biochemistry and Chemistry, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Australia
- Institute for Health and Sport, Victoria University, Melbourne, Victoria, Australia
| | - Maria Kaparakis-Liaskos
- Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Bundoora, Australia
- Research Centre for Extracellular Vesicles, La Trobe University, Bundoora, Australia
| |
Collapse
|
2
|
Maz TG, Caliskan HB, Capan I, Caliskan B, Özçelik B, Banoglu E. Design, Synthesis and Evaluation of Aryl‐Tailored Oxadiazole‐thiones as New Urease Inhibitors. ChemistrySelect 2023. [DOI: 10.1002/slct.202204449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Affiliation(s)
- Tugce Gur Maz
- Faculty of Pharmacy Department of Pharmaceutical Chemistry Gazi University 06560 Ankara Turkey
| | - H. Burak Caliskan
- Faculty of Engineering Department of Biomedical Engineering TOBB ETU Economy and Technology University 06560 Ankara Turkey
| | - Irfan Capan
- Technical Science Vocational College Department of Material and Material Processing Technologies Gazi University 06560 Ankara Turkey
| | - Burcu Caliskan
- Faculty of Pharmacy Department of Pharmaceutical Chemistry Gazi University 06560 Ankara Turkey
| | - Berrin Özçelik
- Faculty of Pharmacy Department of Pharmaceutical Microbiology Gazi University 06560 Ankara Turkey
| | - Erden Banoglu
- Faculty of Pharmacy Department of Pharmaceutical Chemistry Gazi University 06560 Ankara Turkey
| |
Collapse
|
3
|
Yaqoob S, Hameed A, Ahmed M, Imran M, Qadir MA, Ramzan M, Yousaf N, Iqbal J, Muddassar M. Antiurease screening of alkyl chain-linked thiourea derivatives: in vitro biological activities, molecular docking, and dynamic simulations studies. RSC Adv 2022; 12:6292-6302. [PMID: 35424581 PMCID: PMC8981555 DOI: 10.1039/d1ra08694d] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 02/08/2022] [Indexed: 12/23/2022] Open
Abstract
Urease has become an important therapeutic target because it stimulates the pathogenesis of many human health conditions, such as pyelonephritis, the development of urolithiasis, hepatic encephalopathy, peptic ulcers, gastritis and gastric cancer. A series of alkyl chain-linked thiourea derivatives were synthesized to screen for urease inhibition activity. Structure elucidation of these compounds was done by spectral studies, such as IR, 1H NMR and 13C NMR, and MS analysis. In vitro urease enzyme inhibition assay revealed that compound 3c was the most potent thiourea derivative among the series with IC50 values of 10.65 ± 0.45 μM, while compound 3g also exhibited good activity with an IC50 value of 15.19 ± 0.58 μM compared to standard thiourea with an IC50 value of 15.51 ± 0.11 μM. The other compounds in the series possessed moderate to weak urease inhibition activity with IC50 values ranging from 20.16 ± 0.48 to 60.11 ± 0.78 μM. The most potent compounds 3c and 3g were docked to jack bean urease (PDB ID: 4H9M) to evaluate their binding affinities and to find the plausible binding poses. The docked complexes were refined through 100 ns-long MD simulations. The simulation results revealed that the average RMSD of 3c was less than that of the 3g compound. Furthermore, the radius of gyration plots for both complexes showed that 3c and 3g docking predicted binding modes did not induce any conformational change in the urease structure. Urease has become an important therapeutic target because it stimulates the pathogenesis of many human health conditions, such as pyelonephritis, the development of urolithiasis, hepatic encephalopathy, peptic ulcers, gastritis and gastric cancer.![]()
Collapse
Affiliation(s)
- Sana Yaqoob
- H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi Karachi Pakistan
| | - Abdul Hameed
- H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi Karachi Pakistan .,Department of Chemistry, University of Sahiwal Sahiwal Pakistan
| | - Mahmood Ahmed
- Department of Chemistry, Division of Science and Technology, University of Education College Road Lahore Pakistan
| | - Muhammad Imran
- KAM-School of Life Sciences, FC College (A Chartered University) Lahore Pakistan
| | | | - Mahwish Ramzan
- Department of Biosciences, COMSATS University Islamabad Park Road Islamabad Pakistan
| | - Numan Yousaf
- Department of Biosciences, COMSATS University Islamabad Park Road Islamabad Pakistan
| | - Jamshed Iqbal
- Center for Advanced Drug Research, COMSATS Institute of Information Technology Abbottabad 22060 Pakistan
| | - Muhammad Muddassar
- Department of Biosciences, COMSATS University Islamabad Park Road Islamabad Pakistan
| |
Collapse
|
4
|
Mehmood R, Sadiq A, Alsantali RI, Mughal EU, Alsharif MA, Naeem N, Javid A, Al-Rooqi MM, Chaudhry GES, Ahmed SA. Synthesis and Evaluation of 1,3,5-Triaryl-2-Pyrazoline Derivatives as Potent Dual Inhibitors of Urease and α-Glucosidase Together with Their Cytotoxic, Molecular Modeling and Drug-Likeness Studies. ACS Omega 2022; 7:3775-3795. [PMID: 35128286 PMCID: PMC8811919 DOI: 10.1021/acsomega.1c06694] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 01/11/2022] [Indexed: 05/04/2023]
Abstract
In the present work, a concise library of 1,3,5-triaryl-2-pyrazolines (2a-2q) was designed and synthesized by employing a multistep strategy, and the newly synthesized compounds were screened for their urease and α-glucosidase inhibitory activities. The compounds (2a-2q) were characterized using a combination of several spectroscopic techniques including FT-IR, 1H NMR, 13C NMR, and EI-MS. All the synthesized compounds, except compound 2i, were potent against urease as compared to the standard inhibitor thiourea (IC50 = 21.37 ± 0.26 μM). These analogs disclosed varying degrees of urease inhibitory activities ranging from 9.13 ± 0.25 to 18.42 ± 0.42 μM. Compounds 2b, 2g, 2m, and 2q having IC50 values of 9.36 ± 0.27, 9.13 ± 0.25, 9.18 ± 0.35, and 9.35 ± 0.35 μM, respectively, showed excellent inhibitory activity as compared to standard thiourea (IC50 = 21.37 ± 0.26 μM). A kinetic study of compound 2g revealed that compound 2g inhibited urease in a competitive mode. Among the synthesized pyrazolines, the compounds 2c, 2k, 2m, and 2o exhibited excellent α-glucosidase inhibitory activity with the lowest IC50 values of 212.52 ± 1.31, 237.26 ± 1.28, 138.35 ± 1.32, and 114.57 ± 1.35 μM, respectively, as compared to the standard acarbose (IC50 = 375.82 ± 1.76 μM). The compounds (2a-2q) showed α-glucosidase IC50 values in the range of 114.57 ± 1.35 to 462.94 ± 1.23 μM. Structure-activity relationship revealed that the size and electron-donating or -withdrawing effects of substituents influenced the activities, which led to the urease and α-glucosidase inhibiting properties. Compound 2m was a dual potent inhibitor against urease and α-glucosidase due to the presence of 2-CF3 electron-withdrawing functionality on the phenyl ring. To the best of our knowledge, these synthetic compounds were found to be the most potent dual inhibitors of urease and α-glucosidase with minimum IC50 values. The cytotoxicity of the compounds (2a-2q) was also investigated against human cell lines MCF-7 and HeLa. Compound 2l showed moderate cytotoxic activity against MCF-7 and HeLa cell lines. Moreover, in silico studies on most active compounds were also performed to understand the binding interaction of most active compounds with active sites of urease and α-glucosidase enzymes. Some compounds exhibited drug-like characteristics due to their lower cytotoxic and good ADME profiles.
Collapse
Affiliation(s)
- Rabia Mehmood
- Department
of Chemistry, Govt. College Women University, Sialkot 51300, Pakistan
| | - Amina Sadiq
- Department
of Chemistry, Govt. College Women University, Sialkot 51300, Pakistan
| | - Reem I. Alsantali
- Department
of Pharmaceutical Chemistry, College of Pharmacy, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
| | | | - Meshari A. Alsharif
- Department
of Chemistry, Faculty of Applied Sciences, Umm Al-Qura University, Makkah 21955, Saudi Arabia
| | - Nafeesa Naeem
- Department
of Chemistry, University of Gujrat, Gujrat 50700, Pakistan
| | - Asif Javid
- Department
of Chemistry, University of Gujrat, Gujrat 50700, Pakistan
| | - Munirah M. Al-Rooqi
- Department
of Chemistry, Faculty of Applied Sciences, Umm Al-Qura University, Makkah 21955, Saudi Arabia
| | - Gul-e-Saba Chaudhry
- Institute
of Marine Biotechnology, Universiti Malaysia
Terengganu, Kuala Nerus 21030, Terengganu, Malaysia
- Microbiology
and Biotechnology Research Lab, Fatima Jinnah
Women University, Rawalpindi 23451, Pakistan
| | - Saleh A. Ahmed
- Department
of Chemistry, Faculty of Applied Sciences, Umm Al-Qura University, Makkah 21955, Saudi Arabia
- Department
of Chemistry, Faculty of Science, Assiut
University, Assiut 71516, Egypt
- ,
| |
Collapse
|
5
|
Tirmazi SAAS, Qadir MA, Ahmed M, Imran M, Hussain R, Sharif M, Yousaf M, Muddassar M. Levofloxacin and sulfa drugs linked via Schiff bases: Exploring their urease inhibition, enzyme kinetics and in silico studies. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130226] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
6
|
Pedebos C, Smith IPS, Boags A, Khalid S. The hitchhiker's guide to the periplasm: Unexpected molecular interactions of polymyxin B1 in E. coli. Structure 2021; 29:444-456.e2. [PMID: 33577754 DOI: 10.1016/j.str.2021.01.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 12/11/2020] [Accepted: 01/21/2021] [Indexed: 12/19/2022]
Abstract
The periplasm of Gram-negative bacteria is a complex, highly crowded molecular environment. Little is known about how antibiotics move across the periplasm and the interactions they experience. Here, atomistic molecular dynamics simulations are used to study the antibiotic polymyxin B1 within models of the periplasm, which are crowded to different extents. We show that PMB1 is likely to be able to "hitchhike" within the periplasm by binding to lipoprotein carriers-a previously unreported passive transport route. The simulations reveal that PMB1 forms both transient and long-lived interactions with proteins, osmolytes, lipids of the outer membrane, and the cell wall, and is rarely uncomplexed when in the periplasm. Furthermore, it can interfere in the conformational dynamics of native proteins. These are important considerations for interpreting its mechanism of action and are likely to also hold for other antibiotics that rely on diffusion to cross the periplasm.
