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Herlah B, Pavlin M, Perdih A. Molecular choreography: Unveiling the dynamic landscape of type IIA DNA topoisomerases before T-segment passage through all-atom simulations. Int J Biol Macromol 2024; 269:131991. [PMID: 38714283 DOI: 10.1016/j.ijbiomac.2024.131991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 04/09/2024] [Accepted: 04/28/2024] [Indexed: 05/09/2024]
Abstract
Type IIA DNA topoisomerases are molecular nanomachines responsible for controlling topological states of DNA molecules. Here, we explore the dynamic landscape of yeast topoisomerase IIA during key stages of its catalytic cycle, focusing in particular on the events preceding the passage of the T-segment. To this end, we generated six configurations of fully catalytic yeast topo IIA, strategically inserted a T-segment into the N-gate in relevant configurations, and performed all-atom simulations. The essential motion of topo IIA protein dimer was characterized by rotational gyrating-like movement together with sliding motion within the DNA-gate. Both appear to be inherent properties of the enzyme and an inbuilt feature that allows passage of the T-segment through the cleaved G-segment. Coupled dynamics of the N-gate and DNA-gate residues may be particularly important for controlled and smooth passage of the T-segment and consequently the prevention of DNA double-strand breaks. QTK loop residue Lys367, which interacts with ATP and ADP molecules, is involved in regulating the size and stability of the N-gate. The unveiled features of the simulated configurations provide insights into the catalytic cycle of type IIA topoisomerases and elucidate the molecular choreography governing their ability to modulate the topological states of DNA topology.
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Affiliation(s)
- Barbara Herlah
- Theory Department, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia; University of Ljubljana, Faculty of Pharmacy, Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Matic Pavlin
- Department of Catalysis and Chemical Reaction Engineering, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Andrej Perdih
- Theory Department, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia; University of Ljubljana, Faculty of Pharmacy, Aškerčeva 7, 1000 Ljubljana, Slovenia.
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2
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Pavlin M, Herlah B, Valjavec K, Perdih A. Unveiling the interdomain dynamics of type II DNA topoisomerase through all-atom simulations: Implications for understanding its catalytic cycle. Comput Struct Biotechnol J 2023; 21:3746-3759. [PMID: 37602233 PMCID: PMC10436251 DOI: 10.1016/j.csbj.2023.07.019] [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: 04/23/2023] [Revised: 07/01/2023] [Accepted: 07/19/2023] [Indexed: 08/22/2023] Open
Abstract
Type IIA DNA topoisomerases are complex molecular nanomachines that manage topological states of the DNA molecule in the cell and play a crucial role in cellular processes such as cell division and transcription. They are also established targets of cancer chemotherapy. Starting from the available crystal structure of a fully catalytic topoisomerase IIA homodimer from Saccharomyces cerevisiae, we constructed three states of this molecular motor primarily changing the configurations of the DNA segment bound in the DNA gate and performed μs-long all-atom molecular simulations. A comprehensive analysis revealed a sliding motion within the DNA gate and a teamwork between the N-gate and DNA gate that may be associated with the necessary molecular events that allow passage of the T-segment of DNA. The observed movement of the ATPase dimer relative to the DNA domain was reflected in different interaction patterns between the K-loops of the transducer domain and the B-A-B form of the bound DNA. Based on the obtained results, we mapped simulated configurations to the structures in the proposed catalytic cycle through which type IIA topoisomerases exert their function and discussed the possible transition events. The results extend our understanding of the mechanism of action of type IIA topoisomerases and provide an atomistic interpretation of some of the observed features of these molecular motors.
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Affiliation(s)
- Matic Pavlin
- Department of Catalysis and Chemical Reaction Engineering, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Barbara Herlah
- Theory Department, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Katja Valjavec
- Theory Department, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Andrej Perdih
- Theory Department, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva 7, 1000 Ljubljana, Slovenia
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3
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Jian JY, Osheroff N. Telling Your Right Hand from Your Left: The Effects of DNA Supercoil Handedness on the Actions of Type II Topoisomerases. Int J Mol Sci 2023; 24:11199. [PMID: 37446377 PMCID: PMC10342825 DOI: 10.3390/ijms241311199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/05/2023] [Accepted: 07/05/2023] [Indexed: 07/15/2023] Open
Abstract
Type II topoisomerases are essential enzymes that modulate the topological state of DNA supercoiling in all living organisms. These enzymes alter DNA topology by performing double-stranded passage reactions on over- or underwound DNA substrates. This strand passage reaction generates a transient covalent enzyme-cleaved DNA structure known as the cleavage complex. Al-though the cleavage complex is a requisite catalytic intermediate, it is also intrinsically dangerous to genomic stability in biological systems. The potential threat of type II topoisomerase function can also vary based on the nature of the supercoiled DNA substrate. During essential processes such as DNA replication and transcription, cleavage complex formation can be inherently more dangerous on overwound versus underwound DNA substrates. As such, it is important to understand the profound effects that DNA topology can have on the cellular functions of type II topoisomerases. This review will provide a broad assessment of how human and bacterial type II topoisomerases recognize and act on their substrates of various topological states.
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Affiliation(s)
- Jeffrey Y. Jian
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA;
| | - Neil Osheroff
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA;
- Department of Medicine (Hematology/Oncology), Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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Moreira F, Arenas M, Videira A, Pereira F. Evolutionary History of TOPIIA Topoisomerases in Animals. J Mol Evol 2022; 90:149-165. [PMID: 35165762 DOI: 10.1007/s00239-022-10048-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 01/26/2022] [Indexed: 01/15/2023]
Abstract
TOPIIA topoisomerases are required for the regulation of DNA topology by DNA cleavage and re-ligation and are important targets of antibiotic and anticancer agents. Humans possess two TOPIIA paralogue genes (TOP2A and TOP2B) with high sequence and structural similarity but distinct cellular functions. Despite their functional and clinical relevance, the evolutionary history of TOPIIA is still poorly understood. Here we show that TOPIIA is highly conserved in Metazoa. We also found that TOPIIA paralogues from jawed and jawless vertebrates had different origins related with tetraploidization events. After duplication, TOP2B evolved under a stronger purifying selection than TOP2A, perhaps promoted by the more specialized role of TOP2B in postmitotic cells. We also detected genetic signatures of positive selection in the highly variable C-terminal domain (CTD), possibly associated with adaptation to cellular interactions. By comparing TOPIIA from modern and archaic humans, we found two amino acid substitutions in the TOP2A CTD, suggesting that TOP2A may have contributed to the evolution of present-day humans, as proposed for other cell cycle-related genes. Finally, we identified six residues conferring resistance to chemotherapy differing between TOP2A and TOP2B. These six residues could be targets for the development of TOP2A-specific inhibitors that would avoid the side effects caused by inhibiting TOP2B. Altogether, our findings clarify the origin, diversification and selection pressures governing the evolution of animal TOPIIA.
