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Dewan A, Jain C, Das M, Tripathi A, Sharma AK, Singh H, Malhotra N, Seshasayee ASN, Chakrapani H, Singh A. Intracellular peroxynitrite perturbs redox balance, bioenergetics, and Fe-S cluster homeostasis in Mycobacterium tuberculosis. Redox Biol 2024; 75:103285. [PMID: 39128229 PMCID: PMC11369450 DOI: 10.1016/j.redox.2024.103285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2024] [Revised: 07/21/2024] [Accepted: 07/23/2024] [Indexed: 08/13/2024] Open
Abstract
The ability of Mycobacterium tuberculosis (Mtb) to tolerate nitric oxide (•NO) and superoxide (O2•-) produced by phagocytes contributes to its success as a human pathogen. Recombination of •NO and O2•- generates peroxynitrite (ONOO-), a potent oxidant produced inside activated macrophages causing lethality in diverse organisms. While the response of Mtb toward •NO and O2•- is well established, how Mtb responds to ONOO- remains unclear. Filling this knowledge gap is important to understand the persistence mechanisms of Mtb during infection. We synthesized a series of compounds that generate both •NO and O2•-, which should combine to produce ONOO-. From this library, we identified CJ067 that permeates Mtb to reliably enhance intracellular ONOO- levels. CJ067-exposed Mtb strains, including multidrug-resistant (MDR) and extensively drug-resistant (XDR) clinical isolates, exhibited dose-dependent, long-lasting oxidative stress and growth inhibition. In contrast, Mycobacterium smegmatis (Msm), a fast-growing, non-pathogenic mycobacterial species, maintained redox balance and growth in response to intracellular ONOO-. RNA-sequencing with Mtb revealed that CJ067 induces antioxidant machinery, sulphur metabolism, metal homeostasis, and a 4Fe-4S cluster repair pathway (suf operon). CJ067 impaired the activity of the 4Fe-4S cluster-containing TCA cycle enzyme, aconitase, and diminished bioenergetics of Mtb. Work with Mtb strains defective in SUF and IscS involved in Fe-S cluster biogenesis pathways showed that both systems cooperatively protect Mtb from intracellular ONOO- in vitro and inducible nitric oxide synthase (iNOS)-dependent growth inhibition during macrophage infection. Thus, Mtb is uniquely sensitive to intracellular ONOO- and targeting Fe-S cluster homeostasis is expected to promote iNOS-dependent host immunity against tuberculosis (TB).
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Affiliation(s)
- Arshiya Dewan
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, Bengaluru, 560012, India
| | - Charu Jain
- Department of Chemistry, Indian Institute of Science Education and Research, Pune, 411008, India
| | - Mayashree Das
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, Bengaluru, 560012, India
| | - Ashutosh Tripathi
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, Bengaluru, 560012, India
| | - Ajay Kumar Sharma
- Department of Chemistry, Indian Institute of Science Education and Research, Pune, 411008, India
| | - Harshit Singh
- Department of Chemistry, Indian Institute of Science Education and Research, Pune, 411008, India
| | - Nitish Malhotra
- National Center for Biological Sciences, Bengaluru, 560065, India
| | | | - Harinath Chakrapani
- Department of Chemistry, Indian Institute of Science Education and Research, Pune, 411008, India.
| | - Amit Singh
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, Bengaluru, 560012, India.
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Cusack P. Alternatives to conventional antibiotics for the prevention and treatment of commonly occurring diseases in feedlot cattle. Aust Vet J 2024; 102:229-241. [PMID: 38267062 DOI: 10.1111/avj.13314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 12/06/2023] [Accepted: 12/20/2023] [Indexed: 01/26/2024]
Abstract
Antibiotic-resistant bacteria are a problem in human medicine. The development of antibiotic resistance in bacteria in feedlot cattle could have negative effects on their health and welfare and there is a theoretical possibility of transmission of antibiotic-resistant bacteria from food animals to humans. Alternatives to conventional antibiotics in feedlot health management could reduce the selective pressure for the development of antibiotic resistance. This review assesses the evidence supporting potential alternatives to conventional antibiotics in the prevention and treatment of diseases in feedlot cattle, including nitric oxide, plant extracts, supplemental yeast or yeast products, bacterial probiotics, organic acids, bacteriophages and non-specific immunostimulants. Further research is warranted with lactate utilising bacteria, the organic acid malate, bacteriophages and the non-specific immunostimulants β-1,3 glucan and those based on pox viruses. However, none of the alternatives to conventional antibiotics investigated in this review have sufficient supporting evidence to date to justify their use with feedlot cattle. Frequently, statistically weak results and studies without negative controls are cited as support for similar studies. The health and welfare of feedlot cattle are dependent on the use of products that have robust supporting data to ensure efficacy and to avoid adverse outcomes.
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Affiliation(s)
- Pmv Cusack
- Australian Livestock Production Services, Cowra, New South Wales, 2794, Australia
- School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, 2678, Australia
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Smiejkowska N, Oorts L, Van Calster K, De Vooght L, Geens R, Mattelaer HP, Augustyns K, Strelkov SV, Lamprecht D, Temmerman K, Sterckx YGJ, Cappoen D, Cos P. A high-throughput target-based screening approach for the identification and assessment of Mycobacterium tuberculosis mycothione reductase inhibitors. Microbiol Spectr 2024; 12:e0372323. [PMID: 38315026 PMCID: PMC10913476 DOI: 10.1128/spectrum.03723-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 12/21/2023] [Indexed: 02/07/2024] Open
Abstract
The World Health Organization's goal to combat tuberculosis (TB) is hindered by the emergence of anti-microbial resistance, therefore necessitating the exploration of new drug targets. Multidrug regimens are indispensable in TB therapy as they provide synergetic bactericidal effects, shorten treatment duration, and reduce the risk of resistance development. The research within our European RespiriTB consortium explores Mycobacterium tuberculosis energy metabolism to identify new drug candidates that synergize with bedaquiline, with the aim of discovering more efficient combination drug regimens. In this study, we describe the development and validation of a luminescence-coupled, target-based assay for the identification of novel compounds inhibiting Mycobacterium tuberculosis mycothione reductase (MtrMtb), an enzyme with a role in the protection against oxidative stress. Recombinant MtrMtb was employed for the development of a highly sensitive, robust high-throughput screening (HTS) assay by coupling enzyme activity to a bioluminescent readout. Its application in a semi-automated setting resulted in the screening of a diverse library of ~130,000 compounds, from which 19 hits were retained after an assessment of their potency, selectivity, and specificity. The selected hits formed two clusters and four fragment molecules, which were further evaluated in whole-cell and intracellular infection assays. The established HTS discovery pipeline offers an opportunity to deliver novel MtrMtb inhibitors and lays the foundation for future efforts in developing robust biochemical assays for the identification and triaging of inhibitors from high-throughput library screens. IMPORTANCE The growing anti-microbial resistance poses a global public health threat, impeding progress toward eradicating tuberculosis. Despite decades of active research, there is still a dire need for the discovery of drugs with novel modes of action and exploration of combination drug regimens. Within the European RespiriTB consortium, we explore Mycobacterium tuberculosis energy metabolism to identify new drug candidates that synergize with bedaquiline, with the aim of discovering more efficient combination drug regimens. In this study, we present the development of a high-throughput screening pipeline that led to the identification of M. tuberculosis mycothione reductase inhibitors.
