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Francis SM, Pattar Kadavan S, Natesh R. Oligomerization states of the Mycobacterium tuberculosis RNA polymerase core and holoenzymes. Arch Microbiol 2024; 206:230. [PMID: 38649511 DOI: 10.1007/s00203-024-03955-z] [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: 02/24/2024] [Accepted: 04/04/2024] [Indexed: 04/25/2024]
Abstract
During the past few decades, a wealth of knowledge has been made available for the transcription machinery in bacteria from the structural, functional and mechanistic point of view. However, comparatively little is known about the homooligomerization of the multisubunit M. tuberculosis RNA polymerase (RNAP) enzyme and its functional relevance. While E. coli RNAP has been extensively studied, many aspects of RNAP of the deadly pathogenic M. tuberculosis are still unclear. We used biophysical and biochemical methods to study the oligomerization states of the core and holoenzymes of M. tuberculosis RNAP. By size exclusion chromatography and negative staining Transmission Electron Microscopy (TEM) studies and quantitative analysis of the TEM images, we demonstrate that the in vivo reconstituted RNAP core enzyme (α2ββ'ω) can also exist as dimers in vitro. Using similar methods, we also show that the holoenzyme (core + σA) does not dimerize in vitro and exist mostly as monomers. It is tempting to suggest that the oligomeric changes that we see in presence of σA factor might have functional relevance in the cellular process. Although reported previously in E. coli, to our knowledge we report here for the first time the study of oligomeric nature of M. tuberculosis RNAP in presence and absence of σA factor.
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Affiliation(s)
- Sandrea Maureen Francis
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, 695551, India
| | - Shehna Pattar Kadavan
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, 695551, India
| | - Ramanathan Natesh
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, 695551, India.
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Kumar G, Adhikrao PA. Targeting Mycobacterium tuberculosis iron-scavenging tools: a recent update on siderophores inhibitors. RSC Med Chem 2023; 14:1885-1913. [PMID: 37859726 PMCID: PMC10583813 DOI: 10.1039/d3md00201b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 08/22/2023] [Indexed: 10/21/2023] Open
Abstract
Among the various bacterial infections, tuberculosis (TB) remains a life-threatening infectious disease responsible as the most significant cause of mortality and morbidity worldwide. The co-infection of human immunodeficiency virus (HIV) in association with TB burdens the healthcare system substantially. Notably, M.tb possesses defence against most antitubercular antibiotic drugs, and the efficacy of existing frontline anti-TB drugs is waning. Also, new and recurring cases of TB from resistant bacteria such as multidrug-resistant TB (MDR), extensively drug-resistant TB (XDR), and totally drug-resistant TB (TDR) strains are increasing. Hence, TB begs the scientific community to explore the new therapeutic class of compounds with their novel mechanism. M.tb requires iron from host cells to sustain, grow, and carry out several biological processes. M.tb has developed strategic methods of acquiring iron from the surrounding environment. In this communication, we discuss an overview of M.tb iron-scavenging tools. Also, we have summarized recently identified MbtA and MbtI inhibitors, which prevent M.tb from scavenging iron. These iron-scavenging tool inhibitors have the potential to be developed as anti-TB agents/drugs.
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Affiliation(s)
- Gautam Kumar
- Department of Natural Products, Chemical Sciences, National Institute of Pharmaceutical Education and Research-Hyderabad (NIPER-Hyderabad) Balanagar Hyderabad 500037 India
| | - Patil Amruta Adhikrao
- Department of Natural Products, Chemical Sciences, National Institute of Pharmaceutical Education and Research-Hyderabad (NIPER-Hyderabad) Balanagar Hyderabad 500037 India
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Calil Brondani J, Afful D, Nune H, Hart J, Cook S, Momany C. Overproduction, purification, and transcriptional activity of recombinant Acinetobacter baylyi ADP1 RNA polymerase holoenzyme. Protein Expr Purif 2023; 206:106254. [PMID: 36804950 DOI: 10.1016/j.pep.2023.106254] [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: 01/05/2023] [Revised: 02/14/2023] [Accepted: 02/15/2023] [Indexed: 02/19/2023]
Abstract
Acinetobacter baylyi is an interesting model organism to investigate bacterial metabolism due to its vast repertoire of metabolic enzymes and ease of genetic manipulation. However, the study of gene expression in vitro is dependent on the availability of its RNA polymerase (RNAp), an essential enzyme in transcription. In this work, we developed a convenient method of producing the recombinant A. baylyi ADP1 RNA polymerase holoenzyme (RNApholo) in E. coli that yields 22 mg of a >96% purity protein from a 1-liter shake flask culture. We further characterized the A. baylyi ADP1 RNApholo kinetic profile using T7 Phage DNA as template and demonstrated that it is a highly transcriptionally active enzyme with an elongation rate of 24 nt/s and a termination efficiency of 94%. Moreover, the A. baylyi ADP1 RNApholo has a substantial sequence identity (∼95%) with the RNApholo from the human pathogen Acinetobacter baumannii. This protein can serve as a source of material for structural and biological studies towards advancing our understanding of genome expression and regulation in Acinetobacter species.
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Affiliation(s)
- Juliana Calil Brondani
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, 30602, USA
| | - Derrick Afful
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, 30602, USA
| | - Hanna Nune
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, 30602, USA
| | - Jesse Hart
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, 30602, USA
| | - Shelby Cook
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, 30602, USA
| | - Cory Momany
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, 30602, USA.
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Zhu DX, Stallings CL. Transcription regulation by CarD in mycobacteria is guided by basal promoter kinetics. J Biol Chem 2023; 299:104724. [PMID: 37075846 DOI: 10.1016/j.jbc.2023.104724] [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: 01/23/2023] [Revised: 03/30/2023] [Accepted: 04/11/2023] [Indexed: 04/21/2023] Open
Abstract
Bacterial pathogens like Mycobacterium tuberculosis (Mtb) employ transcription factors to adapt their physiology to the diverse environments within their host. CarD is a conserved bacterial transcription factor that is essential for viability in Mtb. Unlike classical transcription factors that recognize promoters by binding to specific DNA sequence motifs, CarD binds directly to the RNA polymerase (RNAP) to stabilize the open complex intermediate (RPo) during transcription initiation. We previously showed using RNA-sequencing that CarD is capable of both activating and repressing transcription in vivo. However, it is unknown how CarD achieves promoter specific regulatory outcomes in Mtb despite binding indiscriminate of DNA sequence. We propose a model where CarD's regulatory outcome depends on the promoter's basal RPo stability and test this model using in vitro transcription from a panel of promoters with varying levels of RPo stability. We show that CarD directly activates full-length transcript production from the Mtb ribosomal RNA promoter rrnAP3 (AP3) and that the degree of transcription activation by CarD is negatively correlated with RPo stability. Using targeted mutations in the extended -10 and discriminator region of AP3, we show that CarD directly represses transcription from promoters that form relatively stable RPo. DNA supercoiling also influenced RPo stability and affected the direction of CarD regulation, indicating that the outcome of CarD activity can be regulated by factors beyond promoter sequence. Our results provide experimental evidence for how RNAP-binding transcription factors like CarD can exert specific regulatory outcomes based on the kinetic properties of a promoter.
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Affiliation(s)
- Dennis X Zhu
- Department of Molecular Microbiology, Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Christina L Stallings
- Department of Molecular Microbiology, Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO, 63110, USA.
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Zhu DX, Stallings CL. Transcription regulation by CarD in mycobacteria is guided by basal promoter kinetics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.16.533025. [PMID: 36993566 PMCID: PMC10055060 DOI: 10.1101/2023.03.16.533025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Bacterial pathogens like Mycobacterium tuberculosis ( Mtb ) employ transcription factors to adapt their physiology to the diverse environments within their host. CarD is a conserved bacterial transcription factor that is essential for viability in Mtb . Unlike classical transcription factors that recognize promoters by binding to specific DNA sequence motifs, CarD binds directly to the RNA polymerase (RNAP) to stabilize the open complex intermediate (RP o ) during transcription initiation. We previously showed using RNA-sequencing that CarD is capable of both activating and repressing transcription in vivo . However, it is unknown how CarD achieves promoter specific regulatory outcomes in Mtb despite binding indiscriminate of DNA sequence. We propose a model where CarD's regulatory outcome depends on the promoter's basal RP o stability and test this model using in vitro transcription from a panel of promoters with varying levels of RP o stability. We show that CarD directly activates full-length transcript production from the Mtb ribosomal RNA promoter rrnA P3 (AP3) and that the degree of transcription activation by CarD is negatively correlated with RP o stability. Using targeted mutations in the extended -10 and discriminator region of AP3, we show that CarD directly represses transcription from promoters that form relatively stable RP o . DNA supercoiling also influenced RP o stability and affected the direction of CarD regulation, indicating that the outcome of CarD activity can be regulated by factors beyond promoter sequence. Our results provide experimental evidence for how RNAP-binding transcription factors like CarD can exert specific regulatory outcomes based on the kinetic properties of a promoter.