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Affiliation(s)
- Filipa Moreira
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), University of Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Matosinhos, Portugal
- ICBAS - Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Rua Jorge de Viterbo Ferreira 228, 4050-313, Porto, Portugal
| | - Miguel Arenas
- Department of Biochemistry, Genetics and Immunology, University of Vigo, 36310, Vigo, Spain
- CINBIO, Universidade de Vigo, 36310, Vigo, Spain
- Galicia Sur Health Research Institute (IIS Galicia Sur), 36310, Vigo, Spain
| | - Arnaldo Videira
- ICBAS - Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Rua Jorge de Viterbo Ferreira 228, 4050-313, Porto, Portugal
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Filipe Pereira
- IDENTIFICA Genetic Testing, Rua Simão Bolívar 259 3º Dir Tras, 4470-214, Maia, Portugal.
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal.
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Vanden Broeck A, Lotz C, Drillien R, Haas L, Bedez C, Lamour V. Structural basis for allosteric regulation of Human Topoisomerase IIα. Nat Commun 2021; 12:2962. [PMID: 34016969 PMCID: PMC8137924 DOI: 10.1038/s41467-021-23136-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 04/15/2021] [Indexed: 12/01/2022] Open
Abstract
The human type IIA topoisomerases (Top2) are essential enzymes that regulate DNA topology and chromosome organization. The Topo IIα isoform is a prime target for antineoplastic compounds used in cancer therapy that form ternary cleavage complexes with the DNA. Despite extensive studies, structural information on this large dimeric assembly is limited to the catalytic domains, hindering the exploration of allosteric mechanism governing the enzyme activities and the contribution of its non-conserved C-terminal domain (CTD). Herein we present cryo-EM structures of the entire human Topo IIα nucleoprotein complex in different conformations solved at subnanometer resolutions (3.6-7.4 Å). Our data unveils the molecular determinants that fine tune the allosteric connections between the ATPase domain and the DNA binding/cleavage domain. Strikingly, the reconstruction of the DNA-binding/cleavage domain uncovers a linker leading to the CTD, which plays a critical role in modulating the enzyme's activities and opens perspective for the analysis of post-translational modifications.
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Affiliation(s)
- Arnaud Vanden Broeck
- Université de Strasbourg, CNRS, INSERM, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France
- Department of Integrated Structural Biology, IGBMC, Illkirch, France
| | - Christophe Lotz
- Université de Strasbourg, CNRS, INSERM, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France
- Department of Integrated Structural Biology, IGBMC, Illkirch, France
| | - Robert Drillien
- Université de Strasbourg, CNRS, INSERM, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France
- Department of Integrated Structural Biology, IGBMC, Illkirch, France
| | - Léa Haas
- Université de Strasbourg, CNRS, INSERM, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France
- Department of Integrated Structural Biology, IGBMC, Illkirch, France
| | - Claire Bedez
- Université de Strasbourg, CNRS, INSERM, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France
- Department of Integrated Structural Biology, IGBMC, Illkirch, France
| | - Valérie Lamour
- Université de Strasbourg, CNRS, INSERM, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.
- Department of Integrated Structural Biology, IGBMC, Illkirch, France.
- Hôpitaux Universitaires de Strasbourg, Strasbourg, France.
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Keck JM, Conner JD, Wilson JT, Jiang X, Lisic EC, Deweese JE. Clarifying the Mechanism of Copper(II) α-(N)-Heterocyclic Thiosemicarbazone Complexes on DNA Topoisomerase IIα and IIβ. Chem Res Toxicol 2019; 32:2135-2143. [PMID: 31512855 DOI: 10.1021/acs.chemrestox.9b00311] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Topoisomerase II is a nuclear enzyme involved in the maintenance of DNA and is an effective anticancer drug target. However, several clinical topoisomerase II-targeted agents display significant off-target toxicities and adverse events. Thus, it is important to continue characterizing compounds with activity against topoisomerase II. We previously analyzed α-(N)-heterocyclic thiosemicarbazone copper(II) complexes against human topoisomerase IIα (TOP2A), but humans also express topoisomerase IIβ (TOP2B), which has distinct functional roles. Therefore, we examined two α-(N)-heterocyclic thiosemicarbazone copper [Cu(II)] complexes for activity against TOP2B in a purified system. The Cu(II) complexes, Cu(APY-ETSC)Cl and Cu(BZP-ETSC)Cl, were examined using plasmid DNA cleavage, supercoiled DNA relaxation, enzyme inactivation, protein cross-linking, DNA ligation, and ATP hydrolysis assays with TOP2B to determine whether these compounds act similarly against both enzymes. Both of the Cu(II) thiosemicarbazone (Cu-TSC) complexes we tested disrupted the function of TOP2B in a way similar to the effect on TOP2A. In particular, TOP2B DNA cleavage activity is increased in the presence of these compounds, while the relaxation and ATPase activities are inhibited. Further, both Cu-TSCs stabilize the N-terminal DNA clamp of TOP2A and TOP2B and rapidly inactivate TOP2B when the compounds are present before DNA. Our data provide evidence that the Cu-TSC complexes we tested utilize a similar mechanism against both isoforms of the enzyme. This mechanism may involve interaction with the ATPase domain of TOP2A and TOP2B outside of the ATP binding pocket. Additionally, these data support a model of TOP2 function where the ATPase domain communicates with the DNA cleavage/ligation domain.
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Affiliation(s)
- J Myles Keck
- Department of Pharmaceutical Sciences , Lipscomb University College of Pharmacy and Health Sciences , Nashville , Tennessee 37204-3951 , United States
| | - Jennifer D Conner
- Department of Chemistry , Tennessee Technological University , Cookeville , Tennessee 38505 , United States
| | - James T Wilson
- Department of Pharmaceutical Sciences , Lipscomb University College of Pharmacy and Health Sciences , Nashville , Tennessee 37204-3951 , United States
| | - Xiaohua Jiang
- Department of Chemistry , Tennessee Technological University , Cookeville , Tennessee 38505 , United States
| | - Edward C Lisic
- Department of Chemistry , Tennessee Technological University , Cookeville , Tennessee 38505 , United States
| | - Joseph E Deweese
- Department of Pharmaceutical Sciences , Lipscomb University College of Pharmacy and Health Sciences , Nashville , Tennessee 37204-3951 , United States.,Department of Biochemistry , Vanderbilt University School of Medicine , Nashville , Tennessee 37232-0146 , United States
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7
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Petrella S, Capton E, Raynal B, Giffard C, Thureau A, Bonneté F, Alzari PM, Aubry A, Mayer C. Overall Structures of Mycobacterium tuberculosis DNA Gyrase Reveal the Role of a Corynebacteriales GyrB-Specific Insert in ATPase Activity. Structure 2019; 27:579-589.e5. [PMID: 30744994 DOI: 10.1016/j.str.2019.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 10/13/2018] [Accepted: 01/14/2019] [Indexed: 01/03/2023]
Abstract
Despite sharing common features, previous studies have shown that gyrases from different species have been modified throughout evolution to modulate their properties. Here, we report two crystal structures of Mycobacterium tuberculosis DNA gyrase, an apo and AMPPNP-bound form at 2.6-Å and 3.3-Å resolution, respectively. These structures provide high-resolution structural data on the quaternary organization and interdomain connections of a gyrase (full-length GyrB-GyrA57)2 thus providing crucial inputs on this essential drug target. Together with small-angle X-ray scattering studies, they revealed an "extremely open" N-gate state, which persists even in the DNA-free gyrase-AMPPNP complex and an unexpected connection between the ATPase and cleavage core domains mediated by two Corynebacteriales-specific motifs, respectively the C-loop and DEEE-loop. We show that the C-loop participates in the stabilization of this open conformation, explaining why this gyrase has a lower ATPase activity. Our results image a conformational state which might be targeted for drug discovery.