Collapse
Affiliation(s)
- Conrado Pedebos
- School of Chemistry, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - Iain Peter Shand Smith
- School of Chemistry, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - Alister Boags
- School of Chemistry, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - Syma Khalid
- School of Chemistry, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK.
| |
Collapse
|
7
|
Ahmed M, Imran M, Muddassar M, Hussain R, Khan MU, Ahmad S, Mehboob MY, Ashfaq S. Benzenesulfonohydrazides inhibiting urease: Design, synthesis, their in vitro and in silico studies. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128740] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
8
|
Ozen T, Bora N, Yenigun S, Korkmaz H. An investigation of chemical content, enzyme inhibitory propert, antioxidant and antibacterial activity of
Aristolochia bodamae
Dingler (develiotu) (Aristolochiaceae) root extracts from Samsun, Turkey. FLAVOUR FRAG J 2020. [DOI: 10.1002/ffj.3559] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Tevfik Ozen
- Faculty of Science and Letters Department of Chemistry Ondokuz Mayis University Samsun Turkey
| | - Neslihan Bora
- Faculty of Science and Letters Department of Chemistry Ondokuz Mayis University Samsun Turkey
| | - Semiha Yenigun
- Faculty of Science and Letters Department of Chemistry Ondokuz Mayis University Samsun Turkey
| | - Hasan Korkmaz
- Faculty of Science and Letters Department of Biology Ondokuz Mayis University Samsun Turkey
| |
Collapse
|
9
|
Abstract
For a long time, antibiotics have been 'magical weapons' to combat pathogenic microbes. The success of antibiotics is now greatly threatened by resistance to antibiotics and many scientists have already talked about the coming of the postantibiotic era. This special issue is prepared to understand recent research findings and new concepts about antibiotic resistance. Above all, this special issue explores mechanisms for the generation, selection, and spread of antibiotic resistance, and gives insight into what to target to prevent the development of antibiotic resistance. Just as antibiotics came from the concept of "magic bullet", a breakthrough will come from a new concept based on a profound understanding of antibiotic resistance.
Collapse
Affiliation(s)
- Joon-Hee Lee
- Department of Pharmacy, College of Pharmacy, Pusan National University, Busan, 46241, Republic of Korea.
| |
Collapse
|
10
|
Lee SM, Park SY, Kim MJ, Cho EA, Jun CH, Park CH, Kim HS, Choi SK, Rew JS. Key lime ( Citrus aurantifolia) inhibits the growth of triple drug resistant Helicobacter pylori. Gut Pathog 2018; 10:16. [PMID: 29942354 PMCID: PMC5961513 DOI: 10.1186/s13099-018-0244-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 05/15/2018] [Indexed: 01/17/2023] Open
Abstract
Background Eradication rate for Helicobacter pylori (H. pylori) has decreased due to antibiotic resistance. Therefore, new strategies are needed to enhance H. pylori eradication, especially for H. pylori with high antibiotic resistance. The objective of this study was to evaluate anti-H. pylori activities of constituents from key lime (Citrus aurantifolia) and their possible inhibitory effects on urease activity of H. pylori. Methods Helicobacter pylori strain ATCC 43526 and triple drug resistant (TDR) H. pylori strains were used in this study. Urease activities of H. pylori strains were measured by ammonia colorimetrical quantification using ELISA reader. Minimum inhibitory concentrations were determined by agar dilution method for antibiotics and by modified media dilution method for each constituent of Citrus aurantifolia (C. aurantifolia). Results Citrus aurantifolia extract decreased the number of colonies of H. pylori strain ATCC 43526 and TDR H. pylori stains. An increasing concentration of C. aurantifolia extract attenuated urease activities of H. pylori strain ATCC 43526 and TDR H. pylori strains. Among constituents of C. aurantifolia, citral and 4-hexen-3-one were found to be able to inhibit the growth of H. pylori strain ATCC 43526 and TDR H. pylori strains. Furthermore, citral and 4-hexen-3-one inhibited urease activities of H. pylori strain ATCC 43526 and TDR H. pylori strains in a dose-dependent manner. Conclusion Citrus aurantifolia has antimicrobial effect on TDR H. pylori strains, suggesting that C. aurantifolia might have therapeutic potential to control antibiotic-resistant H. pylori strains that cause eradication failure using other antibiotics.
Collapse
Affiliation(s)
- Su-Mi Lee
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Chonnam National University Medical School, 42, Jaebongro, Dong-ku Gwangju, 501-757 South Korea
| | - Seon-Young Park
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Chonnam National University Medical School, 42, Jaebongro, Dong-ku Gwangju, 501-757 South Korea
| | - Moon-Ju Kim
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Chonnam National University Medical School, 42, Jaebongro, Dong-ku Gwangju, 501-757 South Korea
| | - Eun-Ae Cho
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Chonnam National University Medical School, 42, Jaebongro, Dong-ku Gwangju, 501-757 South Korea
| | - Chung-Hwan Jun
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Chonnam National University Medical School, 42, Jaebongro, Dong-ku Gwangju, 501-757 South Korea
| | - Chang-Hwan Park
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Chonnam National University Medical School, 42, Jaebongro, Dong-ku Gwangju, 501-757 South Korea
| | - Hyun-Soo Kim
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Chonnam National University Medical School, 42, Jaebongro, Dong-ku Gwangju, 501-757 South Korea
| | - Sung-Kyu Choi
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Chonnam National University Medical School, 42, Jaebongro, Dong-ku Gwangju, 501-757 South Korea
| | - Jong-Sun Rew
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Chonnam National University Medical School, 42, Jaebongro, Dong-ku Gwangju, 501-757 South Korea
| |
Collapse
|
11
|
Tan L, Li C, Chen H, Mo Z, Zhou J, Liu Y, Ma Z, Xu Y, Yang X, Xie J, Su Z. Epiberberine, a natural protoberberine alkaloid, inhibits urease of Helicobacter pylori and jack bean: Susceptibility and mechanism. Eur J Pharm Sci 2017; 110:77-86. [PMID: 28167234 DOI: 10.1016/j.ejps.2017.02.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 01/28/2017] [Accepted: 02/02/2017] [Indexed: 12/31/2022]
Abstract
In our previous study, Rhizoma Coptidis extract was found to exert more potent inhibitory effect than its major component berberine towards urease from Helicobacter pylori (HPU) and jack bean (JBU). In continuation of our work, the present study was designed to further comparatively investigate the urease inhibitory activities of five major protoberberine alkaloids in Rhizoma Coptidis, namely berberine, palmatine, coptisine, epiberberine, jateorhizine to identify the bioactive constituent, and illuminate the potential mechanism of action. Results indicated that the five protoberberine alkaloids acted as concentration-dependent inactivators of urease with IC50 values ranging between 3.0 and 5087μM for HPU and 2.3->10,000μM for JBU, respectively. Notably, epiberberine (EB) was found to be the most potent inhibitor against both ureases with IC50 values of 3.0±0.01μM for HPU and 2.3±0.01μM for JBU, which was more effective than the standard urease inhibitor, acetohydroxamic acid (83±0.01μM for HPU and 22±0.01μM for JBU, respectively). Further kinetic analysis revealed that the type of EB inhibition against HPU was slow-binding and uncompetitive, with Ki of 10.6±0.01μM, while slow-binding and competitive against JBU with Ki of 4.6±0.01μM. Addition of thiol reagents, such as l-cysteine, glutathione and dithiothreitol, significantly abolished the inhibition, while Ni2+ competitive inhibitors, boric acid and sodium fluoride, synergetically inhibited urease with EB, indicating the obligatory role of the active site sulfhydryl group for the inhibition. In addition, binding of EB with the urease proved to be reversible, as about 65% and 90% enzymatic activity of HPU and JBU, respectively, could be restored by dithiothreitol application. These findings highlighted the potential role of Rhizoma Coptidis protoberberine alkaloids, especially EB, as a lead urease inhibitor in the treatment of diseases associated with ureolytic bacteria. Thus, EB had good potential for further development into a promising therapeutic approach for the treatment of urease-related diseases.
