1
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Unraveling topoisomerase IA gate dynamics in presence of PPEF and its preclinical evaluation against multidrug-resistant pathogens. Commun Biol 2023; 6:195. [PMID: 36807602 PMCID: PMC9938908 DOI: 10.1038/s42003-023-04412-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 01/03/2023] [Indexed: 02/20/2023] Open
Abstract
Type IA topoisomerases maintain DNA topology by cleaving ssDNA and relaxing negative supercoils. The inhibition of its activity in bacteria prevents the relaxation of negative supercoils, which in turn impedes DNA metabolic processes leading to cell death. Using this hypothesis, two bisbenzimidazoles, PPEF and BPVF are synthesized, selectively inhibiting bacterial TopoIA and TopoIII. PPEF stabilizes the topoisomerase and topoisomerase-ssDNA complex, acts as an interfacial inhibitor. PPEF display high efficacy against ~455 multi-drug resistant gram positive and negative bacteria. To understand molecular mechanism of inhibition of TopoIA and PPEF, accelerated MD simulation is carried out, and results suggested that PPEF binds, stabilizes the closed conformation of TopoIA with -6Kcal/mol binding energy and destabilizes the binding of ssDNA. The TopoIA gate dynamics model can be used as a tool to screen TopoIA inhibitors as therapeutic candidates. PPEF and BPVF cause cellular filamentation and DNA fragmentation leading to bacterial cell death. PPEF and BPVF show potent efficacy against systemic and neutropenic mouse models harboring E. coli, VRSA, and MRSA infection without cellular toxicity.
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2
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Ferdous S, Dasgupta T, Annamalai T, Tan K, Tse-Dinh YC. The interaction between transport-segment DNA and topoisomerase IA-crystal structure of MtbTOP1 in complex with both G- and T-segments. Nucleic Acids Res 2022; 51:349-364. [PMID: 36583363 PMCID: PMC9841409 DOI: 10.1093/nar/gkac1205] [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: 06/13/2022] [Revised: 11/16/2022] [Accepted: 12/06/2022] [Indexed: 12/31/2022] Open
Abstract
Each catalytic cycle of type IA topoisomerases has been proposed to comprise multistep reactions. The capture of the transport-segment DNA (T-segment) into the central cavity of the N-terminal toroidal structure is an important action, which is preceded by transient gate-segment (G-segment) cleavage and succeeded by G-segment religation for the relaxation of negatively supercoiled DNA and decatenation of DNA. The T-segment passage in and out of the central cavity requires significant domain-domain rearrangements, including the movement of D3 relative to D1 and D4 for the opening and closing of the gate towards the central cavity. Here we report a direct observation of the interaction of a duplex DNA in the central cavity of a type IA topoisomerase and its associated domain-domain conformational changes in a crystal structure of a Mycobacterium tuberculosis topoisomerase I complex that also has a bound G-segment. The duplex DNA within the central cavity illustrates the non-sequence-specific interplay between the T-segment DNA and the enzyme. The rich structural information revealed from the novel topoisomerase-DNA complex, in combination with targeted mutagenesis studies, provides new insights into the mechanism of the topoisomerase IA catalytic cycle.
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Affiliation(s)
| | | | - Thirunavukkarasu Annamalai
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA,Biomolecular Sciences Institute, Florida International University, 11200 SW 8th St, Miami, FL 33199, USA
| | - Kemin Tan
- Correspondence may also be addressed to Kemin Tan. Tel: +1 630 252 3948;
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3
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Garcia PK, Martinez Borrero R, Annamalai T, Diaz E, Balarezo S, Tiwari PB, Tse-Dinh YC. Localization of Mycobacterium tuberculosis topoisomerase I C-terminal sequence motif required for inhibition by endogenous toxin MazF4. Front Microbiol 2022; 13:1032320. [PMID: 36545199 PMCID: PMC9760754 DOI: 10.3389/fmicb.2022.1032320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 11/17/2022] [Indexed: 12/08/2022] Open
Abstract
Only about half the multi-drug resistant tuberculosis (MDR-TB) cases are successfully cured. Thus, there is an urgent need of new TB treatment against a novel target. Mycobacterium tuberculosis (Mtb) topoisomerase I (TopA) is the only type IA topoisomerase in this organism and has been validated as an essential target for TB drug discovery. Toxin-antitoxin (TA) systems participate as gene regulators within bacteria. The TA systems contribute to the long-term dormancy of Mtb within the host-cell environment. Mtb's toxin MazF4 (Rv1495) that is part of the MazEF4 TA system has been shown to have dual activities as endoribonuclease and topoisomerase I inhibitor. We have developed a complementary assay using an Escherichia coli strain with temperature-sensitive topA mutation to provide new insights into the MazF4 action. The assay showed that E. coli is not sensitive to the endoribonuclease activity of Mtb MazF4 but became vulnerable to MazF4 growth inhibition when recombinant Mtb TopA relaxation activity is required for growth. Results from the complementation by Mtb TopA mutants with C-terminal deletions showed that the lysine-rich C-terminal tail is required for interaction with MazF4. Site-directed mutagenesis is utilized to identify two lysine residues within a conserved motif in this C-terminal tail that are critical for MazF4 inhibition. We performed molecular dynamics simulations to predict the Mtb TopA-MazF4 complex. Our simulation results show that the complex is stabilized by hydrogen bonds and electrostatic interactions established by residues in the TopA C-terminal tail including the two conserved lysines. The mechanism of Mtb TopA inhibition by MazF4 could be useful for the discovery of novel inhibitors against a new antibacterial target in pathogenic mycobacteria for treatment of both TB and diseases caused by the non-tuberculosis mycobacteria (NTM).
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Affiliation(s)
- Pamela K. Garcia
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, United States
| | | | - Thirunavukkarasu Annamalai
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, United States,Biomolecular Sciences Institute, Florida International University, Miami, FL, United States
| | - Esnel Diaz
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, United States
| | - Steve Balarezo
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, United States
| | | | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, United States,Biomolecular Sciences Institute, Florida International University, Miami, FL, United States,*Correspondence: Yuk-Ching Tse-Dinh,
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4
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Yang X, Saha S, Yang W, Neuman KC, Pommier Y. Structural and biochemical basis for DNA and RNA catalysis by human Topoisomerase 3β. Nat Commun 2022; 13:4656. [PMID: 35945419 PMCID: PMC9363430 DOI: 10.1038/s41467-022-32221-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 07/21/2022] [Indexed: 11/09/2022] Open
Abstract
In metazoans, topoisomerase 3β (TOP3B) regulates R-loop dynamics and mRNA translation, which are critical for genome stability, neurodevelopment and normal aging. As a Type IA topoisomerase, TOP3B acts by general acid-base catalysis to break and rejoin single-stranded DNA. Passage of a second DNA strand through the transient break permits dissipation of hypernegative DNA supercoiling and catenation/knotting. Additionally, hsTOP3B was recently demonstrated as the human RNA topoisomerase, required for normal neurodevelopment and proposed to be a potential anti-viral target upon RNA virus infection. Here we elucidate the biochemical mechanisms of human TOP3B. We delineate the roles of divalent metal ions, and of a conserved Lysine residue (K10) in the differential catalysis of DNA and RNA. We also demonstrate that three regulatory factors fine-tune the catalytic performance of TOP3B: the TOP3B C-terminal tail, its protein partner TDRD3, and the sequence of its DNA/RNA substrates.
