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Gupta R, Rohde KH. Implementation of a mycobacterial CRISPRi platform in Mycobacterium abscessus and demonstration of the essentiality of ftsZ Mab. Tuberculosis (Edinb) 2023; 138:102292. [PMID: 36495774 DOI: 10.1016/j.tube.2022.102292] [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: 08/13/2022] [Revised: 11/22/2022] [Accepted: 11/27/2022] [Indexed: 12/04/2022]
Abstract
Mycobacterium abscessus (Mab) is a highly drug-resistant non-tuberculous mycobacterial species that causes debilitating TB-like pulmonary infections. The lack of genetic tools has hampered characterization of its extensive repertoire of virulence factors, antimicrobial resistance mechanisms, and drug targets. In this study, we evaluated the performance of a mycobacterial single plasmid CRISPRi-dCas9 system optimized for M. tuberculosis and M. smegmatis for inducible gene silencing in Mab. The efficacy of CRISPRi-mediated repression of two antibiotic resistance genes (blaMab, whiB7Mab) and two putative essential genes (ftsZMab,topAMab) was determined by measuring mRNA transcript levels and phenotypic outcomes. While our results support the utility of this mycobacterial CRISPRi dCas9Sth1 single-plasmid platform for inducible silencing of specific target genes in Mab, they also highlighted several caveats and nuances that may warrant species-specific optimization for Mab. We observed overall lower levels of gene repression in Mab including variable silencing of different target genes despite use of PAMs of similar predicted strength. In addition, leaky gene repression in the absence of inducer was noted for some genes but not others. Nonetheless, using CRISPRi we demonstrated the silencing of multiple target genes and validated ftsZMab as an essential gene and promising drug target for the first time.
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Affiliation(s)
- Rashmi Gupta
- Division of Immunity and Pathogenesis, College of Medicine, Burnett School of Biomedical Sciences, University of Central Florida, 6900 Lake Nona Blvd, FL, 32827, USA.
| | - Kyle H Rohde
- Division of Immunity and Pathogenesis, College of Medicine, Burnett School of Biomedical Sciences, University of Central Florida, 6900 Lake Nona Blvd, FL, 32827, USA.
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2
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Wu K, Peng X, Chen M, Li Y, Tang G, Peng J, Peng Y, Cao X. Recent progress of research on anti‐tumor agents using benzimidazole as the structure unit. Chem Biol Drug Des 2022; 99:736-757. [DOI: 10.1111/cbdd.14022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 01/10/2022] [Accepted: 01/15/2022] [Indexed: 11/26/2022]
Affiliation(s)
- Kaiyue Wu
- Institute of Pharmacy and Pharmacology Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study College of Pharmacy Hengyang Medical School University of South China Hengyang China
| | - Xiaoyu Peng
- Institute of Pharmacy and Pharmacology Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study College of Pharmacy Hengyang Medical School University of South China Hengyang China
| | - Miaojia Chen
- Department of Pharmacy the first People's Hospital Pingjiang Yueyang Hunan China
| | - Yang Li
- Institute of Pharmacy and Pharmacology Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study College of Pharmacy Hengyang Medical School University of South China Hengyang China
| | - Guotao Tang
- Institute of Pharmacy and Pharmacology Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study College of Pharmacy Hengyang Medical School University of South China Hengyang China
| | - Junmei Peng
- Institute of Pharmacy and Pharmacology Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study College of Pharmacy Hengyang Medical School University of South China Hengyang China
| | - Yuanyuan Peng
- School of Electrical and Automation Engineering East China Jiaotong University Nanchang 330000 China
| | - Xuan Cao
- Institute of Pharmacy and Pharmacology Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study College of Pharmacy Hengyang Medical School University of South China Hengyang China
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Rani P, Kalladi SM, Bansia H, Rao S, Jha RK, Jain P, Bhaduri T, Nagaraja V. A Type IA DNA/RNA Topoisomerase with RNA Hydrolysis Activity Participates in Ribosomal RNA Processing. J Mol Biol 2020; 432:5614-5631. [DOI: 10.1016/j.jmb.2020.08.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 08/13/2020] [Accepted: 08/14/2020] [Indexed: 01/19/2023]
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Veale CGL, Müller R. Recent Highlights in Anti-infective Medicinal Chemistry from South Africa. ChemMedChem 2020; 15:809-826. [PMID: 32149446 DOI: 10.1002/cmdc.202000086] [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: 02/11/2020] [Indexed: 12/17/2022]
Abstract
Global advancements in biological technologies have vastly increased the variety of and accessibility to bioassay platforms, while simultaneously improving our understanding of druggable chemical space. In the South African context, this has resulted in a rapid expansion in the number of medicinal chemistry programmes currently operating, particularly on university campuses. Furthermore, the modern medicinal chemist has the advantage of being able to incorporate data from numerous related disciplines into the medicinal chemistry process, allowing for informed molecular design to play a far greater role than previously possible. Accordingly, this review focusses on recent highlights in drug-discovery programmes, in which South African medicinal chemistry groups have played a substantive role in the design and optimisation of biologically active compounds which contribute to the search for promising agents for infectious disease.