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Affiliation(s)
- Natalia Smiejkowska
- Laboratory of Microbiology, Parasitology and Hygiene, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Wilrijk, Antwerp, Belgium
- Laboratory of Medical Biochemistry, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Wilrijk, Antwerp, Belgium
| | - Lauren Oorts
- Laboratory of Microbiology, Parasitology and Hygiene, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Wilrijk, Antwerp, Belgium
| | - Kevin Van Calster
- Laboratory of Microbiology, Parasitology and Hygiene, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Wilrijk, Antwerp, Belgium
| | - Linda De Vooght
- Laboratory of Microbiology, Parasitology and Hygiene, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Wilrijk, Antwerp, Belgium
| | - Rob Geens
- Laboratory of Medical Biochemistry, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Wilrijk, Antwerp, Belgium
| | - Henri-Philippe Mattelaer
- Laboratory of Medicinal Chemistry, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Wilrijk, Antwerp, Belgium
| | - Koen Augustyns
- Laboratory of Medicinal Chemistry, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Wilrijk, Antwerp, Belgium
| | - Sergei V. Strelkov
- Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | | | | | - Yann G.-J. Sterckx
- Laboratory of Medical Biochemistry, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Wilrijk, Antwerp, Belgium
| | - Davie Cappoen
- Laboratory of Microbiology, Parasitology and Hygiene, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Wilrijk, Antwerp, Belgium
| | - Paul Cos
- Laboratory of Microbiology, Parasitology and Hygiene, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Wilrijk, Antwerp, Belgium
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Nguyen MVH, Daley CL. Treatment of Mycobacterium avium Complex Pulmonary Disease: When Should I Treat and What Therapy Should I Start? Clin Chest Med 2023; 44:771-783. [PMID: 37890915 DOI: 10.1016/j.ccm.2023.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/29/2023]
Abstract
Treatment of M avium pulmonary disease requires a three-drug, macrolide-based regimen that is administered for 12 months beyond culture conversion. The regimen can be administered 3 days a week in non-cavitary, nodular bronchiectatic disease but should be given daily when cavitary disease is present. For treatment refractory disease, amikacin liposome inhalation suspension is added to the regimen. Parenteral amikacin or streptomycin should be administered in the setting of extensive radiographic involvement or macrolide resistance. Recurrence of disease is common and often due to reinfection. Novel and repurposed agents are being evaluated in clinical trials.
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Affiliation(s)
- Minh-Vu H Nguyen
- Division of Mycobacterial and Respiratory Infections, National Jewish Health, Denver, CO 80206, USA
| | - Charles L Daley
- Division of Mycobacterial and Respiratory Infections, National Jewish Health, Denver, CO 80206, USA.
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Yoshizumi T, Shibui Y, Kogo M, Honma S, Ito S, Yajima S, Sasaki Y. Mycothiol maintains the homeostasis and signalling of nitric oxide in Streptomyces coelicolor A3(2) M145. BMC Microbiol 2023; 23:285. [PMID: 37798648 PMCID: PMC10552308 DOI: 10.1186/s12866-023-03036-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 10/01/2023] [Indexed: 10/07/2023] Open
Abstract
BACKGROUND Previous studies have revealed a nitric oxide (NO) metabolic cycle in which NO, nitrate (NO3-), and nitrite (NO2-) circulate. The NO produced in this cycle serves as a signalling molecule that regulates actinorhodin (ACT) production via the DevS/DevR NO-dependent two-component system (TCS) in Streptomyces coelicolor A3(2) M145. However, the mechanisms involved in the regulation of NO signalling in S. coelicolor have not yet been elucidated. Mycothiol (MSH), a thiol molecule produced by Actinomyces, is involved in the defence mechanisms against oxidative stress. Therefore, this study focused on the correlation between intracellular NO and MSH levels. RESULTS To investigate the interaction of MSH with endogenously produced NO, we generated an S. coelicolor A3(2) strain deficient in MSH biosynthesis. This mutant strain exhibited a decrease in low-molecular-weight S-nitrosothiols and intracellular NO levels during culture compared to those of the wild-type strain. Moreover, the mutant strain exhibited reduced activity of the DevS/DevR TCS, a regulator of NO homeostasis and ACT production, from the early stage of culture, along with a decrease in ACT production compared to those of the wild-type strain. CONCLUSIONS This study suggests that MSH maintains intracellular NO homeostasis by forming S-nitrosomycothiol, which induces NO signalling. Finally, we propose a metabolic model in which MSH from endogenously produced NO facilitates the maintenance of both NO homeostasis and signalling in S. coelicolor A3(2) M145.
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Affiliation(s)
- Tomoki Yoshizumi
- Department of Bioscience, Faculty of Life Sciences, Tokyo University of Agriculture, Sakuragaoka, Tokyo, Setagaya-Ku, 156-8502, Japan
| | - Yukiko Shibui
- Department of Bioscience, Faculty of Life Sciences, Tokyo University of Agriculture, Sakuragaoka, Tokyo, Setagaya-Ku, 156-8502, Japan
| | - Minori Kogo
- Department of Bioscience, Faculty of Life Sciences, Tokyo University of Agriculture, Sakuragaoka, Tokyo, Setagaya-Ku, 156-8502, Japan
| | - Sota Honma
- Department of Bioscience, Faculty of Life Sciences, Tokyo University of Agriculture, Sakuragaoka, Tokyo, Setagaya-Ku, 156-8502, Japan
| | - Shinsaku Ito
- Department of Bioscience, Faculty of Life Sciences, Tokyo University of Agriculture, Sakuragaoka, Tokyo, Setagaya-Ku, 156-8502, Japan
| | - Shunsuke Yajima
- Department of Bioscience, Faculty of Life Sciences, Tokyo University of Agriculture, Sakuragaoka, Tokyo, Setagaya-Ku, 156-8502, Japan
| | - Yasuyuki Sasaki
- Department of Bioscience, Faculty of Life Sciences, Tokyo University of Agriculture, Sakuragaoka, Tokyo, Setagaya-Ku, 156-8502, Japan.
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6
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Bogdanovski K, Chau T, Robinson CJ, MacDonald SD, Peterson AM, Mashek CM, Wallin WA, Rimkus M, Montgomery F, Lucas da Silva J, Gupta S, Ghaffari A, Zelazny AM, Olivier KN. Antibacterial activity of high-dose nitric oxide against pulmonary Mycobacterium abscessus disease. Access Microbiol 2020; 2:acmi000154. [PMID: 33195983 PMCID: PMC7656188 DOI: 10.1099/acmi.0.000154] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 06/15/2020] [Indexed: 12/27/2022] Open
Abstract
Introduction Mycobacterium abscessus is an emerging pulmonary pathogen with limited treatment options. Nitric oxide (NO) demonstrates antibacterial activity against various bacterial species, including mycobacteria. In this study, we evaluated the effect of adjunctive inhaled NO therapy, using a novel NO generator, in a CF patient with pulmonary M. abscessus disease, and examined heterogeneity of response to NO in vitro. Methods In the compassionate-use treatment, a 24-year-old CF patient with pulmonary M. abscessus was treated with two courses of adjunctive intermittent NO, first at 160 p.p.m. for 21 days and subsequently by escalating the dose up to 240 p.p.m. for 8 days. Methemoglobin, pulmonary function, 6 min walk distance (6MWD), qualify of life and sputum microbiology were assessed. In vitro susceptibility tests were performed against patient's isolate and comparison clinical isolates and quantified by Hill's slopes calculated from time-kill curves. Results M. abscessus lung infection eradication was not achieved, but improvements in selected qualify of life domains, lung function and 6MWD were observed during the study. Inhaled NO was well tolerated at 160 p.p.m. Dosing at 240 p.p.m. was stopped due to adverse symptoms, although methemoglobin levels remained within safety thresholds. In vitro susceptibility tests showed a dose-dependent NO effect on M. abscessus susceptibility and significant heterogeneity in response between M. abscessus clinical isolates. The patient's isolate was found to be the least susceptible strain in vitro. Conclusion These results demonstrate heterogeneity in M. abscessus susceptibility to NO and suggest that longer treatment regimens could be required to see the reduction or eradication of more resistant pulmonary strains.
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Affiliation(s)
- Kristijan Bogdanovski
- Laboratory of Chronic Airway Infection, Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Trisha Chau
- Laboratory of Chronic Airway Infection, Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Chevalia J Robinson
- Laboratory of Chronic Airway Infection, Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Sandra D MacDonald
- Laboratory of Chronic Airway Infection, Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ann M Peterson
- Nursing Department, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - Christine M Mashek
- Nursing Department, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - Windy A Wallin
- Critical Care Therapy Section, Clinical Center, National Institutes of Health, Bethesda, USA
| | | | | | - Joas Lucas da Silva
- Laboratory of Chronic Airway Infection, Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Shashank Gupta
- Laboratory of Chronic Airway Infection, Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | | | - Adrian M Zelazny
- Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - Kenneth N Olivier
- Laboratory of Chronic Airway Infection, Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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Inhaled Antibiotics for Mycobacterial Lung Disease. Pharmaceutics 2019; 11:pharmaceutics11070352. [PMID: 31331119 PMCID: PMC6680843 DOI: 10.3390/pharmaceutics11070352] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 07/09/2019] [Accepted: 07/15/2019] [Indexed: 12/22/2022] Open
Abstract
Mycobacterial lung diseases are an increasing global health concern. Tuberculosis and nontuberculous mycobacteria differ in disease severity, epidemiology, and treatment strategies, but there are also a number of similarities. Pathophysiology and disease progression appear to be relatively similar between these two clinical diagnoses, and as a result these difficult to treat pulmonary infections often require similarly extensive treatment durations of multiple systemic drugs. In an effort to improve treatment outcomes for all mycobacterial lung diseases, a significant body of research has investigated the use of inhaled antibiotics. This review discusses previous research into inhaled development programs, as well as ongoing research of inhaled therapies for both nontuberculous mycobacterial lung disease, and tuberculosis. Due to the similarities between the causative agents, this review will also discuss the potential cross-fertilization of development programs between these similar-yet-different diseases. Finally, we will discuss some of the perceived difficulties in developing a clinically utilized inhaled antibiotic for mycobacterial diseases, and potential arguments in favor of the approach.