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Jensen D, Manzano AR, Rector M, Tomko EJ, Record MT, Galburt EA. High-throughput, fluorescent-aptamer-based measurements of steady-state transcription rates for Mycobacterium tuberculosis RNA polymerase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.13.532464. [PMID: 36993414 PMCID: PMC10054983 DOI: 10.1101/2023.03.13.532464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The first step in gene expression is the transcription of DNA sequences into RNA. Regulation at the level of transcription leads to changes in steady-state concentrations of RNA transcripts, affecting the flux of downstream functions and ultimately cellular phenotypes. Changes in transcript levels are routinely followed in cellular contexts via genome-wide sequencing techniques. However, in vitro mechanistic studies of transcription have lagged with respect to throughput. Here, we describe the use of a real-time, fluorescent-aptamer-based method to quantitate steady-state transcription rates of the Mycobacterium tuberculosis RNA polymerase. We present clear controls to show that the assay specifically reports on promoter-dependent, full-length RNA transcription rates that are in good agreement with the kinetics determined by gel-resolved, α- 32 P NTP incorporation experiments. We illustrate how the time-dependent changes in fluorescence can be used to measure regulatory effects of nucleotide concentrations and identity, RNAP and DNA concentrations, transcription factors, and antibiotics. Our data showcase the ability to easily perform hundreds of parallel steady-state measurements across varying conditions with high precision and reproducibility to facilitate the study of the molecular mechanisms of bacterial transcription. Significance Statement RNA polymerase transcription mechanisms have largely been determined from in vitro kinetic and structural biology methods. In contrast to the limited throughput of these approaches, in vivo RNA sequencing provides genome-wide measurements but lacks the ability to dissect direct biochemical from indirect genetic mechanisms. Here, we present a method that bridges this gap, permitting high-throughput fluorescence-based measurements of in vitro steady-state transcription kinetics. We illustrate how an RNA-aptamer-based detection system can be used to generate quantitative information on direct mechanisms of transcriptional regulation and discuss the far-reaching implications for future applications.
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Affiliation(s)
- Drake Jensen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, 63108, USA
| | - Ana Ruiz Manzano
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, 63108, USA
| | - Maxwell Rector
- Department of Biochemistry, University of Wisconsin, Madison, WI, 53706, USA
| | - Eric J. Tomko
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, 63108, USA
| | - M. Thomas Record
- Department of Biochemistry, University of Wisconsin, Madison, WI, 53706, USA
| | - Eric A. Galburt
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, 63108, USA
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Ni H, Kwan-wai Chan B, Cheng Q, Chen K, Xie M, Wang H, Wai-chi Chan E, Chen S. A novel clinical therapy to combat infections caused by Hypervirulent Carbapenem-Resistant Klebsiella pneumoniae. J Infect 2022; 85:174-211. [DOI: 10.1016/j.jinf.2022.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 05/06/2022] [Indexed: 11/29/2022]
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Prusa J, Zhu DX, Flynn AJ, Jensen D, Ruiz Manzano A, Galburt EA, Stallings CL. Molecular dissection of RbpA-mediated regulation of fidaxomicin sensitivity in mycobacteria. J Biol Chem 2022; 298:101752. [PMID: 35189142 PMCID: PMC8956947 DOI: 10.1016/j.jbc.2022.101752] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 02/11/2022] [Accepted: 02/13/2022] [Indexed: 01/13/2023] Open
Abstract
RNA polymerase (RNAP) binding protein A (RbpA) is essential for mycobacterial viability and regulates transcription initiation by increasing the stability of the RNAP-promoter open complex (RPo). RbpA consists of four domains: an N-terminal tail (NTT), a core domain (CD), a basic linker, and a sigma interaction domain. We have previously shown that truncation of the RbpA NTT and CD increases RPo stabilization by RbpA, implying that these domains inhibit this activity of RbpA. Previously published structural studies showed that the NTT and CD are positioned near multiple RNAP-σA holoenzyme functional domains and predict that the RbpA NTT contributes specific amino acids to the binding site of the antibiotic fidaxomicin (Fdx), which inhibits the formation of the RPo complex. Furthermore, deletion of the NTT results in decreased Mycobacterium smegmatis sensitivity to Fdx, but whether this is caused by a loss in Fdx binding is unknown. We generated a panel of rbpA mutants and found that the RbpA NTT residues predicted to directly interact with Fdx are partially responsible for RbpA-dependent Fdx activity in vitro, while multiple additional RbpA domains contribute to Fdx activity in vivo. Specifically, our results suggest that the RPo-stabilizing activity of RbpA decreases Fdx activity in vivo. In support of the association between RPo stability and Fdx activity, we find that another factor that promotes RPo stability in bacteria, CarD, also impacts to Fdx sensitivity. Our findings highlight how RbpA and other factors may influence RNAP dynamics to affect Fdx sensitivity.
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Affiliation(s)
- Jerome Prusa
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Dennis X. Zhu
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Aidan J. Flynn
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Drake Jensen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Ana Ruiz Manzano
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Eric A. Galburt
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Christina L. Stallings
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA,For correspondence: Christina L. Stallings
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Chow LT, Vassylyev DG. Application of a Novel CL7/Im7 Affinity System in Purification of Complex and Pharmaceutical Proteins. Methods Mol Biol 2022; 2466:61-82. [PMID: 35585311 DOI: 10.1007/978-1-0716-2176-9_5] [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: 06/15/2023]
Abstract
We have developed the CL7/Im7 protein purification system to achieve high-yield, high-purity and high-activity (HHH) products in one step. The system is based on the natural ultrahigh-affinity complex between the two small proteins encoded by colicinogenic plasmids carried by certain E. coli strains, the DNAse domain of colicin E7 (CE7; MW ~ 15 kDa) and its natural endogenous inhibitor, the immunity protein 7 (Im7; MW ~ 10 kDa). CL7 is an engineered variant of CE7, in which the toxic DNA-binding and catalytic activities have been eliminated while retaining the high affinity to Im7. CL7 is used as a protein tag, while Im7 is covalently attached to agarose beads. To make the CL7/Im7 technique easy to use, we have designed a set of the E. coli expression vectors for fusion of a target protein to the protease-cleavable CL7-tag either at the N- or the C-terminus, and also have the options of the dual (CL7/His8) tag. A subset of vectors is dedicated for cloning membrane and multisubunit proteins. The CL7/Im7 system has several notable advatantages over other available affinity purification techniques. First, high concentrations of the small Im7 protein are coupled to the beads resulting in the high column capacities (up to 60 mg/mL). Second, an exceptional stability of Im7 allows for multiple (100+) regeneration cycles with no loss of binding capacities. Third, the CL7-tag improves protein expression levels, solubility and, in some cases, assists folding of the target proteins. Fourth, the on-column proteolytic elution produces purified proteins with few or no extra amino acid residues. Finally, the CL7/Im7 affinity is largely insensitive to high salt concentrations. For many target proteins, loading the bacterial lysates on the Im7 column in high salt is a key to high purity. Altogether, these properties of the CL7/Im7 system allow for a one-step HHH purification of most challenging, biologically and clinically significant proteins.
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Affiliation(s)
- Louise T Chow
- Department of Biochemistry and Molecular Genetics, Schools of Medicine and Dentistry, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Dmitry G Vassylyev
- Department of Biochemistry and Molecular Genetics, Schools of Medicine and Dentistry, University of Alabama at Birmingham, Birmingham, AL, USA.