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Affiliation(s)
- Stéphanie Petrella
- Unité de Microbiologie Structurale, Institut Pasteur, CNRS UMR 3528, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France; Université Paris Diderot, Sorbonne Paris Cité, 75724 Paris Cedex 15, France.
| | - Estelle Capton
- Sorbonne Université, Centre d'Immunologie et des Maladies Infectieuses-Paris, Cimi-Paris, INSERM U1135, National Reference Center for Mycobacteria, Laboratoire de Bactériologie-Hygiène, AP-HP, Hôpitaux Universitaires Pitié-Salpêtrière - Charles Foix, 75013 Paris, France
| | - Bertrand Raynal
- Plateforme de Biophysique Moléculaire, Institut Pasteur, CNRS UMR 3528, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France
| | - Clément Giffard
- Unité de Microbiologie Structurale, Institut Pasteur, CNRS UMR 3528, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France; Université Paris Diderot, Sorbonne Paris Cité, 75724 Paris Cedex 15, France
| | - Aurélien Thureau
- Synchrotron SOLEIL, l'Orme des Merisiers, 91410 Saint Aubin, France
| | - Françoise Bonneté
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Institut de Biologie Physico-Chimique, CNRS UMR7099 and Université Paris Didérot, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Pedro M Alzari
- Unité de Microbiologie Structurale, Institut Pasteur, CNRS UMR 3528, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France; Université Paris Diderot, Sorbonne Paris Cité, 75724 Paris Cedex 15, France
| | - Alexandra Aubry
- Sorbonne Université, Centre d'Immunologie et des Maladies Infectieuses-Paris, Cimi-Paris, INSERM U1135, National Reference Center for Mycobacteria, Laboratoire de Bactériologie-Hygiène, AP-HP, Hôpitaux Universitaires Pitié-Salpêtrière - Charles Foix, 75013 Paris, France.
| | - Claudine Mayer
- Unité de Microbiologie Structurale, Institut Pasteur, CNRS UMR 3528, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France; Université Paris Diderot, Sorbonne Paris Cité, 75724 Paris Cedex 15, France
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Novel xanthone-polyamine conjugates as catalytic inhibitors of human topoisomerase IIα. Bioorg Med Chem Lett 2017; 27:4687-4693. [PMID: 28919339 DOI: 10.1016/j.bmcl.2017.09.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 08/31/2017] [Accepted: 09/04/2017] [Indexed: 01/03/2023]
Abstract
It has been proposed that xanthone derivatives with anticancer potential act as topoisomerase II inhibitors because they interfere with the ability of the enzyme to bind its ATP cofactor. In order to further characterize xanthone mechanism and generate compounds with potential as anticancer drugs, we synthesized a series of derivatives in which position 3 was substituted with different polyamine chains. As determined by DNA relaxation and decatenation assays, the resulting compounds are potent topoisomerase IIα inhibitors. Although xanthone derivatives inhibit topoisomerase IIα-catalyzed ATP hydrolysis, mechanistic studies indicate that they do not act at the ATPase site. Rather, they appear to function by blocking the ability of DNA to stimulate ATP hydrolysis. On the basis of activity, competition, and modeling studies, we propose that xanthones interact with the DNA cleavage/ligation active site of topoisomerase IIα and inhibit the catalytic activity of the enzyme by interfering with the DNA strand passage step.
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Balaña-Fouce R, Alvarez-Velilla R, Fernández-Prada C, García-Estrada C, Reguera RM. Trypanosomatids topoisomerase re-visited. New structural findings and role in drug discovery. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2014; 4:326-37. [PMID: 25516844 PMCID: PMC4266802 DOI: 10.1016/j.ijpddr.2014.07.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
There is an urgent need of new treatments against trypanosomatids-borne diseases. DNA topoisomerases are pointed as potential drug targets against unicellular parasites. Trypanosomatids have a full set of DNA topoisomerases in both nucleus and kinetoplast. TopII and TopIII are located in the kinetoplast and fully involved in kDNA replication. Tritryps TopIB differ in structure from mammalian’s pointing to an attractive target.
The Trypanosomatidae family, composed of unicellular parasites, causes severe vector-borne diseases that afflict human populations worldwide. Chagas disease, sleeping sickness, as well as different sorts of leishmaniases are amongst the most important infectious diseases produced by Trypanosoma cruzi, Trypanosoma brucei and Leishmania spp., respectively. All these infections are closely related to weak health care services in low-income populations of less developed and least economically developed countries. Search for new therapeutic targets in order to hit these pathogens is of paramount priority, as no effective vaccine is currently in use against any of these parasites. Furthermore, present-day chemotherapy comprises old-fashioned drugs full of important side effects. Besides, they are prone to produce tolerance and resistance as a consequence of their continuous use for decades. DNA topoisomerases (Top) are ubiquitous enzymes responsible for solving the torsional tensions caused during replication and transcription processes, as well as in maintaining genomic stability during DNA recombination. As the inhibition of these enzymes produces cell arrest and triggers cell death, Top inhibitors are among the most effective and most widely used drugs in both cancer and antibacterial therapies. Top relaxation and decatenation activities, which are based on a common nicking–closing cycle involving one or both DNA strands, have been pointed as a promising drug target. Specific inhibitors that bind to the interface of DNA-Top complexes can stabilize Top-mediated transient DNA breaks. In addition, important structural differences have been found between Tops from the Trypanosomatidae family members and Tops from the host. Such dissimilarities make these proteins very interesting for drug design and molecular intervention. The present review is a critical update of the last findings regarding trypanosomatid’s Tops, their new structural features, their involvement both in the physiology and virulence of these parasites, as well as their use as promising targets for drug discovery.