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Affiliation(s)
- Clinton G L Veale
- School of Chemistry and Physics, Pietermaritzburg Campus, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South Africa
| | - Ronel Müller
- School of Chemistry and Physics, Pietermaritzburg Campus, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South Africa
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Franch O, Han X, Marcussen LB, Givskov A, Andersen MB, Godbole AA, Harmsen C, Nørskov-Lauritsen N, Thomsen J, Pedersen FS, Wang Y, Shi D, Wejse C, Pødenphant L, Nagaraja V, Bertl J, Stougaard M, Ho YP, Hede MS, Labouriau R, Knudsen BR. A new DNA sensor system for specific and quantitative detection of mycobacteria. NANOSCALE 2019; 11:587-597. [PMID: 30556557 DOI: 10.1039/c8nr07850e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In the current study, we describe a novel DNA sensor system for specific and quantitative detection of mycobacteria, which is the causative agent of tuberculosis. Detection is achieved by using the enzymatic activity of the mycobacterial encoded enzyme topoisomerase IA (TOP1A) as a biomarker. The presented work is the first to describe how the catalytic activities of a member of the type IA family of topoisomerases can be exploited for specific detection of bacteria. The principle for detection relies on a solid support anchored DNA substrate with dual functions namely: (1) the ability to isolate mycobacterial TOP1A from crude samples and (2) the ability to be converted into a closed DNA circle upon reaction with the isolated enzyme. The DNA circle can act as a template for rolling circle amplification generating a tandem repeat product that can be visualized at the single molecule level by fluorescent labelling. This reaction scheme ensures specific, sensitive, and quantitative detection of the mycobacteria TOP1A biomarker as demonstrated by the use of purified mycobacterial TOP1A and extracts from an array of non-mycobacteria and mycobacteria species. When combined with mycobacteriophage induced lysis as a novel way of effective yet gentle extraction of the cellular content from the model Mycobacterium smegmatis, the DNA sensor system allowed detection of mycobacteria in small volumes of cell suspensions. Moreover, it was possible to detect M. smegmatis added to human saliva. Depending on the composition of the sample, we were able to detect 0.6 or 0.9 million colony forming units (CFU) per mL of mycobacteria, which is within the range of clinically relevant infection numbers. We, therefore, believe that the presented assay, which relies on techniques that can be adapted to limited resource settings, may be the first step towards the development of a new point-of-care diagnostic test for tuberculosis.
