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Yeware A, Akhtar S, Sarkar D. Probes and techniques used in active and the hypoxia-based dormant state of an antitubercular drug screening assay. MEDICINE IN DRUG DISCOVERY 2022. [DOI: 10.1016/j.medidd.2021.100115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Shahbaaz M, Potemkin V, Bisetty K, Hassan MI, Hussien MA. Classification and functional analyses of putative virulence factors of Mycobacterium tuberculosis: A combined sequence and structure based study. Comput Biol Chem 2020; 87:107270. [PMID: 32438116 DOI: 10.1016/j.compbiolchem.2020.107270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 04/16/2020] [Accepted: 04/26/2020] [Indexed: 11/17/2022]
Abstract
The emergence of the drug-resistant mechanisms in Mycobacterium tuberculosis poses the biggest challenges to the current therapeutic measures, which necessitates the identification of new drug targets. The Hypothetical Proteins (HPs), a class of functionally uncharacterized proteins, may provide a new class of undiscovered therapeutic targets. The genome of M. tuberculosis contains 1000 HPs with their sequences were analyzed using a variety of bioinformatics tools and the functional annotations were performed. The functions of 662 HPs were successfully predicted and further classified 483 HPs as enzymes, 141 HPs were predicted to be involved in the diverse cellular mechanisms and 38 HPs may function as transporters and carriers proteins. Furthermore, 28 HPs were predicted to be virulent in nature. Amongst them, the HP P95201, HP P9WM79, HP I6WZ30, HP I6 × 9T8, HP P9WKP3, and HP P9WK89 showed the highest virulence scores. Therefore, these proteins were subjected to extensive structure analyses and dynamics of their conformations were investigated using the principles of molecular dynamics simulations, each for a 150 ns time scale. This study provides a deeper understanding of the undiscovered drug targets and the generated outputs will facilitate the process of drug design and discovery against the infection of M. tuberculosis.
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Affiliation(s)
- Mohd Shahbaaz
- South African Medical Research Council Bioinformatics Unit, South African National Bioinformatics Institute (SANBI), University of the Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa; Laboratory of Computational Modeling of Drugs, South Ural State University, 76 Lenin prospekt, 454080 Chelyabinsk, Russia
| | - Vladimir Potemkin
- Laboratory of Computational Modeling of Drugs, South Ural State University, 76 Lenin prospekt, 454080 Chelyabinsk, Russia
| | - Krishna Bisetty
- Department of Chemistry, Durban University of Technology, Durban, 4000, South Africa
| | - Md Imtaiyaz Hassan
- Center for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India
| | - Mostafa A Hussien
- Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203 Jeddah 21589, Saudi Arabia; Department of Chemistry, Faculty of Science, Port Said University, Port Said, 42521, Egypt
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Simple and rapid method to determine antimycobacterial potency of compounds by using autoluminescent Mycobacterium tuberculosis. Antimicrob Agents Chemother 2014; 58:5801-8. [PMID: 25049243 DOI: 10.1128/aac.03205-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
A major obstacle in the process of discovery of drugs against Mycobacterium tuberculosis is its extremely slow growth rate and long generation time (∼20 to 24 h). Consequently, determination of MICs and minimum bactericidal concentrations (MBCs) of potential drug candidates using current methods requires 7 days (resazurin-based MIC assay [REMA]) and 1 month (CFU enumeration), respectively. We employed a synthetic luciferase operon optimized for expression in high-GC-content bacteria and adapted it for use in mycobacteria. Using luminescence-based readouts, we were able to determine the MICs and bactericidal activities of approved tuberculosis (TB) drugs, which correlated well with currently used methods. Although luminescence-based readouts have been used previously to determine the MICs and bactericidal activities of approved TB drugs, in this study we adapted this assay to carry out a pilot screen using a library of 1,114 compounds belonging to diverse chemical scaffolds. We found that MICs derived from a 3-day luminescence assay matched well with REMA-based MIC values. To determine the bactericidal potencies of compounds, a 1:10 dilution of the cultures from the MIC plate was carried out on day 7, and the bactericidal concentrations determined based on time to positivity in 2 weeks were found to be comparable with MBC values determined by the conventional CFU approach. Thus, the luminescent mycobacterium-based approach not only is very simple and inexpensive but also allowed us to generate the information in half the time required by conventional methods.