Collapse
Affiliation(s)
- Lihua Tan
- School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, People's Republic of China; Guangdong Provincial Key Laboratory of New Chinese Medicinal Development and Research, Guangzhou 510006, People's Republic of China
| | - Cailan Li
- School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, People's Republic of China; Guangdong Provincial Key Laboratory of New Chinese Medicinal Development and Research, Guangzhou 510006, People's Republic of China
| | - Hanbin Chen
- The First Affiliated Hospital of Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou 510405, People's Republic of China
| | - Zhizhun Mo
- School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, People's Republic of China; Guangdong Provincial Key Laboratory of New Chinese Medicinal Development and Research, Guangzhou 510006, People's Republic of China
| | - Jiangtao Zhou
- School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, People's Republic of China; Guangdong Provincial Key Laboratory of New Chinese Medicinal Development and Research, Guangzhou 510006, People's Republic of China
| | - Yuhong Liu
- School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, People's Republic of China; Guangdong Provincial Key Laboratory of New Chinese Medicinal Development and Research, Guangzhou 510006, People's Republic of China
| | - Zhilin Ma
- School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, People's Republic of China
| | - Yuyao Xu
- School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, People's Republic of China
| | - Xiaobo Yang
- Guangdong Provincial Key Laboratory of Clinical Research on Traditional Chinese Medicine Syndrome, The Second Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou 510120, People's Republic of China
| | - Jianhui Xie
- Guangdong Provincial Key Laboratory of Clinical Research on Traditional Chinese Medicine Syndrome, The Second Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou 510120, People's Republic of China.
| | - Ziren Su
- School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, People's Republic of China; Guangdong Provincial Key Laboratory of New Chinese Medicinal Development and Research, Guangzhou 510006, People's Republic of China; Dongguan Mathematical Engineering Academy of Chinese Medicine, Guangzhou University of Chinese Medicine, Dongguan 523808, People's Republic of China.
| |
Collapse
|
12
|
Hassan STS, Šudomová M. The Development of Urease Inhibitors: What Opportunities Exist for Better Treatment of Helicobacter pylori Infection in Children? Children (Basel) 2017; 4:children4010002. [PMID: 28054971 PMCID: PMC5296663 DOI: 10.3390/children4010002] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 12/25/2016] [Accepted: 12/27/2016] [Indexed: 12/12/2022]
Abstract
Stomach infection with Helicobacter pylori (H. pylori) causes severe gastroduodenal diseases in a large number of patients worldwide. The H. pylori infection breaks up in early childhood, persists lifelong if not treated, and is associated with chronic gastritis and an increased risk of peptic ulcers and gastric cancer. In recent years, the problem of drug-resistant strains has become a global concern that makes the treatment more complicated and the infection persistent at higher levels when the antibiotic treatment is stopped. Such problems have led to the development of new strategies to eradicate an H. pylori infection. Currently, one of the most important strategies for the treatment of H. pylori infection is the use of urease inhibitors. Despite the fact that large numbers of molecules have been shown to exert potent inhibitory activity against H. pylori urease, most of them were prevented from being used in vivo and in clinical trials due to their hydrolytic instability, toxicity, and appearance of undesirable side effects. Therefore, it is crucial to focus attention on the available opportunities for the development of urease inhibitors with suitable pharmacokinetics, high hydrolytic stability, and free toxicological profiles. In this commentary, we aim to afford an outline on the current status of the use of urease inhibitors in the treatment of an H. pylori infection, and to discuss the possibility of their development as effective drugs in clinical trials.
Collapse
Affiliation(s)
- Sherif T S Hassan
- Department of Natural Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences Brno, Palackého tř. 1946/1, 61242 Brno, Czech Republic.
- Department of Applied Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Praha 6-Suchdol, Czech Republic.
| | - Miroslava Šudomová
- Museum of the Brno Region, Museum of Literature in Moravia, Porta Coeli 1001, 66602 Předklášteří, Czech Republic.
| |
Collapse
|
13
|
Macegoniuk K, Grela E, Palus J, Rudzińska-Szostak E, Grabowiecka A, Biernat M, Berlicki Ł. 1,2-Benzisoselenazol-3(2H)-one Derivatives As a New Class of Bacterial Urease Inhibitors. J Med Chem 2016; 59:8125-33. [DOI: 10.1021/acs.jmedchem.6b00986] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Katarzyna Macegoniuk
- Department
of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Ewa Grela
- Department
of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Jerzy Palus
- Department
of Organic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Ewa Rudzińska-Szostak
- Department
of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Agnieszka Grabowiecka
- Department
of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Monika Biernat
- Department
of Microbiology, Medical University of Wrocław, Tytusa Chałubińskiego
4, 50-368 Wrocław, Poland
| | - Łukasz Berlicki
- Department
of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| |
Collapse
|
14
|
Abstract
INTRODUCTION Urease is the enzyme that catalyzes the hydrolysis of urea, which is involved in serious infections caused by Helicobacter pylori in the gastric tract, as well as Proteus and related species in the urinary tract. The necessity to treat such infections has stimulated intensive studies on various groups of urease inhibitors. AREAS COVERED Patent literature on urease inhibitors with possible applications in medicine is reviewed in this paper. Hydroxamic acids, phosphoramidates, urea derivatives, quinones and heterocyclic compounds constitute the major classes of structures with such activity. EXPERT OPINION Until now, only one compound, acetohydroxamic acid, has been clinically used for the treatment of urinary tract infections by urease inhibition. Unfortunately, it exhibits severe side effects. Thus, it seems that the full potential of urease inhibition has not yet been fully explored. Several Japanese patents related to the use of herbal extracts as sources of polyphenolic urease inhibitors have been considered as complementary or alternative therapy; however, their accessibility is quite possibly due to reduced restrictions for the introduction of natural products to the market.
Collapse
Affiliation(s)
- Paulina Kosikowska
- Wrocław University of Technology, Department of Bioorganic Chemistry, Faculty of Chemistry, Wrocław, Poland
| | | |
Collapse
|
15
|
Vassiliou S, Kosikowska P, Grabowiecka A, Yiotakis A, Kafarski P, Berlicki Ł. Computer-Aided Optimization of Phosphinic Inhibitors of Bacterial Ureases. J Med Chem 2010; 53:5597-606. [DOI: 10.1021/jm100340m] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Stamatia Vassiliou
- Laboratory of Organic Chemistry, Department of Chemistry, University of Athens, Panepistimioplois, Zografou, 15701 Athens, Greece
| | - Paulina Kosikowska
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Agnieszka Grabowiecka
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Athanasios Yiotakis
- Laboratory of Organic Chemistry, Department of Chemistry, University of Athens, Panepistimioplois, Zografou, 15701 Athens, Greece
| | - Paweł Kafarski
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Łukasz Berlicki
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| |
Collapse
|
16
|
Haesebrouck F, Pasmans F, Flahou B, Chiers K, Baele M, Meyns T, Decostere A, Ducatelle R. Gastric helicobacters in domestic animals and nonhuman primates and their significance for human health. Clin Microbiol Rev. 2009;22:202-223, Table of Contents. [PMID: 19366912 DOI: 10.1128/cmr.00041-08] [Citation(s) in RCA: 218] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Helicobacters other than Helicobacter pylori have been associated with gastritis, gastric ulcers, and gastric mucosa-associated lymphoid tissue lymphoma in humans. These very fastidious microorganisms with a typical large spiral-shaped morphology were provisionally designated "H. heilmannii," but in fact they comprise at least five different Helicobacter species, all of which are known to colonize the gastric mucosa of animals. H. suis, which has been isolated from the stomachs of pigs, is the most prevalent gastric non-H. pylori Helicobacter species in humans. Other gastric non-H. pylori helicobacters colonizing the human stomach are H. felis, H. salomonis, H. bizzozeronii, and the still-uncultivable "Candidatus Helicobacter heilmannii." These microorganisms are often detected in the stomachs of dogs and cats. "Candidatus Helicobacter bovis" is highly prevalent in the abomasums of cattle but has only occasionally been detected in the stomachs of humans. There are clear indications that gastric non-H. pylori Helicobacter infections in humans originate from animals, and it is likely that transmission to humans occurs through direct contact. Little is known about the virulence factors of these microorganisms. The recent successes with in vitro isolation of non-H. pylori helicobacters from domestic animals open new perspectives for studying these microorganisms and their interactions with the host.
Collapse
|
17
|
|
18
|
Sangari FJ, Seoane A, Rodríguez MC, Agüero J, García Lobo JM. Characterization of the urease operon of Brucella abortus and assessment of its role in virulence of the bacterium. Infect Immun 2006; 75:774-80. [PMID: 17101645 PMCID: PMC1828483 DOI: 10.1128/iai.01244-06] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Most members of the genus Brucella show strong urease activity. However, the role of this enzyme in the pathogenesis of Brucella infections is poorly understood. We isolated several Tn5 insertion mutants deficient in urease activity from Brucella abortus strain 2308. The mutations of most of these mutants mapped to a 5.7-kbp DNA region essential for urease activity. Sequencing of this region, designated ure1, revealed the presence of seven open reading frames corresponding to the urease structural proteins (UreA, UreB, and UreC) and the accessory proteins (UreD, UreE, UreF, and UreG). In addition to the urease genes, another gene (cobT) was identified, and inactivation of this gene affected urease activity in Brucella. Subsequent analysis of the previously described sequences of the genomes of Brucella spp. revealed the presence of a second urease cluster, ure2, in all them. The ure2 locus was apparently inactive in B. abortus 2308. Urease-deficient mutants were used to evaluate the role of urease in Brucella pathogenesis. The urease-producing strains were found to be resistant in vitro to strong acid conditions in the presence of urea, while urease-negative mutants were susceptible to acid treatment. Similarly, the urease-negative mutants were killed more efficiently than the urease-producing strains during transit through the stomach. These results suggested that urease protects brucellae during their passage through the stomach when the bacteria are acquired by the oral route, which is the major route of infection in human brucellosis.