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Affiliation(s)
- Oskar Franch
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
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The Coordinated Positive Regulation of Topoisomerase Genes Maintains Topological Homeostasis in Streptomyces coelicolor. J Bacteriol 2016; 198:3016-3028. [PMID: 27551021 PMCID: PMC5055605 DOI: 10.1128/jb.00530-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 08/17/2016] [Indexed: 01/08/2023] Open
Abstract
Maintaining an optimal level of chromosomal supercoiling is critical for the progression of DNA replication and transcription. Moreover, changes in global supercoiling affect the expression of a large number of genes and play a fundamental role in adapting to stress. Topoisomerase I (TopA) and gyrase are key players in the regulation of bacterial chromosomal topology through their respective abilities to relax and compact DNA. Soil bacteria such as Streptomyces species, which grow as branched, multigenomic hyphae, are subject to environmental stresses that are associated with changes in chromosomal topology. The topological fluctuations modulate the transcriptional activity of a large number of genes and in Streptomyces are related to the production of antibiotics. To better understand the regulation of topological homeostasis in Streptomyces coelicolor, we investigated the interplay between the activities of the topoisomerase-encoding genes topA and gyrBA. We show that the expression of both genes is supercoiling sensitive. Remarkably, increased chromosomal supercoiling induces the topA promoter but only slightly influences gyrBA transcription, while DNA relaxation affects the topA promoter only marginally but strongly activates the gyrBA operon. Moreover, we showed that exposure to elevated temperatures induces rapid relaxation, which results in changes in the levels of both topoisomerases. We therefore propose a unique mechanism of S. coelicolor chromosomal topology maintenance based on the supercoiling-dependent stimulation, rather than repression, of the transcription of both topoisomerase genes. These findings provide important insight into the maintenance of topological homeostasis in an industrially important antibiotic producer. IMPORTANCE We describe the unique regulation of genes encoding two topoisomerases, topoisomerase I (TopA) and gyrase, in a model Streptomyces species. Our studies demonstrate the coordination of topoisomerase gene regulation, which is crucial for maintenance of topological homeostasis. Streptomyces species are producers of a plethora of biologically active secondary metabolites, including antibiotics, antitumor agents, and immunosuppressants. The significant regulatory factor controlling the secondary metabolism is the global chromosomal topology. Thus, the investigation of chromosomal topology homeostasis in Streptomyces strains is crucial for their use in industrial applications as producers of secondary metabolites.
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Lin H, Annamalai T, Bansod P, Tse-Dinh YC, Sun D. Synthesis and antibacterial evaluation of anziaic acid and analogues as topoisomerase I inhibitors. MEDCHEMCOMM 2013; 4:10.1039/C3MD00238A. [PMID: 24363888 PMCID: PMC3867937 DOI: 10.1039/c3md00238a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Naturally occurring anziaic acid was very recently reported as a topoisomerase I inhibitor with antibacterial activity. Herein total synthesis of anziaic acid and structural analogues is described and the preliminary structure-activity relationship (SAR) has been developed based on topoisomerase inhibition and whole cell antibacterial activity.
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Affiliation(s)
- Hao Lin
- Department of Pharmaceutical Sciences, The Daniel K. Inouye College of Pharmacy, University of Hawai’i at Hilo, 34 Rainbow Drive, Hilo, HI 96720, USA. Fax: 1-(808)-933-2974; Tel: 1-(808)-933-2960
| | - Thirunavukkarasu Annamalai
- Department of Chemistry & Biochemistry, Florida International University, 11200 SW 8 Street, Miami, FL 33199, USA
| | - Priyanka Bansod
- Department of Chemistry & Biochemistry, Florida International University, 11200 SW 8 Street, Miami, FL 33199, USA
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry & Biochemistry, Florida International University, 11200 SW 8 Street, Miami, FL 33199, USA
| | - Dianqing Sun
- Department of Pharmaceutical Sciences, The Daniel K. Inouye College of Pharmacy, University of Hawai’i at Hilo, 34 Rainbow Drive, Hilo, HI 96720, USA. Fax: 1-(808)-933-2974; Tel: 1-(808)-933-2960