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Affiliation(s)
- Rafael Balaña-Fouce
- Departamento de Ciencias Biomédicas, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
| | - Raquel Alvarez-Velilla
- Departamento de Ciencias Biomédicas, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
| | | | - Carlos García-Estrada
- Departamento de Ciencias Biomédicas, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
| | - Rosa M Reguera
- Departamento de Ciencias Biomédicas, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
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DNA topoisomerase II is involved in regulation of cyst wall protein genes and differentiation in Giardia lamblia. PLoS Negl Trop Dis 2013; 7:e2218. [PMID: 23696909 PMCID: PMC3656124 DOI: 10.1371/journal.pntd.0002218] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 04/04/2013] [Indexed: 12/16/2022] Open
Abstract
The protozoan Giardia lamblia differentiates into infectious cysts within the human intestinal tract for disease transmission. Expression of the cyst wall protein (cwp) genes increases with similar kinetics during encystation. However, little is known how their gene regulation shares common mechanisms. DNA topoisomerases maintain normal topology of genomic DNA. They are necessary for cell proliferation and tissue development as they are involved in transcription, DNA replication, and chromosome condensation. A putative topoisomerase II (topo II) gene has been identified in the G. lamblia genome. We asked whether Topo II could regulate Giardia encystation. We found that Topo II was present in cell nuclei and its gene was up-regulated during encystation. Topo II has typical ATPase and DNA cleavage activity of type II topoisomerases. Mutation analysis revealed that the catalytic important Tyr residue and cleavage domain are important for Topo II function. We used etoposide-mediated topoisomerase immunoprecipitation assays to confirm the binding of Topo II to the cwp promoters in vivo. Interestingly, Topo II overexpression increased the levels of cwp gene expression and cyst formation. Microarray analysis identified up-regulation of cwp and specific vsp genes by Topo II. We also found that the type II topoisomerase inhibitor etoposide has growth inhibition effect on Giardia. Addition of etoposide significantly decreased the levels of cwp gene expression and cyst formation. Our results suggest that Topo II has been functionally conserved during evolution and that Topo II plays important roles in induction of the cwp genes, which is key to Giardia differentiation into cysts. Giardia lamblia becomes infective by differentiation into water-resistant cysts. During encystation, cyst wall proteins (CWPs) are highly synthesized and are targeted to the cyst wall. However, little is known about the regulation mechanisms of these genes. DNA topoisomerases can resolve the topological problems and are needed for a variety of key cellular functions, including cell proliferation, cell differentiation and organ development in higher eukaryotes. We found that giardial Topo II was highly expressed during encystation. Topo II is present in Giardia nuclei and is associated with the encystation-induced cwp gene promoters. Topo II has typical DNA cleavage activity of type II topoisomerases. Interestingly, overexpression of Topo II can induce cwp gene expression and cyst formation. Addition of a type II topoisomerase inhibitor, etoposide, significantly decreased the levels of cwp gene expression and cyst formation. Etoposide also has growth inhibition effect on Giardia. Our results suggest that Topo II plays an important role in induction of encystation by up-regulation of the cwp gene expression. Our results provide insights into the function of Topo II in parasite differentiation into cysts and help develop ways to interrupt the parasite life cycle.
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11
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Lee I, Dong KC, Berger JM. The role of DNA bending in type IIA topoisomerase function. Nucleic Acids Res 2013; 41:5444-56. [PMID: 23580548 PMCID: PMC3664819 DOI: 10.1093/nar/gkt238] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Type IIA topoisomerases control DNA supercoiling and separate newly replicated chromosomes using a complex DNA strand cleavage and passage mechanism. Structural and biochemical studies have shown that these enzymes sharply bend DNA by as much as 150°; an invariant isoleucine, which has been seen structurally to intercalate between two base pairs outside of the DNA cleavage site, has been suggested to promote deformation. To test this assumption, we examined the role of isoleucine on DNA binding, bending and catalytic activity for a bacterial type IIA topoisomerase, Escherichia coli topoisomerase IV (topo IV), using a combination of site-directed mutagenesis and biochemical assays. Our data show that alteration of the isoleucine (Ile172) did not affect the basal ATPase activity of topo IV or its affinity for DNA. However, the amino acid was important for DNA bending, DNA cleavage and supercoil relaxation. Moreover, an ability to bend DNA correlated with efficacy with which nucleic acid substrates stimulate ATP hydrolysis. These data show that DNA binding and bending by topo IV can be uncoupled, and indicate that the stabilization of a highly curved DNA geometry is critical to the type IIA topoisomerase catalytic cycle.
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Affiliation(s)
- Imsang Lee
- Department of Molecular and Cell Biology, MC 3220 University of California, Berkeley, CA 94720-3220, USA
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12
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Structure of a topoisomerase II-DNA-nucleotide complex reveals a new control mechanism for ATPase activity. Nat Struct Mol Biol 2012; 19:1147-54. [PMID: 23022727 PMCID: PMC3492516 DOI: 10.1038/nsmb.2388] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 08/23/2012] [Indexed: 11/22/2022]
Abstract
Type IIA topoisomerases control DNA supercoiling and disentangle chromosomes by a complex, ATP-dependent strand passage mechanism. Although a general framework exists for type IIA topoisomerase function, the architecture of the full-length enzyme has remained undefined. Here we present the first structure of a fully-catalytic Saccharomyces cerevisiae topoisomerase II homodimer, complexed with DNA and a nonhydrolyzable ATP analog. The enzyme adopts a domain-swapped configuration wherein the ATPase domain of one protomer sits atop the nucleolytic region of its partner subunit. This organization produces an unexpected interaction between the bound DNA and a conformational transducing element in the ATPase domain, which we show is critical for both DNA-stimulated ATP hydrolysis and global topoisomerase activity. Our data indicate that the ATPase domains pivot about each other to ensure unidirectional strand passage and that this state senses bound DNA to promote ATP turnover and enzyme reset.
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13
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Gomez-Monterrey I, Campiglia P, Aquino C, Bertamino A, Granata I, Carotenuto A, Brancaccio D, Stiuso P, Scognamiglio I, Rusciano MR, Maione AS, Illario M, Grieco P, Maresca B, Novellino E. Design, Synthesis, and Cytotoxic Evaluation of Acyl Derivatives of 3-Aminonaphtho[2,3-b]thiophene-4,9-dione, a Quinone-Based System. J Med Chem 2011; 54:4077-91. [DOI: 10.1021/jm200094h] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Isabel Gomez-Monterrey
- Department of Pharmaceutical and Toxicological Chemistry, University of Naples “Federico II”, Naples, Italy
| | - Pietro Campiglia
- Department of Pharmaceutical Science, Division of BioMedicine, University of Salerno, Salerno, Italy
| | - Claudio Aquino
- Kellogg School of Science and Technology at The Scripps Research Institute, Scripps Florida, Jupiter, Florida, United States
| | - Alessia Bertamino
- Department of Pharmaceutical and Toxicological Chemistry, University of Naples “Federico II”, Naples, Italy
| | - Ilaria Granata
- Department of Pharmaceutical Science, Division of BioMedicine, University of Salerno, Salerno, Italy
| | - Alfonso Carotenuto
- Department of Pharmaceutical and Toxicological Chemistry, University of Naples “Federico II”, Naples, Italy
| | - Diego Brancaccio
- Department of Pharmaceutical and Toxicological Chemistry, University of Naples “Federico II”, Naples, Italy
| | - Paola Stiuso
- Department of Biochemistry and Biophysics, Second University of Naples, Naples, Italy
| | - Ilaria Scognamiglio
- Department of Biochemistry and Biophysics, Second University of Naples, Naples, Italy
| | - M. Rosaria Rusciano
- Department of Experimental Pharmacology, University of Naples “Federico II”, Naples, Italy
| | - Angela Serena Maione
- Department of Experimental Pharmacology, University of Naples “Federico II”, Naples, Italy
| | - Maddalena Illario
- Department of Experimental Pharmacology, University of Naples “Federico II”, Naples, Italy
| | - Paolo Grieco
- Department of Pharmaceutical and Toxicological Chemistry, University of Naples “Federico II”, Naples, Italy
| | - Bruno Maresca
- Department of Pharmaceutical Science, Division of BioMedicine, University of Salerno, Salerno, Italy
| | - Ettore Novellino
- Department of Pharmaceutical and Toxicological Chemistry, University of Naples “Federico II”, Naples, Italy
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14
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Schoeffler AJ, May AP, Berger JM. A domain insertion in Escherichia coli GyrB adopts a novel fold that plays a critical role in gyrase function. Nucleic Acids Res 2010; 38:7830-44. [PMID: 20675723 PMCID: PMC2995079 DOI: 10.1093/nar/gkq665] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
DNA topoisomerases manage chromosome supercoiling and organization in all forms of life. Gyrase, a prokaryotic heterotetrameric type IIA topo, introduces negative supercoils into DNA by an ATP-dependent strand passage mechanism. All gyrase orthologs rely on a homologous set of catalytic domains for function; however, these enzymes also can possess species-specific auxiliary regions. The gyrases of many gram-negative bacteria harbor a 170-amino acid insertion of unknown architecture and function in the metal- and DNA-binding TOPRIM domain of the GyrB subunit. We have determined the structure of the 212 kDa Escherichia coli gyrase DNA binding and cleavage core containing this insert to 3.1 Å resolution. We find that the insert adopts a novel, extended fold that braces the GyrB TOPRIM domain against the coiled-coil arms of its partner GyrA subunit. Structure-guided deletion of the insert greatly reduces the DNA binding, supercoiling and DNA-stimulated ATPase activities of gyrase. Mutation of a single amino acid at the contact point between the insert and GyrA more modestly impairs supercoiling and ATP turnover, and does not affect DNA binding. Our data indicate that the insert has two functions, acting as a steric buttress to pre-configure the primary DNA-binding site, and serving as a relay that may help coordinate communication between different functional domains.