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Bentur L, Gur M, Ashkenazi M, Livnat-Levanon G, Mizrahi M, Tal A, Ghaffari A, Geffen Y, Aviram M, Efrati O. Pilot study to test inhaled nitric oxide in cystic fibrosis patients with refractory Mycobacterium abscessus lung infection. J Cyst Fibros 2019; 19:225-231. [PMID: 31129068 DOI: 10.1016/j.jcf.2019.05.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 04/30/2019] [Accepted: 05/02/2019] [Indexed: 12/17/2022]
Abstract
BACKGROUND Airways of Cystic Fibrosis (CF) patients are Nitric Oxide (NO) deficient which may contribute to impaired lung function and infection clearance. Mycobacterium abscessus (M. abscessus) infection prevalence is increasing in CF patients and is associated with increased morbidity and mortality. Here, we assess the safety and efficacy of intermittent inhaled NO (iNO) as adjuvant therapy in CF patients with refractory M. abscessus lung infection. METHODS A prospective, open-label pilot study of iNO (160 ppm) administered five times/day during hospitalization (14 days), and three times/day during ambulatory treatment (7 days) was conducted. The primary outcome was safety measured by NO-related adverse events (AEs). Secondary outcomes were six-minute walk distance (6MWD), forced expiratory volume in 1 s (FEV1), and M. abscessus burden in airways. RESULTS Nine subjects were recruited. INO at 160 ppm was well-tolerated and no iNO-related SAEs were observed during the study. Mean FEV1 and 6WMD were increased relative to baseline during NO treatment. M. abscessus culture conversion was not achieved, but 3/9 patients experienced at least one negative culture during the study. Mean time to positivity in M. abscessus culture, and qPCR analysis showed reductions in sputum bacterial load. The study was not powered to achieve statistical significance in FEV1, 6WMD, and bacterial load. CONCLUSIONS Intermittent iNO at 160 ppm is well tolerated and safe and led to increases in mean 6MWD and FEV1. INO exhibited potential antibacterial activity against M. abscessus. Further evaluation of secondary endpoints in a larger cohort of CF patients is warranted to demonstrate statistical significance.
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Affiliation(s)
- Lea Bentur
- Pediatric Pulmonary Institute and CF Center, Ruth Children's Hospital, Rambam Health Care Campus, POB 9602, Haifa, Israel; Technion-Israel Institute of Technology, Haifa, Israel.
| | - Michal Gur
- Pediatric Pulmonary Institute and CF Center, Ruth Children's Hospital, Rambam Health Care Campus, POB 9602, Haifa, Israel; Technion-Israel Institute of Technology, Haifa, Israel
| | - Moshe Ashkenazi
- Pediatric Pulmonary Institute and National CF Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Hashomer 52621, Ramat-Gan, Israel; Pediatric Pulmonary Unit, Soroka University Medical Center POB 151, Beer-Sheva, Israel
| | - Galit Livnat-Levanon
- Pediatric Pulmonology Unit and CF Center, Lady Davis Carmel Medical Center, Haifa, Israel
| | | | - Asher Tal
- AIT Therapeutics Inc, Garden City, NY 11530, USA
| | | | - Yuval Geffen
- Microbiology Laboratory, Rambam Health Care Campus, POB 9602, Haifa, Israel
| | - Micha Aviram
- Pediatric Pulmonary Unit, Soroka University Medical Center POB 151, Beer-Sheva, Israel
| | - Ori Efrati
- Pediatric Pulmonary Institute and National CF Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Hashomer 52621, Ramat-Gan, Israel; Sackler Faculty of Medicine, Tel-Aviv University, POB 39040, Tel-Aviv, Israel
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The role of low molecular weight thiols in Mycobacterium tuberculosis. Tuberculosis (Edinb) 2019; 116:44-55. [PMID: 31153518 DOI: 10.1016/j.tube.2019.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 04/16/2019] [Accepted: 04/22/2019] [Indexed: 02/06/2023]
Abstract
Low molecular weight (LMW) thiols are molecules with a functional sulfhydryl group that enable them to detoxify reactive oxygen species, reactive nitrogen species and other free radicals. Their roles range from their ability to modulate the immune system to their ability to prevent damage of biological molecules such as DNA and proteins by protecting against oxidative, nitrosative and acidic stress. LMW thiols are synthesized and found in both eukaryotes and prokaryotes. Due to their beneficial role to both eukaryotes and prokaryotes, their specific functions need to be elucidated, most especially in pathogenic prokaryotes such as Mycobacterium tuberculosis (M.tb), in order to provide a rationale for targeting their biosynthesis for drug development. Ergothioneine (ERG), mycothiol (MSH) and gamma-glutamylcysteine (GGC) are LMW thiols that have been shown to interplay to protect M.tb against cellular stress. Though ERG, MSH and GGC seem to have overlapping functions, studies are gradually revealing their unique physiological roles. Understanding their unique physiological role during the course of tuberculosis (TB) infection, would pave the way for the development of drugs that target their biosynthetic pathway. This review identifies the knowledge gap in the unique physiological roles of LMW thiols and proposes their mechanistic roles based on previous studies. In addition, it gives an update on identified inhibitors of their biosynthetic enzymes.
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Sao Emani C, Williams MJ, Wiid IJ, Baker B. The functional interplay of low molecular weight thiols in Mycobacterium tuberculosis. J Biomed Sci 2018; 25:55. [PMID: 30001196 PMCID: PMC6042322 DOI: 10.1186/s12929-018-0458-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 07/05/2018] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Three low molecular weight thiols are synthesized by Mycobacterium tuberculosis (M.tb), namely ergothioneine (ERG), mycothiol (MSH) and gamma-glutamylcysteine (GGC). They are able to counteract reactive oxygen species (ROS) and/or reactive nitrogen species (RNS). In addition, the production of ERG is elevated in the MSH-deficient M.tb mutant, while the production of MSH is elevated in the ERG-deficient mutants. Furthermore, the production of GGC is elevated in the MSH-deficient mutant and the ERG-deficient mutants. The propensity of one thiol to be elevated in the absence of the other prompted further investigations into their interplay in M.tb. METHODS To achieve that, we generated two M.tb mutants that are unable to produce ERG nor MSH but are able to produce a moderate (ΔegtD-mshA) or significantly high (ΔegtB-mshA) amount of GGC relative to the wild-type strain. In addition, we generated an M.tb mutant that is unable to produce GGC nor MSH but is able to produce a significantly low level of ERG (ΔegtA-mshA) relative to the wild-type strain. The susceptibilities of these mutants to various in vitro and ex vivo stress conditions were investigated and compared. RESULTS The ΔegtA-mshA mutant was the most susceptible to cellular stress relative to its parent single mutant strains (ΔegtA and ∆mshA) and the other double mutants. In addition, it displayed a growth-defect in vitro, in mouse and human macrophages suggesting; that the complete inhibition of ERG, MSH and GGC biosynthesis is deleterious for the growth of M.tb. CONCLUSIONS This study indicates that ERG, MSH and GGC are able to compensate for each other to maximize the protection and ensure the fitness of M.tb. This study therefore suggests that the most effective strategy to target thiol biosynthesis for anti-tuberculosis drug development would be the simultaneous inhibition of the biosynthesis of ERG, MSH and GGC.