Collapse
Affiliation(s)
- Félix J Sangari
- Departamento de Biología Molecular, Universidad de Cantabria, C/Cardenal Herrera Oria s/n, 39011 Santander, Spain
| | | | | | | | | |
Collapse
|
19
|
Brandi G, Biavati B, Calabrese C, Granata M, Nannetti A, Mattarelli P, Di Febo G, Saccoccio G, Biasco G. Urease-positive bacteria other than Helicobacter pylori in human gastric juice and mucosa. Am J Gastroenterol 2006; 101:1756-61. [PMID: 16780553 DOI: 10.1111/j.1572-0241.2006.00698.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND AND AIM Many bacteria carry the urease enzyme in different human ecosystems, but Helicobacter pylori is the only known bacterium showing urease activity in gastric ecosystems. For this reason, the rapid urease test (RUT) on gastric biopsies and urea breath test (C-UBT) are used to detect H. pylori infection. The aim of this study was to evaluate the presence of urease-positive bacteria other than H. pylori in gastric juice and mucosa in hypochlorhydric subjects. METHODS Twenty-five hypochlorhydric and 10 normochlorhydric patients were analyzed for the presence of H. pylori and bacterial overgrowth both in gastric juice and on the mucosa. During upper gastrointestinal endoscopy at 8.00 a.m. gastric juice samples and biopsy specimens were taken from the antrum and corpus. All samples were analyzed using standard microbiological procedures like aerobic/anaerobic growth, gram-staining, gas chromatography, API test, 96-clone method, and selective medium to search for specific bacteria. In addition, all strains isolated were screened for urease activity using the CP-test. Urease positive strains were tested for the capacity to survive in an acid environment with or without urea (10 mM/L), at pH 7, 4, 3, and 2, respectively, at different times (0, 20, 30, and 60 min). RESULTS Six hypochlorhydric patients had 10 strains of urease-positive non-H. pylori bacteria among which Staphylococcus capitis urealiticum showed the strongest urease activity. CONCLUSIONS Hypochlorhydric patients present many urease-positive bacteria other than H. pylori. The strong urease activity may be responsible for false positive results at RUT or UBT test in patients with suspected H. pylori infection.
Collapse
Affiliation(s)
- Giovanni Brandi
- Institute of Haematology and Medical Oncology (L. e A. Seragnoli), University of Bologna, Bologna, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Abstract
Solenoid proteins, which are distinguished from general globular proteins by their modular architectures, are frequently involved in signal transduction pathways. Proteins from the tetratricopeptide repeat (TPR) and Sel1-like repeat (SLR) families share similar alpha-helical conformations but different consensus sequence lengths and superhelical topologies. Both families are characterized by low sequence similarity levels, rendering the identification of functional homologous difficult. Therefore current knowledge of the molecular and cellular functions of the SLR proteins Sel1, Hrd3, Chs4, Nif1, PodJ, ExoR, AlgK, HcpA, Hsp12, EnhC, LpnE, MotX, and MerG has been reviewed. Although SLR proteins possess different cellular functions they all seem to serve as adaptor proteins for the assembly of macromolecular complexes. Sel1, Hrd3, Hsp12 and LpnE are activated under cellular stress. The eukaryotic Sel1 and Hrd3 proteins are involved in the ER-associated protein degradation, whereas the bacterial LpnE, EnhC, HcpA, ExoR, and AlgK proteins mediate the interactions between bacterial and eukaryotic host cells. LpnE and EnhC are responsible for the entry of L. pneumophila into epithelial cells and macrophages. ExoR from the symbiotic microorganism S. melioti and AlgK from the pathogen P. aeruginosa regulate exopolysaccaride synthesis. Nif1 and Chs4 from yeast are responsible for the regulation of mitosis and septum formation during cell division, respectively, and PodJ guides the cellular differentiation during the cell cycle of the bacterium C. crescentus. Taken together the SLR motif establishes a link between signal transduction pathways from eukaryotes and bacteria. The SLR motif is so far absent from archaea. Therefore the SLR could have developed in the last common ancestor between eukaryotes and bacteria.
Collapse
Affiliation(s)
- Peer R E Mittl
- Biochemisches Institut, Universität Zürich, Winterthurer Strasse 190, 8057 Zürich, Switzerland.
| | | |
Collapse
|
21
|
Abstract
Previous studies have demonstrated that Helicobacter pylori (Hp) delays its entry into macrophages and persists inside megasomes, which are poorly acidified and accumulate early endosome autoantigen 1. Herein, we explored the role of Hp urease in bacterial survival in murine peritoneal macrophages and J774 cells. Plasmid-free mutagenesis was used to replace ureA and ureB with chloramphenicol acetyltransferase in Hp Strains 11637 and 11916. ureAB null Hp lacked detectable urease activity and did not express UreA or UreB as judged by immunoblotting. Deletion of ureAB had no effect on Hp binding to macrophages or the rate or extent of phagocytosis. However, intracellular survival of mutant organisms was impaired significantly. Immunofluorescence microscopy demonstrated that (in contrast to parental organisms) mutant Hp resided in single phagosomes, which were acidic and accumulated the lysosome marker lysosome-associated membrane protein-1 but not early endosome autoantigen 1. A similar phenotype was observed for spontaneous urease mutants derived from Hp Strain 60190. Treatment of macrophages with bafilomycin A1, NH4Cl, or chloroquine prevented acidification of phagosomes containing mutant Hp. However, only ammonium chloride enhanced bacterial viability significantly. Rescue of ureAB null organisms was also achieved by surface adsorption of active urease. Altogether, our data indicate a role for urease and urease-derived ammonia in megasome formation and Hp survival.
Collapse
Affiliation(s)
- Justin T. Schwartz
- Department of Medicine, University of Iowa and the VA Medical Center, Iowa City
- Department of Microbiology, University of Iowa and the VA Medical Center, Iowa City
| | - Lee-Ann H. Allen
- Department of Medicine, University of Iowa and the VA Medical Center, Iowa City
- Department of Microbiology, University of Iowa and the VA Medical Center, Iowa City
- Inflammation Program, University of Iowa and the VA Medical Center, Iowa City
| |
Collapse
|
22
|
Beswick EJ, Pinchuk IV, Minch K, Suarez G, Sierra JC, Yamaoka Y, Reyes VE. The Helicobacter pylori urease B subunit binds to CD74 on gastric epithelial cells and induces NF-kappaB activation and interleukin-8 production. Infect Immun 2006; 74:1148-55. [PMID: 16428763 PMCID: PMC1360328 DOI: 10.1128/iai.74.2.1148-1155.2006] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The pathogenesis associated with Helicobacter pylori infection is the result of both bacterial factors and the host response. We have previously shown that H. pylori binds to CD74 on gastric epithelial cells. In this study, we sought to identify the bacterial protein responsible for this interaction. H. pylori urease from a pool of bacterial surface proteins was found to coprecipitate with CD74. To determine how urease binds to CD74, we used recombinant urease A and B subunits. Recombinant urease B was found to bind directly to CD74 in immunoprecipitation and flow cytometry studies. By utilizing both recombinant urease subunits and urease B knockout bacteria, the urease B-CD74 interaction was shown to induce NF-kappaB activation and interleukin-8 (IL-8) production. This response was decreased by blocking CD74 with monoclonal antibodies. Further confirmation of the interaction of urease B with CD74 was obtained using a fibroblast cell line transfected with CD74 that also responded with NF-kappaB activation and IL-8 production. The binding of the H. pylori urease B subunit to CD74 expressed on gastric epithelial cells presents a novel insight into a previously unrecognized H. pylori interaction that may contribute to the proinflammatory immune response seen during infection.
Collapse
Affiliation(s)
- Ellen J Beswick
- Department of Pediatrics, Children's Hospital, Room 2.300, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, USA
| | | | | | | | | | | | | |
Collapse
|
23
|
Mirbod-Donovan F, Schaller R, Hung CY, Xue J, Reichard U, Cole GT. Urease produced by Coccidioides posadasii contributes to the virulence of this respiratory pathogen. Infect Immun 2006; 74:504-15. [PMID: 16369007 PMCID: PMC1346605 DOI: 10.1128/iai.74.1.504-515.2006] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Urease activity during in vitro growth in the saprobic and parasitic phases of Coccidioides spp. is partly responsible for production of intracellular ammonia released into the culture media and contributes to alkalinity of the external microenvironment. Although the amino acid sequence of the urease of Coccidioides posadasii lacks a predicted signal peptide, the protein is transported from the cytosol into vesicles and the central vacuole of parasitic cells (spherules). Enzymatically active urease is released from the contents of mature spherules during the parasitic cycle endosporulation stage. The endospores, together with the urease and additional material which escape from the ruptured parasitic cells, elicit an intense host inflammatory response. Ammonia production by the spherules of C. posadasii is markedly increased by the availability of exogenous urea found in relatively high concentrations at sites of coccidioidal infection in the lungs of mice. Direct measurement of the pH at these infection sites revealed an alkaline microenvironment. Disruption of the urease gene of C. posadasii resulted in a marked reduction in the amount of ammonia secreted in vitro by the fungal cells. BALB/c mice challenged intranasally with the mutant strain showed increased survival, a well-organized granulomatous response to infection, and better clearance of the pathogen than animals challenged with either the parental or the reconstituted (revertant) strain. We conclude that ammonia and enzymatically active urease released from spherules during the parasitic cycle of C. posadasii contribute to host tissue damage, which exacerbates the severity of coccidioidal infection and enhances the virulence of this human respiratory pathogen.