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Affiliation(s)
- Xi Yang
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892, USA
| | - Sourav Saha
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892, USA
| | - Wei Yang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD, 20892, USA
| | - Keir C Neuman
- Laboratory of Single Molecule Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Yves Pommier
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892, USA.
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5
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Interaction between transcribing RNA polymerase and topoisomerase I prevents R-loop formation in E. coli. Nat Commun 2022; 13:4524. [PMID: 35927234 PMCID: PMC9352719 DOI: 10.1038/s41467-022-32106-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 07/15/2022] [Indexed: 12/30/2022] Open
Abstract
Bacterial topoisomerase I (TopoI) removes excessive negative supercoiling and is thought to relax DNA molecules during transcription, replication and other processes. Using ChIP-Seq, we show that TopoI of Escherichia coli (EcTopoI) is colocalized, genome-wide, with transcribing RNA polymerase (RNAP). Treatment with transcription elongation inhibitor rifampicin leads to EcTopoI relocation to promoter regions, where RNAP also accumulates. When a 14 kDa RNAP-binding EcTopoI C-terminal domain (CTD) is overexpressed, colocalization of EcTopoI and RNAP along the transcription units is reduced. Pull-down experiments directly show that the two enzymes interact in vivo. Using ChIP-Seq and Topo-Seq, we demonstrate that EcTopoI is enriched upstream (within up to 12-15 kb) of highly-active transcription units, indicating that EcTopoI relaxes negative supercoiling generated by transcription. Uncoupling of the RNAP:EcTopoI interaction by either overexpression of EcTopoI competitor (CTD or inactive EcTopoI Y319F mutant) or deletion of EcTopoI domains involved in the interaction is toxic for cells and leads to excessive negative plasmid supercoiling. Moreover, uncoupling of the RNAP:EcTopoI interaction leads to R-loops accumulation genome-wide, indicating that this interaction is required for prevention of R-loops formation. In E. coli, disruption of TopoI and RNAP interaction decreases cells viability and leads to hypernegative DNA supercoiling and R loops accumulation. TopoI and DNA gyrase bind around transcription units and TopoI recognizes cleavage sites by a specific motif and negative supercoiling.
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6
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Mital S, Christie G, Dikicioglu D. Recombinant expression of insoluble enzymes in Escherichia coli: a systematic review of experimental design and its manufacturing implications. Microb Cell Fact 2021; 20:208. [PMID: 34717620 PMCID: PMC8557517 DOI: 10.1186/s12934-021-01698-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 10/22/2021] [Indexed: 02/06/2023] Open
Abstract
Recombinant enzyme expression in Escherichia coli is one of the most popular methods to produce bulk concentrations of protein product. However, this method is often limited by the inadvertent formation of inclusion bodies. Our analysis systematically reviews literature from 2010 to 2021 and details the methods and strategies researchers have utilized for expression of difficult to express (DtE), industrially relevant recombinant enzymes in E. coli expression strains. Our review identifies an absence of a coherent strategy with disparate practices being used to promote solubility. We discuss the potential to approach recombinant expression systematically, with the aid of modern bioinformatics, modelling, and ‘omics’ based systems-level analysis techniques to provide a structured, holistic approach. Our analysis also identifies potential gaps in the methods used to report metadata in publications and the impact on the reproducibility and growth of the research in this field.
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Affiliation(s)
- Suraj Mital
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Graham Christie
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Duygu Dikicioglu
- Department of Biochemical Engineering, University College London, London, WC1E 6BT, UK.
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7
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Yano N, Emi T, Gregory DJ, Fedulov AV. Consideration on Efficient Recombinant Protein Production: Focus on Substrate Protein-Specific Compatibility Patterns of Molecular Chaperones. Protein J 2021; 40:756-764. [PMID: 34052952 DOI: 10.1007/s10930-021-09995-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/07/2021] [Indexed: 10/21/2022]
Abstract
Expression of recombinant proteins requires at times the aid of molecular chaperones for efficient post-translational folding into functional structure. However, predicting the compatibility of a protein substrate with the right type of chaperone to produce functional proteins is a daunting issue. To study the difference in effects of chaperones on His-tagged recombinant proteins with different characteristics, we performed in vitro proteins expression using Escherichia coli overexpressed with several chaperone 'teams': Trigger Factor (TF), GroEL/GroES and DnaK/DnaJ/GrpE, alone or in combinations, with the aim to determine whether protein secondary structure can serve as predictor for chaperone success. Protein A, which has a helix dominant structure, showed the most efficient folding with GroES/EL or TF chaperones alone, whereas Protein B, which has less helix in the structure, showed a remarkable effect on the DnaK/J/GrpE system alone. This tendency was also seen with other recombinant proteins with particular properties. With the chaperons' assistance, both proteins were synthesized more efficiently in the culture at 22.5 °C for 20 h than at 37 °C for 3 h. These findings suggest a novel avenue to study compatibility of chaperones with substrate proteins and optimal culture conditions for producing functional proteins with a potential for predictive analysis of the success of chaperones based on the properties of the substrate protein.
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Affiliation(s)
- Naohiro Yano
- Division of Surgical Research, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, NAB-210. 593 Eddy Street, Providence, RI, 02903, USA
| | - Tania Emi
- Division of Surgical Research, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, NAB-210. 593 Eddy Street, Providence, RI, 02903, USA
| | - David J Gregory
- Department of Pediatrics, Harvard Medical School, Massachusetts General Hospital, Boston, MA, USA
| | - Alexey V Fedulov
- Division of Surgical Research, Department of Surgery, Rhode Island Hospital, Alpert Medical School of Brown University, NAB-210. 593 Eddy Street, Providence, RI, 02903, USA.
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8
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Dasgupta T, Ferdous S, Tse-Dinh YC. Mechanism of Type IA Topoisomerases. Molecules 2020; 25:E4769. [PMID: 33080770 PMCID: PMC7587558 DOI: 10.3390/molecules25204769] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/12/2020] [Accepted: 10/15/2020] [Indexed: 11/16/2022] Open
Abstract
Topoisomerases in the type IA subfamily can catalyze change in topology for both DNA and RNA substrates. A type IA topoisomerase may have been present in a last universal common ancestor (LUCA) with an RNA genome. Type IA topoisomerases have since evolved to catalyze the resolution of topological barriers encountered by genomes that require the passing of nucleic acid strand(s) through a break on a single DNA or RNA strand. Here, based on available structural and biochemical data, we discuss how a type IA topoisomerase may recognize and bind single-stranded DNA or RNA to initiate its required catalytic function. Active site residues assist in the nucleophilic attack of a phosphodiester bond between two nucleotides to form a covalent intermediate with a 5'-phosphotyrosine linkage to the cleaved nucleic acid. A divalent ion interaction helps to position the 3'-hydroxyl group at the precise location required for the cleaved phosphodiester bond to be rejoined following the passage of another nucleic acid strand through the break. In addition to type IA topoisomerase structures observed by X-ray crystallography, we now have evidence from biophysical studies for the dynamic conformations that are required for type IA topoisomerases to catalyze the change in the topology of the nucleic acid substrates.
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Affiliation(s)
- Tumpa Dasgupta
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; (T.D.); (S.F.)
- Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA
- Biochemistry PhD Program, Florida International University, Miami, FL 33199, USA
| | - Shomita Ferdous
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; (T.D.); (S.F.)
- Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA
- Biochemistry PhD Program, Florida International University, Miami, FL 33199, USA
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; (T.D.); (S.F.)
- Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA
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9
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Cao N, Tan K, Zuo X, Annamalai T, Tse-Dinh YC. Mechanistic insights from structure of Mycobacterium smegmatis topoisomerase I with ssDNA bound to both N- and C-terminal domains. Nucleic Acids Res 2020; 48:4448-4462. [PMID: 32232337 PMCID: PMC7192597 DOI: 10.1093/nar/gkaa201] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 02/20/2020] [Accepted: 03/18/2020] [Indexed: 12/17/2022] Open
Abstract
Type IA topoisomerases interact with G-strand and T-strand ssDNA to regulate DNA topology. However, simultaneous binding of two ssDNA segments to a type IA topoisomerase has not been observed previously. We report here the crystal structure of a type IA topoisomerase with ssDNA segments bound in opposite polarity to the N- and C-terminal domains. Titration of small ssDNA oligonucleotides to Mycobacterium smegmatis topoisomerase I with progressive C-terminal deletions showed that the C-terminal region has higher affinity for ssDNA than the N-terminal active site. This allows the C-terminal domains to capture one strand of underwound negatively supercoiled DNA substrate first and position the N-terminal domains to bind and cleave the opposite strand in the relaxation reaction. Efficiency of negative supercoiling relaxation increases with the number of domains that bind ssDNA primarily with conserved aromatic residues and possibly with assistance from polar/basic residues. A comparison of bacterial topoisomerase I structures showed that a conserved transesterification unit (N-terminal toroid structure) for cutting and rejoining of a ssDNA strand can be combined with two different types of C-terminal ssDNA binding domains to form diverse bacterial topoisomerase I enzymes that are highly efficient in their physiological role of preventing excess negative supercoiling in the genome.
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Affiliation(s)
- Nan Cao
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
- Biomolecular Sciences Institute, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA
| | - Kemin Tan
- Structural Biology Center, X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL 60439, USA
| | - Xiaobing Zuo
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL 60439, USA
| | - Thirunavukkarasu Annamalai
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
- Biomolecular Sciences Institute, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
- Biomolecular Sciences Institute, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA
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10
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Bachar A, Itzhaki E, Gleizer S, Shamshoom M, Milo R, Antonovsky N. Point mutations in topoisomerase I alter the mutation spectrum in E. coli and impact the emergence of drug resistance genotypes. Nucleic Acids Res 2020; 48:761-769. [PMID: 31777935 PMCID: PMC6954433 DOI: 10.1093/nar/gkz1100] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 09/27/2019] [Accepted: 11/21/2019] [Indexed: 11/14/2022] Open
Abstract
Identifying the molecular mechanisms that give rise to genetic variation is essential for the understanding of evolutionary processes. Previously, we have used adaptive laboratory evolution to enable biomass synthesis from CO2 in Escherichia coli. Genetic analysis of adapted clones from two independently evolving populations revealed distinct enrichment for insertion and deletion mutational events. Here, we follow these observations to show that mutations in the gene encoding for DNA topoisomerase I (topA) give rise to mutator phenotypes with characteristic mutational spectra. Using genetic assays and mutation accumulation lines, we find that point mutations in topA increase the rate of sequence deletion and duplication events. Interestingly, we observe that a single residue substitution (R168C) results in a high rate of head-to-tail (tandem) short sequence duplications, which are independent of existing sequence repeats. Finally, we show that the unique mutation spectrum of topA mutants enhances the emergence of antibiotic resistance in comparison to mismatch-repair (mutS) mutators, and leads to new resistance genotypes. Our findings highlight a potential link between the catalytic activity of topoisomerases and the fundamental question regarding the emergence of de novo tandem repeats, which are known modulators of bacterial evolution.
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Affiliation(s)
- Amit Bachar
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Elad Itzhaki
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Shmuel Gleizer
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Melina Shamshoom
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Ron Milo
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Niv Antonovsky
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 7610001, Israel.,Laboratory of Genetically Encoded Small Molecules, The Rockefeller University, New York, NY 10065, USA
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11
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Cao N, Tan K, Annamalai T, Joachimiak A, Tse-Dinh YC. Investigating mycobacterial topoisomerase I mechanism from the analysis of metal and DNA substrate interactions at the active site. Nucleic Acids Res 2019; 46:7296-7308. [PMID: 29905859 PMCID: PMC6101483 DOI: 10.1093/nar/gky492] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 05/25/2018] [Indexed: 12/18/2022] Open
Abstract
We have obtained new crystal structures of Mycobacterium tuberculosis topoisomerase I, including structures with ssDNA substrate bound to the active site, with and without Mg2+ ion present. Significant enzyme conformational changes upon DNA binding place the catalytic tyrosine in a pre-transition state position for cleavage of a specific phosphodiester linkage. Meanwhile, the enzyme/DNA complex with bound Mg2+ ion may represent the post-transition state for religation in the enzyme's multiple-step DNA relaxation catalytic cycle. The first observation of Mg2+ ion coordinated with the TOPRIM residues and DNA phosphate in a type IA topoisomerase active site allows assignment of likely catalytic role for the metal and draws a comparison to the proposed mechanism for type IIA topoisomerases. The critical function of a strictly conserved glutamic acid in the DNA cleavage step was assessed through site-directed mutagenesis. The functions assigned to the observed Mg2+ ion can account for the metal requirement for DNA rejoining but not DNA cleavage by type IA topoisomerases. This work provides new structural insights into a more stringent requirement for DNA rejoining versus cleavage in the catalytic cycle of this essential enzyme, and further establishes the potential for selective interference of DNA rejoining by this validated TB drug target.
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Affiliation(s)
- Nan Cao
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA.,Biomolecular Sciences Institute, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA
| | - Kemin Tan
- Structural Biology Center, Biosciences, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA
| | - Thirunavukkarasu Annamalai
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA.,Biomolecular Sciences Institute, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA
| | - Andrzej Joachimiak
- Structural Biology Center, Biosciences, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA.,Biomolecular Sciences Institute, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA
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12
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Mechanism and resistance for antimycobacterial activity of a fluoroquinophenoxazine compound. PLoS One 2019; 14:e0207733. [PMID: 30794538 PMCID: PMC6386362 DOI: 10.1371/journal.pone.0207733] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 02/07/2019] [Indexed: 01/28/2023] Open
Abstract
We have previously reported the inhibition of bacterial topoisomerase I activity by a fluoroquinophenoxazine compound (FP-11g) with a 6-bipiperidinyl lipophilic side chain that exhibited promising antituberculosis activity (MIC = 2.5 μM against Mycobacterium tuberculosis, SI = 9.8). Here, we found that the compound is bactericidal towards Mycobacterium smegmatis, resulting in greater than 5 Log10 reduction in colony-forming units [cfu]/mL following a 10 h incubation at 1.25 μM (4X MIC) concentration. Growth inhibition (MIC = 50 μM) and reduction in cfu could also be observed against a clinical isolate of Mycobacterium abscessus. Stepwise isolation of resistant mutants of M. smegmatis was conducted to explore the mechanism of resistance. Mutations in the resistant isolates were identified by direct comparison of whole-genome sequencing data from mutant and wild-type isolates. These include mutations in genes likely to affect the entry and retention of the compound. FP-11g inhibits Mtb topoisomerase I and Mtb gyrase with IC50 of 0.24 and 27 μM, respectively. Biophysical analysis showed that FP-11g binds DNA as an intercalator but the IC50 for inhibition of Mtb topoisomerase I activity is >10 fold lower than the compound concentrations required for producing negatively supercoiled DNA during ligation of nicked circular DNA. Thus, the DNA-binding property of FP-11g may contribute to its antimycobacterial mechanism, but that alone cannot account for the observed inhibition of Mtb topoisomerase I.