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Chakraborty AK, Saha S, Poria K, Samanta T, Gautam S, Mukhopadhyay J. A saponin-polybromophenol antibiotic (CU1) from Cassia fistula Bark Against Multi-Drug Resistant Bacteria Targeting RNA polymerase. CURRENT RESEARCH IN PHARMACOLOGY AND DRUG DISCOVERY 2022; 3:100090. [PMID: 35198968 PMCID: PMC8844791 DOI: 10.1016/j.crphar.2022.100090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 01/09/2022] [Accepted: 01/31/2022] [Indexed: 11/26/2022] Open
Abstract
Background Gradual increase of multidrug resistant infections is a threat to the human race as MDR plasmids have acquired.>10 mdr and drug efflux genes to inactivate antibiotics. Plants secret anti-metabolites to retard growth of soil and water bacteria and are ideal source of antibiotics. Purpose Purpose of the study is to discover an alternate phyto-drug from medicinal plants of India that selectively kills MDR bacteria. Methods MDR bacteria isolated from Ganga river water, milk, chicken meat and human hair for testing phyto-extracts. Eighty medicinal plants were searched and six phyto-extracts were selected having good antibacterial activities as demonstrated by agar-hole assays giving 15 mm or greater lysis zone. Phyto-extracts were made in ethanol or methanol (1:5 w/v) for overnight and were concentrated. Preparative TLC and HPLC were performed to purify phytochemical. MASS, NMR, FTIR methods were used for chemical analysis of CU1. In vitro RNA polymerase and DNA polymerase assays were performed for target identification. Results CU1 belongs to a saponin bromo-polyphenol compound with a large structure that purified on HPLC C18 column at 3min. CU1 is bacteriocidal but three times less active than rifampicin in Agar-hole assay. While in LB medium it shows greater than fifteen times poor inhibitor due to solubility problem. CU1 inhibited transcription from Escherichia coli as well as Mycobacterium tuberculosis RNA Polymerases. Gel shift assays demonstrated that CU1 interferes at the open promoter complex formation step. On the other hand CU1 did not inhibit DNA polymerase. Conclusion Phyto-chemicals from Cassia fistula bark are abundant, less toxic, target specific and may be a safer low cost drug against MDR bacterial diseases. A new saponin-polybromophenol antibiotic (CU1) was isolated from Cassia fistula bark ethanol extract and purified by TLC and HPLC. The CU1 inhibits MDR bacteria isolated from human, animal, milk and water resources using agar-hole assay but highly refractile to in vitro assays using LB media due to poor solubility of CU1 in water. The chemical structure was partially elucidated by Mass, NMR, FT-IR and UV–Vis spectroscopy. It was suggested that triterpine moiety was linked to two polyphenol derivatives with six bromine atoms. The CU1 drug inhibits RNA polymerase of E. coli and M. tuberculosis as compare to conventional drug rifampicin. The CU1 phyto-chemical is less water soluble and less toxic in rat and fish models and will be a low cost drug which is resistant to most mdr bacteria.
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Functional insights into Mycobacterium tuberculosis DevR-dependent transcriptional machinery utilizing Escherichia coli. Biochem J 2021; 478:3079-3098. [PMID: 34350952 DOI: 10.1042/bcj20210268] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 08/02/2021] [Accepted: 08/05/2021] [Indexed: 11/17/2022]
Abstract
DevR/DosR response regulator is believed to participate in virulence, dormancy adaptation and antibiotic tolerance mechanisms of Mycobacterium tuberculosis by regulating the expression of the dormancy regulon. We have previously shown that the interaction of DevR with RNA polymerase is essential for the expression of DevR-regulated genes. Here, we developed a M. tuberculosis-specific in vivo transcription system to enrich our understanding of DevR-RNA polymerase interaction. This in vivo assay involves co-transforming E. coli with two plasmids that express α, β, β' and σA subunits of M. tuberculosis RNA polymerase and a third plasmid that harbors a DevR expression cassette and a GFP reporter gene under the DevR-regulated fdxA promoter. We show that DevR-dependent transcription is sponsored exclusively by M. tuberculosis RNA polymerase and regulated by α and σA subunits of M. tuberculosis RNA polymerase. Using this E. coli triple plasmid system to express mutant variants of M. tuberculosis RNA polymerase, we identified E280 residue in C-terminal domain of α and K513 and R515 residues of σA to participate in DevR-dependent transcription. In silico modeling of a ternary complex of DevR, σA domain 4 and fdxA promoter suggest an interaction of Q505, R515 and K513 residues of σA with E178 and D172 residues of DevR and E471 of σA, respectively. These findings provide us with new insights into the interactions between DevR and RNA polymerase of M. tuberculosis which can be targeted for intercepting DevR function. Finally, we demonstrate the utility of this system for screening of anti-DevR compounds.
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Kaur G, Kapoor S, Kaundal S, Dutta D, Thakur KG. Structure-Guided Designing and Evaluation of Peptides Targeting Bacterial Transcription. Front Bioeng Biotechnol 2020; 8:797. [PMID: 33014990 PMCID: PMC7505949 DOI: 10.3389/fbioe.2020.00797] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 06/22/2020] [Indexed: 11/17/2022] Open
Abstract
The mycobacterial RNA polymerase (RNAP) is an essential and validated drug target for developing antibacterial drugs. The β-subunit of Mycobacterium tuberculosis (Mtb) RNAP (RpoB) interacts with an essential and global transcription factor, CarD, and confers antibiotic and oxidative stress resistance to Mtb. Compromising the RpoB/CarD interactions results in the killing of mycobacteria, hence disrupting the RpoB/CarD interaction has been proposed as a novel strategy for the development of anti-tubercular drugs. Here, we describe the first approach to rationally design and test the efficacy of the peptide-based inhibitors which specifically target the conserved PPI interface between the bacterial RNAP β/transcription factor complex. We performed in silico protein-peptide docking studies along with biochemical assays to characterize the novel peptide-based inhibitors. Our results suggest that the top ranked peptides are highly stable, soluble in aqueous buffer, and capable of inhibiting transcription with IC50 > 50 μM concentration. Using peptide-based molecules, our study provides the first piece of evidence to target the conserved RNAP β/transcription factor interface for designing new inhibitors. Our results may hence form the basis to further improve the potential of these novel peptides in modulating bacterial gene expression, thus inhibiting bacterial growth and combating bacterial infections.
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Affiliation(s)
- Gundeep Kaur
- Structural Biology Laboratory, G. N. Ramachandran Protein Centre, Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh, India
| | - Srajan Kapoor
- Structural Biology Laboratory, G. N. Ramachandran Protein Centre, Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh, India
| | - Soni Kaundal
- Structural Biology Laboratory, G. N. Ramachandran Protein Centre, Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh, India
| | - Dipak Dutta
- Molecular Microbiology Laboratory, Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh, India
| | - Krishan Gopal Thakur
- Structural Biology Laboratory, G. N. Ramachandran Protein Centre, Council of Scientific and Industrial Research-Institute of Microbial Technology, Chandigarh, India
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Evidence of Robustness in a Two-Component System Using a Synthetic Circuit. J Bacteriol 2020; 202:JB.00672-19. [PMID: 31792012 DOI: 10.1128/jb.00672-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 11/25/2019] [Indexed: 01/06/2023] Open
Abstract
Variation in the concentration of biological components is inescapable for any cell. Robustness in any biological circuit acts as a cushion against such variation and enables the cells to produce homogeneous output despite the fluctuation. The two-component system (TCS) with a bifunctional sensor kinase (that possesses both kinase and phosphatase activities) is proposed to be a robust circuit. Few theoretical models explain the robustness of a TCS, although the criteria and extent of robustness by these models differ. Here, we provide experimental evidence to validate the extent of the robustness of a TCS signaling pathway. We have designed a synthetic circuit in Escherichia coli using a representative TCS of Mycobacterium tuberculosis, MprAB, and monitored the in vivo output signal by systematically varying the concentration of either of the components or both. We observed that the output of the TCS is robust if the concentration of MprA is above a threshold value. This observation is further substantiated by two in vitro assays, in which we estimated the phosphorylated MprA pool or MprA-dependent transcription yield by varying either of the components of the TCS. This synthetic circuit could be used as a model system to analyze the relationship among different components of gene regulatory networks.IMPORTANCE Robustness in essential biological circuits is an important feature of the living organism. A few pieces of evidence support the existence of robustness in vivo in the two-component system (TCS) with a bifunctional sensor kinase (SK). The assays were done under physiological conditions in which the SK was much lower than the response regulator (RR). Here, using a synthetic circuit, we varied the concentrations of the SK and RR of a representative TCS to monitor output robustness in vivo. In vitro assays were also performed under conditions where the concentration of the SK was greater than that of the RR. Our results demonstrate the extent of output robustness in the TCS signaling pathway with respect to the concentrations of the two components.