Collapse
Affiliation(s)
- Fariba Mirbod-Donovan
- Department of Biology, Margaret Batts Tobin Building, Room 1.308E, University of Texas at San Antonio, 6900 North Loop 1604 West, San Antonio, TX 78249, USA
| | | | | | | | | | | |
Collapse
|
24
|
Tannaes T, Bukholm IK, Bukholm G. High relative content of lysophospholipids ofHelicobacter pylorimediates increased risk for ulcer disease. ACTA ACUST UNITED AC 2005; 44:17-23. [PMID: 15780574 DOI: 10.1016/j.femsim.2004.10.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2004] [Revised: 09/29/2004] [Accepted: 10/07/2004] [Indexed: 11/27/2022]
Abstract
Helicobacter pylori phospholipase A (OMPLA) degrades bacterial membrane phospholipids to lysophospholipids. High levels of lysophospholipids are associated with higher hemolytic activity, increased release of urease and vacA and better adherence to epithelial cells in vitro. The phospholipase A gene (pldA) displays phase variation due to a slippage in a homopolymeric tract. The aim of this study was to determine if the relative amount of lysophospholipids in the cell wall is associated with ulcer disease, and to further investigate the significance of pldA phase variation. H. pylori isolates of 40 patients were examined. The relative lysophospholipid content of each isolate was determined and the pldA gene was sequenced. The study indicated that H. pylori can regulate its OMPLA activity by phase variation in the pldA gene or by protein level regulation among phase variants in the pldA 'ON' status. We found a significant difference between the relative amount of lysophospholipids of the ulcer group and the non-ulcer group (p=0.022). When the lysophospholipid/phospholipid ratios were compared with outcome, the OR for ulcer disease was 9.0 (95% CI 1.6-49.4; p=0.014). Isolates with a high OMPLA activity are significantly associated with patients with ulcer disease.
Collapse
Affiliation(s)
- Tone Tannaes
- Institute of Clinical Epidemiology and Molecular Biology, University of Oslo, Oslo, Norway
| | | | | |
Collapse
|
25
|
Saridakis CE, Johnson RP, Benson A, Ziebell K, Gyles CL. Influence of animal origin and lineage on survival of Escherichia coli O157:H7 strains in strong and weak acid challenges. J Food Prot 2004; 67:1591-6. [PMID: 15330520 DOI: 10.4315/0362-028x-67.8.1591] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Twenty-five strains of Escherichia coli O157:H7 isolated from humans, cattle, and pigs were maintained in HCl (pH 2.5) and in a volatile fatty acid (VFA) mixture (pH 4.0) for up to 6 h at 37 degrees C to assess their ability to survive in acidic conditions that simulate those of the stomach and ileum, respectively. In HCl, the average group survival of bovine strains was significantly higher than that of porcine and human strains, whereas in VFAs, porcine strains were significantly more resistant than bovine and human strains. Bovine strains exhibited significantly higher average survival in HCl than in VFAs. The average survival of strains classified as octamer-based genome scanning (OBGS) lineage II was significantly superior to that of strains classified as OBGS lineage I in HCl. The group of lineage I strains was more resistant in VFAs compared with lineage II, but only after 6 h of challenge. The possible involvement of urease in acid resistance of E. coli O157:H7 was also examined. Although the strains possessed the ureC gene, as shown by PCR, this gene did not appear to contribute to acid resistance under the conditions tested. The data indicate that there is a relationship between acid resistance and source or lineage of O157:H7 strains.
Collapse
|
26
|
Berdoz J, Corthésy B. Human polymeric IgA is superior to IgG and single-chain Fv of the same monoclonal specificity to inhibit urease activity associated with Helicobacter pylori. Mol Immunol 2004; 41:1013-22. [PMID: 15302163 DOI: 10.1016/j.molimm.2004.05.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Indexed: 12/24/2022]
Abstract
Helicobacter-induced gastritis is considered nowadays an epidemic, the prevalence of which is one of the highest world-wide (70%), with as much as 40% of the population in industrialized countries. Helicobacter pylori (H. pylori) antigens (Ag) capable to elicit a protective immune response in animal models have been identified, but these antigens have not been shown to be strongly immunogenic when administered to humans. Due to their stability in the gastric environment and avidity, passive administration of secretory immunoglobulin A (SIgA) antibodies (Ab) targeting protective Ag might be particularly relevant as a substitute or complement to current therapies. To this aim, we have designed expression vectors to convert a scFv polypeptide specific for H. pylori urease subunit A into human IgG, polymeric IgA (IgAp/d) and SIgA. Purified proteins show proper binding characteristics toward both the native and denatured forms of H. pylori urease. The direct comparison between different isotype and molecular forms, but of unique specificity, demonstrates that SIgA and IgAp/d are more efficient in blocking free and H. pylori-associated urease than IgG and scFv. We conclude that the expression system reported herein will represent a valuable tool to produce human SIgA Ab of multiple specificities against H. pylori antigens involved in colonization and persistence.
Collapse
Affiliation(s)
- José Berdoz
- Galli-Valerio Institute, Rue César-Roux 37, 1014 Lausanne, Switzerland
| | | |
Collapse
|
27
|
de Jonge R, Bakker D, van Vliet AHM, Kuipers EJ, Vandenbroucke-Grauls CMJE, Kusters JG. Direct random insertion mutagenesis of Helicobacter pylori. J Microbiol Methods 2003; 52:93-100. [PMID: 12401231 DOI: 10.1016/s0167-7012(02)00136-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Random insertion mutagenesis is a widely used technique for the identification of bacterial virulence genes. Most strategies for random mutagenesis involve cloning in Escherichia coli for passage of plasmids or for phenotypic selection. This can result in biased selection due to restriction or instability of the cloned DNA, or toxicity of the encoded products. We therefore created two mutant libraries in the human pathogen Helicobacter pylori using a simple, direct mutagenesis technique, which does not require E. coli as intermediate. H. pylori total DNA was digested, circularized and digested again with a frequently cutting restriction enzyme, and the resulting fragments were ligated to a kanamycin antibiotic resistance cassette. Subsequently, the ligation mixture was transformed into the parental H. pylori strain 1061. Insertion of the kanamycin cassette by double homologous recombination into the genome of H. pylori 1061 resulted in approximately 2500 kanamycin resistant colonies. Heterogeneity of kanamycin cassette insertion was confirmed by Southern blotting. The isolation of two independent H. pylori mutants defective in production of urease from this library underlines the potential of this mutagenesis strategy.
Collapse
Affiliation(s)
- Ramon de Jonge
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands
| | | | | | | | | | | |
Collapse
|
28
|
Abstract
BACKGROUND & AIMS Helicobacter pylori, a neutralophile, uses acid neutralization by urease to combat gastric acidity, allowing gastric colonization. Both acute and chronic acid resistance mechanisms are present. Acute mechanisms of acid adaptation could be due to surface urease, increased inner-membrane urea permeability via UreI, or both. Slower mechanisms may involve increased nickel insertion into apoenzyme, posttranscriptional regulation, or increased enzyme synthesis. The aim of this study was to further define regulation of urease under acidic conditions. METHODS Surface-bound urease was analyzed by measurement of free and bound urease after centrifugation through a step gradient and by quantitative urease immunostaining of intact and fixed bacteria. Changes in urease synthesis or assembly were determined by incubation of the organisms at pH 5.5 or 7.0 in the absence and presence of chloramphenicol, urea, or nickel chelator and in ureI-positive and -negative organisms. RESULTS The amount of surface urease was below detection limits with either centrifugation washing or immunostaining. Total bacterial urease activity was increased 3-5-fold by incubation at pH 5.5 in the presence of chloramphenicol but not in nickel-free medium or in ureI knockout organisms. There was also a 3-fold increase in survival of acid shock in acid-adapted organisms. CONCLUSIONS Surface-bound urease is too low to contribute to acid resistance. Acidic medium pH induces UreI-dependent nickel incorporation into apoenzyme. This augmentation of urease activity increases survival in acid and is part of the gastric colonization strategy of the organism.
Collapse
Affiliation(s)
- David R Scott
- Department of Physiology, University of California Los Angeles, Los Angeles, California 90073, USA
| | | | | | | |
Collapse
|
29
|
Stingl K, Uhlemann EM, Schmid R, Altendorf K, Bakker EP. Energetics of Helicobacter pylori and its implications for the mechanism of urease-dependent acid tolerance at pH 1. J Bacteriol 2002; 184:3053-60. [PMID: 12003947 PMCID: PMC135060 DOI: 10.1128/jb.184.11.3053-3060.2002] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the presence of urea the neutrophilic human pathogen Helicobacter pylori survives for several hours at pH 1 with concomitant cytoplasmic pH homeostasis. To study this effect in detail, the transmembrane proton motive force and cytoplasmic urease activity of H. pylori were determined at various pH values. In the absence of urea, the organism maintained a close-to-neutral cytoplasm and an internally negative membrane potential at external pH values greater than 4 to 5. In the presence of urea, H. pylori accomplished cytoplasmic pH homeostasis down to an external pH of 1.2. At this external pH, the cytoplasmic pH was 4.9 and the membrane potential was slightly negative inside. The latter finding is in contrast to the situation in acidophiles, which develop inside-positive membrane potentials under similar conditions. Measurements of the time course of the membrane potential confirmed that addition of urea to the cells led to hyperpolarization. Most likely, this effect was due to electrogenic export of ammonium cations from the cytoplasm. The urease activity of intact cells increased nearly exponentially with decreasing external pH. This activation was not due to enhanced gene expression at low external pH values. In cell extracts the pH optimum of urease activity was dependent on the buffer system and was about pH 5 in sodium citrate buffer. Since this is the cytoplasmic pH of the cells at pH 1 to 2, we propose that cytoplasmic pH is a factor in the in vivo activation of the urease at low external pH values. The mechanism by which urease activity leads to cytoplasmic pH homeostasis in H. pylori is discussed.