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Leelaram MN, Bhat AG, Godbole AA, Bhat RS, Manjunath R, Nagaraja V. Type IA topoisomerase inhibition by clamp closure. FASEB J 2013; 27:3030-8. [PMID: 23612788 DOI: 10.1096/fj.12-226118] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Bacterial DNA topoisomerase I (topoI) catalyzes relaxation of negatively supercoiled DNA. The enzyme alters DNA topology through protein-operated DNA gate, switching between open and closed conformations during its reaction. We describe the mechanism of inhibition of Mycobacterium smegmatis and Mycobacterium tuberculosis topoI by monoclonal antibodies (mAbs) that bind with high affinity and inhibit at 10-50 nM concentration. Unlike other inhibitors of topoisomerases, the mAbs inhibited several steps of relaxation reaction, namely DNA binding, cleavage, strand passage, and enzyme-DNA dissociation. The enhanced religation of the cleaved DNA in presence of the mAb indicated closing of the enzyme DNA gate. The formation of enzyme-DNA heterocatenane in the presence of the mAbs as a result of closing the gate could be inferred by the salt resistance of the complex, visualized by atomic force microscopy and confirmed by fluorescence measurements. Locking the enzyme-DNA complex as a closed clamp restricted the movements of the DNA gate, affecting all of the major steps of the relaxation reaction. Enzyme trapped on DNA in closed clamp conformation formed roadblock for the elongating DNA polymerase. The unusual multistep inhibition of mycobacterial topoisomerases may facilitate lead molecule development, and the mAbs would also serve as valuable tools to probe the enzyme mechanism.
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Affiliation(s)
- Majety Naga Leelaram
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012, India
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Godbole AA, Leelaram MN, Bhat AG, Jain P, Nagaraja V. Characterization of DNA topoisomerase I from Mycobacterium tuberculosis: DNA cleavage and religation properties and inhibition of its activity. Arch Biochem Biophys 2012; 528:197-203. [DOI: 10.1016/j.abb.2012.10.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 10/02/2012] [Accepted: 10/09/2012] [Indexed: 11/30/2022]
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Leelaram MN, Bhat AG, Hegde SM, Manjunath R, Nagaraja V. Inhibition of type IA topoisomerase by a monoclonal antibody through perturbation of DNA cleavage-religation equilibrium. FEBS J 2011; 279:55-65. [DOI: 10.1111/j.1742-4658.2011.08398.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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11
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Narula G, Becker J, Cheng B, Dani N, Abrenica MV, Tse-Dinh YC. The DNA relaxation activity and covalent complex accumulation of Mycobacterium tuberculosis topoisomerase I can be assayed in Escherichia coli: application for identification of potential FRET-dye labeling sites. BMC BIOCHEMISTRY 2010; 11:41. [PMID: 20920291 PMCID: PMC2958883 DOI: 10.1186/1471-2091-11-41] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Accepted: 09/30/2010] [Indexed: 01/30/2023]
Abstract
Background Mycobacterium tuberculosis topoisomerase I (MtTOP1) and Escherichia coli topoisomerase I have highly homologous transesterification domains, but the two enzymes have distinctly different C-terminal domains. To investigate the structure-function of MtTOP1 and to target its activity for development of new TB therapy, it is desirable to have a rapid genetic assay for its catalytic activity, and potential bactericidal consequence from accumulation of its covalent complex. Results We show that plasmid-encoded recombinant MtTOP1 can complement the temperature sensitive topA function of E. coli strain AS17. Moreover, expression of MtTOP1-G116 S enzyme with the TOPRIM mutation that inhibits DNA religation results in SOS induction and loss of viability in E. coli. The absence of cysteine residues in the MtTOP1 enzyme makes it an attractive system for introduction of potentially informative chemical or spectroscopic probes at specific positions via cysteine mutagenesis. Such probes could be useful for development of high throughput screening (HTS) assays. We employed the AS17 complementation system to screen for sites in MtTOP1 that can tolerate cysteine substitution without loss of complementation function. These cysteine substitution mutants were confirmed to have retained the relaxation activity. One such mutant of MtTOP1 was utilized for fluorescence probe incorporation and fluorescence resonance energy transfer measurement with fluorophore-labeled oligonucleotide substrate. Conclusions The DNA relaxation and cleavage complex accumulation of M. tuberculosis topoisomerase I can be measured with genetic assays in E. coli, facilitating rapid analysis of its activities, and discovery of new TB therapy targeting this essential enzyme.