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Mishra S, Anand D, Vijayarangan N, Ajitkumar P. An accurate method for the qualitative detection and quantification of mycobacterial promoter activity. Open Microbiol J 2013; 7:1-5. [PMID: 23359792 PMCID: PMC3553492 DOI: 10.2174/1874285801307010001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 11/07/2012] [Accepted: 11/20/2012] [Indexed: 11/22/2022] Open
Abstract
The present study was designed to determine the half-life of gfpm2+ mRNA, which encodes mycobacterial co-don-optimised highly fluorescent GFPm2+ protein, and to find out whether mycobacterial promoter activity can be quanti-tated more accurately using the mRNA levels of the reporter gene, gfpm2+, than the fluorescence intensity of the GFPm2+ protein. Quantitative PCR of gfpm2+ mRNA in the pulse-chased samples of the rifampicin-treated Mycobacterium smegmatis/gfpm2+ transformant showed the half-life of gfpm2+ mRNA to be 4.081 min. The levels of the gfpm2+ mRNA and the fluorescence intensity of the GFPm2+ protein, which were expressed by the promoters of Mycobacterium tuberculosis cell division gene, ftsZ (MtftsZ), were determined using quantitative PCR and fluorescence spectrophotometry, respectively. The data revealed that quantification of mycobacterial promoter activity by determining the gfpm2+ mRNA levels is more accurate and statistically significant than the measurement of GFPm2+ fluorescence intensity, especially for weak promoters.
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Affiliation(s)
- Saurabh Mishra
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore - 560012, Karnataka, India
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Zhang T, Li SY, Nuermberger EL. Autoluminescent Mycobacterium tuberculosis for rapid, real-time, non-invasive assessment of drug and vaccine efficacy. PLoS One 2012; 7:e29774. [PMID: 22253776 PMCID: PMC3256174 DOI: 10.1371/journal.pone.0029774] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2011] [Accepted: 12/04/2011] [Indexed: 11/19/2022] Open
Abstract
Preclinical efforts to discover and develop new drugs and vaccines for tuberculosis are hampered by the reliance on colony-forming unit (CFU) counts as primary outcomes for in vivo efficacy studies and the slow growth of Mycobacterium tuberculosis. The utility of bioluminescent M. tuberculosis reporter strains for real-time in vitro and ex vivo assessment of drug and vaccine activity has been demonstrated but a simple, non-invasive, real-time surrogate marker to replace CFU counts for real-time evaluation of drug and vaccine efficacy in vivo has not been described. We describe the development of a fully virulent and stable autoluminescent strain of M. tuberculosis and proof-of-concept experiments demonstrating its utility for in vivo bioluminescence imaging to assess the efficacy of new drugs and vaccines for tuberculosis in a mouse model. Relative light unit (RLU) counts paralleled CFU counts during the active phase of bacterial growth, with a lower limit of detection of approximately 106 CFU in live, anesthetized mice. Experiments distinguishing active from inactive anti-tuberculosis drugs and bacteriostatic drug effects from bactericidal effects were completed in less than 5 days. The ability of a recombinant BCG vaccine to limit bacterial growth was demonstrated within 3 weeks. Use of this autoluminescent reporter strain has the potential to drastically reduce the time, effort, animals and costs consumed in the evaluation of drug activity in vitro and the in vivo assessment of drug and vaccine efficacy.