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Affiliation(s)
- Allyn J. Schoeffler
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California, Berkeley and Fluidigm Corporation, South San Francisco, CA 94080, USA,*To whom correspondence should be addressed. Tel: 505 643 9483; Fax: 505 666 2768;
| | - Andrew P. May
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California, Berkeley and Fluidigm Corporation, South San Francisco, CA 94080, USA
| | - James M. Berger
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California, Berkeley and Fluidigm Corporation, South San Francisco, CA 94080, USA,*To whom correspondence should be addressed. Tel: 505 643 9483; Fax: 505 666 2768;
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15
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García-Estrada C, Prada CF, Fernández-Rubio C, Rojo-Vázquez F, Balaña-Fouce R. DNA topoisomerases in apicomplexan parasites: promising targets for drug discovery. Proc Biol Sci 2010; 277:1777-87. [PMID: 20200034 DOI: 10.1098/rspb.2009.2176] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The phylum Apicomplexa includes a large group of protozoan parasites responsible for a wide range of animal and human diseases. Destructive pathogens, such as Plasmodium falciparum and Plasmodium vivax, causative agents of human malaria, Cryptosporidium parvum, responsible of childhood diarrhoea, and Toxoplasma gondii, responsible for miscarriages and abortions in humans, are frequently associated with HIV immunosuppression in AIDS patients. The lack of effective vaccines, along with years of increasing pressure to eradicate outbreaks with the use of drugs, has favoured the formation of multi-drug resistant strains in endemic areas. Almost all apicomplexan of medical interest contain two endosymbiotic organelles that contain their own mitochondrial and apicoplast DNA. Apicoplast is an attractive target for drug testing because in addition to harbouring singular metabolic pathways absent in the host, it also has its own transcription and translation machinery of bacterial origin. Accordingly, apicomplexan protozoa contain an interesting mixture of enzymes to unwind DNA from eukaryotic and prokaryotic origins. On the one hand, the main mechanism of DNA unwinding includes the scission of one-type I-or both DNA strands-type II eukaryotic topoisomerases, establishing transient covalent bonds with the scissile end. These enzymes are targeted by camptothecin and etoposide, respectively, two natural drugs whose semisynthetic derivatives are currently used in cancer chemotherapy. On the other hand, DNA gyrase is a bacterial-borne type II DNA topoisomerase that operates within the apicoplast and is effectively targeted by bacterial antibiotics like fluoroquinolones and aminocoumarins. The present review is an update on the new findings concerning topoisomerases in apicomplexan parasites and the role of these enzymes as targets for therapeutic agents.
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Affiliation(s)
- Carlos García-Estrada
- Departamento de Ciencias Biomédicas (INTOXCAL), Universidad de León, , Campus de Vegazana s/n, León, Spain
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16
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A unique 45-amino-acid region in the toprim domain of Plasmodium falciparum gyrase B is essential for its activity. EUKARYOTIC CELL 2009; 8:1759-69. [PMID: 19700639 DOI: 10.1128/ec.00149-09] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
DNA gyrase is the only topoisomerase that can introduce negative supercoils into the DNA at the cost of ATP hydrolysis. Some but not all the steps of the topoisomerization reaction are understood clearly for both eukaryotic topoII and DNA gyrase. This study is an attempt to understand whether the B subunit of DNA gyrase binds to DNA directly, which may be central to the stimulation of its ATPase activity essential for gyrase function. We have dissected the Plasmodium falciparum gyrase B (PfGyrB) subunit to identify a 45-amino-acid region in the toprim domain that is responsible for its intrinsic DNA binding activity, DNA-stimulated ATPase activity, and DNA cleavage. We find that DNA has to enter through the ATP-operated clamp of PfGyrB to gain access to the DNA binding region. Furthermore, the rate of ATP hydrolysis of PfGyrB increases significantly with increasing DNA length, suggesting a possible communication between the ATPase domain and the DNA binding region that can account for its optimal ATPase activity. These results not only highlight the mechanism of GyrB action in the deadly human parasite P. falciparum but also provide meaningful insights into the current mechanistic model of DNA transport by gyrase during the topoisomerization reaction.
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17
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Bendsen S, Oestergaard VH, Skouboe C, Brinch M, Knudsen BR, Andersen AH. The QTK loop is essential for the communication between the N-terminal atpase domain and the central cleavage--ligation region in human topoisomerase IIalpha. Biochemistry 2009; 48:6508-15. [PMID: 19485418 DOI: 10.1021/bi9005978] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We have characterized a human topoisomerase IIalpha enzyme with a deletion of the conserved QTK loop, which extends from the transducer domain to the ATP-binding pocket in the GHKL domain. The loop has been suggested to play a role for interdomain communication in type II topoisomerases. The mutant enzyme performs only very low levels of strand passage, although it is able to cleave and ligate DNA as well as close the N-terminal clamp. Cleavage is nearly unaffected by ATP and ATP analogues relative to the wild-type enzyme. Although the enzyme is able to close the clamp, the clamp has altered characteristics, allowing trapping of DNA also in the absence of an ATP analogue. The enzyme furthermore retains intrinsic levels of ATPase activity, but the activity is not stimulated by DNA. Our observations demonstrate that the QTK loop is an important player for the interdomain communication in human topoisomerase IIalpha. First, the loop seems to play a role in keeping the N-terminal clamp in an open conformation when no nucleotide is present. Once the nucleotide binds, it facilitates clamp closure, although it is not essential for this event. The QTK loop, in contrast, is essential for the DNA-stimulated ATPase activity of human topoisomerase IIalpha.