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Lee TH, Kim KS, Kim JH, Jeong JH, Woo HR, Park SR, Sohn MH, Lee HJ, Rhee JH, Cha SS, Hwang JH, Chung KM. Novel short peptide tag from a bacterial toxin for versatile applications. J Immunol Methods 2020; 479:112750. [PMID: 31981564 DOI: 10.1016/j.jim.2020.112750] [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: 06/24/2019] [Revised: 12/25/2019] [Accepted: 01/21/2020] [Indexed: 11/26/2022]
Abstract
The specific recognition between a monoclonal antibody (mAb) and its epitope can be used in a tag system that has proved valuable in a wide range of biological applications. Herein, we describe a novel tag called RA-tag that is composed of a seven amino acid sequence (DIDLSRI) and recognized by a highly specific mAb, 47RA, against the bacterial toxin Vibrio vulnificus RtxA1/MARTXVv. By using recombinant proteins with the RA-tag at the N-terminal, C-terminal, or an internal site, we demonstrated that the tag system could be an excellent biological system for both protein purification and protein detection in enzyme-linked immunosorbent, Western blot, flow cytometry, and immunofluorescence staining analyses in Escherichia coli, mammalian cell lines, yeast, and plant. In addition, our RA-tag/47RA mAb combination showed high sensitivity and reliable affinity (KD = 5.90 × 10-8 M) when compared with conventional tags. Overall, our results suggest that the RA-tag system could facilitate the development of a broadly applicable tag system for biological research.
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Affiliation(s)
- Tae Hee Lee
- Department of Microbiology and Immunology, Jeonbuk National University Medical School, Jeonju, Jeonbuk 54896, Republic of Korea; Institute for Medical Science, Jeonbuk National University Medical School, Jeonju, Jeonbuk 54896, Republic of Korea
| | - Kwang Soo Kim
- Department of Microbiology, Chonnam National University Medical School, Hwasun-gun 58128, Republic of Korea; Combinatorial Tumor Immunotherapy Medical Research Center, Chonnam National University Medical School, Hwasun-gun 58128, Republic of Korea
| | - Jin Hee Kim
- Subtropical Horticulture Research Institute, Jeju National University, Jeju 63243, Republic of Korea; Department of New Biology, DGIST, Daegu 42988, Republic of Korea
| | - Jae-Ho Jeong
- Department of Microbiology, Chonnam National University Medical School, Hwasun-gun 58128, Republic of Korea; Combinatorial Tumor Immunotherapy Medical Research Center, Chonnam National University Medical School, Hwasun-gun 58128, Republic of Korea
| | - Hye Ryun Woo
- Department of New Biology, DGIST, Daegu 42988, Republic of Korea
| | - So Ra Park
- New Drug Development Center, Osong Medical Innovation Foundation, Cheongju, Chungbuk 28160, Republic of Korea
| | - Myung-Ho Sohn
- New Drug Development Center, Osong Medical Innovation Foundation, Cheongju, Chungbuk 28160, Republic of Korea
| | - Hyeon Ju Lee
- Department of Microbiology and Immunology, Jeonbuk National University Medical School, Jeonju, Jeonbuk 54896, Republic of Korea
| | - Joon Haeng Rhee
- Department of Microbiology, Chonnam National University Medical School, Hwasun-gun 58128, Republic of Korea; Combinatorial Tumor Immunotherapy Medical Research Center, Chonnam National University Medical School, Hwasun-gun 58128, Republic of Korea; Clinical Vaccine R&D Center, Chonnam National University Medical School, Hwasun-gun 58128, Republic of Korea; Vaxcell-Bio Therapeutics, Hwasun-gun 58141, Republic of Korea
| | - Sun-Shin Cha
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Joo-Hee Hwang
- Department of Internal Medicine, Jeonbuk National University Medical School, Jeonju, Jeonbuk 54896, Republic of Korea; Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, Jeonbuk 54907, Republic of Korea.
| | - Kyung Min Chung
- Department of Microbiology and Immunology, Jeonbuk National University Medical School, Jeonju, Jeonbuk 54896, Republic of Korea; Institute for Medical Science, Jeonbuk National University Medical School, Jeonju, Jeonbuk 54896, Republic of Korea; Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, Jeonbuk 54907, Republic of Korea.
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15
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Jensen D, Manzano AR, Rammohan J, Stallings CL, Galburt EA. CarD and RbpA modify the kinetics of initial transcription and slow promoter escape of the Mycobacterium tuberculosis RNA polymerase. Nucleic Acids Res 2020; 47:6685-6698. [PMID: 31127308 PMCID: PMC6648326 DOI: 10.1093/nar/gkz449] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 04/11/2019] [Accepted: 05/09/2019] [Indexed: 12/17/2022] Open
Abstract
The pathogen Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, enacts unique transcriptional regulatory mechanisms when subjected to host-derived stresses. Initiation of transcription by the Mycobacterial RNA polymerase (RNAP) has previously been shown to exhibit different open complex kinetics and stabilities relative to Escherichia coli (Eco) RNAP. However, transcription initiation rates also depend on the kinetics following open complex formation such as initial nucleotide incorporation and subsequent promoter escape. Here, using a real-time fluorescence assay, we present the first in-depth kinetic analysis of initial transcription and promoter escape for the Mtb RNAP. We show that in relation to Eco RNAP, Mtb displays slower initial nucleotide incorporation but faster overall promoter escape kinetics on the Mtb rrnAP3 promoter. Furthermore, in the context of the essential transcription factors CarD and RbpA, Mtb promoter escape is slowed via differential effects on initially transcribing complexes. Finally, based on their ability to increase the rate of open complex formation and decrease the rate of promoter escape, we suggest that CarD and RbpA are capable of activation or repression depending on the rate-limiting step of a given promoter's basal initiation kinetics.
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Affiliation(s)
- Drake Jensen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Ana Ruiz Manzano
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jayan Rammohan
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Christina L Stallings
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Eric A Galburt
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
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16
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Afful D, Cai L, Momany C. Overproduction and purification of highly active recombinant Pseudomonas aeruginosa str. PAO1 RNA polymerase holoenzyme complex. Protein Expr Purif 2019; 163:105448. [PMID: 31279833 DOI: 10.1016/j.pep.2019.105448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/25/2019] [Accepted: 07/01/2019] [Indexed: 02/05/2023]
Abstract
The bacterial RNA polymerase (RNAP) is a large, complex molecular machine that is the engine of gene expression. Despite global conservation in their structures and function, RNAPs from different bacteria can have unique features in promoter and transcription factor recognition. Therefore, availability of purified RNAP from different bacteria is key to understanding these species-specific aspects and will be valuable for antibiotic drug discovery. Pseudomonas aeruginosa is one of the leading causes of hospital and community acquired infections worldwide - making the organism an important public health pathogen. We developed a method for producing high quantities of highly pure and active recombinant P. aeruginosa str. PAO1 RNAP core and holoenzyme complexes that employed two-vector systems for expressing the core enzyme (α, β, β', and ω subunits) and for expressing the holoenzyme complex (core + σ70). Unlike other RNAP expression approaches, we used a low temperature autoinduction system in E. coli with T7 promoters that produced high cell yields and stable protein expression. The purification strategy comprised of four chromatographic separation steps (metal chelate, heparin, and ion-exchange) with yields of up to 11 mg per 500 mL culture. Purified holoenzyme and reconstituted holoenzyme from core and σ70 were highly active at transcribing both small and large-sized DNA templates, with a determined elongation rate of ~18 nt/s for the holoenzyme. The successful purification of the P. aeruginosa RNAP provides a gateway for studies focusing on in vitro transcriptional regulation in this pathogen.
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Affiliation(s)
- Derrick Afful
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, 30602, USA
| | - Liming Cai
- Department of Computer Sciences, University of Georgia, Athens, GA, 30602, USA
| | - Cory Momany
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, 30602, USA.
