scholarly journals Structural basis of Mycobacterium tuberculosis transcription and transcription inhibition

2017 ◽  
Author(s):  
Wei Lin ◽  
Soma Mandal ◽  
David Degen ◽  
Yu Liu ◽  
Yon W. Ebright ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Rna Polymerase ◽  
Crystal Structures ◽  
Binding Sites ◽  
Structural Basis ◽  
Cross Resistance ◽  
Antituberculosis Drug ◽  
Transcription Inhibition ◽  
First Line ◽  
Related Compounds

One Sentence SummaryStructures of Mycobacterium tuberculosis RNA polymerase reveal taxon-specific properties and binding sites of known and new antituberculosis agentsAbstractMycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis, which kills 1.8 million annually. Mtb RNA polymerase (RNAP) is the target of the first-line antituberculosis drug rifampin (Rif). We report crystal structures of Mtb RNAP, alone and in complex with Rif. The results identify an Mtb-specific structural module of Mtb RNAP and establish that Rif functions by a steric-occlusion mechanism that prevents extension of RNA. We also report novel non-Rif-related compounds–Nα-aroyl-N-aryl-phenylalaninamides (AAPs)–that potently and selectively inhibit Mtb RNAP and Mtb growth, and we report crystal structures of Mtb RNAP in complex with AAPs. AAPs bind to a different site on Mtb RNAP than Rif, exhibit no cross-resistance with Rif, function additively when co-administered with Rif, and suppress resistance emergence when co-administered with Rif.

scholarly journals Structural Basis of ECF-σ-Factor-Dependent Transcription Initiation

2018 ◽  
Author(s):  
Wei Lin ◽  
Sukhendu Mandal ◽  
David Degen ◽  
Min Sung Cho ◽  
Yu Feng ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Rna Polymerase ◽  
Crystal Structures ◽  
Transcription Initiation ◽  
Structural Basis ◽  
Functional Modules ◽  
Dna Interactions ◽  
Protein Dna Interactions ◽  
Σ Factor ◽  
Promoter Dna

SUMMARYExtracytoplasmic (ECF) σ factors, the largest class of alternative σ factors, are related to primary σ factors, but have simpler structures, comprising only two of the six conserved functional modules present in primary σ factors: region 2 (σR2) and region 4 (σR4). Here, we report crystal structures of transcription initiation complexes containing Mycobacterium tuberculosis RNA polymerase (RNAP), M. tuberculosis ECF σ factor σL, and promoter DNA. The structures show that σR2 and σR4 of the ECF σ factor occupy the same sites on RNAP as in primary σ factors, show that the connector between σR2 and σR4 of the ECF σ factor--although unrelated in sequence--follows the same path through RNAP as in primary σ factors, and show that the ECF σ factor uses the same strategy to bind and unwind promoter DNA as primary σ factors. The results define protein-protein and protein-DNA interactions involved in ECF-σ-factor-dependent transcription initiation.

scholarly journals Structural basis of transcription inhibition by the DNA mimic protein Ocr of bacteriophage T7

2019 ◽  
Author(s):  
Fuzhou Ye ◽  
Ioly Kotta-Loizou ◽  
Milija Jovanovic ◽  
Xiaojiao Liu ◽  
David T. F. Dryden ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Protein A ◽  
Restriction Enzymes ◽  
Sigma Factors ◽  
Structural Basis ◽  
Bacteriophage T7 ◽  
Transcription Inhibition ◽  
Host Restriction ◽  
Dna Mimicry ◽  
Host Defence System

AbstractBacteriophage T7 infects Escherichia coli and evades the host defence system. The Ocr protein of T7 was shown to exist as a dimer mimicking DNA and to bind to host restriction enzymes, thus preventing the degradation of the viral genome by the host. Here we report that Ocr can also inhibit host transcription by directly binding to bacterial RNA polymerase (RNAP) and competing with the recruitment of RNAP by sigma factors. Using cryo electron microscopy, we determined the structures of Ocr bound to RNAP. The structures show that an Ocr dimer binds to RNAP in the cleft, where key regions of sigma bind and where DNA resides during transcription synthesis, thus providing a structural basis for the transcription inhibition. Our results reveal the versatility of Ocr in interfering with host systems and suggest possible strategies that could be exploited in adopting DNA mimicry as a basis for forming novel antibiotics.Impact statementDNA mimicry Ocr protein, a well-studied T7 phage protein that inhibits host restriction enzymes, can also inhibit host transcription through competing with sigma factors in binding to RNA polymerase.

