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1.
Indole-3-Glycerol Phosphate Synthase From Mycobacterium tuberculosis: A Potential New Drug Target.
Esposito, N, Konas, DW, Goodey, NM
Chembiochem : a European journal of chemical biology. 2022;(2):e202100314
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Abstract
Tuberculosis (TB), caused by the pathogen Mycobacterium tuberculosis, affects millions of people worldwide. Several TB drugs have lost efficacy due to emerging drug resistance and new anti-TB targets are needed. Recent research suggests that indole-3-glycerol phosphate synthase (IGPS) in M. tuberculosis (MtIGPS) could be such a target. IGPS is a (β/α)8 -barrel enzyme that catalyzes the conversion of 1-(o-carboxyphenylamino)-1-deoxyribulose 5'-phosphate (CdRP) into indole-glycerol-phosphate (IGP) in the bacterial tryptophan biosynthetic pathway. M. tuberculosis over expresses the tryptophan pathway genes during an immune response and inhibition of MtIGPS allows CD4 T-cells to more effectively fight against M. tuberculosis. Here we review the published data on MtIGPS expression, kinetics, mechanism, and inhibition. We also discuss MtIGPS crystal structures and compare them to other IGPS structures to reveal potential structure-function relationships of interest for the purposes of drug design and biocatalyst engineering.
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Collocating Novel Targets for Tuberculosis (TB) Drug Discovery.
Gandhi, K, Patel, M
Current drug discovery technologies. 2021;(2):307-316
Abstract
BACKGROUND Mycobacterium tuberculosis, being a resistive species is an incessant threat to the world population for the treatment of Tuberculosis (TB). An advanced genetic or a molecular level approach is mandatory for both diagnosis and therapy as the prevalence of multi drug-resistant (MDR) and extensively drug- resistant (XDR) TB. METHODS A literature review was conducted, focusing essentially on the development of biomarkers and targets to extrapolate the Tuberculosis Drug Discovery process. RESULTS AND DISCUSSION In this article, we have discussed several substantial targets and genetic mutations occurring in a diseased or treatment condition of TB patients. It includes expressions in Bhlhe40, natural resistance associated macrophage protein 1 (NRAMP1) and vitamin D receptor (VDR) with its mechanistic actions that have made a significant impact on TB. Moreover, recently identified compounds; imidazopyridine amine derivative (Q203), biphenyl amide derivative (DG70), azetidine, thioquinazole, tetrahydroindazole and 2- mercapto- quinazoline scaffolds for several targets such as adenosine triphosphate (ATP), amino acid and fatty acid have been briefed for their confirmed hits and therapeutic activity.
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Something Old, Something New: Ion Channel Blockers as Potential Anti-Tuberculosis Agents.
Mitini-Nkhoma, SC, Chimbayo, ET, Mzinza, DT, Mhango, DV, Chirambo, AP, Mandalasi, C, Lakudzala, AE, Tembo, DL, Jambo, KC, Mwandumba, HC
Frontiers in immunology. 2021;:665785
Abstract
Tuberculosis (TB) remains a challenging global health concern and claims more than a million lives every year. We lack an effective vaccine and understanding of what constitutes protective immunity against TB to inform rational vaccine design. Moreover, treatment of TB requires prolonged use of multi-drug regimens and is complicated by problems of compliance and drug resistance. While most Mycobacterium tuberculosis (Mtb) bacilli are quickly killed by the drugs, the prolonged course of treatment is required to clear persistent drug-tolerant subpopulations. Mtb's differential sensitivity to drugs is, at least in part, determined by the interaction between the bacilli and different host macrophage populations. Therefore, to design better treatment regimens for TB, we need to understand and modulate the heterogeneity and divergent responses that Mtb bacilli exhibit within macrophages. However, developing drugs de-novo is a long and expensive process. An alternative approach to expedite the development of new TB treatments is to repurpose existing drugs that were developed for other therapeutic purposes if they also possess anti-tuberculosis activity. There is growing interest in the use of immune modulators to supplement current anti-TB drugs by enhancing the host's antimycobacterial responses. Ion channel blocking agents are among the most promising of the host-directed therapeutics. Some ion channel blockers also interfere with the activity of mycobacterial efflux pumps. In this review, we discuss some of the ion channel blockers that have shown promise as potential anti-TB agents.