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Affiliation(s)
- Gagandeep Narula
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York 10595, USA
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12
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Annamalai T, Dani N, Cheng B, Tse-Dinh YC. Analysis of DNA relaxation and cleavage activities of recombinant Mycobacterium tuberculosis DNA topoisomerase I from a new expression and purification protocol. BMC BIOCHEMISTRY 2009; 10:18. [PMID: 19519900 PMCID: PMC2702276 DOI: 10.1186/1471-2091-10-18] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Accepted: 06/11/2009] [Indexed: 11/29/2022]
Abstract
Background Mycobacterium tuberculosis DNA topoisomerase I is an attractive target for discovery of novel TB drugs that act by enhancing the accumulation of the topoisomerase-DNA cleavage product. It shares a common transesterification domain with other type IA DNA topoisomerases. There is, however, no homology between the C-terminal DNA binding domains of Escherichia coli and M. tuberculosis DNA topoisomerase I proteins. Results A new protocol for expression and purification of recombinant M. tuberculosis DNA topoisomerase I (MtTOP) has been developed to produce enzyme of much higher specific activity than previously characterized recombinant enzyme. MtTOP was found to be less efficient than E. coli DNA topoisomerase I (EcTOP) in removal of remaining negative supercoils from partially relaxed DNA. DNA cleavage by MtTOP was characterized for the first time. Comparison of DNA cleavage site selectivity with EcTOP showed differences in cleavage site preferences, but the preferred sites of both enzymes have a C nucleotide in the -4 position. Conclusion Recombinant M. tuberculosis DNA topoisomerase I can be expressed as a soluble protein and purified in high yield from E. coli host with a new protocol. Analysis of DNA cleavage with M. tuberculosis DNA substrate showed that the preferred DNA cleavage sites have a C nucleotide in the -4 position.
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SOS induction by stabilized topoisomerase IA cleavage complex occurs via the RecBCD pathway. J Bacteriol 2008; 190:3399-403. [PMID: 18310346 DOI: 10.1128/jb.01674-07] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Accumulation of mutant topoisomerase I cleavage complex can lead to SOS induction and cell death in Escherichia coli. The single-stranded break associated with mutant topoisomerase I cleavage complex is converted to double-stranded break, which then is processed by the RecBCD pathway, followed by association of RecA with the single-stranded DNA.
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Jain P, Nagaraja V. Indispensable, Functionally Complementing N and C-terminal Domains Constitute Site-specific Topoisomerase I. J Mol Biol 2006; 357:1409-21. [PMID: 16490213 DOI: 10.1016/j.jmb.2006.01.079] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2005] [Revised: 01/20/2006] [Accepted: 01/23/2006] [Indexed: 11/19/2022]
Abstract
Mycobacterium smegmatis topoisomerase I differs from the typical type IA topoisomerase in many properties. The enzyme recognizes both single and double-stranded DNA with high affinity and makes sequence-specific contacts during DNA relaxation reaction. The enzyme has a conserved N-terminal domain and a highly varied C-terminal domain, which lacks the characteristic zinc binding motifs found in most of the type I eubacterial enzymes. The roles of the individual domains of the enzyme in the topoisomerase I catalyzed reactions were examined by comparing the properties of full-length topoisomerase I with those of truncated polypeptides lacking the conserved N-terminal or the divergent C-terminal region. The N-terminal larger fragment retained the site-specific binding, DNA cleavage and religation properties, hallmark characteristics of the full-length M.smegmatis topoisomerase I. In contrast, the non-conserved C-terminal fragment lacking the typical DNA binding motif, exhibited non-specific DNA binding behaviour. The two polypeptide fragments, on their own do not catalyze DNA relaxation reaction. The relaxation activity is restored when both the fragments are mixed in vitro reconstituting the enzyme function. These results along with the DNA interaction pattern of the proteins implicate an essential role for the C-terminal region in single-strand DNA passage between the two transesterification reactions catalyzed by the N-terminal domain.