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Affiliation(s)
- Tianyu Zhang
- Center for Tuberculosis Research, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- State Key Laboratory of Respiratory Disease, Center for Infection and Immunity, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, Guangdong, People's Republic of China
| | - Si-Yang Li
- Center for Tuberculosis Research, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Eric L. Nuermberger
- Center for Tuberculosis Research, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * E-mail:
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Roy S, Narayana Y, Balaji KN, Ajitkumar P. Highly fluorescent GFPm 2+ -based genome integration-proficient promoter probe vector to study Mycobacterium tuberculosis promoters in infected macrophages. Microb Biotechnol 2011; 5:98-105. [PMID: 21958386 PMCID: PMC3815276 DOI: 10.1111/j.1751-7915.2011.00305.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Study of activity of cloned promoters in slow‐growing Mycobacterium tuberculosis during long‐term growth conditions in vitro or inside macrophages, requires a genome‐integration proficient promoter probe vector, which can be stably maintained even without antibiotics, carrying a substrate‐independent, easily scorable and highly sensitive reporter gene. In order to meet this requirement, we constructed pAKMN2, which contains mycobacterial codon‐optimized gfpm2+ gene, coding for GFPm2+ of highest fluorescence reported till date, mycobacteriophage L5 attP‐int sequence for genome integration, and a multiple cloning site. pAKMN2 showed stable integration and expression of GFPm2+ from M. tuberculosis and M. smegmatis genome. Expression of GFPm2+, driven by the cloned minimal promoters of M. tuberculosis cell division gene, ftsZ (MtftsZ), could be detected in the M. tuberculosis/pAKMN2‐promoter integrants, growing at exponential phase in defined medium in vitro and inside macrophages. Stable expression from genome‐integrated format even without antibiotic, and high sensitivity of detection by flow cytometry and fluorescence imaging, in spite of single copy integration, make pAKMN2 useful for the study of cloned promoters of any mycobacterial species under long‐term in vitro growth or stress conditions, or inside macrophages.
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Affiliation(s)
- Sougata Roy
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore - 560012, Karnataka, India
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Rapid assessment of antibacterial activity against Mycobacterium ulcerans by using recombinant luminescent strains. Antimicrob Agents Chemother 2010; 54:2806-13. [PMID: 20421401 DOI: 10.1128/aac.00400-10] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mycobacterium ulcerans causes Buruli ulcer, an emerging infectious disease for which antimicrobial therapy has only recently proven to be beneficial. The discovery and development of new drugs against M. ulcerans are severely impeded by its very slow growth. Recombinant bioluminescent strains have proven useful in drug development for other mycobacterial infections, but the ability of such strains to discriminate bacteriostatic from bactericidal activity has not been well demonstrated. We engineered recombinant M. ulcerans strains to express luxAB from Vibrio harveyi. In drug susceptibility tests employing a wide range of antimicrobial agents and concentrations, the relative light unit (RLU) count measured in real time was a reliable surrogate marker for CFU counts available 3 months later, indicating utility for the rapid determination of drug susceptibility and discrimination of bacteriostatic and bactericidal effects. A second important finding of this study is that the addition of subinhibitory concentrations of the ATP-binding cassette transporter inhibitor reserpine increases the susceptibility of M. ulcerans to tetracycline and erythromycin, indicating that drug efflux may explain at least part of the intrinsic resistance of M. ulcerans to these agents.
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Cyclic AMP in mycobacteria: characterization and functional role of the Rv1647 ortholog in Mycobacterium smegmatis. J Bacteriol 2008; 190:3824-34. [PMID: 18390660 DOI: 10.1128/jb.00138-08] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mycobacterial genomes are endowed with many eukaryote-like nucleotide cyclase genes encoding proteins that can synthesize 3',5'-cyclic AMP (cAMP). However, the roles of cAMP and the need for such redundancy in terms of adenylyl cyclase genes remain unknown. We measured cAMP levels in Mycobacterium smegmatis during growth and under various stress conditions and report the first biochemical and functional characterization of the MSMEG_3780 adenylyl cyclase, whose orthologs in Mycobacterium tuberculosis (Rv1647) and Mycobacterium leprae (ML1399) have been recently characterized in vitro. MSMEG_3780 was important for producing cAMP levels in the logarithmic phase of growth, since the DeltaMSMEG_3780 strain showed lower intracellular cAMP levels at this stage of growth. cAMP levels decreased in wild-type M. smegmatis under conditions of acid stress but not in the DeltaMSMEG_3780 strain. This was correlated with a reduction in MSMEG_3780 promoter activity, indicating that the effect of the reduction in cAMP levels on acid stress was caused by a decrease in the transcription of MSMEG_3780. Complementation of the DeltaMSMEG_3780 strain with the genomic integration of MSMEG_3780 or the Rv1647 gene could restore cAMP levels during logarithmic growth. The Rv1647 promoter was also acid sensitive, emphasizing the biochemical and functional similarities in these two adenylyl cyclases. This study therefore represents the first detailed biochemical and functional analysis of an adenylyl cyclase that is important for maintaining cAMP levels in mycobacteria and underscores the subtle roles that these genes may play in the physiology of the organism.
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