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13
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Chowdhury SR, Majumder HK. DNA Topoisomerases in Unicellular Pathogens: Structure, Function, and Druggability. Trends Biochem Sci 2019; 44:415-432. [PMID: 30609953 DOI: 10.1016/j.tibs.2018.12.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/20/2018] [Accepted: 12/03/2018] [Indexed: 02/06/2023]
Abstract
All organisms, including unicellular pathogens, compulsorily possess DNA topoisomerases for successful nucleic acid metabolism. But particular subtypes of topoisomerases exist, in all prokaryotes and in some unicellular eukaryotes, that are absent in higher eukaryotes. Moreover, topoisomerases from pathogenic members of a niche possess some unique molecular architecture and functionalities completely distinct from their nonpathogenic colleagues. This review will highlight the unique attributes associated with the structures and functions of topoisomerases from the unicellular pathogens, with special reference to bacteria and protozoan parasites. It will also summarise the progress made in the domain pertaining to the druggability of these topoisomerases, upon which a future platform for therapeutic development can be successfully constructed.
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Affiliation(s)
- Somenath Roy Chowdhury
- Laboratory of Molecular Parasitology, Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700 032, India
| | - Hemanta K Majumder
- Laboratory of Molecular Parasitology, Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700 032, India.
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14
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Abstract
Bacterial Topoisomerase I is a potential target for the identification of novel topoisomerase poison inhibitors that could provide leads for a new class of antibacterial compounds. Here we describe in detail a fluorescence-based cleavage assay that is successfully used in HTS for the discovery of bacterial topoisomerase Ι poisons.
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15
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Evidence for Inhibition of Topoisomerase 1A by Gold(III) Macrocycles and Chelates Targeting Mycobacterium tuberculosis and Mycobacterium abscessus. Antimicrob Agents Chemother 2018; 62:AAC.01696-17. [PMID: 29483110 DOI: 10.1128/aac.01696-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 02/08/2018] [Indexed: 01/15/2023] Open
Abstract
Mycobacterium tuberculosis and the fast-growing species Mycobacterium abscessus are two important human pathogens causing persistent pulmonary infections that are difficult to cure and require long treatment times. The emergence of drug-resistant M. tuberculosis strains and the high level of intrinsic resistance of M. abscessus call for novel drug scaffolds that effectively target both pathogens. In this study, we evaluated the activity of bis(pyrrolide-imine) gold(III) macrocycles and chelates, originally designed as DNA intercalators capable of targeting human topoisomerase types I and II (Topo1 and Topo2), against M. abscessus and M. tuberculosis We identified a total of 5 noncytotoxic compounds active against both mycobacterial pathogens under replicating in vitro conditions. We chose one of these hits, compound 14, for detailed analysis due to its potent bactericidal mode of inhibition and scalable synthesis. The clinical relevance of this compound was demonstrated by its ability to inhibit a panel of diverse M. tuberculosis and M. abscessus clinical isolates. Prompted by previous data suggesting that compound 14 may target topoisomerase/gyrase enzymes, we demonstrated that it lacked cross-resistance with fluoroquinolones, which target the M. tuberculosis gyrase. In vitro enzyme assays confirmed the potent activity of compound 14 against bacterial topoisomerase 1A (Topo1) enzymes but not gyrase. Novel scaffolds like compound 14 with potent, selective bactericidal activity against M. tuberculosis and M. abscessus that act on validated but underexploited targets like Topo1 represent a promising starting point for the development of novel therapeutics for infections by pathogenic mycobacteria.
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16
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Discovery of novel bacterial topoisomerase I inhibitors by use of in silico docking and in vitro assays. Sci Rep 2018; 8:1437. [PMID: 29362471 PMCID: PMC5780498 DOI: 10.1038/s41598-018-19944-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 01/10/2018] [Indexed: 02/07/2023] Open
Abstract
Topoisomerases are important targets for antibacterial and anticancer therapies. Bacterial topoisomerase I remains to be exploited for antibiotics that can be used in the clinic. Inhibitors of bacterial topoisomerase I may provide leads for novel antibacterial drugs against pathogens resistant to current antibiotics. TB is the leading infectious cause of death worldwide, and new TB drugs against an alternative target are urgently needed to overcome multi-drug resistance. Mycobacterium tuberculosis topoisomerase I (MtbTopI) has been validated genetically and chemically as a TB drug target. Here we conducted in silico screening targeting an active site pocket of MtbTopI. The top hits were assayed for inhibition of MtbTopI activity. The shared structural motif found in the active hits was utilized in a second round of in silico screening and in vitro assays, yielding selective inhibitors of MtbTopI with IC50s as low as 2 µM. Growth inhibition of Mycobacterium smegmatis by these compounds in combination with an efflux pump inhibitor was diminished by the overexpression of recombinant MtbTopI. This work demonstrates that in silico screening can be utilized to discover new bacterial topoisomerase I inhibitors, and identifies a novel structural motif which could be explored further for finding selective bacterial topoisomerase I inhibitors.
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17
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Banda S, Cao N, Tse-Dinh YC. Distinct Mechanism Evolved for Mycobacterial RNA Polymerase and Topoisomerase I Protein-Protein Interaction. J Mol Biol 2017; 429:2931-2942. [PMID: 28843989 DOI: 10.1016/j.jmb.2017.08.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 08/14/2017] [Accepted: 08/19/2017] [Indexed: 01/01/2023]
Abstract
We report here a distinct mechanism of interaction between topoisomerase I and RNA polymerase in Mycobacterium tuberculosis and Mycobacterium smegmatis that has evolved independently from the previously characterized interaction between bacterial topoisomerase I and RNA polymerase. Bacterial DNA topoisomerase I is responsible for preventing the hyper-negative supercoiling of genomic DNA. The association of topoisomerase I with RNA polymerase during transcription elongation could efficiently relieve transcription-driven negative supercoiling. Our results demonstrate a direct physical interaction between the C-terminal domains of topoisomerase I (TopoI-CTDs) and the β' subunit of RNA polymerase of M. smegmatis in the absence of DNA. The TopoI-CTDs in mycobacteria are evolutionarily unrelated in amino acid sequence and three-dimensional structure to the TopoI-CTD found in the majority of bacterial species outside Actinobacteria, including Escherichia coli. The functional interaction between topoisomerase I and RNA polymerase has evolved independently in mycobacteria and E. coli, with distinctively different structural elements of TopoI-CTD utilized for this protein-protein interaction. Zinc ribbon motifs in E. coli TopoI-CTD are involved in the interaction with RNA polymerase. For M. smegmatis TopoI-CTD, a 27-amino-acid tail that is rich in basic residues at the C-terminal end is responsible for the interaction with RNA polymerase. Overexpression of recombinant TopoI-CTD in M. smegmatis competed with the endogenous topoisomerase I for protein-protein interactions with RNA polymerase. The TopoI-CTD overexpression resulted in decreased survival following treatment with antibiotics and hydrogen peroxide, supporting the importance of the protein-protein interaction between topoisomerase I and RNA polymerase during stress response of mycobacteria.