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Affiliation(s)
- Paras Jain
- Department of Microbiology and Cell Biology, Indian Institute of Science, CV Raman Avenue, Bangalore 560012, India
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Hansen G, Harrenga A, Wieland B, Schomburg D, Reinemer P. Crystal structure of full length topoisomerase I from Thermotoga maritima. J Mol Biol 2006; 358:1328-40. [PMID: 16600296 DOI: 10.1016/j.jmb.2006.03.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2005] [Revised: 03/05/2006] [Accepted: 03/06/2006] [Indexed: 12/01/2022]
Abstract
DNA topoisomerases are a family of enzymes altering the topology of DNA by concerted breakage and rejoining of the phosphodiester backbone of DNA. Bacterial and archeal type IA topoisomerases, including topoisomerase I, topoisomerase III, and reverse gyrase, are crucial in regulation of DNA supercoiling and maintenance of genetic stability. The crystal structure of full length topoisomerase I from Thermotoga maritima was determined at 1.7A resolution and represents an intact and fully active bacterial topoisomerase I. It reveals the torus-like structure of the conserved transesterification core domain comprising domains I-IV and a tightly associated C-terminal zinc ribbon domain (domain V) packing against domain IV of the core domain. The previously established zinc-independence of the functional activity of T.maritima topoisomerase I is further supported by its crystal structure as no zinc ion is bound to domain V. However, the structural integrity is preserved by the formation of two disulfide bridges between the four Zn-binding cysteine residues. A functional role of domain V in DNA binding and recognition is suggested and discussed in the light of the structure and previous biochemical findings. In addition, implications for bacterial topoisomerases I are provided.
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Affiliation(s)
- Guido Hansen
- Bayer HealthCare AG, Pharma R and D Europe, Enabling Technologies, D-42096 Wuppertal, Germany
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Cheng B, Shukla S, Vasunilashorn S, Mukhopadhyay S, Tse-Dinh YC. Bacterial cell killing mediated by topoisomerase I DNA cleavage activity. J Biol Chem 2005; 280:38489-95. [PMID: 16159875 PMCID: PMC1351368 DOI: 10.1074/jbc.m509722200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA topoisomerases are important clinical targets for antibacterial and anticancer therapy. At least one type IA DNA topoisomerase can be found in every bacterium, making it a logical target for antibacterial agents that can convert the enzyme into poison by trapping its covalent complex with DNA. However, it has not been possible previously to observe the consequence of having such a stabilized covalent complex of bacterial topoisomerase I in vivo. We isolated a mutant of recombinant Yersinia pestis topoisomerase I that forms a stabilized covalent complex with DNA by screening for the ability to induce the SOS response in Escherichia coli. Overexpression of this mutant topoisomerase I resulted in bacterial cell death. From sequence analysis and site-directed mutagenesis, it was determined that a single amino acid substitution in the TOPRIM domain changing a strictly conserved glycine residue to serine in either the Y. pestis or E. coli topoisomerase I can result in a mutant enzyme that has the SOS-inducing and cell-killing properties. Analysis of the purified mutant enzymes showed that they have no relaxation activity but retain the ability to cleave DNA and form a covalent complex. These results demonstrate that perturbation of the active site region of bacterial topoisomerase I can result in stabilization of the covalent intermediate, with the in vivo consequence of bacterial cell death. Small molecules that induce similar perturbation in the enzyme-DNA complex should be candidates as leads for novel antibacterial agents.
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Affiliation(s)
- Bokun Cheng
- From the Department of Biochemistry and Molecular Biology
| | - Shikha Shukla
- From the Department of Biochemistry and Molecular Biology
| | | | - Somshuvra Mukhopadhyay
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595, USA
| | - Yuk-Ching Tse-Dinh
- From the Department of Biochemistry and Molecular Biology
- Address correspondence to: Yuk-Ching Tse-Dinh, Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, Tel. 914-594-4061, Fax 914-594-4058, E-mail:
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