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Affiliation(s)
- Simon Bendsen
- Department of Molecular Biology, C. F. Moellers Alle, Building 1130, University of Aarhus, 8000 Arhus C, Denmark
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18
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Abstract
DNA topoisomerases are a diverse set of essential enzymes responsible for maintaining chromosomes in an appropriate topological state. Although they vary considerably in structure and mechanism, the partnership between topoisomerases and DNA has engendered commonalities in how these enzymes engage nucleic acid substrates and control DNA strand manipulations. All topoisomerases can harness the free energy stored in supercoiled DNA to drive their reactions; some further use the energy of ATP to alter the topology of DNA away from an enzyme-free equilibrium ground state. In the cell, topoisomerases regulate DNA supercoiling and unlink tangled nucleic acid strands to actively maintain chromosomes in a topological state commensurate with particular replicative and transcriptional needs. To carry out these reactions, topoisomerases rely on dynamic macromolecular contacts that alternate between associated and dissociated states throughout the catalytic cycle. In this review, we describe how structural and biochemical studies have furthered our understanding of DNA topoisomerases, with an emphasis on how these complex molecular machines use interfacial interactions to harness and constrain the energy required to manage DNA topology.
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19
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Bates AD, Maxwell A. Energy coupling in type II topoisomerases: why do they hydrolyze ATP? Biochemistry 2007; 46:7929-41. [PMID: 17580973 DOI: 10.1021/bi700789g] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Type II topoisomerases are essential enzymes in all cells. They help to solve the topological problems of DNA by passing one double helix through a transient break in another, in a reaction coupled to the hydrolysis of ATP. Members of one class of the enzymes, DNA gyrases, are configured to carry out an intramolecular reaction, removing positive supercoiling and introducing negative supercoiling into circular DNA using free energy derived from ATP hydrolysis. The nonsupercoiling class, including bacterial topoisomerase IV and eukaryotic topoisomerase II enzymes, can carry out both intra- and intermolecular reactions, and their primary role is the unlinking (decatenation) of daughter replicons before partition. In these enzymes, ATP hydrolysis is coupled to a reduction in DNA complexity (catenation, supercoiling, and knotting) below the level expected at equilibrium. This review discusses our current understanding of the mechanisms behind the coupling of the energy of ATP hydrolysis to topological changes catalyzed by both of these classes of enzyme.
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Affiliation(s)
- Andrew D Bates
- School of Biological Sciences, University of Liverpool, UK. bates@ liv.ac.uk
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20
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Gilroy KL, Leontiou C, Padget K, Lakey JH, Austin CA. mAMSA resistant human topoisomerase IIbeta mutation G465D has reduced ATP hydrolysis activity. Nucleic Acids Res 2006; 34:1597-607. [PMID: 16549872 PMCID: PMC1405819 DOI: 10.1093/nar/gkl057] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Type II Human DNA Topoisomerases (topos II) play an essential role in DNA replication and transcription and are important targets for cancer chemotherapeutic drugs. Topoisomerase II causes transient double-strand breaks in DNA, forming a gate through which another double helix is passed, and acts as a DNA dependent ATPase. Mutations in topoII have been linked to atypical multi-drug resistance. Both human Topoisomerase II isoforms, α and β, are targeted by amsacrine. We have used a forced molecular evolution approach to identify mutations conferring resistance to acridines. Here we report mutation βG465D, which was selected with mAMSA and DACA and is cross-resistant to etoposide, ellipticine and doxorubicin. Resistance to mAMSA appears to decrease over time indicating a previously unreported resistance mechanism. G465D lies within the B′ domain in the region that contacts the cleaved gate helix. There is a 3-fold decrease in ATP affinity and ATP hydrolysis and an altered requirement for magnesium in decatenation assays. The decatenation rate is decreased for the mutated G465D protein. And we report for the first time the use of fluorescence anisotropy with intact human topoisomerase II.
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Affiliation(s)
- Kathryn L Gilroy
- The Institute for Cell and Molecular Biosciences, The University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
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21
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Sengupta T, Mukherjee M, Das A, Mandal C, Das R, Mukherjee T, Majumder H. Characterization of the ATPase activity of topoisomerase II from Leishmania donovani and identification of residues conferring resistance to etoposide. Biochem J 2006; 390:419-26. [PMID: 15901238 PMCID: PMC1198921 DOI: 10.1042/bj20042128] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have cloned and expressed the 43 kDa N-terminal domain of Leishmania donovani topoisomerase II. This protein has an intrinsic ATPase activity and obeys Michaelis-Menten kinetics. Cross-linking studies indicate that the N-terminal domain exists as a dimer both in the presence and absence of nucleotides. Etoposide, an effective antitumour drug, traps eukaryotic DNA topoisomerase II in a covalent complex with DNA. In the present study, we report for the first time that etoposide inhibits the ATPase activity of the recombinant N-terminal domain of L. donovani topoisomerase II. We have modelled the structure of this 43 kDa protein and performed molecular docking analysis with the drug. Mutagenesis of critical amino acids in the vicinity of the ligand-binding pocket reveals less efficient inhibition of the ATPase activity of the enzyme by etoposide. Taken together, these results provide an insight for the development of newer therapeutic agents with specific selectivity.
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Affiliation(s)
- Tanushri Sengupta
- *Molecular Parasitology Laboratory, Indian Institute of Chemical Biology, Kolkata-700032, India
| | - Mandira Mukherjee
- *Molecular Parasitology Laboratory, Indian Institute of Chemical Biology, Kolkata-700032, India
| | - Aditi Das
- †Sealy Center for Molecular Sciences, University of Texas Medical Branch at Galveston, Galveston, TX-77555, U.S.A
| | - Chhabinath Mandal
- ‡Department of Drug Design, Development and Molecular Modeling, Indian Institute of Chemical Biology, Kolkata-700032, India
| | - Rakhee Das
- *Molecular Parasitology Laboratory, Indian Institute of Chemical Biology, Kolkata-700032, India
| | - Tanmoy Mukherjee
- §Infectious Disease Group, Indian Institute of Chemical Biology, Kolkata-700032, India
| | - Hemanta K. Majumder
- *Molecular Parasitology Laboratory, Indian Institute of Chemical Biology, Kolkata-700032, India
- To whom correspondence should be addressed (email )
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22
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Sorensen TK, Grauslund M, Jensen PB, Sehested M, Jensen LH. Separation of bisdioxopiperazine- and vanadate resistance in topoisomerase II. Biochem Biophys Res Commun 2005; 334:853-60. [PMID: 16053917 DOI: 10.1016/j.bbrc.2005.06.177] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2005] [Accepted: 06/26/2005] [Indexed: 11/16/2022]
Abstract
Bisdioxopiperazines are inhibitors of topoisomerase II trapping this protein as a closed clamp on DNA with concomitant inhibition of its ATPase activity. Here, we analyse the effects of N-terminal mutations identified in bisdioxopiperazine-resistant cells on ATP hydrolysis by this enzyme. We present data consistent with bisdioxopiperazine resistance arising by two different mechanisms; one involving reduced stability of the N-terminal clamp (the N-gate) and one involving reduced affinity for bisdioxopiperazines. Vanadate is a general inhibitor of type P ATPases and has recently been demonstrated to lock topoisomerase II as a salt-stable closed clamp on DNA analogous to the bisdioxopiperazines. We show that a R162K mutation in human topoisomerase II alpha renders this enzyme highly resistant towards vanadate while having little effect on bisdioxopiperazine sensitivity. The implications of these findings for the mechanism of action of bisdioxopiperazines versus vanadate with topoisomerase II are discussed.