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Targeting amino acid metabolism of Mycobacterium tuberculosis for developing inhibitors to curtail its survival.
Yelamanchi, SD, Surolia, A
IUBMB life. 2021;(4):643-658
Abstract
Tuberculosis caused by the bacterium, Mycobacterium tuberculosis (Mtb), continues to remain one of the most devastating infectious diseases afflicting humans. Although there are several drugs for treating tuberculosis available currently, the emergence of the drug resistant forms of this pathogen has made its treatment and eradication a challenging task. While the replication machinery, protein synthesis and cell wall biogenesis of Mtb have been targeted often for anti-tubercular drug development a number of essential metabolic pathways crucial to its survival have received relatively less attention. In this context a number of amino acid biosynthesis pathways have recently been shown to be essential for the survival and pathogenesis of Mtb. Many of these pathways and or their key enzymes homologs are absent in humans hence they could be harnessed for anti-tubercular drug development. In this review, we describe comprehensively the amino acid metabolic pathways essential in Mtb and the key enzymes involved therein that are being investigated for developing inhibitors that compromise the survival and pathogenesis caused by this pathogen.
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Unique structural and mechanistic properties of mycobacterial F-ATP synthases: Implications for drug design.
Kamariah, N, Ragunathan, P, Shin, J, Saw, WG, Wong, CF, Dick, T, Grüber, G
Progress in biophysics and molecular biology. 2020;:64-73
Abstract
The causative agent of Tuberculosis (TB) Mycobacterium tuberculosis (Mtb) encounters unfavourable environmental conditions in the lungs, including nutrient limitation, low oxygen tensions and/or low/high pH values. These harsh conditions in the host triggers Mtb to enter a dormant state in which the pathogen does not replicate and uses host-derived fatty acids instead of carbohydrates as an energy source. Independent to the energy source, the bacterium's energy currency ATP is generated by oxidative phosphorylation, in which the F1FO-ATP synthase uses the proton motive force generated by the electron transport chain. This catalyst is essential in Mtb and inhibition by the diarylquinoline class of drugs like Bedaquilline, TBAJ-587, TBAJ-876 or squaramides demonstrated that this engine is an attractive target in TB drug discovery. A special feature of the mycobacterial F-ATP synthase is its inability to establish a significant proton gradient during ATP hydrolysis, and its latent ATPase activity, to prevent energy waste and to control the membrane potential. Recently, unique epitopes of mycobacterial F1FO-ATP synthase subunits absent in their prokaryotic or mitochondrial counterparts have been identified to contribute to the regulation of the low ATPase activity. Most recent structural insights into individual subunits, the F1 domain or the entire mycobacterial enzyme added to the understanding of mechanisms, regulation and differences of the mycobacterial F1FO-ATP synthase compared to other bacterial and eukaryotic engines. These novel insights provide the basis for the design of new compounds targeting this engine and even novel regimens for multidrug resistant TB.
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The Dual-Targeting Activity of the Metabolite Substrate of Para-amino Salicyclic Acid in the Mycobacterial Folate Pathway: Atomistic and Structural Perspectives.