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Affiliation(s)
- Srikanth Banda
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA
| | - Nan Cao
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA.
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18
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Cheng B, Zhou Q, Weng L, Leszyk JD, Greenberg MM, Tse-Dinh YC. Identification of proximal sites for unwound DNA substrate in Escherichia coli topoisomerase I with oxidative crosslinking. FEBS Lett 2016; 591:28-38. [PMID: 27926785 DOI: 10.1002/1873-3468.12517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 11/21/2016] [Accepted: 11/22/2016] [Indexed: 11/11/2022]
Abstract
Topoisomerases catalyze changes in DNA topology by directing the movement of DNA strands through consecutive cleavage-rejoining reactions of the DNA backbone. We describe the use of a phenylselenyl-modified thymidine incorporated into a specific position of a partially unwound DNA substrate in crosslinking studies of Escherichia coli topoisomerase I to gain new insights into its catalytic mechanism. Crosslinking of the phenylselenyl-modified thymidine to the topoisomerase protein was achieved by the addition of a mild oxidant. Following nuclease and trypsin digestion, lysine residues on topoisomerase I crosslinked to the modified thymidine were identified by mass spectrometry. The crosslinked sites may correspond to proximal sites for the unwound DNA strand as it interacts with enzyme in the different stages of the catalytic cycle.
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Affiliation(s)
- Bokun Cheng
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY, USA
| | - Qingxuan Zhou
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, USA.,Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
| | - Liwei Weng
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, USA
| | - John D Leszyk
- Department of Biochemistry and Molecular Pharmacology and Proteomics and Mass Spectrometry Facility, University of Massachusetts Medical School, Worcester, MA, USA
| | - Marc M Greenberg
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, USA
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, USA.,Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
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19
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Small-Molecule Inhibitors Targeting Topoisomerase I as Novel Antituberculosis Agents. Antimicrob Agents Chemother 2016; 60:4028-36. [PMID: 27114277 DOI: 10.1128/aac.00288-16] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 04/15/2016] [Indexed: 01/30/2023] Open
Abstract
Bacterial topoisomerase functions are required for regulation of DNA supercoiling and overcoming the DNA topological barriers that are encountered during many vital cellular processes. DNA gyrase and topoisomerase IV of the type IIA bacterial topoisomerase family are important clinical targets for antibacterial therapy. Topoisomerase I, belonging to the type IA topoisomerase family, has recently been validated as a potential antitubercular target. The topoisomerase I activity has been shown to be essential for bacterial viability and infection in a murine model of tuberculosis. Mixture-based combinatorial libraries were screened in this study to identify novel bacterial topoisomerase I inhibitors. Using positional-scanning deconvolution, selective small-molecule inhibitors of bacterial topoisomerase I were identified starting from a polyamine scaffold. Antibacterial assays demonstrated that four of these small-molecule inhibitors of bacterial topoisomerase I are bactericidal against Mycobacterium smegmatis and Mycobacterium tuberculosis The MICs for growth inhibition of M. smegmatis increased with overexpression of recombinant M. tuberculosis topoisomerase I, consistent with inhibition of intracellular topoisomerase I activity being involved in the antimycobacterial mode of action.
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20
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Ahmad M, Xue Y, Lee SK, Martindale JL, Shen W, Li W, Zou S, Ciaramella M, Debat H, Nadal M, Leng F, Zhang H, Wang Q, Siaw GEL, Niu H, Pommier Y, Gorospe M, Hsieh TS, Tse-Dinh YC, Xu D, Wang W. RNA topoisomerase is prevalent in all domains of life and associates with polyribosomes in animals. Nucleic Acids Res 2016; 44:6335-49. [PMID: 27257063 PMCID: PMC4994864 DOI: 10.1093/nar/gkw508] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/25/2016] [Indexed: 12/14/2022] Open
Abstract
DNA Topoisomerases are essential to resolve topological problems during DNA metabolism in all species. However, the prevalence and function of RNA topoisomerases remain uncertain. Here, we show that RNA topoisomerase activity is prevalent in Type IA topoisomerases from bacteria, archaea, and eukarya. Moreover, this activity always requires the conserved Type IA core domains and the same catalytic residue used in DNA topoisomerase reaction; however, it does not absolutely require the non-conserved carboxyl-terminal domain (CTD), which is necessary for relaxation reactions of supercoiled DNA. The RNA topoisomerase activity of human Top3β differs from that of Escherichia coli topoisomerase I in that the former but not the latter requires the CTD, indicating that topoisomerases have developed distinct mechanisms during evolution to catalyze RNA topoisomerase reactions. Notably, Top3β proteins from several animals associate with polyribosomes, which are units of mRNA translation, whereas the Top3 homologs from E. coli and yeast lack the association. The Top3β-polyribosome association requires TDRD3, which directly interacts with Top3β and is present in animals but not bacteria or yeast. We propose that RNA topoisomerases arose in the early RNA world, and that they are retained through all domains of DNA-based life, where they mediate mRNA translation as part of polyribosomes in animals.