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Affiliation(s)
- C. Sao Emani
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research; SAMRC Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics; Department of Biomedical Sciences, Faculty of Medicine and Health Sciences; Stellenbosch University, PO Box 241, Francie van Zijl Drive, Tygerberg 8000, Cape Town, South Africa
| | - M. J. Williams
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research; SAMRC Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics; Department of Biomedical Sciences, Faculty of Medicine and Health Sciences; Stellenbosch University, PO Box 241, Francie van Zijl Drive, Tygerberg 8000, Cape Town, South Africa
| | - I. J. Wiid
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research; SAMRC Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics; Department of Biomedical Sciences, Faculty of Medicine and Health Sciences; Stellenbosch University, PO Box 241, Francie van Zijl Drive, Tygerberg 8000, Cape Town, South Africa
| | - B. Baker
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research; SAMRC Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics; Department of Biomedical Sciences, Faculty of Medicine and Health Sciences; Stellenbosch University, PO Box 241, Francie van Zijl Drive, Tygerberg 8000, Cape Town, South Africa
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Regev G, Martins J, Sheridan MP, Leemhuis J, Thompson J, Miller C. Feasibility and preliminary safety of nitric oxide releasing solution as a treatment for bovine mastitis. Res Vet Sci 2018. [DOI: 10.1016/j.rvsc.2018.02.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Compassionate Nitric Oxide Adjuvant Treatment of Persistent Mycobacterium Infection in Cystic Fibrosis Patients. Pediatr Infect Dis J 2018; 37:336-338. [PMID: 28885458 DOI: 10.1097/inf.0000000000001780] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Mycobacterium abscessus is one of the most antibiotic-resistant pathogens in cystic fibrosis (CF) patients. Nitric oxide (NO) has broad-spectrum antimicrobial activity. Clinical studies indicated that it is safe and tolerable when given as 160 ppm intermittent inhalations. METHODS A prospective compassionate adjunctive inhaled NO therapy in 2 CF patients with persistent Mycobacterium abscessus infection. RESULTS No adverse events were reported. Both subjects showed significant reduction in quantitative polymerase chain reaction results for Mycobacterium abscessus load in sputum during treatment; estimated colony forming unit decreased from 7000 to 550 and from 3000 to 0 for patient 1 and patient 2, respectively. CONCLUSIONS Intermittent inhalations with 160 ppm NO are well tolerated, safe and result in significant reduction of Mycobacterium abscessus load. It may constitute an adjuvant therapeutic approach for CF patients with Mycobacterium abscessus lung disease. Further studies are needed to define dosing, duration and long-term clinical outcome.
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13
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Tal A, Greenberg D, Av-Gay Y, Golan-Tripto I, Feinstein Y, Ben-Shimol S, Dagan R, Goldbart AD. Nitric oxide inhalations in bronchiolitis: A pilot, randomized, double-blinded, controlled trial. Pediatr Pulmonol 2018; 53:95-102. [PMID: 29178284 DOI: 10.1002/ppul.23905] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 10/11/2017] [Indexed: 11/08/2022]
Abstract
AIM The aims of this pilot study were to determine safety, tolerability (primary outcome) and efficacy (secondary outcome) of high-dose inhaled nitric oxide for the treatment of infants with moderately severe bronchiolitis. METHODS This was a pilot, double-blinded, randomized controlled study (phase IIa). Intermittent inhalations of nitric oxide 160 ppm for 30 min or oxygen/air (control) were given 5 times/day to hospitalized infants (2-11 months) with acute bronchiolitis. Oxygen saturation, methemoglobin, and nitric dioxide (NO2 ) levels and vital signs were monitored. RESULTS Forty-three infants were enrolled. Baseline characteristics were comparable in both study groups. Mean clinical score, comprised of four components: respiratory rate, use of accessory muscles, wheezes and crackles, and % room-air oxygen saturation, was 7.86 (±1.1) and 8.09 (±1.2) in the NO and control groups, respectively, consistent with moderate severity. The overall frequency of adverse events was similar between the groups. Repeated nitric oxide inhalations did not result in increased inhaled NO2 levels or cumulative effect on methemoglobin levels. Secondary outcomes of efficacy were measured by length of hospitalization (LOS) in hours: LOS did not differ between groups. However, in a post-hoc analysis of a subgroup of infants hospitalized for >24 h (n = 24), the median LOS was shorter in the nitric oxide (41.9 h) than in the control group (62.5 h) (P = 0.014). CONCLUSION Our study was unable to detect a difference in side effects using intermittent high-dose nitric-oxide inhalation or supportive treatment alone, in infants with moderate bronchiolitis. Preliminary efficacy outcomes are encouraging.
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Affiliation(s)
- Asher Tal
- Department of Pediatrics, Soroka University Medical Center, Beer-Sheva, Israel.,Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Advanced Inhalation Therapies (A.I.T.) Ltd., Rehovot, Israel
| | - David Greenberg
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Advanced Inhalation Therapies (A.I.T.) Ltd., Rehovot, Israel.,Pediatric Infectious Diseases Unit, Soroka University Medical Center, Beer-Sheva, Israel
| | - Yossef Av-Gay
- Advanced Inhalation Therapies (A.I.T.) Ltd., Rehovot, Israel.,Department of Medicine, University of British Columbia, Vancouver, Canada
| | - Inbal Golan-Tripto
- Department of Pediatrics, Soroka University Medical Center, Beer-Sheva, Israel.,Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Yael Feinstein
- Department of Pediatrics, Soroka University Medical Center, Beer-Sheva, Israel.,Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Shalom Ben-Shimol
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Pediatric Infectious Diseases Unit, Soroka University Medical Center, Beer-Sheva, Israel
| | - Ron Dagan
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Aviv D Goldbart
- Department of Pediatrics, Soroka University Medical Center, Beer-Sheva, Israel.,Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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14
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Sao Emani C, Williams M, Van Helden P, Taylor M, Wiid I, Baker B. Gamma-glutamylcysteine protects ergothioneine-deficient Mycobacterium tuberculosis mutants against oxidative and nitrosative stress. Biochem Biophys Res Commun 2018; 495:174-178. [DOI: 10.1016/j.bbrc.2017.10.163] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Accepted: 10/29/2017] [Indexed: 11/15/2022]
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15
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Abstract
Reversible protein phosphorylation is the most common type of epigenetic posttranslational modification in living cells used as a major regulation mechanism of biological processes. The Mycobacterium tuberculosis genome encodes for 11 serine/threonine protein kinases that are responsible for sensing environmental signals to coordinate a cellular response to ensure the pathogen's infectivity, survival, and growth. To overcome killing mechanisms generated within the host during infection, M. tuberculosis enters a state of nonreplicating persistence that is characterized by arrested growth, limited metabolic activity, and phenotypic resistance to antimycobacterial drugs. In this article we focus our attention on the role of M. tuberculosis serine/threonine protein kinases in sensing the host environment to coordinate the bacilli's physiology, including growth, cell wall components, and central metabolism, to establish a persistent infection.
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16
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Deppisch C, Herrmann G, Graepler-Mainka U, Wirtz H, Heyder S, Engel C, Marschal M, Miller CC, Riethmüller J. Gaseous nitric oxide to treat antibiotic resistant bacterial and fungal lung infections in patients with cystic fibrosis: a phase I clinical study. Infection 2016; 44:513-20. [PMID: 26861246 DOI: 10.1007/s15010-016-0879-x] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Accepted: 01/27/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND Individuals with cystic fibrosis (CF) receive antibiotics continuously throughout their entire life which leads to drug resistant microbial lung infections which are difficult to treat. Nitric oxide (NO) gas possesses antimicrobial activity against a wide variety of microorganisms in vitro, in vivo in animal models and a phase I study in healthy adults showed administration of intermittent 160 ppm NO to be safe. METHODS We assessed feasibility and safety of inhaled NO in eight CF patients who received 160 ppm NO for 30 min, three times daily for 2 periods of 5 days. RESULTS The NO treatment was safe and in none of the patients were serious drug-related adverse events observed which caused termination of the study. The intention-to-treat analysis revealed a significant mean reduction of the colony forming units of all bacteria and all fungi, while mean forced expiratory volume 1 s % predicted (FEV1) relative to baseline increased 17.3 ± 8.9 % (P = 0.012). CONCLUSIONS NO treatment may improve the therapy of chronic microbial lung infections in CF patients, particularly concerning pathogens with intrinsic or acquired resistance to antibiotics.