PanB over-representation as part of pyrazinamide action: a proteomic insight

2021 ◽  
Author(s):  
Isabella Letícia Esteves Barros ◽  
Jean Eduardo Meneguello ◽  
Luciana Dias Ghiraldi-Lopes ◽  
Gláucia Sayuri Arita ◽  
João Vitor de Oliveira Silva ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Drug Target ◽  
Culture Medium ◽  
Acidic Ph ◽  
Antituberculosis Drug ◽  
First Line ◽  
Proteomic Approach

Background: Pyrazinamide (PZA) represents a milestone as a first-line antituberculosis drug due to its sterilizing activity against Mycobacterium tuberculosis. Materials & Methods: The protein changes induced by subinhibitory PZA exposure of M. tuberculosis in acidic pH were evaluated by a proteomic approach. Results: Among the 1059 M. tuberculosis proteins identified, the specific acidification in the culture medium induced the over-representation of MurF (Rv2157c), and its underrepresentation was induced by 12 h of PZA exposure. PanB (Rv2225) was over-represented at 24 h of PZA exposure. Conclusion: The authors highlight the over-representation of PanB in M. tuberculosis correlates of PZA action in acidic pH, reinforcing the role of the pantothenate pathway as a bacillus drug target to be explored.

scholarly journals Structural Basis of Mycobacterium tuberculosis Transcription and Transcription Inhibition

2017 ◽  
Vol 66 (2) ◽  
pp. 169-179.e8 ◽  
Author(s):  
Wei Lin ◽  
Soma Mandal ◽  
David Degen ◽  
Yu Liu ◽  
Yon W. Ebright ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Structural Basis ◽  
Transcription Inhibition

scholarly journals Pantothenate and Pantetheine Antagonize the Antitubercular Activity of Pyrazinamide

2014 ◽  
Vol 58 (12) ◽  
pp. 7258-7263 ◽  
Author(s):  
Nicholas A. Dillon ◽  
Nicholas D. Peterson ◽  
Brandon C. Rosen ◽  
Anthony D. Baughn
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Nicotinic Acid ◽  
Active Form ◽  
Laboratory Strain ◽  
Antitubercular Activity ◽  
First Line ◽  
Auxotrophic Strain ◽  
Content Type ◽  
Related Compounds ◽  
Pyrazinoic Acid

ABSTRACTPyrazinamide (PZA) is a first-line tuberculosis drug that inhibits the growth ofMycobacterium tuberculosisvia an as yet undefined mechanism. AnM. tuberculosislaboratory strain that was auxotrophic for pantothenate was found to be insensitive to PZA and to the active form, pyrazinoic acid (POA). To determine whether this phenotype was strain or condition specific, the effect of pantothenate supplementation on PZA activity was assessed using prototrophic strains ofM. tuberculosis. It was found that pantothenate and other β-alanine-containing metabolites abolished PZA and POA susceptibility, suggesting that POA might selectively target pantothenate synthesis. However, when the pantothenate-auxotrophic strain was cultivated using a subantagonistic concentration of pantetheine in lieu of pantothenate, susceptibility to PZA and POA was restored. In addition, we found that β-alanine could not antagonize PZA and POA activity against the pantothenate-auxotrophic strain, indicating that the antagonism is specific to pantothenate. Moreover, pantothenate-mediated antagonism was observed for structurally related compounds, includingn-propyl pyrazinoate, 5-chloropyrazinamide, and nicotinamide, but not for nicotinic acid or isoniazid. Taken together, these data demonstrate that while pantothenate can interfere with the action of PZA, pantothenate synthesis is not directly targeted by PZA. Our findings suggest that targeting of pantothenate synthesis has the potential to enhance PZA efficacy and possibly to restore PZA susceptibility in isolates withpanD-linked resistance.

Ethambutol

1968 ◽  
Vol 6 (19) ◽  
pp. 73-74
Keyword(s):  
Cell Death ◽  
Mycobacterium Tuberculosis ◽  
Atypical Mycobacteria ◽  
Cross Resistance ◽  
Antituberculosis Drug ◽  
Antituberculosis Drugs ◽  
Solid Media

Ethambutol (Myambutol - Lederle), a new antituberculosis drug, was developed from a compound discovered during development of rubber additives. It is chemically different from all other antituberculosis drugs, and shows no cross-resistance with any of them. The drug diffuses actively into mycobacteria, arresting multiplication and causing cell death.1 Most strains of Mycobacterium tuberculosis are susceptible to about 5 mcg/ml of ethambutol in solid media. Some atypical mycobacteria are also susceptible.

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