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17
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Li L, Fang C, Zhuang N, Wang T, Zhang Y. Structural basis for transcription initiation by bacterial ECF σ factors. Nat Commun 2019; 10:1153. [PMID: 30858373 PMCID: PMC6411747 DOI: 10.1038/s41467-019-09096-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 02/01/2019] [Indexed: 01/07/2023] Open
Abstract
Bacterial RNA polymerase employs extra-cytoplasmic function (ECF) σ factors to regulate context-specific gene expression programs. Despite being the most abundant and divergent σ factor class, the structural basis of ECF σ factor-mediated transcription initiation remains unknown. Here, we determine a crystal structure of Mycobacterium tuberculosis (Mtb) RNAP holoenzyme comprising an RNAP core enzyme and the ECF σ factor σH (σH-RNAP) at 2.7 Å, and solve another crystal structure of a transcription initiation complex of Mtb σH-RNAP (σH-RPo) comprising promoter DNA and an RNA primer at 2.8 Å. The two structures together reveal the interactions between σH and RNAP that are essential for σH-RNAP holoenzyme assembly as well as the interactions between σH-RNAP and promoter DNA responsible for stringent promoter recognition and for promoter unwinding. Our study establishes that ECF σ factors and primary σ factors employ distinct mechanisms for promoter recognition and for promoter unwinding.
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Affiliation(s)
- Lingting Li
- 0000000119573309grid.9227.eKey Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032 China ,0000 0004 1797 8419grid.410726.6University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Chengli Fang
- 0000000119573309grid.9227.eKey Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032 China ,0000 0004 1797 8419grid.410726.6University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Ningning Zhuang
- 0000000119573309grid.9227.eKey Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032 China
| | - Tiantian Wang
- 0000000119573309grid.9227.eKey Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032 China ,0000 0004 1797 8419grid.410726.6University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Yu Zhang
- 0000000119573309grid.9227.eKey Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032 China
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18
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Structural basis of ECF-σ-factor-dependent transcription initiation. Nat Commun 2019; 10:710. [PMID: 30755604 PMCID: PMC6372665 DOI: 10.1038/s41467-019-08443-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 01/11/2019] [Indexed: 01/24/2023] Open
Abstract
Extracytoplasmic (ECF) σ factors, the largest class of alternative σ factors, are related to primary σ factors, but have simpler structures, comprising only two of six conserved functional modules 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 shorter and 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. No structural data have been available for RNA polymerase holoenzymes or transcription initiation complexes that contain extracytoplasmic σ factors. Here the authors report the crystal structures of transcription initiation complexes comprising Mycobacterium tuberculosis RNA polymerase, extracytoplasmic σ factor σL and promoter DNA.
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19
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Bhawsinghka N, Dutta A, Mukhopadhyay J, Das Gupta SK. A transcriptomic analysis of the mycobacteriophage D29 genome reveals the presence of novel stoperator-associated promoters in its right arm. Microbiology (Reading) 2018; 164:1168-1179. [DOI: 10.1099/mic.0.000693] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Niketa Bhawsinghka
- 1Department of Microbiology, Bose Institute, P-1/12 C.I.T. Scheme VIIM, Kolkata 700054, India
| | - Arkajyoti Dutta
- 2Department of Chemistry, Bose Institute, 93/1 APC Road, Kolkata 700009, India
| | | | - Sujoy K. Das Gupta
- 1Department of Microbiology, Bose Institute, P-1/12 C.I.T. Scheme VIIM, Kolkata 700054, India
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20
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Association of ω with the C-Terminal Region of the β' Subunit Is Essential for Assembly of RNA Polymerase in Mycobacterium tuberculosis. J Bacteriol 2018; 200:JB.00159-18. [PMID: 29632095 DOI: 10.1128/jb.00159-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 04/02/2018] [Indexed: 11/20/2022] Open
Abstract
The ω subunit is the smallest subunit of bacterial RNA polymerase (RNAP). Although homologs of ω are essential in both eukaryotes and archaea, this subunit has been known to be dispensable for RNAP in Escherichia coli and in other bacteria. In this study, we characterized an indispensable role of the ω subunit in Mycobacterium tuberculosis Unlike the well-studied E. coli RNAP, the M. tuberculosis RNAP core enzyme cannot be functionally assembled in the absence of the ω subunit. Importantly, substitution of M. tuberculosis ω with ω subunits from E. coli or Thermus thermophilus cannot restore the assembly of M. tuberculosis RNAP. Furthermore, by replacing different regions in M. tuberculosis ω with the corresponding regions from E. coli ω, we found a nonconserved loop region in M. tuberculosis ω essential for its function in RNAP assembly. From RNAP structures, we noticed that the location of the C-terminal region of the β' subunit (β'CTD) in M. tuberculosis RNAP but not in E. coli or T. thermophilus RNAP is close to the ω loop region. Deletion of this β'CTD in M. tuberculosis RNAP destabilized the binding of M. tuberculosis ω on RNAP and compromised M. tuberculosis core assembly, suggesting that these two regions may function together to play a role in ω-dependent RNAP assembly in M. tuberculosis Sequence alignment of the ω loop and the β'CTD regions suggests that the essential role of ω is probably restricted to mycobacteria. Together, our study characterized an essential role of M. tuberculosis ω and highlighted the importance of the ω loop region in M. tuberculosis RNAP assembly.IMPORTANCE DNA-dependent RNA polymerase (RNAP), which consists of a multisubunit core enzyme (α2ββ'ω) and a dissociable σ subunit, is the only enzyme in charge of transcription in bacteria. As the smallest subunit, the roles of ω remain the least well studied. In Escherichia coli and some other bacteria, the ω subunit is known to be nonessential for RNAP. In this study, we revealed an essential role of the ω subunit for RNAP assembly in the human pathogen Mycobacterium tuberculosis, and a mycobacterium-specific ω loop that plays a role in this function was also characterized. Our study provides fresh insights for further characterizing the roles of bacterial ω subunit.
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21
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Domains within RbpA Serve Specific Functional Roles That Regulate the Expression of Distinct Mycobacterial Gene Subsets. J Bacteriol 2018; 200:JB.00690-17. [PMID: 29686140 DOI: 10.1128/jb.00690-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 04/18/2018] [Indexed: 11/20/2022] Open
Abstract
The RNA polymerase (RNAP) binding protein A (RbpA) contributes to the formation of stable RNAP-promoter open complexes (RPo) and is essential for viability in mycobacteria. Four domains have been identified in the RbpA protein, i.e., an N-terminal tail (NTT) that interacts with RNAP β' and σ subunits, a core domain (CD) that contacts the RNAP β' subunit, a basic linker (BL) that binds DNA, and a σ-interaction domain (SID) that binds group I and group II σ factors. Limited in vivo studies have been performed in mycobacteria, however, and how individual structural domains of RbpA contribute to RbpA function and mycobacterial gene expression remains mostly unknown. We investigated the roles of the RbpA structural domains in mycobacteria using a panel of rbpA mutants that target individual RbpA domains. The function of each RbpA domain was required for Mycobacterium tuberculosis viability and optimal growth in Mycobacterium smegmatis We determined that the RbpA SID is both necessary and sufficient for RbpA interaction with the RNAP, indicating that the primary functions of the NTT and CD are not solely association with the RNAP. We show that the RbpA BL and SID are required for RPo stabilization in vitro, while the NTT and CD antagonize this activity. Finally, RNA-sequencing analyses suggest that the NTT and CD broadly activate gene expression, whereas the BL and SID activate or repress gene expression in a gene-dependent manner for a subset of mycobacterial genes. Our findings highlight specific outcomes for the activities of the individual functional domains in RbpA.IMPORTANCEMycobacterium tuberculosis is the causative agent of tuberculosis and continues to be the most lethal infectious disease worldwide. Improved molecular understanding of the essential proteins involved in M. tuberculosis transcription, such as RbpA, could provide targets for much needed future therapeutic agents aimed at combatting this pathogen. In this study, we expand our understanding of RbpA by identifying the RbpA structural domains responsible for the interaction of RbpA with the RNAP and the effects of RbpA on transcription initiation and gene expression. These experiments expand our knowledge of RbpA while also broadening our understanding of bacterial transcription in general.