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Affiliation(s)
- Caroline Deppisch
- Comprehensive Cystic Fibrosis Center, Children's Clinic, Tübingen, Germany
| | - Gloria Herrmann
- Comprehensive Cystic Fibrosis Center, Children's Clinic, Tübingen, Germany
| | | | - Hubertus Wirtz
- Medizinische Klinik I, Pneumologie, Universität Leipzig, Leipzig, Germany
| | - Susanne Heyder
- Klinik Schillerhöhe, Robert Bosch Krankenhaus GmbH, Gerlingen, Germany
| | - Corinna Engel
- Comprehensive Cystic Fibrosis Center, Children's Clinic, Tübingen, Germany
| | - Matthias Marschal
- Institute of Medical Microbiology and Hygiene, Universitätsklinikum Tübingen, Tübingen, Germany
| | - Christopher C Miller
- Nitric Oxide Laboratory, Division of Respiratory and Infectious Diseases, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Joachim Riethmüller
- Comprehensive Cystic Fibrosis Center, Children's Clinic, Tübingen, Germany. .,University Childrens' Hospital, Universitätsklinikum Tübingen, Hoppe-Seyler-Str. 1, 72076, Tübingen, Germany.
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17
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Saini V, Cumming BM, Guidry L, Lamprecht DA, Adamson JH, Reddy VP, Chinta KC, Mazorodze JH, Glasgow JN, Richard-Greenblatt M, Gomez-Velasco A, Bach H, Av-Gay Y, Eoh H, Rhee K, Steyn AJC. Ergothioneine Maintains Redox and Bioenergetic Homeostasis Essential for Drug Susceptibility and Virulence of Mycobacterium tuberculosis. Cell Rep 2016; 14:572-585. [PMID: 26774486 DOI: 10.1016/j.celrep.2015.12.056] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Revised: 10/30/2015] [Accepted: 12/09/2015] [Indexed: 02/06/2023] Open
Abstract
The mechanisms by which Mycobacterium tuberculosis (Mtb) maintains metabolic equilibrium to survive during infection and upon exposure to antimycobacterial drugs are poorly characterized. Ergothioneine (EGT) and mycothiol (MSH) are the major redox buffers present in Mtb, but the contribution of EGT to Mtb redox homeostasis and virulence remains unknown. We report that Mtb WhiB3, a 4Fe-4S redox sensor protein, regulates EGT production and maintains bioenergetic homeostasis. We show that central carbon metabolism and lipid precursors regulate EGT production and that EGT modulates drug sensitivity. Notably, EGT and MSH are both essential for redox and bioenergetic homeostasis. Transcriptomic analyses of EGT and MSH mutants indicate overlapping but distinct functions of EGT and MSH. Last, we show that EGT is critical for Mtb survival in both macrophages and mice. This study has uncovered a dynamic balance between Mtb redox and bioenergetic homeostasis, which critically influences Mtb drug susceptibility and pathogenicity.
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Affiliation(s)
- Vikram Saini
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA; Centers for AIDS Research and Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Bridgette M Cumming
- KwaZulu-Natal Research Institute for Tuberculosis and HIV, Durban 4001, South Africa
| | - Loni Guidry
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Dirk A Lamprecht
- KwaZulu-Natal Research Institute for Tuberculosis and HIV, Durban 4001, South Africa
| | - John H Adamson
- KwaZulu-Natal Research Institute for Tuberculosis and HIV, Durban 4001, South Africa
| | - Vineel P Reddy
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Krishna C Chinta
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - James H Mazorodze
- KwaZulu-Natal Research Institute for Tuberculosis and HIV, Durban 4001, South Africa
| | - Joel N Glasgow
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | | | | | - Horacio Bach
- Department of Medicine, University of British Columbia, Vancouver, BC V6H 3Z6, Canada
| | - Yossef Av-Gay
- Department of Medicine, University of British Columbia, Vancouver, BC V6H 3Z6, Canada
| | - Hyungjin Eoh
- Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA
| | - Kyu Rhee
- Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA
| | - Adrie J C Steyn
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA; Centers for AIDS Research and Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA; KwaZulu-Natal Research Institute for Tuberculosis and HIV, Durban 4001, South Africa; Department of Pathology, Nelson Mandela School of Medicine, University of KwaZulu-Natal, Durban 4001, South Africa.
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18
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Richard-Greenblatt M, Bach H, Adamson J, Peña-Diaz S, Li W, Steyn AJC, Av-Gay Y. Regulation of Ergothioneine Biosynthesis and Its Effect on Mycobacterium tuberculosis Growth and Infectivity. J Biol Chem 2015; 290:23064-76. [PMID: 26229105 DOI: 10.1074/jbc.m115.648642] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Indexed: 11/06/2022] Open
Abstract
Ergothioneine (EGT) is synthesized in mycobacteria, but limited knowledge exists regarding its synthesis, physiological role, and regulation. We have identified Rv3701c from Mycobacterium tuberculosis to encode for EgtD, a required histidine methyltransferase that catalyzes first biosynthesis step in EGT biosynthesis. EgtD was found to be phosphorylated by the serine/threonine protein kinase PknD. PknD phosphorylates EgtD both in vitro and in a cell-based system on Thr(213). The phosphomimetic (T213E) but not the phosphoablative (T213A) mutant of EgtD failed to restore EGT synthesis in a ΔegtD mutant. The findings together with observed elevated levels of EGT in a pknD transposon mutant during in vitro growth suggests that EgtD phosphorylation by PknD negatively regulates EGT biosynthesis. We further showed that EGT is required in a nutrient-starved model of persistence and is needed for long term infection of murine macrophages.
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Affiliation(s)
| | - Horacio Bach
- From the Division of Infectious Diseases, Department of Medicine and
| | - John Adamson
- Kwazulu-Natal Research Institute for Tuberculosis and HIV, Durban, South Africa 4001
| | - Sandra Peña-Diaz
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6H 3Z6, Canada
| | - Wu Li
- Institute of Modern Biopharmaceuticals, School of Life Sciences, Southwest University, Chongqing 400715, China, and
| | - Adrie J C Steyn
- Kwazulu-Natal Research Institute for Tuberculosis and HIV, Durban, South Africa 4001, Department of Microbiology and Centers for AIDS Research and Free Radical Biology, University of Alabama, Birmingham, Alabama 35233
| | - Yossef Av-Gay
- From the Division of Infectious Diseases, Department of Medicine and
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19
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Regev-Shoshani G, McMullin B, Nation N, Church JS, Dorin C, Miller C. Non-inferiority of nitric oxide releasing intranasal spray compared to sub-therapeutic antibiotics to reduce incidence of undifferentiated fever and bovine respiratory disease complex in low to moderate risk beef cattle arriving at a commercial feedlot. Prev Vet Med 2015; 138:162-169. [PMID: 25975664 DOI: 10.1016/j.prevetmed.2015.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 03/31/2015] [Accepted: 04/13/2015] [Indexed: 10/23/2022]
Abstract
Undifferentiated fever, or bovine respiratory disease complex (BRDc), is a challenging multi-factorial health issue caused by viral/bacterial pathogens and stressors linked to the transport and mixing of cattle, negatively impacting the cattle feedlot industry. Common practice during processing at feedlots is administration of antibiotic metaphylaxis to reduce the incidence of BRDc. Nitric oxide (NO) is a naturally occurring nano-molecule with a wide range of physiological attributes. This study evaluated the metaphylactic use of intranasal NO releasing spray (NORS) to control BRDc incidence in calves at low-moderate risk of developing BRDc, arriving at a commercial feedlot as compared to conventional antibiotic metaphylaxis. One thousand and eighty crossbred, multiple-sourced, commingled, commercial, weaned beef calves were screened, enrolled, randomized and treated upon arrival. Animals appearing sick were pulled (from their pen) by blinded pen keepers then assessed for BRDc symptoms; blood samples were taken for haptoglobin quantification and the animals were rescued with an antibiotic. After 35 days both groups showed no significant difference in BRDc incidence (5.2% of animals from NORS group and 3.2% from antibiotic group). Average daily weight gain of animals at day 150 for the NORS cohort was 1.17kg compared to 1.18kg for the antibiotic group (p>0.05). There was no significant difference in mortality in the first 35 days (p=0.7552), however, general mortality over 150 days trended higher in the antibiotic cohort. NORS treatment was shown to be safe, causing neither distress nor adverse effects on the animals. This large randomized controlled study in low-moderate BRDc incidence risk calves demonstrates that NORS treatment, as compared to conventional metaphylactic antibiotics, is non-inferior based on BRDc incidence and other metrics like weight and mortality. These data justify further studies in higher BRDc incidence risk populations to evaluate NORS as an alternative strategy to reduce sub-therapeutic metaphylaxis antibiotic use in beef cattle production.