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Affiliation(s)
- Tina K Sorensen
- Department of Pathology, Diagnostic Centre RH5444, Copenhagen University Hospital, Frederik V's Vej 11, DK-2100 Copenhagen, Denmark
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23
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Wei H, Ruthenburg AJ, Bechis SK, Verdine GL. Nucleotide-dependent domain movement in the ATPase domain of a human type IIA DNA topoisomerase. J Biol Chem 2005; 280:37041-7. [PMID: 16100112 DOI: 10.1074/jbc.m506520200] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type IIA DNA topoisomerases play multiple essential roles in the management of higher-order DNA structure, including modulation of topological state, chromosome segregation, and chromatin condensation. These diverse physiologic functions are all accomplished through a common molecular mechanism, wherein the protein catalyzes transient cleavage of a DNA duplex (the G-segment) to yield a double-stranded gap through which another duplex (the T-segment) is passed. The overall process is orchestrated by the opening and closing of molecular "gates" in the topoisomerase structure, which is regulated by ATP binding, hydrolysis, and release of ADP and inorganic phosphate. Here we present two crystal structures of the ATPase domain of human DNA topoisomerase IIalpha in different nucleotide-bound states. Comparison of these structures revealed rigid-body movement of the structural modules within the ATPase domain, suggestive of the motions of a molecular gate.
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Affiliation(s)
- Hua Wei
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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24
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Vaughn J, Huang S, Wessel I, Sorensen TK, Hsieh T, Jensen LH, Jensen PB, Sehested M, Nitiss JL. Stability of the topoisomerase II closed clamp conformation may influence DNA-stimulated ATP hydrolysis. J Biol Chem 2005; 280:11920-9. [PMID: 15647268 DOI: 10.1074/jbc.m411841200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type II DNA topoisomerases catalyze changes in DNA topology and use nucleotide binding and hydrolysis to control conformational changes required for the enzyme reaction. We examined the ATP hydrolysis activity of a bisdioxopiperazine-resistant mutant of human topoisomerase II alpha with phenylalanine substituted for tyrosine at residue 50 in the ATP hydrolysis domain of the enzyme. This substitution reduced the DNA-dependent ATP hydrolysis activity of the mutant protein without affecting the relaxation activity of the enzyme. A similar but stronger effect was seen when the homologous mutation (Tyr28 --> Phe) was introduced in yeast Top2. The ATPase activities of human TOP2alpha(Tyr50 --> Phe) and yeast Top2(Tyr28 --> Phe) were resistant to both bisdioxopiperazines and the ATPase inhibitor sodium orthovanadate. Like bisdioxopiperazines, vanadate traps the enzyme in a salt-stable closed conformation termed the closed clamp, which can be detected in the presence of circular DNA substrates. Consistent with the vanadate-resistant ATPase activity, salt-stable closed clamps were not detected in reactions containing the yeast or human mutant protein, vanadate, and ATP. Similarly, ADP trapped wild-type topoisomerase II as a closed clamp, but could not trap either the human or yeast mutant enzymes. Our results demonstrate that bisdioxopiperazine-resistant mutants exhibit a difference in the stability of the closed clamp formed by the enzyme and that this difference in stability may lead to a loss of DNA-stimulated ATPase. We suggest that the DNA-stimulated ATPase of topoisomerase II is intimately connected with steps that occur while the N-terminal domain of the enzyme is dimerized.
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Affiliation(s)
- Jerrylaine Vaughn
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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25
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Wang BB, Maghami N, Goodlin VL, Smith PJ. Critical structural motif for the catalytic inhibition of human topoisomerase II by UK-1 and analogs. Bioorg Med Chem Lett 2005; 14:3221-6. [PMID: 15149679 DOI: 10.1016/j.bmcl.2004.03.095] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2004] [Revised: 03/29/2004] [Accepted: 03/30/2004] [Indexed: 10/26/2022]
Abstract
Three new analogs of UK-1 have been synthesized and their efficacies as topoisomerase II inhibitors have been determined. Results show that UK-1 and two of these analogs are catalytic inhibitors of topo II and identifies a critical structure motif necessary for enzyme inhibition.
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Affiliation(s)
- Ben B Wang
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
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26
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Oestergaard VH, Knudsen BR, Andersen AH. Dissecting the cell-killing mechanism of the topoisomerase II-targeting drug ICRF-193. J Biol Chem 2004; 279:28100-5. [PMID: 15123716 DOI: 10.1074/jbc.m402119200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Topoisomerase II is an essential enzyme that is targeted by a number of clinically valuable anticancer drugs. One class referred to as topoisomerase II poisons works by increasing the cellular level of topoisomerase II-mediated DNA breaks, resulting in apoptosis. Another class of topoisomerase II-directed drugs, the bis-dioxopiperazines, stabilizes the conformation of the enzyme where it attains an inactive salt-stable closed clamp structure. Bis-dioxopiperazines, similar to topoisomerase II poisons, induce cell killing, but the underlying mechanism is presently unclear. In this study, we use three different biochemically well characterized human topoisomerase IIalpha mutant enzymes to dissect the catalytic requirements needed for the enzyme to cause dominant sensitivity in yeast to the bis-dioxopirazine ICRF-193 and the topoisomerase II poison m-AMSA. We find that the clamp-closing activity, the DNA cleavage activity, and even both activities together are insufficient for topoisomerase II to cause dominant sensitivity to ICRF-193 in yeast. Rather, the strand passage event per se is an absolute requirement, most probably because this involves a simultaneous interaction of the enzyme with two DNA segments. Furthermore, we show that the ability of human topoisomerase IIalpha to cause dominant sensitivity to m-AMSA in yeast does not depend on clamp closure or strand passage but is directly related to the capability of the enzyme to respond to m-AMSA with increased DNA cleavage complex formation.