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Affiliation(s)
- Muzammil Ahmad
- Genome Instability and Chromatin Remodeling Section, Lab of Genetics, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Yutong Xue
- Genome Instability and Chromatin Remodeling Section, Lab of Genetics, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Seung Kyu Lee
- Genome Instability and Chromatin Remodeling Section, Lab of Genetics, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Jennifer L Martindale
- RNA Regulation Section, Lab of Genetics, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Weiping Shen
- Genome Instability and Chromatin Remodeling Section, Lab of Genetics, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Wen Li
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, PeKing University, Beijing 1000871, China
| | - Sige Zou
- Translational Gerontology Branch, National Institute on Aging, National Institute of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Maria Ciaramella
- Institute of Biosciences and Bioresources, National Research Council of Italy, Naples 80131, Italy
| | - Hélène Debat
- Institut Jacques Monod, CNRS-Université Paris Diderot-UMR7592, 15 rue Hélène Brion, 75205 Paris Cedex, France
| | - Marc Nadal
- Institut Jacques Monod, CNRS-Université Paris Diderot-UMR7592, 15 rue Hélène Brion, 75205 Paris Cedex, France
| | - Fenfei Leng
- Department of Chemistry & Biochemistry, Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA
| | - Hongliang Zhang
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Quan Wang
- Molecular and Cellular Biochemistry Department, Indiana University, 212 South Hawthorne Drive, Bloomington, IN 47405, USA
| | - Grace Ee-Lu Siaw
- Institute of Cellular Organistic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Hengyao Niu
- Molecular and Cellular Biochemistry Department, Indiana University, 212 South Hawthorne Drive, Bloomington, IN 47405, USA
| | - Yves Pommier
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Myriam Gorospe
- RNA Regulation Section, Lab of Genetics, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Tao-Shih Hsieh
- Institute of Cellular Organistic Biology, Academia Sinica, Taipei 11529, Taiwan Department of Biochemistry, Duke University Medical Center, Durham, NC 73532, USA
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry & Biochemistry, Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA
| | - Dongyi Xu
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, PeKing University, Beijing 1000871, China
| | - Weidong Wang
- Genome Instability and Chromatin Remodeling Section, Lab of Genetics, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD 21224, USA
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21
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Tan K, Cao N, Cheng B, Joachimiak A, Tse-Dinh YC. Insights from the Structure of Mycobacterium tuberculosis Topoisomerase I with a Novel Protein Fold. J Mol Biol 2015; 428:182-193. [PMID: 26655023 DOI: 10.1016/j.jmb.2015.11.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 11/24/2015] [Accepted: 11/25/2015] [Indexed: 01/17/2023]
Abstract
The DNA topoisomerase I enzyme of Mycobacterium tuberculosis (MtTOP1) is essential for the viability of the organism and survival in a murine model. This topoisomerase is being pursued as a novel target for the discovery of new therapeutic agents for the treatment of drug-resistant tuberculosis. In this study, we succeeded in obtaining a structure of MtTOP1 by first predicting that the C-terminal region of MtTOP1 contains four repeated domains that do not involve the Zn-binding tetracysteine motifs seen in the C-terminal domains of Escherichia coli topoisomerase I. A construct (amino acids A2-T704), MtTOP1-704t, that includes the N-terminal domains (D1-D4) and the first predicted C-terminal domain (D5) of MtTOP1 was expressed and found to retain DNA cleavage-religation activity and catalyze single-stranded DNA catenation. MtTOP1-704t was crystallized, and a structure of 2.52Å resolution limit was obtained. The structure of the MtTOP1 N-terminal domains has features that have not been observed in other previously available bacterial topoisomerase I crystal structures. The first C-terminal domain D5 forms a novel protein fold of a four-stranded antiparallel β-sheet stabilized by a crossing-over α-helix. Since there is only one type IA topoisomerase present in Mycobacteriaceae and related Actinobacteria, this subfamily of type IA topoisomerase may be required for multiple functions in DNA replication, transcription, recombination, and repair. The unique structural features observed for MtTOP1 may allow these topoisomerase I enzymes to carry out physiological functions associated with topoisomerase III enzyme in other bacteria.
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Affiliation(s)
- Kemin Tan
- Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA.
| | - Nan Cao
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Bokun Cheng
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA
| | - Andrzej Joachimiak
- Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA.
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22
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Cheng B, Annamalai T, Sandhaus S, Bansod P, Tse-Dinh YC. Inhibition of Zn(II) binding type IA topoisomerases by organomercury compounds and Hg(II). PLoS One 2015; 10:e0120022. [PMID: 25798600 PMCID: PMC4370478 DOI: 10.1371/journal.pone.0120022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 01/18/2015] [Indexed: 11/19/2022] Open
Abstract
Type IA topoisomerase activities are essential for resolving DNA topological barriers via an enzyme-mediated transient single strand DNA break. Accumulation of topoisomerase DNA cleavage product can lead to cell death or genomic rearrangement. Many antibacterial and anticancer drugs act as topoisomerase poison inhibitors that form stabilized ternary complexes with the topoisomerase covalent intermediate, so it is desirable to identify such inhibitors for type IA topoisomerases. Here we report that organomercury compounds were identified during a fluorescence based screening of the NIH diversity set of small molecules for topoisomerase inhibitors that can increase the DNA cleavage product of Yersinia pestis topoisomerase I. Inhibition of relaxation activity and accumulation of DNA cleavage product were confirmed for these organomercury compounds in gel based assays of Escherichia coli topoisomerase I. Hg(II), but not As(III), could also target the cysteines that form the multiple Zn(II) binding tetra-cysteine motifs found in the C-terminal domains of these bacterial topoisomerase I for relaxation activity inhibition. Mycobacterium tuberculosis topoisomerase I activity is not sensitive to Hg(II) or the organomercury compounds due to the absence of the Zn(II) binding cysteines. It is significant that the type IA topoisomerases with Zn(II) binding domains can still cleave DNA when interfered by Hg(II) or organomercury compounds. The Zn(II) binding domains found in human Top3α and Top3β may be potential targets of toxic metals and organometallic complexes, with potential consequence on genomic stability and development.
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Affiliation(s)
- Bokun Cheng
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, United States of America
| | - Thirunavukkarasu Annamalai
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Shayna Sandhaus
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Priyanka Bansod
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
- Biomolecular Sciences Institute, Florida International University, Miami, Florida, United States of America
- * E-mail:
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23
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Sridevi JP, Suryadevara P, Janupally R, Sridhar J, Soni V, Anantaraju HS, Yogeeswari P, Sriram D. Identification of potential Mycobacterium tuberculosis topoisomerase I inhibitors: a study against active, dormant and resistant tuberculosis. Eur J Pharm Sci 2015; 72:81-92. [PMID: 25769524 DOI: 10.1016/j.ejps.2015.02.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 02/12/2015] [Accepted: 02/24/2015] [Indexed: 10/23/2022]
Abstract
Mycobacterium tuberculosis (Mtb) topoisomerase I (Topo I), involved in the relaxation of negatively supercoiled DNA, plays an important role in the viability of pathogen Mtb. Being one of the most significant enzymes; it also takes part in crucial biological pathways such as transcription and replication of the pathogen. The present study aims at the development of Mtb Topo I 3D protein structure which in turn was employed for the virtual screening of compound libraries in a process of identification of a hit molecule. The identified hit, hydroxycamptothecin, was active at 6.25 μM which was further derivatized synthetically into fifteen novel analogues. Among these, four compounds (3b, 3g, 3h and 3l) emerged to be active displaying IC50 values ranging from 2.9 to 9.3 μM against Mtb Topo I and were non-cytotoxic at 25 μM. These four compounds also proved their efficacy when tested against active, dormant and resistant forms of Mtb. The most potent inhibitor 3b was screened for in vivo anti-mycobacterial activity using zebrafish model and was found to be more effective when compared to first line anti-tubercular drugs, isoniazid and rifampicin. The binding affinity of this compound towards Mtb Topo I was analyzed by differential scanning fluorimetry which resulted in a positive shift in melting temperature when compared to the native protein thereby proving its stabilization effect over protein.