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Affiliation(s)
- G Regev-Shoshani
- Faculty of Medicine, Respiratory Division, University of British Columbia, Vancouver, British Columbia, Canada
| | - B McMullin
- Faculty of Medicine, Respiratory Division, University of British Columbia, Vancouver, British Columbia, Canada
| | - N Nation
- Animal Pathology Services (APS) Ltd., 18208 Ellerslie Road, Edmonton, Alberta, Canada
| | - J S Church
- Department of Natural Resources, Thompson Rivers University, Kamloops, British Columbia, Canada
| | - C Dorin
- Veterinary AGRI-Health Services, 201-151 East Blvd, Airdrie, Alberta, Canada
| | - C Miller
- Faculty of Medicine, Respiratory Division, University of British Columbia, Vancouver, British Columbia, Canada.
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20
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Abstract
ABSTRACT
During infection,
Mycobacterium tuberculosis
is exposed to a diverse array of microenvironments in the human host, each with its own unique set of redox conditions. Imbalances in the redox environment of the bacillus or the host environment serve as stimuli, which could regulate virulence. The ability of
M. tuberculosis
to evade the host immune response and cause disease is largely owing to the capacity of the mycobacterium to sense changes in its environment, such as host-generated gases, carbon sources, and pathological conditions, and alter its metabolism and redox balance accordingly for survival. In this article we discuss the redox sensors that are, to date, known to be present in
M. tuberculosis
, such as the Dos dormancy regulon, WhiB family, anti-σ factors, and MosR, in addition to the strategies present in the bacillus to neutralize free radicals, such as superoxide dismutases, catalase-peroxidase, thioredoxins, and methionine sulfoxide reductases, among others.
M. tuberculosis
is peculiar in that it appears to have a hierarchy of redox buffers, namely, mycothiol and ergothioneine. We discuss the current knowledge of their biosynthesis, function, and regulation. Ergothioneine is still an enigma, although it appears to have distinct and overlapping functions with mycothiol, which enable it to protect against a wide range of toxic metabolites and free radicals generated by the host. Developing approaches to quantify the intracellular redox status of the mycobacterium will enable us to determine how the redox balance is altered in response to signals and environments that mimic those encountered in the host.
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21
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Regev-Shoshani G, Vimalanathan S, Prema D, Church J, Reudink M, Nation N, Miller C. Safety, bioavailability and mechanism of action of nitric oxide to control Bovine Respiratory Disease Complex in calves entering a feedlot. Res Vet Sci 2014; 96:328-37. [DOI: 10.1016/j.rvsc.2013.12.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 12/06/2013] [Accepted: 12/22/2013] [Indexed: 10/25/2022]
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22
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Pramanik S, Konwarh R, Barua N, Buragohain AK, Karak N. Bio-based hyperbranched poly(ester amide)–MWCNT nanocomposites: multimodalities at the biointerface. Biomater Sci 2014; 2:192-202. [PMID: 32481879 DOI: 10.1039/c3bm60170f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/03/2023]
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23
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Miller CC, Hergott CA, Rohan M, Arsenault-Mehta K, Döring G, Mehta S. Inhaled nitric oxide decreases the bacterial load in a rat model of Pseudomonas aeruginosa pneumonia. J Cyst Fibros 2013; 12:817-20. [DOI: 10.1016/j.jcf.2013.01.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 01/30/2013] [Accepted: 01/31/2013] [Indexed: 11/25/2022]
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24
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Regev-Shoshani G, Church JS, Cook NJ, Schaefer AL, Miller C. Prophylactic nitric oxide treatment reduces incidence of bovine respiratory disease complex in beef cattle arriving at a feedlot. Res Vet Sci 2013; 95:606-11. [PMID: 23850382 DOI: 10.1016/j.rvsc.2013.06.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 04/05/2013] [Accepted: 06/18/2013] [Indexed: 11/16/2022]
Abstract
Bovine respiratory disease complex (BRDc), is a challenging multi-factorial health issue caused by viral/bacterial pathogens and stressors linked with the transport and mixing of cattle, negatively impacting the cattle feedlot industry. Nitric oxide (NO) is a naturally occurring molecule with antimicrobial attributes. This study tests whether NO can prevent the symptoms associated with BRDc. Eighty-five, crossbred, multiple-sourced, commingled commercial weaned beef calves were monitored and scored for temperature, white blood count, clinical score, hematology, cortisol levels and neutrophil/lymphocyte ratio. NO treatment or placebo were given once on arrival to the stockyard. After one week 87.5% of sick animals were from the control while 12.5% from treatment groups and after two weeks 72% and 28% respectively. Treatment was shown to be safe, causing neither distress nor adverse effects on the animals. These data show that NO treatment on arrival to the feedlot significantly decreased the incidence of BRDc in this study.
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Affiliation(s)
- G Regev-Shoshani
- Faculty of Medicine, Respiratory Division, University of British Columbia, Vancouver, British Columbia, Canada
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25
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Fahey RC. Glutathione analogs in prokaryotes. Biochim Biophys Acta Gen Subj 2012; 1830:3182-98. [PMID: 23075826 DOI: 10.1016/j.bbagen.2012.10.006] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 09/25/2012] [Accepted: 10/08/2012] [Indexed: 01/17/2023]
Abstract
BACKGROUND Oxygen is both essential and toxic to all forms of aerobic life and the chemical versatility and reactivity of thiols play a key role in both aspects. Cysteine thiol groups have key catalytic functions in enzymes but are readily damaged by reactive oxygen species (ROS). Low-molecular-weight thiols provide protective buffers against the hazards of ROS toxicity. Glutathione is the small protective thiol in nearly all eukaryotes but in prokaryotes the situation is far more complex. SCOPE OF REVIEW This review provides an introduction to the diversity of low-molecular-weight thiol protective systems in bacteria. The topics covered include the limitations of cysteine as a protector, the multiple origins and distribution of glutathione biosynthesis, mycothiol biosynthesis and function in Actinobacteria, recent discoveries involving bacillithiol found in Firmicutes, new insights on the biosynthesis and distribution of ergothioneine, and the potential protective roles played by coenzyme A and other thiols. MAJOR CONCLUSIONS Bacteria have evolved a diverse collection of low-molecular-weight protective thiols to deal with oxygen toxicity and environmental challenges. Our understanding of how many of these thiols are produced and utilized is still at an early stage. GENERAL SIGNIFICANCE Extensive diversity existed among prokaryotes prior to evolution of the cyanobacteria and the development of an oxidizing atmosphere. Bacteria that managed to adapt to life under oxygen evolved, or acquired, the ability to produce a variety of small thiols for protection against the hazards of aerobic metabolism. Many pathogenic prokaryotes depend upon novel thiol protection systems that may provide targets for new antibacterial agents. This article is part of a Special Issue entitled Cellular functions of glutathione.
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Affiliation(s)
- Robert C Fahey
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.
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26
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Nokwequ MG, Nkambule CM, Gammon DW. Armed–disarmed effect on the stability of cysteine thioglucosides. Carbohydr Res 2012; 359:18-23. [DOI: 10.1016/j.carres.2012.06.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 06/22/2012] [Accepted: 06/30/2012] [Indexed: 11/25/2022]
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27
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Miller C, Miller M, McMullin B, Regev G, Serghides L, Kain K, Road J, Av-Gay Y. A phase I clinical study of inhaled nitric oxide in healthy adults. J Cyst Fibros 2012; 11:324-31. [PMID: 22520076 DOI: 10.1016/j.jcf.2012.01.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 01/18/2012] [Indexed: 12/31/2022]
Abstract
BACKGROUND Nitric oxide (NO) is an approved pulmonary vasodilator for neonates and full term infants up to a dose of 80 ppm. At 100 ppm to 200 ppm, NO has potent antimicrobial activities in vitro and in animal studies which suggest its therapeutic use for infectious diseases in humans. However, whether inhaled NO is safe at 160 ppm in healthy human adults is unknown. The aim of the phase I study was to assess the safety of delivery and the physiologic effects of intermittent 160 ppm NO in healthy human adults. METHODS Ten healthy adult volunteers (5 males, 5 females; 20-62 years) were recruited and inhaled 163.3 ppm (SD: 4.0) NO for 30 min, 5 times daily, for 5 consecutive days. Lung function and blood levels of methemoglobin, nitrites/nitrates, prothrombin, pro-inflammatory cytokines and chemokines were determined before and during treatment. RESULTS All individuals tolerated the NO treatment courses well. No significant adverse events occurred and three minor adverse events, not attributable to NO, were reported. Forced expiratory volume in 1 sec % predicted and other lung function parameters, serum nitrites/nitrates, prothrombin, pro-inflammatory cytokine and chemokine levels did not differ between baseline and day 5, while methemoglobin increased significantly during the study period to a level of 0.9% (SD: 0.08) (p<0.001). CONCLUSION These data suggest that inhalation of 160 ppm NO for 30 min, 5 times daily, for 5 consecutive days, is safe and well tolerated in healthy individuals.