Agoni, C, Ramharack, P, Salifu, EY, Soliman, MES
The protein journal. 2020;(2):106-117
Abstract
Therapeutic targeting of folate biosynthetic pathway has recently been explored as a viable strategy in the treatment of tuberculosis. The bioactive metabolite substrate of Para-amino salicyclic acid (PAS-M) reportedly dual-targets dihydrofolate reductase (DHFR) and flavin-dependent thymidylate synthase (FDTS), two essential enzymes in folate biosynthetic pathway. However, the molecular mechanisms and structural dynamics of this dual inhibitory activity of the PAS-M remain elusive. Molecular dynamics simulations revealed that binding of PAS-M towards DHFR is characterized by a recurrence of strong conventional hydrogen bond interactions between a peculiar DHFR binding site residue (Asp27) and the 2-amino-decahydropteridin-4-ol group of PAS-M. Similarly, the binding of PAS-M towards FDTS also involved consistent strong conventional hydrogen bond interactions between some specific residues (Tyr101, Arg172, Thr4, Gln103, Arg87 and Gln106) and, the 2-amino-decahydropteridin-4-ol group, thus establishing the cruciality of the group. Structural dynamics of the bound complexes of both enzymes revealed that, upon binding, PAS-M is anchored at the entrance of hydrophobic pockets by strong hydrogen bond interactions while the rest of the structure gains access to deeper hydrophobic residues to engage in favorable interactions. Further analysis of atomistic changes of both enzymes showed increased C-α atom deviations as well as an increase C-α atoms radius of gyration consistent with structural disorientations. These conformational changes possibly interfered with the biological functions of the enzymes and hence their inhibition as experimentally reported. Structural Insights provided could open up a novel paradigm of structure-based design of multi-targeting inhibitors of biological targets in the folate biosynthetic pathway toward tuberculosis therapy.
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Pulmonary tuberculosis presenting as henoch-schönlein purpura: Case report and literature review.
Li, J, Wang, XZ, Wang, RC, Yang, J, Hao, HL, Xue, LY
Medicine. 2020;(40):e22583
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Abstract
INTRODUCTION Henoch-Schönlein purpura (HSP) is an extremely rare condition in patients with pulmonary tuberculosis, with only a few reported cases. Compared to patients with typical clinical symptoms, it is difficult to make a definitive diagnosis when HSP presents as an initial manifestation in pulmonary tuberculosis patients. Herein, a case of pulmonary tuberculosis that showed HSP at first was reported, and the related literatures were reviewed. PATIENT CONCERNS A 24-year-old man presented with palpable purpura on the extremities, accompanied by abdominal pain, bloody stools, and knee pain. DIAGNOSES The patient was diagnosed with pulmonary tuberculosis based on the results of interferon gamma release assays, purified protein derivative test, and computed tomography. INTERVENTIONS The patient was treated with vitamin C and chlorpheniramine for 2 weeks, and the above-mentioned symptoms were relieved. However, 3 weeks later, the purpura recurred with high-grade fever and chest pain during the inspiratory phase. The patient was then treated with anti-tuberculosis drugs, and the purpura as well as the high fever disappeared. OUTCOMES The patient recovered well and remained free of symptoms during the follow-up examination. CONCLUSION Pulmonary tuberculosis presenting with HSP as an initial manifestation is not common. Therefore, it is difficult to clinically diagnose and treat this disease. When an adult patient shows HSP, it is important to consider the possibility of tuberculosis to avoid misdiagnosis and delayed treatment.
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The effect of micro-nutrients on malnutrition, immunity and therapeutic effect in patients with pulmonary tuberculosis: A systematic review and meta-analysis of randomised controlled trials.
Haiqing Cai, , Chen, L, Yin, C, Liao, Y, Meng, X, Lu, C, Tang, S, Li, X, Wang, X
Tuberculosis (Edinburgh, Scotland). 2020;:101994
Abstract
OBJECTIVE Micro-nutrients are closely related to pulmonary tuberculosis (PTB). Most patients with PTB suffer from micro-nutrients deficiency. We aimed to evaluate the efficacy of micro-nutrients support on clinical therapy and chronic inflammation in patients with PTB. METHODS We searched Pubmed, Springer link, Web of Science, Cochrane, Wan Fang and CNKI databases for randomised controlled trials (RCTs). The patients with anti-TB treatments were divided into two groups, the control group with nutritional advice or placebo, and the experimental group with micro-nutrients support for more than 2 weeks. Two reviewers conducted data extraction and quality assessment of the studies independently, and ReviewManager 5.2 software was used to input and analyse the data. The dichotomous variable was expressed in the risk ratios (RRS) and 95% CI, the continuous data were expressed in the mean difference (MD) and 95% CI, and the heterogeneity of subgroup was evaluated by I (Kerantzas and Jacobs, Jr., 2017) [2] test. RESULTS A total of 13 trials (2847 participants) were included. First, micro-nutrients improved sputum smears or culture negative conversion rates (OR 0.16 0.03-0.77, 2.29; MD -2.36, -4.72~-0.01, z = 1.97). Meanwhile, micro-nutrients support increased lymphocytes and decreased leukocytes, neutrophils, CRP and ESR (MD 0.20, 0.06-0.35, z = 2.78; MD -0.42, -0.65~-0.18, z = 3.48; MD -0.66, -1.12~-0.20, z = 2.82). However it had not impact on body weight, MUAC, haemoglobin, albumin or monocytes (p > 0.05). CONCLUSION Micro-nutrients support can reduce chronic inflammation and improve sputum smears or culture conversions to contribute to anti-TB treatment.