Collapse
Affiliation(s)
- Kerstin Stingl
- Abteilung Mikrobiologie, Universität Osnabrück, D-49069 Osnabrück, Germany.
| | | | | | | | | |
Collapse
|
30
|
Abstract
Coccidioides immitis, the causative agent of San Joaquin Valley fever (coccidioidomycosis), produces a urease which has been suggested to contribute to the virulence of this fungal pathogen. Urease catalyzes the hydrolysis of urea and has been proposed to at least partly account for alkalinity of the microenvironment in which C. immitis grows due to the release of ammonia and ammonium ions. The C. immitis urease was purified to homogeneity (1048-fold) from the mycelial cytosol by chromatographic fractionation. The sequence of 12 N-terminal amino-acid residues of the purified, native polypeptide was identical to that predicted by the translated urease gene sequence which has been reported. The isolated enzyme exhibited a specific activity in the presence of urea of 1750 micromol min(-1) mg(-1) protein, has a native molecular mass of 450 kDa, revealed a Km for urea of 4.1 mM, had a pH optimum of 8.0 and is heat stable. Hydroxyurea, acetohydroxamic acid (AHA) and boric acid each inhibited activity of the purified enzyme. Urease activity was enhanced by the presence of 5-10 mM concentrations of Mg2+ or Mn2+, but inhibited by Li+, Ni2+, Cu2+ or Zn2+. The reversible urease inhibitor, AHA, blocked enzyme activity in the crude mycelial cytosolic fraction when added at a concentration of 10 mM. On the other hand, 10 mM AHA added to 4-day-old mycelial cultures only partially decreased the amount of ammonium detected in the culture medium. It is evident, therefore, that C. immitis urease activity does not account for the total amount of ammonia secreted during in vitro growth of the pathogen. Other metabolic sources of ammonia, which may also contribute to the virulence of C. immitis, are under investigation.
Collapse
Affiliation(s)
- F Mirbod
- Department of Microbiology and Immunology, Medical College of Ohio, Toledo 43614-5806, USA
| | | | | |
Collapse
|
31
|
Abstract
Helicobacter pylori can survive for several hours at pH 1 in the presence of urea. Under these conditions, the organism maintains its cytoplasmic pH at a value close to neutral. The role of the cytoplasmically located urease enzyme in this process is a matter of debate. We propose that cytoplasmic ammonia generated by the action of urease is protonated by H(+) ions leaking in from the acidic medium and that the NH(4)(+) formed is extruded from the cytoplasm via an as-yet-unidentified transport system. This mechanism is compared with the general mechanism of cytoplasmic pH homeostasis in microorganisms.
Collapse
Affiliation(s)
- Kerstin Stingl
- Abteilung Mikrobiologie, Universität Osnabrück, D-49069, Germany.
| | | | | |
Collapse
|
32
|
Tannaes T, Dekker N, Bukholm G, Bijlsma JJ, Appelmelk BJ. Phase variation in the Helicobacter pylori phospholipase A gene and its role in acid adaptation. Infect Immun 2001; 69:7334-40. [PMID: 11705905 PMCID: PMC98819 DOI: 10.1128/iai.69.12.7334-7340.2001] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Previously, we have shown that Helicobacter pylori can spontaneously and reversibly change its membrane lipid composition, producing variants with low or high content of lysophospholipids. The "lyso" variant contains a high percentage of lysophospholipids, adheres better to epithelial cells, and releases more proteins such as urease and VacA, compared to the "normal" variant, which has a low content of lysophospholipids. Prolonged growth of the normal variant at pH 3.5, but not under neutral conditions, leads to enrichment of lyso variant colonies, suggesting that the colony switch is relevant to acid adaptation. In this study we show that the change in membrane lipid composition is due to phase variation in the pldA gene. A change in the (C) tract length of this gene results in reversible frameshifts, translation of a full-length or truncated pldA, and the production of active or inactive outer membrane phospholipase A (OMPLA). The role of OMPLA in determining the colony morphology was confirmed by the construction of an OMPLA-negative mutant. Furthermore, variants with an active OMPLA were able to survive acidic conditions better than variants with the inactive form. This explains why the lyso variant is selected at low pH. Our studies demonstrate that phase variation in the pldA gene, resulting in an active form of OMPLA, is important for survival under acidic conditions. We also demonstrated the active OMPLA genotype in fresh isolates of H. pylori from patients referred to gastroscopy for dyspepsia.
Collapse
Affiliation(s)
- T Tannaes
- Institute of Medical Microbiology, University of Oslo, Oslo, Norway.
| | | | | | | | | |
Collapse
|
33
|
Ha N, Oh B. The importance of the surface urease of Helicobacter pylori: a reconciling picture. Trends Microbiol 2001; 9:534. [DOI: 10.1016/s0966-842x(01)02225-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
34
|
|
35
|
Bury-Moné S, Skouloubris S, Labigne A, De Reuse H. The Helicobacter pylori UreI protein: role in adaptation to acidity and identification of residues essential for its activity and for acid activation. Mol Microbiol 2001; 42:1021-34. [PMID: 11737644 DOI: 10.1046/j.1365-2958.2001.02689.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Helicobacter pylori is a human gastric pathogen that survives the strong acidity of the stomach by virtue of its urease activity. This activity produces ammonia, which neutralizes the bacterial microenvironment. UreI, an inner membrane protein, is essential for resistance to low pH and for the gastric colonization of mice by H. pylori. In the heterologous Xenopus oocytes expression system, UreI behaves like an H+-gated urea channel, and His-123 was found to be important for low pH activation. We investigated the role of UreI directly in H. pylori and showed that, in the presence of urea, strains expressing wild-type UreI displayed very rapid stimulation of extracellular ammonia production upon exposure to pH </= 5. This response was not observed when acetamide was used as a source of ammonia; therefore, it is specific for urea hydrolysis. To identify residues critical for UreI activity or activation, we constructed H. pylori strains carrying individual chromosomal mutations of UreI (i) in the four conserved histidine residues (H71, H123, H131, H193) and (ii) in a conserved region of the third intracellular loop (L165, G166, K167, F168). The distal H193 (and not H123) was found to be crucial for stimulating the production of ammonia at low pH; a single mutation in this residue uncoupled the UreI activity from its acid activation. The third intracellular loop of UreI was shown to be important for UreI activity. Thus, in H. pylori, UreI is necessary for the adaptation of urease activity to the extracellular pH. UreI behaves like a novel type of urea transporter, and the identification of residues essential for its function in H. pylori provides new insight into the unusual molecular mechanism of low pH activation.
Collapse
Affiliation(s)
- S Bury-Moné
- Institut Pasteur, Unité de Pathogénie Bactérienne des Muqueuses, 28 rue du Dr Roux, 75724 Paris Cedex 15, France
| | | | | | | |
Collapse
|
36
|
Tullius MV, Harth G, Horwitz MA. High extracellular levels of Mycobacterium tuberculosis glutamine synthetase and superoxide dismutase in actively growing cultures are due to high expression and extracellular stability rather than to a protein-specific export mechanism. Infect Immun 2001; 69:6348-63. [PMID: 11553579 PMCID: PMC98770 DOI: 10.1128/iai.69.10.6348-6363.2001] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Glutamine synthetase (GS) and superoxide dismutase (SOD), large multimeric enzymes that are thought to play important roles in the pathogenicity of Mycobacterium tuberculosis, are among the bacterium's major culture filtrate proteins in actively growing cultures. Although these proteins lack a leader peptide, their presence in the extracellular medium during early stages of growth suggested that they might be actively secreted. To understand their mechanism of export, we cloned the homologous genes (glnA1 and sodA) from the rapid-growing, nonpathogenic Mycobacterium smegmatis, generated glnA1 and sodA mutants of M. smegmatis by allelic exchange, and quantitated expression and export of both mycobacterial and nonmycobacterial GSs and SODs in these mutants. We also quantitated expression and export of homologous and heterologous SODs from M. tuberculosis. When each of the genes was expressed from a multicopy plasmid, M. smegmatis exported comparable proportions of both the M. tuberculosis and M. smegmatis GSs (in the glnA1 strain) or SODs (in the sodA strain), in contrast to previous observations in wild-type strains. Surprisingly, recombinant M. smegmatis and M. tuberculosis strains even exported nonmycobacterial SODs. To determine the extent to which export of these large, leaderless proteins is expression dependent, we constructed a recombinant M. tuberculosis strain expressing green fluorescent protein (GFP) at high levels and a recombinant M. smegmatis strain coexpressing the M. smegmatis GS, M. smegmatis SOD, and M. tuberculosis BfrB (bacterioferritin) at high levels. The recombinant M. tuberculosis strain exported GFP even in early stages of growth and at proportions very similar to those of the endogenous M. tuberculosis GS and SOD. Similarly, the recombinant M. smegmatis strain exported bacterioferritin, a large (approximately 500-kDa), leaderless, multimeric protein, in proportions comparable to GS and SOD. In contrast, high-level expression of the large, leaderless, multimeric protein malate dehydrogenase did not lead to extracellular accumulation because the protein was highly unstable extracellularly. These findings indicate that, contrary to expectations, export of M. tuberculosis GS and SOD in actively growing cultures is not due to a protein-specific export mechanism, but rather to bacterial leakage or autolysis, and that the extracellular abundance of these enzymes is simply due to their high level of expression and extracellular stability. The same determinants likely explain the presence of other leaderless proteins in the extracellular medium of actively growing M. tuberculosis cultures.