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Affiliation(s)
- Chris Miller
- Respiratory Division, Department of Medicine, University of British Columbia, Vancouver, Canada.
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28
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Privett BJ, Broadnax AD, Bauman SJ, Riccio DA, Schoenfisch MH. Examination of bacterial resistance to exogenous nitric oxide. Nitric Oxide 2012; 26:169-73. [PMID: 22349019 DOI: 10.1016/j.niox.2012.02.002] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 12/29/2011] [Accepted: 02/12/2012] [Indexed: 11/19/2022]
Abstract
While much research has been directed to harnessing the antimicrobial properties of exogenous NO, the possibility of bacteria developing resistance to such therapy has not been thoroughly studied. Herein, we evaluate potential NO resistance using spontaneous and serial passage mutagenesis assays. Specifically, Staphylococcus aureus, Methicillin-resistant S. aureus (MRSA), Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa were systematically exposed to NO-releasing 75mol% MPTMS-TEOS nitrosothiol particles at or below minimum inhibitory concentration (MIC) levels. In the spontaneous mutagenesis assay, bacteria that survived exposure to lethal concentrations of NO showed no increase in MIC. Similarly, no increase in MIC was observed in the serial passage mutagenesis assay after exposure of these species to sub-inhibitory concentrations of NO through 20 d.
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Affiliation(s)
- Benjamin J Privett
- University of North Carolina at Chapel Hill, Department of Chemistry, Chapel Hill, NC 27599, United States
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29
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Abstract
Mycobacterium tuberculosis (Mtb) has evolved into a highly successful human pathogen. It deftly subverts the bactericidal mechanisms of alveolar macrophages, ultimately inducing granuloma formation and establishing long-term residence in the host. These hallmarks of Mtb infection are facilitated by the metabolic adaptation of the pathogen to its surrounding environment and the biosynthesis of molecules that mediate its interactions with host immune cells. The sulfate assimilation pathway of Mtb produces a number of sulfur-containing metabolites with important contributions to pathogenesis and survival. This pathway is regulated by diverse environmental cues and regulatory proteins that mediate sulfur transactions in the cell. Here, we discuss the transcriptional and biochemical mechanisms of sulfur metabolism regulation in Mtb and potential small molecule regulators of the sulfate assimilation pathway that are collectively poised to aid this intracellular pathogen in its expert manipulation of the host. From this global analysis, we have identified a subset of sulfur-metabolizing enzymes that are sensitive to multiple regulatory cues and may be strong candidates for therapeutic intervention.
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Affiliation(s)
- Stavroula K. Hatzios
- Department of Chemistry, University of California, Berkeley, Berkeley, California, United States of America
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, United States of America
| | - Carolyn R. Bertozzi
- Department of Chemistry, University of California, Berkeley, Berkeley, California, United States of America
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, United States of America
- * E-mail:
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Abstract
Bacillithiol (BSH), the α-anomeric glycoside of l-cysteinyl-d-glucosamine with l-malic acid, plays a dominant role in the cytosolic thiol redox chemistry of the low guanine and cytosine (GC) Gram-positive bacteria (phylum Firmicutes). BSH is functionally analogous to glutathione (GSH) but differs sufficiently in chemical structure that cells have evolved a distinct set of enzymes that use BSH as cofactor. BSH was discovered in Bacillus subtilis as a mixed disulfide with the redox-sensing repressor OhrR and in B. anthracis by biochemical analysis of pools of labeled thiols. The structure of BSH was determined after purification from Deinococcus radiodurans. Similarities in structure between BSH and mycothiol (MSH) facilitated the identification of biosynthetic genes for BSH in the model organism B. subtilis. Phylogenomic analyses have identified several candidate BSH-using or associated proteins, including a BSH reductase, glutaredoxin-like thiol-dependent oxidoreductases (bacilliredoxins), and a BSH-S-transferase (FosB) involved in resistance to the epoxide antibiotic fosfomycin. Preliminary results implicate BSH in cellular processes to maintain cytosolic redox balance and for adaptation to reactive oxygen, nitrogen, and electrophilic species. BSH also is predicted to chelate metals avidly, in part due to the appended malate moiety, although the implications of BSH for metal ion homeostasis have yet to be explored in detail.
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Affiliation(s)
- John D Helmann
- Department of Microbiology, Cornell University, Ithaca, New York 14853-8101, USA.
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Farhana A, Guidry L, Srivastava A, Singh A, Hondalus MK, Steyn AJC. Reductive stress in microbes: implications for understanding Mycobacterium tuberculosis disease and persistence. Adv Microb Physiol 2011; 57:43-117. [PMID: 21078441 DOI: 10.1016/b978-0-12-381045-8.00002-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mycobacterium tuberculosis (Mtb) is a remarkably successful pathogen that is capable of persisting in host tissues for decades without causing disease. Years after initial infection, the bacilli may resume growth, the outcome of which is active tuberculosis (TB). In order to establish infection, resist host defences and re-emerge, Mtb must coordinate its metabolism with the in vivo environmental conditions and nutrient availability within the primary site of infection, the lung. Maintaining metabolic homeostasis for an intracellular pathogen such as Mtb requires a carefully orchestrated series of oxidation-reduction reactions, which, if unbalanced, generate oxidative or reductive stress. The importance of oxidative stress in microbial pathogenesis has been appreciated and well studied over the past several decades. However, the role of its counterpart, reductive stress, has been largely ignored. Reductive stress is defined as an aberrant increase in reducing equivalents, the magnitude and identity of which is determined by host carbon source utilisation and influenced by the presence of host-generated gases (e.g. NO, CO, O(2) and CO(2)). This increased reductive power must be dissipated for bacterial survival. To recycle reducing equivalents, microbes have evolved unique electron 'sinks' that are distinct for their particular environmental niche. In this review, we describe the specific mechanisms that some microbes have evolved to dispel reductive stress. The intention of this review is to introduce the concept of reductive stress, in tuberculosis research in particular, in the hope of stimulating new avenues of investigation.
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Affiliation(s)
- Aisha Farhana
- Department of Microbiology, University of Alabama at Birmingham, AL, USA
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Kaur D, Guerin ME, Skovierová H, Brennan PJ, Jackson M. Chapter 2: Biogenesis of the cell wall and other glycoconjugates of Mycobacterium tuberculosis. ADVANCES IN APPLIED MICROBIOLOGY 2009; 69:23-78. [PMID: 19729090 DOI: 10.1016/s0065-2164(09)69002-x] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The re-emergence of tuberculosis in its present-day manifestations - single, multiple and extensive drug-resistant forms and as HIV-TB coinfections - has resulted in renewed research on fundamental questions such as the nature of the organism itself, Mycobacterium tuberculosis, the molecular basis of its pathogenesis, definition of the immunological response in animal models and humans, and development of new intervention strategies such as vaccines and drugs. Foremost among these developments has been the precise chemical definition of the complex and distinctive cell wall of M. tuberculosis, elucidation of the relevant pathways and underlying genetics responsible for the synthesis of the hallmark moieties of the tubercle bacillus such as the mycolic acid-arabinogalactan-peptidoglycan complex, the phthiocerol- and trehalose-containing effector lipids, the phosphatidylinositol-containing mannosides, lipomannosides and lipoarabinomannosides, major immunomodulators, and others. In this review, the laboratory personnel who have been the focal point of some to these developments review recent progress towards a comprehensive understanding of the basic physiology and functions of the cell wall of M. tuberculosis.