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22
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Lin W, Das K, Degen D, Mazumder A, Duchi D, Wang D, Ebright YW, Ebright RY, Sineva E, Gigliotti M, Srivastava A, Mandal S, Jiang Y, Liu Y, Yin R, Zhang Z, Eng ET, Thomas D, Donadio S, Zhang H, Zhang C, Kapanidis AN, Ebright RH. Structural Basis of Transcription Inhibition by Fidaxomicin (Lipiarmycin A3). Mol Cell 2018; 70:60-71.e15. [PMID: 29606590 PMCID: PMC6205224 DOI: 10.1016/j.molcel.2018.02.026] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 02/14/2018] [Accepted: 02/23/2018] [Indexed: 12/16/2022]
Abstract
Fidaxomicin is an antibacterial drug in clinical use for treatment of Clostridium difficile diarrhea. The active ingredient of fidaxomicin, lipiarmycin A3 (Lpm), functions by inhibiting bacterial RNA polymerase (RNAP). Here we report a cryo-EM structure of Mycobacterium tuberculosis RNAP holoenzyme in complex with Lpm at 3.5-Å resolution. The structure shows that Lpm binds at the base of the RNAP "clamp." The structure exhibits an open conformation of the RNAP clamp, suggesting that Lpm traps an open-clamp state. Single-molecule fluorescence resonance energy transfer experiments confirm that Lpm traps an open-clamp state and define effects of Lpm on clamp dynamics. We suggest that Lpm inhibits transcription by trapping an open-clamp state, preventing simultaneous interaction with promoter -10 and -35 elements. The results account for the absence of cross-resistance between Lpm and other RNAP inhibitors, account for structure-activity relationships of Lpm derivatives, and enable structure-based design of improved Lpm derivatives.
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Affiliation(s)
- Wei Lin
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Kalyan Das
- Rega Institute and Department of Microbiology and Immunology, KU Leuven, 3000 Leuven, Belgium.
| | - David Degen
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Abhishek Mazumder
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Diego Duchi
- Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Dongye Wang
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Yon W Ebright
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Richard Y Ebright
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Elena Sineva
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Matthew Gigliotti
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Aashish Srivastava
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Sukhendu Mandal
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Yi Jiang
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Yu Liu
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Ruiheng Yin
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Zhening Zhang
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York NY 10027, USA
| | - Edward T Eng
- The National Resource for Automated Molecular Microscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York NY 10027, USA
| | - Dennis Thomas
- Center for Integrative Proteomics, Rutgers University, Piscataway, NJ 08854, USA
| | | | - Haibo Zhang
- South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
| | - Changsheng Zhang
- South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
| | | | - Richard H Ebright
- Waksman Institute and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA.
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23
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du Plessis J, Cloete R, Burchell L, Sarkar P, Warren RM, Christoffels A, Wigneshweraraj S, Sampson SL. Exploring the potential of T7 bacteriophage protein Gp2 as a novel inhibitor of mycobacterial RNA polymerase. Tuberculosis (Edinb) 2017; 106:82-90. [PMID: 28802409 DOI: 10.1016/j.tube.2017.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 07/04/2017] [Accepted: 07/13/2017] [Indexed: 11/17/2022]
Abstract
Over the past six decades, there has been a decline in novel therapies to treat tuberculosis, while the causative agent of this disease has become increasingly resistant to current treatment regimens. Bacteriophages (phages) are able to kill bacterial cells and understanding this process could lead to novel insights for the treatment of mycobacterial infections. Phages inhibit bacterial gene transcription through phage-encoded proteins which bind to RNA polymerase (RNAP), thereby preventing bacterial transcription. Gp2, a T7 phage protein which binds to the beta prime (β') subunit of RNAP in Escherichia coli, has been well characterized in this regard. Here, we aimed to determine whether Gp2 is able to inhibit RNAP in Mycobacterium tuberculosis as this may provide new possibilities for inhibiting the growth of this deadly pathogen. Results from an electrophoretic mobility shift assay and in vitro transcription assay revealed that Gp2 binds to mycobacterial RNAP and inhibits transcription; however to a much lesser degree than in E. coli. To further understand the molecular basis of these results, a series of in silico techniques were used to assess the interaction between mycobacterial RNAP and Gp2, providing valuable insight into the characteristics of this protein-protein interaction.
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Affiliation(s)
- J du Plessis
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, SA MRC Centre for TB Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa.
| | - R Cloete
- South African National Bioinformatics Institute (SANBI), SA Medical Research Council Bioinformatics Unit, University of the Western Cape, South Africa.
| | - L Burchell
- MRC Centre for Molecular Bacteriology and Infection, Faculty of Medicine, South Kensington Campus, Imperial College, United Kingdom.
| | - P Sarkar
- MRC Centre for Molecular Bacteriology and Infection, Faculty of Medicine, South Kensington Campus, Imperial College, United Kingdom.
| | - R M Warren
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, SA MRC Centre for TB Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa.
| | - A Christoffels
- South African National Bioinformatics Institute (SANBI), SA Medical Research Council Bioinformatics Unit, University of the Western Cape, South Africa.
| | - S Wigneshweraraj
- MRC Centre for Molecular Bacteriology and Infection, Faculty of Medicine, South Kensington Campus, Imperial College, United Kingdom.
| | - S L Sampson
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, SA MRC Centre for TB Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa.
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24
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Datta A, Yadav V, Ghosh A, Choi J, Bhattacharyya D, Kar RK, Ilyas H, Dutta A, An E, Mukhopadhyay J, Lee D, Sanyal K, Ramamoorthy A, Bhunia A. Mode of Action of a Designed Antimicrobial Peptide: High Potency against Cryptococcus neoformans. Biophys J 2017; 111:1724-1737. [PMID: 27760359 DOI: 10.1016/j.bpj.2016.08.032] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 08/11/2016] [Accepted: 08/29/2016] [Indexed: 12/11/2022] Open
Abstract
There is a significant need for developing compounds that kill Cryptococcus neoformans, the fungal pathogen that causes meningoencephalitis in immunocompromised individuals. Here, we report the mode of action of a designed antifungal peptide, VG16KRKP (VARGWKRKCPLFGKGG) against C. neoformans. It is shown that VG16KRKP kills fungal cells mainly through membrane compromise leading to efflux of ions and cell metabolites. Intracellular localization, inhibition of in vitro transcription, and DNA binding suggest a secondary mode of action for the peptide, hinting at possible intracellular targets. Atomistic structure of the peptide determined by NMR experiments on live C. neoformans cells reveals an amphipathic arrangement stabilized by hydrophobic interactions among A2, W5, and F12, a conventional folding pattern also known to play a major role in peptide-mediated Gram-negative bacterial killing, revealing the importance of this motif. These structural details in the context of live cell provide valuable insights into the design of potent peptides for effective treatment of human and plant fungal infections.
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Affiliation(s)
- Aritreyee Datta
- Department of Biophysics, P-1/12 CIT Scheme VII (M), Kolkata, India
| | - Vikas Yadav
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Anirban Ghosh
- Department of Biophysics, P-1/12 CIT Scheme VII (M), Kolkata, India
| | - Jaesun Choi
- Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul, Korea
| | | | - Rajiv K Kar
- Department of Biophysics, P-1/12 CIT Scheme VII (M), Kolkata, India
| | - Humaira Ilyas
- Department of Biophysics, P-1/12 CIT Scheme VII (M), Kolkata, India
| | | | - Eunseol An
- Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul, Korea
| | | | - Dongkuk Lee
- Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul, Korea
| | - Kaustuv Sanyal
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | | | - Anirban Bhunia
- Department of Biophysics, P-1/12 CIT Scheme VII (M), Kolkata, India.
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25
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Efficient, ultra-high-affinity chromatography in a one-step purification of complex proteins. Proc Natl Acad Sci U S A 2017; 114:E5138-E5147. [PMID: 28607052 DOI: 10.1073/pnas.1704872114] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Protein purification is an essential primary step in numerous biological studies. It is particularly significant for the rapidly emerging high-throughput fields, such as proteomics, interactomics, and drug discovery. Moreover, purifications for structural and industrial applications should meet the requirement of high yield, high purity, and high activity (HHH). It is, therefore, highly desirable to have an efficient purification system with a potential to meet the HHH benchmark in a single step. Here, we report a chromatographic technology based on the ultra-high-affinity (Kd ∼ 10-14-10-17 M) complex between the Colicin E7 DNase (CE7) and its inhibitor, Immunity protein 7 (Im7). For this application, we mutated CE7 to create a CL7 tag, which retained the full binding affinity to Im7 but was inactivated as a DNase. To achieve high capacity, we developed a protocol for a large-scale production and highly specific immobilization of Im7 to a solid support. We demonstrated its utility with one-step HHH purification of a wide range of traditionally challenging biological molecules, including eukaryotic, membrane, toxic, and multisubunit DNA/RNA-binding proteins. The system is simple, reusable, and also applicable to pulldown and kinetic activity/binding assays.