Collapse
Affiliation(s)
- M V Tullius
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of California, Los Angeles, California 90095-1688, USA
| | | | | |
Collapse
|
37
|
van Vliet AH, Kuipers EJ, Waidner B, Davies BJ, de Vries N, Penn CW, Vandenbroucke-Grauls CM, Kist M, Bereswill S, Kusters JG. Nickel-responsive induction of urease expression in Helicobacter pylori is mediated at the transcriptional level. Infect Immun 2001; 69:4891-7. [PMID: 11447165 PMCID: PMC98579 DOI: 10.1128/iai.69.8.4891-4897.2001] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The nickel-containing enzyme urease is an essential colonization factor of the gastric pathogen Helicobacter pylori, as it allows the bacterium to survive the acidic conditions in the gastric mucosa. Although urease can represents up to 10% of the total protein content of H. pylori, expression of urease genes is thought to be constitutive. Here it is demonstrated that H. pylori regulates the expression and activity of its urease enzyme as a function of the availability of the cofactor nickel. Supplementation of brucella growth medium with 1 or 100 microM NiCl(2) resulted in up to 3.5-fold-increased expression of the urease subunit proteins UreA and UreB and up to 12-fold-increased urease enzyme activity. The induction was specific for nickel, since the addition of cadmium, cobalt, copper, iron, manganese, or zinc did not affect the expression of urease. Both Northern hybridization studies and a transcriptional ureA::lacZ fusion demonstrated that the observed nickel-responsive regulation of urease is mediated at the transcriptional level. Mutation of the HP1027 gene, encoding the ferric uptake regulator (Fur), did not affect the expression of urease in unsupplemented medium but reduced the nickel induction of urease expression to only twofold. This indicates that Fur is involved in the modulation of urease expression in response to nickel. These data demonstrate nickel-responsive regulation of H. pylori urease, a phenomenon likely to be of importance during the colonization and persistence of H. pylori in the gastric mucosa.
Collapse
Affiliation(s)
- A H van Vliet
- Department of Medical Microbiology, Faculty of Medicine, Vrije Universiteit, Amsterdam, The Netherlands.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Abstract
BACKGROUND Helicobacter pylori is a neutralophilic bacterium that colonizes the acidic human gastric surface using the neutralizing capacity of a constitutively produced urease. Urease is present both in the cytoplasm and bound to the outside surface of the bacteria. The origin of the surface urease continues to be controversial. This study provides additional evidence that the origin of surface urease is cell lysis, not secretion. METHODS H. Pylori was transformed with a plasmid encoding green fluorescent protein (GFP), a non-native cytoplasmic protein. Cultures supplemented with beta-cyclodextrin or horse serum were collected over various time periods and spun through a ficoll cushion to gently separate whole bacteria from released protein. The pellet and supernatant fractions were analyzed by fluorimetry, SDS-PAGE and Coomassie blue or Western analysis. RESULTS GFP fluorescence and antigenic reactivity in the supernatant increased at each time point. GFP, the non-native cytoplasmic protein, and UreB, a native cytoplasmic protein, increased over time in the supernatant and both proteins were always present in the pellet fraction. UreI, an inner membrane protein, was only present in the pellet fraction. beta-galactosidase, a protein not found in H. pylori, was used as a negative control. CONCLUSIONS Since it is unlikely that there is an intrinsic secretion system for GFP, a non-native protein, its increasing presence over time in the supernate fraction along with UreB, and retention of UreI in the pellet fraction implies that cell lysis accounts for the presence of urease on the surface of H. pylori.
Collapse
Affiliation(s)
- E A Marcus
- Department of Physiology, University of California, Los Angeles and VA Greater Los Angeles Health Care System, Los Angeles, CA 90073, USA
| | | |
Collapse
|
39
|
Song Q, Zirnstein GW, Swaminathan B, Gold BD. Pretreatment with urea-hydrochloric acid enhances the isolation of Helicobacter pylori from contaminated specimens. J Clin Microbiol 2001; 39:1967-8. [PMID: 11326024 PMCID: PMC88059 DOI: 10.1128/jcm.39.5.1967-1968.2001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Human saliva seeded with H. pylori was incubated in urea-HCl and then cultured on nonselective media. Pretreatment with 0.06 N HCl-0.08 M urea for 5 min at 37 degrees C resulted in reproducible isolation of H. pylori, even at low inocula (< or =10(2) CFU/ml of saliva), despite the presence of large numbers of contaminating organisms.
Collapse
Affiliation(s)
- Q Song
- Foodborne and Diarrheal Diseases Branch, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
| | | | | | | |
Collapse
|
40
|
Abstract
Bacteria can inhabit a wide range of environmental conditions, including extremes in pH ranging from 1 to 11. The primary strategy employed by bacteria in acidic environments is to maintain a constant cytoplasmic pH value. However, many data demonstrate that bacteria can grow under conditions in which pH values are out of the range in which cytoplasmic pH is kept constant. Based on these observations, a novel notion was proposed that bacteria have strategies to survive even if the cytoplasm is acidified by low external pH. Under these conditions, bacteria are obliged to use acid-resistant systems, implying that multiple systems having the same physiological role are operating at different cytoplasmic pH values. If this is true, it is quite likely that bacteria have genes that are induced by environmental stimuli under different pH conditions. In fact, acid-inducible genes often respond to another factor(s) besides pH. Furthermore, distinct genes might be required for growth or survival at acid pH under different environmental conditions because functions of many systems are dependent on external conditions. Systems operating at acid pH have been described to date, but numerous genes remain to be identified that function to protect bacteria from an acid challenge. Identification and analysis of these genes is critical, not only to elucidate bacterial physiology, but also to increase the understanding of bacterial pathogenesis.
Collapse
Affiliation(s)
- Hiroshi Kobayashi
- Faculty of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
| | | | | |
Collapse
|
41
|
Athmann C, Zeng N, Kang T, Marcus EA, Scott DR, Rektorschek M, Buhmann A, Melchers K, Sachs G. Local pH elevation mediated by the intrabacterial urease of Helicobacter pylori cocultured with gastric cells. J Clin Invest 2000; 106:339-47. [PMID: 10930437 PMCID: PMC314326 DOI: 10.1172/jci9351] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Helicobacter pylori resists gastric acidity by modulating the proton-gated urea channel UreI, allowing for pH(out)-dependent regulation of urea access to intrabacterial urease. We employed pH- and Ca(2+)-sensitive fluorescent dyes and confocal microscopy to determine the location, rate, and magnitude of pH changes in an H. pylori-AGS cell coculture model, comparing wild-type bacteria with nonpolar ureI-deletion strains (ureI-ve). Addition of urea at pH 5.5 to the coculture resulted first in elevation of bacterial periplasmic pH, followed by an increase of medium pH and then pH in AGS cells. No change in periplasmic pH occurred in ureI-deletion mutants, which also induced a slower increase in the pH of the medium. Pretreatment of the mutant bacteria with the detergent C(12)E(8) before adding urea resulted in rapid elevation of bacterial cytoplasmic pH and medium pH. UreI-dependent NH(3) generation by intrabacterial urease buffers the bacterial periplasm, enabling acid resistance at the low urea concentrations found in gastric juice. Perfusion of AGS cells with urea-containing medium from coculture at pH 5.5 did not elevate pH(in) or [Ca(2+)](in), unless the conditioned medium was first neutralized to elevate the NH(3)/NH(4)(+) ratio. Therefore, cellular effects of intrabacterial ammonia generation under acidic conditions are indirect and not through a type IV secretory complex. The pH(in) and [Ca(2+)](in) elevation that causes the NH(3)/NH(4)(+) ratio to increase after neutralization of infected gastric juice may contribute to the gastritis seen with H. pylori infection.
Collapse
Affiliation(s)
- C Athmann
- University of California at Los Angeles and Veterans Administration, Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Affiliation(s)
- L A Allen
- Department of Medicine and the Inflammation Program, University of Iowa and the Veteran's Affairs Medical Center, Iowa City, Iowa 52242, USA.
| |
Collapse
|
43
|
Abstract
Ureases are multi-subunit, nickel-containing enzymes that catalyze the hydrolysis of urea to carbon dioxide and ammonia. This brief review discusses the biochemistry and genetics of bacterial ureases and outlines the roles of urea metabolism in microbial ecology and pathogenesis of some of the principle ureolytic species affecting human health.
Collapse
Affiliation(s)
- R A Burne
- Department of Microbiology and Immunology, Center for Oral Biology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY, USA
| | | |
Collapse
|
44
|
Rektorschek M, Buhmann A, Weeks D, Schwan D, Bensch KW, Eskandari S, Scott D, Sachs G, Melchers K. Acid resistance of Helicobacter pylori depends on the UreI membrane protein and an inner membrane proton barrier. Mol Microbiol 2000; 36:141-52. [PMID: 10760171 DOI: 10.1046/j.1365-2958.2000.01835.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ureI encodes an inner membrane protein of Helicobacter pylori. The role of the bacterial inner membrane and UreI in acid protection and regulation of cytoplasmic urease activity in the gastric microorganism was studied. The irreversible inhibition of urease when the organism was exposed to a protonophore (3,3',4', 5-tetrachlorsalicylanide; TCS) at acidic pH showed that the inner membrane protected urease from acid. Isogenic ureI knockout mutants of several H. pylori strains were constructed by replacing the ureI gene of the urease gene cluster with a promoterless kanamycin resistance marker gene (kanR). Mutants carrying the modified ureAB-kanR-EFGH operon all showed wild-type levels of urease activity at neutral pH in vitro. The mutants resisted media of pH > 4.0 but not of pH < 4.0. Whereas wild-type bacteria showed high levels of urease activity below pH 4.0, this ability was not retained in the ureI mutants, resulting in inhibition of metabolism and cell death. Gene complementation experiments with plasmid-derived H. pylori ureI restored wild-type properties. The activation of urease activity found in structurally intact but permeabilized bacteria treated with 0.01% detergent (polyoxy-ethylene-8-laurylether; C12E8), suggested a membrane-limited access of urea to internal urease at neutral pH. Measurement of 14C-urea uptake into Xenopus oocytes injected with ureI cRNA showed acid activation of uptake only in injected oocytes. Acceleration of urea uptake by UreI therefore mediates the increase of intracellular urease activity seen under acidic conditions. This increase of urea permeability is essential for H. pylori survival in environments below pH 4.0. ureI-independent urease activity may be sufficient for maintenance of bacterial viability above pH 4.0.