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Affiliation(s)
- Jonnalagadda Padma Sridevi
- Department of Pharmacy, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad 500078, India
| | - Priyanka Suryadevara
- Department of Pharmacy, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad 500078, India
| | - Renuka Janupally
- Department of Pharmacy, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad 500078, India
| | - Jogula Sridhar
- Department of Pharmacy, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad 500078, India
| | - Vijay Soni
- Department of Pharmacy, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad 500078, India
| | - Hasitha Shilpa Anantaraju
- Department of Pharmacy, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad 500078, India
| | - Perumal Yogeeswari
- Department of Pharmacy, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad 500078, India
| | - Dharmarajan Sriram
- Department of Pharmacy, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad 500078, India
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24
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Nimesh H, Sur S, Sinha D, Yadav P, Anand P, Bajaj P, Virdi JS, Tandon V. Synthesis and Biological Evaluation of Novel Bisbenzimidazoles as Escherichia coli Topoisomerase IA Inhibitors and Potential Antibacterial Agents. J Med Chem 2014; 57:5238-57. [DOI: 10.1021/jm5003028] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Hemlata Nimesh
- Department
of Chemistry, University of Delhi, Delhi 110 007, India
| | - Souvik Sur
- Department
of Chemistry, University of Delhi, Delhi 110 007, India
| | - Devapriya Sinha
- Department
of Chemistry, University of Delhi, Delhi 110 007, India
| | - Pooja Yadav
- Department
of Chemistry, University of Delhi, Delhi 110 007, India
| | - Prachi Anand
- Department of Chemistry & Biochemistry, CUNY−Hunter College, New York, New York 10065, United States
| | - Priyanka Bajaj
- Department
of Microbiology, University of Delhi, Delhi 110 021, India
| | | | - Vibha Tandon
- Department
of Chemistry, University of Delhi, Delhi 110 007, India
- Special
Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110 067, India
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25
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Ahmed W, Menon S, Godbole AA, Karthik PVDNB, Nagaraja V. Conditional silencing of topoisomerase I gene of Mycobacterium tuberculosis validates its essentiality for cell survival. FEMS Microbiol Lett 2014; 353:116-23. [PMID: 24593153 DOI: 10.1111/1574-6968.12412] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 02/25/2014] [Accepted: 02/27/2014] [Indexed: 12/19/2022] Open
Abstract
Topoisomerases are an important class of enzymes for regulating the DNA transaction processes. Mycobacterium tuberculosis (Mtb) is one of the most formidable pathogens also posing serious challenges for therapeutic interventions. The organism contains only one type IA topoisomerase (Rv3646c), offering an opportunity to test its potential as a candidate drug target. To validate the essentiality of M. tuberculosis topoisomerase I (TopoI(Mt) ) for bacterial growth and survival, we have generated a conditionally regulated strain of topoI in Mtb. The conditional knockdown mutant exhibited delayed growth on agar plate. In liquid culture, the growth was drastically impaired when TopoI expression was suppressed. Additionally, novobiocin and isoniazid showed enhanced inhibitory potential against the conditional mutant. Analysis of the nucleoid revealed its altered architecture upon TopoI depletion. These studies establish the essentiality of TopoI for the M. tuberculosis growth and open up new avenues for targeting the enzyme.
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Affiliation(s)
- Wareed Ahmed
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
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26
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Tiwari PB, Annamalai T, Cheng B, Narula G, Wang X, Tse-Dinh YC, He J, Darici Y. A surface plasmon resonance study of the intermolecular interaction between Escherichia coli topoisomerase I and pBAD/Thio supercoiled plasmid DNA. Biochem Biophys Res Commun 2014; 445:445-50. [PMID: 24530905 DOI: 10.1016/j.bbrc.2014.02.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 02/05/2014] [Indexed: 11/17/2022]
Abstract
To date, the bacterial DNA topoisomerases are one of the major target biomolecules for the discovery of new antibacterial drugs. DNA topoisomerase regulates the topological state of DNA, which is very important for replication, transcription and recombination. The relaxation of negatively supercoiled DNA is catalyzed by bacterial DNA topoisomerase I (topoI) and this reaction requires Mg(2+). In this report, we first quantitatively studied the intermolecular interactions between Escherichia coli topoisomerase I (EctopoI) and pBAD/Thio supercoiled plasmid DNA using surface plasmon resonance (SPR) technique. The equilibrium dissociation constant (Kd) for EctopoI-pBAD/Thio interactions was determined to be about 8 nM. We then studied the effect of Mg(2+) on the catalysis of EctopoI-pBAD/Thio reaction. A slightly higher equilibrium dissociation constant (~15 nM) was obtained for Mg(2+) coordinated EctopoI (Mg(2+)EctopoI)-pBAD/Thio interactions. In addition, we observed a larger dissociation rate constant (kd) for Mg(2+)EctopoI-pBAD/Thio interactions (~0.043 s(-1)), compared to EctopoI-pBAD/Thio interactions (~0.017 s(-1)). These results suggest that enzyme turnover during plasmid DNA relaxation is enhanced due to the presence of Mg(2+) and furthers the understanding of importance of the Mg(2+) ion for bacterial topoisomerase I catalytic activity.
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Affiliation(s)
| | - Thirunavukkarasu Annamalai
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, United States
| | - Bokun Cheng
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, United States
| | - Gagandeep Narula
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, United States
| | - Xuewen Wang
- Department of Physics, Florida International University, Miami, FL 33199, United States
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, United States.
| | - Jin He
- Department of Physics, Florida International University, Miami, FL 33199, United States.
| | - Yesim Darici
- Department of Physics, Florida International University, Miami, FL 33199, United States.
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Sissi C, Cheng B, Lombardo V, Tse-Dinh YC, Palumbo M. Metal ion and inter-domain interactions as functional networks in E. coli topoisomerase I. Gene 2013; 524:253-60. [PMID: 23612251 DOI: 10.1016/j.gene.2013.04.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 04/08/2013] [Accepted: 04/09/2013] [Indexed: 10/26/2022]
Abstract
Escherichia coli topoisomerase I (EcTopoI) is a type IA bacterial topoisomerase which is receiving large attention due to its potential application as novel target for antibacterial therapeutics. Nevertheless, a detailed knowledge of its mechanism of action at molecular level is to some extent lacking. This is partly due to the requirement of several factors (metal ions, nucleic acid) to the proper progress of the enzyme catalytic cycle. Additionally, each of them can differently affect the protein structure. Here we assess the role of the different components (DNA, metal ions, protein domains) in a dynamic environment as in solution by monitoring the catalytic as well as the structural properties of EcTopoI. Our results clearly indicated the interaction among these components as functionally relevant and underlined their mutual involvement. Some similarities with other enzymes of the same family emerged (for example DNA prevents divalent metal ions coordination at non selective binding sites). Interestingly, same interactions (C- and N-terminal domain interaction) appear to be peculiar of this bacterial topoisomerase which suggest they could be favorably exploited to the design of selective inhibitors for this class of enzyme.
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Affiliation(s)
- Claudia Sissi
- Dept. of Pharmaceutical and Pharmacological Sciences, v. Marzolo 5, 35131 Padova, Italy.
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Cheng B, Cao S, Vasquez V, Annamalai T, Tamayo-Castillo G, Clardy J, Tse-Dinh YC. Identification of anziaic acid, a lichen depside from Hypotrachyna sp., as a new topoisomerase poison inhibitor. PLoS One 2013; 8:e60770. [PMID: 23593306 PMCID: PMC3620467 DOI: 10.1371/journal.pone.0060770] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 03/02/2013] [Indexed: 11/18/2022] Open
Abstract
Topoisomerase inhibitors are effective for antibacterial and anticancer therapy because they can lead to the accumulation of the intermediate DNA cleavage complex formed by the topoisomerase enzymes, which trigger cell death. Here we report the application of a novel enzyme-based high-throughput screening assay to identify natural product extracts that can lead to increased accumulation of the DNA cleavage complex formed by recombinant Yersinia pestis topoisomerase I as part of a larger effort to identify new antibacterial compounds. Further characterization and fractionation of the screening positives from the primary assay led to the discovery of a depside, anziaic acid, from the lichen Hypotrachyna sp. as an inhibitor for both Y. pestis and Escherichia coli topoisomerase I. In in vitro assays, anziaic acid exhibits antibacterial activity against Bacillus subtilis and a membrane permeable strain of E. coli. Anziaic acid was also found to act as an inhibitor of human topoisomerase II but had little effect on human topoisomerase I. This is the first report of a depside with activity as a topoisomerase poison inhibitor and demonstrates the potential of this class of natural products as a source for new antibacterial and anticancer compounds.