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26
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Lin W, Mandal S, Degen D, Liu Y, Ebright YW, Li S, Feng Y, Zhang Y, Mandal S, Jiang Y, Liu S, Gigliotti M, Talaue M, Connell N, Das K, Arnold E, Ebright RH. Structural Basis of Mycobacterium tuberculosis Transcription and Transcription Inhibition. Mol Cell 2017; 66:169-179.e8. [PMID: 28392175 DOI: 10.1016/j.molcel.2017.03.001] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 02/15/2017] [Accepted: 02/28/2017] [Indexed: 01/22/2023]
Abstract
Mycobacterium 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, at 3.8-4.4 Å resolution. 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 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.
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Affiliation(s)
- Wei Lin
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Soma Mandal
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - David Degen
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Yu Liu
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Yon W Ebright
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Shengjian Li
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Yu Feng
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Yu Zhang
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Sukhendu Mandal
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Yi Jiang
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Shuang Liu
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Matthew Gigliotti
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Meliza Talaue
- Center for Biodefense and Department of Medicine, New Jersey Medical School, Rutgers University, Newark, NJ 07101, USA
| | - Nancy Connell
- Center for Biodefense and Department of Medicine, New Jersey Medical School, Rutgers University, Newark, NJ 07101, USA
| | - Kalyan Das
- Center for Advanced Biotechnology and Medicine and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Eddy Arnold
- Center for Advanced Biotechnology and Medicine and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Richard H Ebright
- Waksman Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA.
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27
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Synthesis, structural characterization, antibacterial activity, DNA binding and computational studies of bis(2-methyl-1H-imidazole κN3)silver(I)dichromate(VI). J Mol Struct 2017. [DOI: 10.1016/j.molstruc.2016.11.064] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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28
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Herrera-Asmat O, Lubkowska L, Kashlev M, Bustamante CJ, Guerra DG, Kireeva ML. Production and characterization of a highly pure RNA polymerase holoenzyme from Mycobacterium tuberculosis. Protein Expr Purif 2017; 134:1-10. [PMID: 28323168 DOI: 10.1016/j.pep.2017.03.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 03/15/2017] [Accepted: 03/16/2017] [Indexed: 10/19/2022]
Abstract
Recent publications have shown that active RNA polymerase (RNAP) from Mycobacterium tuberculosis (MtbRNAP) can be produced by expressing all four subunits in a single recombinant Escherichia coli strain [1-3]. By reducing the number of plasmids and changing the codon usage of the Mtb genes in the co-expression system published by Banerjee et al. [1], we present a simplified, detailed and reproducible protocol for the purification of recombinant MtbRNAP containing the ω subunit. Moreover, we describe the formation of ternary elongation complexes (TECs) with a short fluorescence-labeled RNA primer and DNA oligonucleotides, suitable for transcription elongation studies. The purification of milligram quantities of the pure and highly active holoenzyme omits ammonium sulfate or polyethylene imine precipitation steps [4] and requires only 5 g of wet cells. Our results indicate that subunit assemblies other than α2ββ'ω·σA can be separated by ion-exchange chromatography on Mono Q column and that assemblies with the wrong RNAP subunit stoichiometry lack transcriptional activity. We show that MtbRNAP TECs can be stalled by NTP substrate deprivation and chased upon the addition of missing NTP(s) without the need of any accessory proteins. Finally, we demonstrate the ability of the purified MtbRNAP to initiate transcription from a promoter and establish that its open promoter complexes are stabilized by the M. tuberculosis protein CarD.
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Affiliation(s)
- Omar Herrera-Asmat
- Jason Choy Laboratory of Single Molecule Biophysics, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA; Laboratorio de Moléculas Individuales, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martin de Porras, Lima-31, Peru
| | | | | | - Carlos J Bustamante
- Jason Choy Laboratory of Single Molecule Biophysics, Department of Molecular and Cell Biology, Department of Physics and Department of Chemistry, Kavli Energy Nanoscience Institute, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA.
| | - Daniel G Guerra
- Laboratorio de Moléculas Individuales, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martin de Porras, Lima-31, Peru.
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29
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Molodtsov V, Scharf NT, Stefan MA, Garcia GA, Murakami KS. Structural basis for rifamycin resistance of bacterial RNA polymerase by the three most clinically important RpoB mutations found in Mycobacterium tuberculosis. Mol Microbiol 2017; 103:1034-1045. [PMID: 28009073 DOI: 10.1111/mmi.13606] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2016] [Indexed: 12/01/2022]
Abstract
Since 1967, Rifampin (RMP, a Rifamycin) has been used as a first line antibiotic treatment for tuberculosis (TB), and it remains the cornerstone of current short-term TB treatment. Increased occurrence of Rifamycin-resistant (RIFR ) TB, ∼41% of which results from the RpoB S531L mutation in RNA polymerase (RNAP), has become a growing problem worldwide. In this study, we determined the X-ray crystal structures of the Escherichia coli RNAPs containing the most clinically important S531L mutation and two other frequently observed RIFR mutants, RpoB D516V and RpoB H526Y. The structures reveal that the S531L mutation imparts subtle if any structural or functional impact on RNAP in the absence of RIF. However, upon RMP binding, the S531L mutant exhibits a disordering of the RIF binding interface, which effectively reduces the RMP affinity. In contrast, the H526Y mutation reshapes the RIF binding pocket, generating significant steric conflicts that essentially prevent any RIF binding. While the D516V mutant does not exhibit any such gross structural changes, certainly the electrostatic surface of the RIF binding pocket is dramatically changed, likely resulting in the decreased affinity for RIFs. Analysis of interactions of RMP with three common RIFR mutant RNAPs suggests that modifications to RMP may recover its efficacy against RIFR TB.
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Affiliation(s)
- Vadim Molodtsov
- Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Nathan T Scharf
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 428 Church St, Ann Arbor, MI, 48109-1065, USA
| | - Maxwell A Stefan
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 428 Church St, Ann Arbor, MI, 48109-1065, USA
| | - George A Garcia
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 428 Church St, Ann Arbor, MI, 48109-1065, USA
| | - Katsuhiko S Murakami
- Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
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30
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Scharf NT, Molodtsov V, Kontos A, Murakami KS, Garcia GA. Novel Chemical Scaffolds for Inhibition of Rifamycin-Resistant RNA Polymerase Discovered from High-Throughput Screening. SLAS DISCOVERY 2016; 22:287-297. [PMID: 28027449 DOI: 10.1177/2472555216679994] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Rifampin has been a cornerstone of tuberculosis (TB) treatment since its introduction. The rise of multidrug-resistant and extensively drug-resistant TB makes the development of novel therapeutics effective against these strains an urgent need. Site-specific mutations in the target enzyme of rifampin, RNA polymerase (RNAP) comprises the majority (~97%) of rifamycin-resistant (RifR) strains of Mycobacterium tuberculosis (MTB). To identify novel inhibitors of bacterial RNAP, an in vitro plasmid-based transcription assay that uses malachite green (MG) to detect transcribed RNA containing MG aptamers was developed. This assay was optimized in a 384-well plate format and used to screen 150,000 compounds against an Escherichia coli homolog of the most clinically relevant RifR RNAP (βS531L) containing a mutation (β'V408G) that compensates for the fitness defect of this RifR mutant. Following confirmation and concentration-response studies, 10 compounds were identified with similar in vitro inhibition values across a panel of wild-type and RifR E. coli and MTB RNAPs. Four compounds identified from the screen are active against MTB in culture at concentrations below 200 µM. Initial follow-up has resulted in the elimination of one scaffold due to potential pan-assay interference.