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Affiliation(s)
- Devinder Kaur
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University, Fort Collins, CO 80523-1682, USA
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Slow release of nitric oxide from charged catheters and its effect on biofilm formation by Escherichia coli. Antimicrob Agents Chemother 2009; 54:273-9. [PMID: 19884372 DOI: 10.1128/aac.00511-09] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Catheter-associated urinary tract infection is the most prevalent cause of nosocomial infections. Bacteria associated with biofilm formation play a key role in the morbidity and pathogenesis of these infections. Nitric oxide (NO) is a naturally produced free radical with proven bactericidal effect. In this study, Foley urinary catheters were impregnated with gaseous NO. The catheters demonstrated slow release of nitric oxide over a 14-day period. The charged catheters were rendered antiseptic, and as such, were able to prevent bacterial colonization and biofilm formation on their luminal and exterior surfaces. In addition, we observed that NO-impregnated catheters were able to inhibit the growth of Escherichia coli within the surrounding media, demonstrating the ability to eradicate a bacterial concentration of up to 10(4) CFU/ml.
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Attarian R, Bennie C, Bach H, Av-Gay Y. Glutathione disulfide and S-nitrosoglutathione detoxification byMycobacteriumtuberculosisthioredoxin system. FEBS Lett 2009; 583:3215-20. [DOI: 10.1016/j.febslet.2009.09.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2009] [Accepted: 09/01/2009] [Indexed: 10/20/2022]
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Biosynthesis and functions of mycothiol, the unique protective thiol of Actinobacteria. Microbiol Mol Biol Rev 2008; 72:471-94. [PMID: 18772286 DOI: 10.1128/mmbr.00008-08] [Citation(s) in RCA: 263] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mycothiol (MSH; AcCys-GlcN-Ins) is the major thiol found in Actinobacteria and has many of the functions of glutathione, which is the dominant thiol in other bacteria and eukaryotes but is absent in Actinobacteria. MSH functions as a protected reserve of cysteine and in the detoxification of alkylating agents, reactive oxygen and nitrogen species, and antibiotics. MSH also acts as a thiol buffer which is important in maintaining the highly reducing environment within the cell and protecting against disulfide stress. The pathway of MSH biosynthesis involves production of GlcNAc-Ins-P by MSH glycosyltransferase (MshA), dephosphorylation by the MSH phosphatase MshA2 (not yet identified), deacetylation by MshB to produce GlcN-Ins, linkage to Cys by the MSH ligase MshC, and acetylation by MSH synthase (MshD), yielding MSH. Studies of MSH mutants have shown that the MSH glycosyltransferase MshA and the MSH ligase MshC are required for MSH production, whereas mutants in the MSH deacetylase MshB and the acetyltransferase (MSH synthase) MshD produce some MSH and/or a closely related thiol. Current evidence indicates that MSH biosynthesis is controlled by transcriptional regulation mediated by sigma(B) and sigma(R) in Streptomyces coelicolor. Identified enzymes of MSH metabolism include mycothione reductase (disulfide reductase; Mtr), the S-nitrosomycothiol reductase MscR, the MSH S-conjugate amidase Mca, and an MSH-dependent maleylpyruvate isomerase. Mca cleaves MSH S-conjugates to generate mercapturic acids (AcCySR), excreted from the cell, and GlcN-Ins, used for resynthesis of MSH. The phenotypes of MSH-deficient mutants indicate the occurrence of one or more MSH-dependent S-transferases, peroxidases, and mycoredoxins, which are important targets for future studies. Current evidence suggests that several MSH biosynthetic and metabolic enzymes are potential targets for drugs against tuberculosis. The functions of MSH in antibiotic-producing streptomycetes and in bioremediation are areas for future study.
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Jothivasan VK, Hamilton CJ. Mycothiol: synthesis, biosynthesis and biological functions of the major low molecular weight thiol in actinomycetes. Nat Prod Rep 2008; 25:1091-117. [PMID: 19030604 DOI: 10.1039/b616489g] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Actinomycetes produce mycothiol as their major low molecular weight thiol, which parallels the functions of glutathione found in prokaryotes and most Gram-negative bacteria. This review covers progress that has so far been made in terms of its distribution, biosynthesis and metabolic functions, as well as chemical syntheses of mycothiol and alternative substrates and inhibitors of mycothiol biosynthesis and mycothiol-dependent enzymes. 152 references are cited.
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Miller C, McMullin B, Ghaffari A, Stenzler A, Pick N, Roscoe D, Ghahary A, Road J, Av-Gay Y. Gaseous nitric oxide bactericidal activity retained during intermittent high-dose short duration exposure. Nitric Oxide 2008; 20:16-23. [PMID: 18789393 DOI: 10.1016/j.niox.2008.08.002] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Revised: 08/06/2008] [Accepted: 08/08/2008] [Indexed: 11/19/2022]
Abstract
Previously, we have shown that gaseous Nitric oxide (gNO) has great potential as an effective topical anti-infective agent for non-healing wounds due to its non-specific antimicrobial properties. These same antimicrobial attributes may be useful for pulmonary infections. However, gNO would have limited usefulness as an inhaled antimicrobial agent as continuous exposure to the concentration required for a bactericidal effect (160-200 ppm) leads to methemoglobinemia. To overcome this problem, we investigated whether a thirty minute exposure of 160 ppm every four hours would retain the same antimicrobial effect as continuous delivery. In vitro, exposure of clinical multi-drug resistant Staphylococcus aureus and Escherichia coli strains isolated from the lungs of nosocomial pneumonia patients and a lethal antibiotic-resistant strain of Pseudomonas aeruginosa, isolated from a deceased cystic fibrosis patient resulted in over a 5 log(10) reduction in bacterial load after multiple thirty minute treatments (4 cycles) every four hours to 160 ppm gNO. The intermittent regimen required 320 (SD=0)ppm h for 100% lethality whereas the continuous exposure required 800 (SD=160)ppm h. We have also shown that selection for a gNO resistant phenotype did not lead to decrease sensitivity to gNO therapy (p>0.05). In addition, no host cellular toxicity was observed in human THP-1 monocytes and macrophages following intermittent delivery of a high concentration of gNO, and the proliferation and migration of pulmonary epithelial cells was not adversely affected by the administration of intermittent high-dose gNO. These results justify further studies that should focus on whether intermittent delivery of 160 ppm of gNO every four hours can technically be administered while keeping inhaled NO(2) levels less than 2 ppm and methemoglobin saturation less than 2.5 percent.
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Affiliation(s)
- Chris Miller
- Division of Infectious Diseases, Department of Medicine, Vancouver Coastal Health at Vancouver General Hospital, University of British Columbia, 2733 Heather Street, Vancouver, BC, Canada.
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den Hengst CD, Buttner MJ. Redox control in actinobacteria. Biochim Biophys Acta Gen Subj 2008; 1780:1201-16. [PMID: 18252205 DOI: 10.1016/j.bbagen.2008.01.008] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Revised: 01/07/2008] [Accepted: 01/14/2008] [Indexed: 10/22/2022]
Abstract
As most actinobacteria are obligate aerobes, they have to cope with endogenously generated reactive oxygen species, and actinobacterial pathogens have to resist oxidative attack by phagocytes. Actinobacteria also have to survive long periods under low oxygen tension; for example, Mycobacterium tuberculosis can persist in the host for years under apparently hypoxic conditions in a latent, non-replicative state. Here we focus on the regulatory switches that control actinobacterial responses to peroxide stress, disulfide stress and low oxygen tension. Other unique aspects of their redox biology will be highlighted, including the use of the pseudodisaccharide mycothiol as their major low-molecular-weight thiol buffer, and the [4Fe-4S]-containing WhiB-like proteins, which play diverse, important roles in actinobacterial biology, but whose biochemical role is still controversial.
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Affiliation(s)
- Chris D den Hengst
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Colney, Norwich, NR4 7UH, UK.
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Rawat M, Johnson C, Cadiz V, Av-Gay Y. Comparative analysis of mutants in the mycothiol biosynthesis pathway in Mycobacterium smegmatis. Biochem Biophys Res Commun 2007; 363:71-6. [PMID: 17826740 DOI: 10.1016/j.bbrc.2007.08.142] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2007] [Accepted: 08/18/2007] [Indexed: 11/16/2022]
Abstract
The role of mycothiol in mycobacteria was examined by comparative analysis of mutants disrupted in the four known genes encoding the protein machinery needed for mycothiol biosynthesis. These mutants were sensitive to acid stress, antibiotic stress, alkylating stress, and oxidative stress indicating that mycothiol and mycothiol-dependent enzymes protect the mycobacterial cell against attack from various different types of stresses and toxic agents.
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Affiliation(s)
- Mamta Rawat
- Department of Biology, California State University-Fresno, Fresno, CA 937401, USA
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