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Affiliation(s)
- Bokun Cheng
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, United States of America
| | - Shugeng Cao
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Victor Vasquez
- Unidad Estrategica de Bioprospeccion, Instituto Nacional de Biodiversidad (INBio) and Escuela de Química, Universidad de Costa Rica, San José, Costa Rica
| | - Thirunavukkarasu Annamalai
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, United States of America
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Giselle Tamayo-Castillo
- Unidad Estrategica de Bioprospeccion, Instituto Nacional de Biodiversidad (INBio) and Escuela de Química, Universidad de Costa Rica, San José, Costa Rica
| | - Jon Clardy
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yuk-Ching Tse-Dinh
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, United States of America
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
- * E-mail:
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Shen CY, Hsieh SC, Yu CL, Wang JY, Lee LN, Yu CJ. Autoantibody prevalence in active tuberculosis: reactive or pathognomonic? BMJ Open 2013; 3:bmjopen-2013-002665. [PMID: 23892369 PMCID: PMC3731725 DOI: 10.1136/bmjopen-2013-002665] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
OBJECTIVES To evaluate the autoantibody in patients without corresponding symptoms, whether these autoantibody are pathognomonic or not. We hypothesised that autoantibody may be reactive to chronic infection, such as tuberculosis (TB). DESIGN Randomised, case-control cohort study. SETTING A tertiary centre in Taiwan. PARTICIPANTS We randomly chose 100 patients out of the data bank of patients with TB in a tertiary medical centre. All patients completed the sera sampling. We chose 100 patients according to autoantibody prevalence in previous literature. We also chose 100 medical staff as control group. INTERVENTIONS We tested anti-SSA, anti-SSB, anti-Sm, anti ribonucleoprotein, anti-Scl 70, anticentromere, anti-double-stranded DNA, anticardiolipin IgG and IgM in all patient and control groups. The clinical symptoms and the underlying disease were all recorded. PRIMARY AND SECONDARY OUTCOME MEASURES The result of sera antibody titre was recorded. For those with specific positive serology results, following examination was carried out after a 3-month anti-TB medication. RESULTS Anticardiolipin IgG titre was significantly higher in patients with TB than in control group. We compared the result with previous population study and found that anti-Scl70 is also significantly higher in patients with TB. The following up data in anti-Scl70 revealed decreased titre after treatment. No correlation between sera titre and clinical conditions was observed. CONCLUSIONS In TB endemic areas, a significant proportion (32%) of patients with TB have elevated autoantibody titres, especially anticardiolipin IgG and anti-Scl-70. Mycobacterial studies should be performed in patients with elevated serum autoantibody titres but without the typical or multiple manifestations of autoimmune diseases. TRIAL REGISTRATION The study was approved by the Institutional Review Board of the hospital (NTUH REC: 9561707008) after informed consent had been obtained from the patients.
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Affiliation(s)
- Chieh-Yu Shen
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Song-Chou Hsieh
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Chia-Li Yu
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Jann-Yuan Wang
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Li-Na Lee
- Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Chong-Jen Yu
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
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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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Bansal S, Sinha D, Singh M, Cheng B, Tse-Dinh YC, Tandon V. 3,4-dimethoxyphenyl bis-benzimidazole, a novel DNA topoisomerase inhibitor that preferentially targets Escherichia coli topoisomerase I. J Antimicrob Chemother 2012; 67:2882-91. [PMID: 22945915 DOI: 10.1093/jac/dks322] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
OBJECTIVES Antibiotic resistance in bacterial pathogens is a serious clinical problem. Novel targets are needed to combat increasing drug resistance in Escherichia coli. Our objective is to demonstrate that 2-(3,4-dimethoxyphenyl)-5-[5-(4-methylpiperazin-1-yl)-1H-benzimidazol-2yl]-1H-benzimidazole (DMA) inhibits E. coli DNA topoisomerase I more strongly than human topoisomerase I. In addition, DMA is non-toxic to mammalian cells at antibiotic dosage level. METHODS In the present study, we have established DMA as an antibacterial compound by determining MICs, post-antibiotic effects (PAEs) and MBCs for different standard as well as clinical strains of E. coli. We have described the differential catalytic inhibitory mechanism of bis-benzimidazole, DMA, for human and E. coli topoisomerase I and topoisomerase II by performing different assays, including relaxation assays, cleavage-religation assays, DNA unwinding assays, ethidium bromide displacement assays, decatenation assays and DNA gyrase supercoiling assays. RESULTS DMA significantly inhibited bacterial growth at a very low concentration, but did not affect human cell viability at higher concentrations. Activity assays showed that it preferentially targeted E. coli topoisomerase I over human topoisomerase I, topoisomerase II and gyrase. Cleavage-religation assays confirmed DMA as a poison inhibitor of E. coli topoisomerase I. This study illuminates new properties of DMA, which may be further modified to develop an efficient topoisomerase inhibitor that is selective towards bacterial topoisomerase I. CONCLUSIONS This is the first report of a bis-benzimidazole acting as an E. coli topoisomerase I inhibitor. DMA is a safe, non-cytotoxic molecule to human cells at concentrations that are needed for antibacterial activity.
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Affiliation(s)
- Sandhya Bansal
- Department of Chemistry, University of Delhi, Delhi 110007, India
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Narula G, Tse-Dinh YC. Residues of E. coli topoisomerase I conserved for interaction with a specific cytosine base to facilitate DNA cleavage. Nucleic Acids Res 2012; 40:9233-43. [PMID: 22833607 PMCID: PMC3467081 DOI: 10.1093/nar/gks688] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Bacterial and archaeal topoisomerase I display selectivity for a cytosine base 4 nt upstream from the DNA cleavage site. Recently, the solved crystal structure of Escherichia coli topoisomerase I covalently linked to a single-stranded oligonucleotide revealed that R169 and R173 interact with the cytosine base at the −4 position via hydrogen bonds while the phenol ring of Y177 wedges between the bases at the −4 and the −5 position. Substituting R169 to alanine changed the selectivity of the enzyme for the base at the −4 position from a cytosine to an adenine. The R173A mutant displayed similar sequence selectivity as the wild-type enzyme, but weaker cleavage and relaxation activity. Mutation of Y177 to serine or alanine rendered the enzyme inactive. Although mutation of each of these residues led to different outcomes, R169, R173 and Y177 work together to interact with a cytosine base at the −4 position to facilitate DNA cleavage. These strictly conserved residues might act after initial substrate binding as a Molecular Ruler to form a protein–DNA complex with the scissile phosphate positioned at the active site for optimal DNA cleavage by the tyrosine hydroxyl nucleophile to facilitate DNA cleavage in the reaction pathway.
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Affiliation(s)
- Gagandeep Narula
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA
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Song JM, An YJ, Kang MH, Lee YH, Cha SS. Cultivation at 6–10°C is an effective strategy to overcome the insolubility of recombinant proteins in Escherichia coli. Protein Expr Purif 2012; 82:297-301. [DOI: 10.1016/j.pep.2012.01.020] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 01/26/2012] [Accepted: 01/27/2012] [Indexed: 11/29/2022]
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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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