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Affiliation(s)
- Nathan T Scharf
- 1 Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI, USA
| | - Vadim Molodtsov
- 2 Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Arrin Kontos
- 1 Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI, USA
| | - Katsuhiko S Murakami
- 2 Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - George A Garcia
- 1 Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI, USA
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31
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Esyunina DM, Kulbachinskiy AV. Purification and characterization of recombinant Deinococcus radiodurans RNA Polymerase. BIOCHEMISTRY (MOSCOW) 2015; 80:1271-8. [DOI: 10.1134/s0006297915100077] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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32
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Ren N, Gao G, Sun Y, Zhang L, Wang H, Hua W, Wan K, Li X. MicroRNA signatures from multidrug‑resistant Mycobacterium tuberculosis. Mol Med Rep 2015; 12:6561-7. [PMID: 26324150 PMCID: PMC4626138 DOI: 10.3892/mmr.2015.4262] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 04/10/2015] [Indexed: 11/30/2022] Open
Abstract
Tuberculosis (TB) infections, caused by multi-drug-resistant Mycobacterium tuberculosis (MDR MTB), remain a significant public health concern worldwide. The regulatory mechanisms underlying the emergence of MDR MTB strains remain to be fully elucidated, and further investigation is required in order to develop better strategies for TB control. The present study investigated the expression profile of microRNA (miRNA) in MTB strains, and examined the differences between sensitive MTB and MDR MTB using next generation sequencing (NGS) with Illumina Deep Sequencing technology to better understand the mechanisms of resistance in MDR MTB, A total of 5, 785 and 195, and 6, 290 and 595 qualified Illumina reads were obtained from two MDR MTB strains, and 6, 673 and 665, and 7, 210 and 217 qualified Illumina reads were obtained from two sensitive MTB strains. The overall de novo assembly of miRNA sequence data generated 62 and 62, and 95 and 112 miRNAs between the 18 and 30 bp long from sensitive MTB strains and MDR MTB strains, respectively. Comparative miRNA analysis revealed that 142 miRNAs were differentially expressed in the MDR MTB strain, compared with the sensitive MTB strain, of which 48 were upregulated and 94 were downregulated. There were six similarly expressed miRNAs between the MDR and sensitive MTB strains, and 108 miRNAs were expressed only in the MDR MTB strain. The present study acquired miRNA data from sensitive MTB and MDR MTB strains using NGS techniques, and this identification miRNAs may serve as an invaluable resource for revealing the molecular basis of the regulation of expression associated with the mechanism of drug-resistance in MTB.
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Affiliation(s)
- Na Ren
- The National Clinical Key Department of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, P.R. China
| | - Guiju Gao
- The National Clinical Key Department of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, P.R. China
| | - Yue Sun
- Department of Infectious Diseases, First Hospital of Tsinghua University, Beijing 100016, P.R. China
| | - Ling Zhang
- The National Clinical Key Department of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, P.R. China
| | - Huizhu Wang
- The National Clinical Key Department of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, P.R. China
| | - Wenhao Hua
- The National Clinical Key Department of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, P.R. China
| | - Kanglin Wan
- National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, State Key Laboratory for Infectious Disease Prevention and Control, Beijing 102206, P.R. China
| | - Xingwang Li
- The National Clinical Key Department of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, P.R. China
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Rudra P, Prajapati RK, Banerjee R, Sengupta S, Mukhopadhyay J. Novel mechanism of gene regulation: the protein Rv1222 of Mycobacterium tuberculosis inhibits transcription by anchoring the RNA polymerase onto DNA. Nucleic Acids Res 2015; 43:5855-67. [PMID: 25999340 PMCID: PMC4499140 DOI: 10.1093/nar/gkv516] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 05/06/2015] [Indexed: 12/21/2022] Open
Abstract
We propose a novel mechanism of gene regulation in Mycobacterium tuberculosis where the protein Rv1222 inhibits transcription by anchoring RNA polymerase (RNAP) onto DNA. In contrast to our existing knowledge that transcriptional repressors function either by binding to DNA at specific sequences or by binding to RNAP, we show that Rv1222-mediated transcription inhibition requires simultaneous binding of the protein to both RNAP and DNA. We demonstrate that the positively charged C-terminus tail of Rv1222 is responsible for anchoring RNAP on DNA, hence the protein slows down the movement of RNAP along the DNA during transcription elongation. The interaction between Rv1222 and DNA is electrostatic, thus the protein could inhibit transcription from any gene. As Rv1222 slows down the RNA synthesis, upon expression of the protein in Mycobacterium smegmatis or Escherichia coli, the growth rate of the bacteria is severely impaired. The protein does not possess any significant affinity for DNA polymerase, thus, is unable to inhibit DNA synthesis. The proposed mechanism by which Rv1222 inhibits transcription reveals a new repertoire of prokaryotic gene regulation.
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Affiliation(s)
- Paulami Rudra
- Department of Chemistry, Bose Institute, 93/1 APC Road, Kolkata-700009, India
| | | | - Rajdeep Banerjee
- Department of Chemistry, Bose Institute, 93/1 APC Road, Kolkata-700009, India
| | - Shreya Sengupta
- Department of Chemistry, Bose Institute, 93/1 APC Road, Kolkata-700009, India
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Sharma AK, Chatterjee A, Gupta S, Banerjee R, Mandal S, Mukhopadhyay J, Basu J, Kundu M. MtrA, an essential response regulator of the MtrAB two-component system, regulates the transcription of resuscitation-promoting factor B of Mycobacterium tuberculosis. MICROBIOLOGY-SGM 2015; 161:1271-81. [PMID: 25833257 DOI: 10.1099/mic.0.000087] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The resuscitation-promoting factors of Mycobacterium tuberculosis are hydrolytic enzymes, which are required for resuscitation of dormant cells. RpfB, a peptidoglycan remodelling enzyme similar to the lytic transglycosylase of Escherichia coli, is required for reactivation of M. tuberculosis from chronic infection in vivo, underscoring the need to understand its transcriptional regulation. Here, we identified the transcriptional and translational start points of rpfB, and suggested from rpf promoter-driven GFP expression and in vitro transcription assays that its transcription possibly occurs in a SigB-dependent manner. We further demonstrated that rpfB transcription is regulated by MtrA - the response regulator of the essential two-component system MtrAB. Association of MtrA with the rpfB promoter region in vivo was confirmed by chromatin immunoprecipitation analysis. Electrophoretic mobility shift assays (EMSAs) revealed a loose direct repeat sequence associated with MtrA binding. Binding of MtrA was enhanced upon phosphorylation. MtrA could be pulled down from lysates of M. tuberculosis using a biotinylated DNA fragment encompassing the MtrA-binding site on the rpfB promoter, confirming that MtrA binds to the rpfB promoter. Enhanced GFP fluorescence driven by the rpfB promoter, upon deletion of the MtrA-binding site, and repression of rpfB expression, upon overexpression of MtrA, suggested that MtrA functions as a repressor of rpfB transcription. This was corroborated by EMSAs showing diminished association of RNA polymerase (RNAP) with the rpfB promoter in the presence of MtrA. In vitro transcription assays confirmed that MtrA inhibits RNAP-driven rpfB transcription.
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Affiliation(s)
- Arun Kumar Sharma
- 1Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Ayan Chatterjee
- 1Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Shamba Gupta
- 1Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Rajdeep Banerjee
- 1Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Sukhendu Mandal
- 2Department of Biochemistry, Bose Institute, P-1/12 CIT Scheme VII M, Kolkata 700054, India
| | - Jayanta Mukhopadhyay
- 1Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Joyoti Basu
- 1Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Manikuntala Kundu
- 1Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
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35
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Banerjee R, Rudra P, Saha A, Mukhopadhyay J. Recombinant reporter assay using transcriptional machinery of Mycobacterium tuberculosis. J Bacteriol 2015; 197:646-53. [PMID: 25448818 PMCID: PMC4285983 DOI: 10.1128/jb.02445-14] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 11/22/2014] [Indexed: 12/19/2022] Open
Abstract
Development of an in vivo gene reporter assay to assess interactions among the components of the transcription machinery in Mycobacterium tuberculosis remains a challenge to scientists due to the tediousness of generation of mutant strains of the extremely slow-growing bacterium. We have developed a recombinant mCherry reporter assay that enables us to monitor the interactions of Mycobacterium tuberculosis transcriptional regulators with its promoters in vivo in Escherichia coli. The assay involves a three-plasmid expression system in E. coli wherein two plasmids are responsible for M. tuberculosis RNA polymerase (RNAP) production and the third plasmid harbors the mCherry reporter gene expression cassette under the control of either a σ factor or a transcriptional regulator-dependent promoter. We observed that the endogenous E. coli RNAP and σ factor do not interfere with the assay. By using the reporter assay, we found that the functional interaction of M. tuberculosis cyclic AMP receptor protein (CRP) occurs with its own RNA polymerase, not with the E. coli polymerase. Performing the recombinant reporter assay in E. coli is much faster than if performed in M. tuberculosis and avoids the hazard of handling the pathogenic bacterium. The approach could be expanded to develop reporter assays for other pathogenic and slow-growing bacterial systems.
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Affiliation(s)
| | - Paulami Rudra
- Department of Chemistry, Bose Institute, Kolkata, India
| | - Abinit Saha
- Department of Biochemistry, Bose Institute, Kolkata, India
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