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Insertion and deletion evolution reflects antibiotics selection pressure in a Mycobacterium tuberculosis outbreak.
Godfroid, M, Dagan, T, Merker, M, Kohl, TA, Diel, R, Maurer, FP, Niemann, S, Kupczok, A
PLoS pathogens. 2020;(9):e1008357
Abstract
In genome evolution, genetic variants are the source of diversity, which natural selection acts upon. Treatment of human tuberculosis (TB) induces a strong selection pressure for the emergence of antibiotic resistance-conferring variants in the infecting Mycobacterium tuberculosis (MTB) strains. MTB evolution in response to treatment has been intensively studied and mainly attributed to point substitutions. However, the frequency and contribution of insertions and deletions (indels) to MTB genome evolution remains poorly understood. Here, we analyzed a multi-drug resistant MTB outbreak for the presence of high-quality indels and substitutions. We find that indels are significantly enriched in genes conferring antibiotic resistance. Furthermore, we show that indels are inherited during the outbreak and follow a molecular clock with an evolutionary rate of 5.37e-9 indels/site/year, which is 23 times lower than the substitution rate. Inherited indels may co-occur with substitutions in genes along related biological pathways; examples are iron storage and resistance to second-line antibiotics. This suggests that epistatic interactions between indels and substitutions affect antibiotic resistance and compensatory evolution in MTB.
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Efficacy of proprietary Lactobacillus casei for anti-tuberculosis associated gastrointestinal adverse reactions in adult patients: a randomized, open-label, dose-response trial.
Lin, S, Zhao, S, Liu, J, Zhang, J, Zhang, C, Hao, H, Sun, Y, Cai, J, Yang, Y, Ma, Y, et al
Food & function. 2020;(1):370-377
Abstract
Anti-tuberculosis (TB) drugs can induce a series of gastrointestinal adverse events, which can seriously affect patients' quality of life and may lead to treatment failure. Studies have shown that probiotics treatments can improve antibiotic-induced gastrointestinal symptoms. In this randomized, open-label, dose-response clinical trial, we investigated the preventive effects of Lactobacillus casei on anti-TB-induced gastrointestinal adverse events. In total, 429 adult patients who underwent intensive-phase anti-TB therapy were included and randomly assigned to consume one bottle of L. casei of per day (low-dose group, n = 142), two bottles of L. casei per day (high-dose group, n = 143), or no intervention (control group, n = 144) for 2 months. Each bottle of L. casei contained 10 billion colony-forming units of live L. casei. Patients' daily gastrointestinal symptoms were recorded during the intervention period. After 2 months of L. casei consumption, 397 patients had completed the intervention. Both the high and low dose L. casei groups (37.6% and 29.4%, respectively) had lower incidences of anti-TB-associated total gastrointestinal adverse events than the control group (50.0%). The high and low dose L. casei groups (3.5 d and 5.8 d, respectively) also had shorter duration anti-TB-associated adverse gastrointestinal symptoms than the control group (6.2 d). Regarding individual symptoms, the higher L. casei dose resulted in a lower incidence of vomiting and appetite loss. Similar dose-dependent protective effects of L. casei were observed regarding the duration of vomiting and appetite loss. These findings indicated that daily L. casei consumption prevented anti-TB-associated gastrointestinal adverse events. This trial was registered at the Chinese Clinical Trial Register (ChiCTR-IOR-17013210).