Collapse
Affiliation(s)
- M Rektorschek
- Department of Molecular Biology, Byk Gulden Pharmaceuticals Konstanz, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Abstract
Helicobacter pylori, a gram-negative, microaerophilic, motile, spiral-shaped bacterium, has been established as the etiologic agent of gastritis and peptic ulcers and is a major risk factor for gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma (MALT). The ability of H. pylori to cause this spectrum of diseases depends on host, bacterial, and environmental factors. Bacterial factors critical for H. pylori colonization of the gastric mucosa include urease, flagella, adhesins, and delta-glutamyltranspeptidase. Lipopolysaccharide, urease, and vacuolating cytotoxin are among the factors that allow H. pylori to persist for decades and invoke an intense inflammatory response, leading to damaged host cells. Genes in the cag pathogenicity island also contribute to the inflammatory response by initiating a signal transduction cascade, resulting in interleukin-8 production. Proinflammatory cytokines and a Th-1 cytokine response further exacerbates the inflammation. Products of the enzymes nitric oxide synthase (iNOS) and cyclooxygenase may perturb the balance between gastric epithelial cell apoptosis (ulcer formation) and proliferation (cancer). The host Th-1 response and antibodies directed against H. pylori do not eliminate the organism, which presents challenges to vaccine development. Vaccines that include urease have shown some promise, but improved adjuvants and animal models should hasten progress in vaccine research. H. pylori is the most genetically diverse organism known, and the panmictic population structure may contribute to the varying ranges of disease severity produced by different strains. The complete genome sequence of two strains of H. pylori has propelled this field forward, and numerous groups are now using genomic, proteomic, and mutagenetic approaches to identify new virulence genes. Discovered only in 1982, H. pylori is now among the most intensely investigated organisms. This review summarizes recent progress in this rapidly moving field.
Collapse
Affiliation(s)
- D J McGee
- University of Maryland School of Medicine, Department of Microbiology and Immunology, Baltimore, Maryland 21201, USA
| | | |
Collapse
|
46
|
McGee DJ, Radcliff FJ, Mendz GL, Ferrero RL, Mobley HL. Helicobacter pylori rocF is required for arginase activity and acid protection in vitro but is not essential for colonization of mice or for urease activity. J Bacteriol 1999; 181:7314-22. [PMID: 10572136 PMCID: PMC103695 DOI: 10.1128/jb.181.23.7314-7322.1999] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Arginase of the Helicobacter pylori urea cycle hydrolyzes L-arginine to L-ornithine and urea. H. pylori urease hydrolyzes urea to carbon dioxide and ammonium, which neutralizes acid. Both enzymes are involved in H. pylori nitrogen metabolism. The roles of arginase in the physiology of H. pylori were investigated in vitro and in vivo, since arginase in H. pylori is metabolically upstream of urease and urease is known to be required for colonization of animal models by the bacterium. The H. pylori gene hp1399, which is orthologous to the Bacillus subtilis rocF gene encoding arginase, was cloned, and isogenic allelic exchange mutants of three H. pylori strains were made by using two different constructs: 236-2 and rocF::aphA3. In contrast to wild-type (WT) strains, all rocF mutants were devoid of arginase activity and had diminished serine dehydratase activity, an enzyme activity which generates ammonium. Compared with WT strain 26695 of H. pylori, the rocF::aphA3 mutant was approximately 1, 000-fold more sensitive to acid exposure. The acid sensitivity of the rocF::aphA3 mutant was not reversed by the addition of L-arginine, in contrast to the WT, and yielded a approximately 10, 000-fold difference in viability. Urease activity was similar in both strains and both survived acid exposure equally well when exogenous urea was added, indicating that rocF is not required for urease activity in vitro. Finally, H. pylori mouse-adapted strain SS1 and the 236-2 rocF isogenic mutant colonized mice equally well: 8 of 9 versus 9 of 11 mice, respectively. However, the rocF::aphA3 mutant of strain SS1 had moderately reduced colonization (4 of 10 mice). The geometric mean levels of H. pylori recovered from these mice (in log(10) CFU) were 6.1, 5.5, and 4.1, respectively. Thus, H. pylori rocF is required for arginase activity and is crucial for acid protection in vitro but is not essential for in vivo colonization of mice or for urease activity.
Collapse
Affiliation(s)
- D J McGee
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
| | | | | | | | | |
Collapse
|
47
|
Abstract
About half of the world's population carries Helicobacter pylori, a gram-negative, spiral bacterium that colonizes the human stomach. The link between H. pylori and, ulceration as well as its association with the development of both gastric cancer and mucosa-associated lymphoid tissue lymphoma in humans is a serious public health concern. The publication of the genome sequences of two stains of H. pylori gives rise to direct evidence on the genetic diversity reported previously with respect to gene organization and nucleotide variability from strain to strain. The genome size of H. pylori strain 26695 is 1,6697,867 bp and is 1,643,831 bp for strain J99. Approximately 89% of the predicted open reading frames are common to both of the strains, confirming H. pylori as a single species. A region containing approximately 45% of H. pylori strain-specific open reading frames, termed the plasticity zone, is present on the chromosomes, verifying that some strain variability exists. Frequent alteration of nucleotides in the third position of the triplet codons and various copies of insertion elements on the individual chromosomes appear to contribute to distinct polymorphic fingerprints among strains analyzed by restriction fragment length polymorphisms, random amplified polymorphic DNA method, and repetitive element-polymerase chain reaction. Disordered chromosomal locations of some genes seen by pulsed-field gel electrophoresis are likely caused by rearrangement or inversion of certain segments in the genomes. Cloning and functional characterization of the genes involved in acidic survival, vacuolating toxin, cag-pathogenicity island, motility, attachment to epithelial cells, natural transformation, and the biosynthesis of lipopolysaccharides have considerably increased our understanding of the molecular genetic basis for the pathogenesis of H. pylori. The homopolymeric nucleotide tracts and dinucleotide repeats, which potentially regulate the on- and off-status of the target genes by the strand-slipped mispairing mechanism, are often found in the genes encoding the outer-membrane proteins, in enzymes for lipopolysaccharide synthesis, and within DNA modification/restriction systems. Therefore, these genes may be involved in the H. pylori-host interaction.
Collapse
Affiliation(s)
- Z Ge
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge 02139, USA
| | | |
Collapse
|
48
|
Abstract
The publication of the complete sequence of Helicobacter pylori 26695 in 1997 and more recently that of strain J99 has provided new insight into the biology of this organism. In this review, we attempt to analyze and interpret the information provided by sequence annotations and to compare these data with those provided by experimental analyses. After a brief description of the general features of the genomes of the two sequenced strains, the principal metabolic pathways are analyzed. In particular, the enzymes encoded by H. pylori involved in fermentative and oxidative metabolism, lipopolysaccharide biosynthesis, nucleotide biosynthesis, aerobic and anaerobic respiration, and iron and nitrogen assimilation are described, and the areas of controversy between the experimental data and those provided by the sequence annotation are discussed. The role of urease, particularly in pH homeostasis, and other specialized mechanisms developed by the bacterium to maintain its internal pH are also considered. The replicational, transcriptional, and translational apparatuses are reviewed, as is the regulatory network. The numerous findings on the metabolism of the bacteria and the paucity of gene expression regulation systems are indicative of the high level of adaptation to the human gastric environment. Arguments in favor of the diversity of H. pylori and molecular data reflecting possible mechanisms involved in this diversity are presented. Finally, we compare the numerous experimental data on the colonization factors and those provided from the genome sequence annotation, in particular for genes involved in motility and adherence of the bacterium to the gastric tissue.
Collapse
Affiliation(s)
- A Marais
- Laboratoire de Bactériologie, Université Victor Segalen Bordeaux 2, 33076 Bordeaux Cedex, France
| | | | | | | |
Collapse
|
49
|
Krishnamurthy P, Parlow MH, Schneider J, Burroughs S, Wickland C, Vakil NB, Dunn BE, Phadnis SH. Identification of a novel penicillin-binding protein from Helicobacter pylori. J Bacteriol 1999; 181:5107-10. [PMID: 10438788 PMCID: PMC94005 DOI: 10.1128/jb.181.16.5107-5110.1999] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Helicobacter pylori genome encodes four penicillin-binding proteins (PBPs). PBPs 1, 2, and 3 exhibit similarities to known PBPs. The sequence of PBP 4 is unique in that it displays a novel combination of two highly conserved PBP motifs and an absence of a third motif. Expression of PBP 4, but not PBP 1, 2, or 3, is significantly increased during mid- to late-log-phase growth.
Collapse
Affiliation(s)
- P Krishnamurthy
- Department of Pathology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | | | | | | | | | | | | | | |
Collapse
|
50
|
Dunn BE, Phadnis SH. Structure, function and localization of Helicobacter pylori urease. Yale J Biol Med 1998; 71:63-73. [PMID: 10378351 PMCID: PMC2578883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Helicobacter pylori is the causative agent of most cases of gastritis. Once acquired, H. pylori establishes chronic persistent infection; it is this long-term infection that, is a subset of patients, leads to gastric or duodenal ulcer, gastric cancer or gastric MALT lymphoma. All fresh isolates of H. pylori express significant urease activity, which is essential to survival and pathogenesis of the bacterium. A significant fraction of urease is associated with the surface of H. pylori both in vivo and in vitro. Surface-associated urease is essential for H. pylori to resist exposure to acid in the presence of urea. The mechanism whereby urease becomes associated with the surface of H. pylori is unique. This process, which we term "altruistic autolysis," involves release of urease (and other cytoplasmic proteins) by genetically programmed autolysis with subsequent adsorption of the released urease onto the surface of neighboring intact bacteria. To our knowledge, this is the first evidence of essential communal behavior in pathogenic bacteria; such behavior is crucial to understanding the pathogenesis of H. pylori.
Collapse
Affiliation(s)
- B E Dunn
- Department of Pathology, Medical College of Wisconsin, Milwaukee, USA
| | | |
Collapse
|