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Affiliation(s)
- Vibe H Oestergaard
- Department of Molecular Biology, University of Aarhus, C. F. Møllers Allé, Building 130, 8000 Aarhus C, Denmark
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27
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Oestergaard VH, Giangiacomo L, Bjergbaek L, Knudsen BR, Andersen AH. Hindering the strand passage reaction of human topoisomerase IIalpha without disturbing DNA cleavage, ATP hydrolysis, or the operation of the N-terminal clamp. J Biol Chem 2004; 279:28093-9. [PMID: 15123700 DOI: 10.1074/jbc.m402120200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA topoisomerase II is an essential enzyme that releases a topological strain in DNA by introduction of transient breaks in one DNA helix through which another helix is passed. While changing DNA topology, ATP is required to drive the enzyme through a series of conformational changes dependent on interdomain communication. We have characterized a human topoisomerase IIalpha enzyme with a two-amino acid insertion at position 351 in the transducer domain. The mutation specifically abolishes the DNA strand passage event of the enzyme, probably because of a sterical hindrance of T-segment transport. Thus, the enzyme fails to decatenate and relax DNA, even though it is fully capable of ATP hydrolysis, closure of the N-terminal clamp, and DNA cleavage. The cleavage activity is increased, suggesting that the transducer domain has a role in regulating DNA cleavage. Furthermore, the enzyme has retained a tendency to increase DNA cleavage upon nucleotide binding and also responds to DNA with elevated ATP hydrolysis. However, the DNA-mediated increase in ATP hydrolysis is lower than that obtained with the wild-type enzyme but similar to that of a cleavage-deficient topoisomerase IIalpha enzyme. Our results strongly suggest that the strand passage event is required for efficient DNA stimulation of topoisomerase II-mediated ATP hydrolysis, whereas the stimulation occurs independent of the DNA cleavage reaction per se. A comparison of the strand passage deficient-enzyme described here and the cleavage-deficient enzyme may have applications in other studies where a clear distinction between strand passage and topoisomerase II-mediated DNA cleavage is desirable.
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Affiliation(s)
- Vibe H Oestergaard
- Department of Molecular Biology, University of Aarhus, C. F. Møllers Allé, Building 130, 8000 Aarhus C, Denmark
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28
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Abstract
The eukaryotic DNA topoisomerase II is a dyadic enzyme that, upon ATP binding, transports one duplex DNA (T-segment) through a transient double-stranded break in another (G-segment). The path of the T-segment involves the sequential crossing of three gates along the dimer interface: the entrance or N-gate, the DNA gate, and the exit or C-gate. Coordination among these gates is critical for dimer stability and the prevention of chromosome damage. This study examines DNA transactions by yeast topoisomerase II derivatives defective in gate function. The results indicate that, although the N-gate is not required for G-segment cleavage, the DNA gate per se is not able to widen unless ATP binds to the N-gate. Next, a captured T-segment cannot be held in the interdomainal region between the N-gate and the DNA gate. Finally, the G-segment can be religated while a T-segment is held in the central cavity of the enzyme between the DNA gate and the C-gate. These quaternary couplings for gate opening and closing suggest that topoisomerase II ensures a transient DNA gating state, during which dimer interface contacts are maximized and backtracking of the transported DNA is minimized.
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Affiliation(s)
- Joaquim Roca
- Instituto de Biología Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, Jordi Girona 18-26, 08034 Barcelona, Spain.
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29
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Oestergaard VH, Bjergbaek L, Skouboe C, Giangiacomo L, Knudsen BR, Andersen AH. The transducer domain is important for clamp operation in human DNA topoisomerase IIalpha. J Biol Chem 2003; 279:1684-91. [PMID: 14583603 DOI: 10.1074/jbc.m309624200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA topoisomerase II is a multidomain homodimeric enzyme that changes DNA topology by coupling ATP hydrolysis to the transport of one DNA helix through a transient double-stranded break in another. The process requires dramatic conformational changes including closure of an ATP-operated clamp, which is comprised of two N-terminal domains from each protomer. The most N-terminal domain contains the ATP-binding site and is directly involved in clamp closure, undergoing dimerization upon ATP binding. The second domain, the transducer domain, forms the walls of the N-terminal clamp and connects the clamp to the enzyme core. Although structurally conserved, it is unclear whether the transducer domain is involved in clamp mechanism. We have purified and characterized a human topoisomerase II alpha enzyme with a two-amino acid insertion at position 408 in the transducer domain. The enzyme retains both ATPase and DNA cleavage activities. However, the insertion, which is situated far from the N-terminal dimerization area, severely disrupts the function of the N-terminal clamp. The clamp-deficient enzyme is catalytically inactive and lacks most aspects of interdomain communication. Surprisingly, it seems to have retained the intersubunit communication, allowing it to bind ATP cooperatively in the presence of DNA. The results show that even distal parts of the transducer domain are important for the dynamics of the N-terminal clamp and furthermore indicate that stable clamp closure is not required for cooperative binding of ATP.
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Affiliation(s)
- Vibe H Oestergaard
- Department of Molecular Biology, University of Aarhus, C. F. Møllers Allé, Building 130, 8000 Aarhus C, Denmark
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30
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Rodríguez AC. Investigating the role of the latch in the positive supercoiling mechanism of reverse gyrase. Biochemistry 2003; 42:5993-6004. [PMID: 12755601 DOI: 10.1021/bi034188l] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reverse gyrase is the only topoisomerase known to positively supercoil DNA and the only protein unique to hyperthermophiles. The enzyme comprises an N-terminal ATPase domain and a C-terminal topoisomerase I domain, which interact to couple the hydrolysis of ATP to the overwinding of DNA. The part of the ATPase domain termed the "latch" represses topoisomerase activity in the absence of nucleotide. Here I provide evidence that the latch, in addition to its regulatory role, participates in the supercoiling mechanism during the DNA cleavage and religation steps. The latch also contributes to the coordination of ATP hydrolysis and positive supercoiling by inhibiting ATPase activity in the absence of supercoiling. The latch therefore plays an important role in the communication between the two domains of reverse gyrase.
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Affiliation(s)
- A Chapin Rodríguez
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom.
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31
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Skouboe C, Bjergbaek L, Oestergaard VH, Larsen MK, Knudsen BR, Andersen AH. A human topoisomerase II alpha heterodimer with only one ATP binding site can go through successive catalytic cycles. J Biol Chem 2003; 278:5768-74. [PMID: 12480934 DOI: 10.1074/jbc.m210332200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Eukaryotic DNA topoisomerase II is a dimeric nuclear enzyme essential for DNA metabolism and chromosome dynamics. It changes the topology of DNA by coupling binding and hydrolysis of two ATP molecules to the transport of one DNA duplex through a temporary break introduced in another. During this process the structurally and functionally complex enzyme passes through a cascade of conformational changes, which requires intra- and intersubunit communication. To study the importance of ATP binding and hydrolysis in relation to DNA strand transfer, we have purified and characterized a human topoisomerase II alpha heterodimer with only one ATP binding site. The heterodimer was able to relax supercoiled DNA, although less efficiently than the wild type enzyme. It furthermore possessed a functional N-terminal clamp and was sensitive to ICRF-187. This demonstrates that human topoisomerase II alpha can pass through all the conformations required for DNA strand passage and enzyme resetting with binding and hydrolysis of only one ATP. However, the heterodimer lacked the normal stimulatory effect of DNA on ATP binding and hydrolysis as well as the stimulatory effect of ATP on DNA cleavage. The results can be explained in a model, where efficient catalysis requires an extensive communication between the second ATP and the DNA segment to be cleaved.
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Affiliation(s)
- Camilla Skouboe
- Department of Molecular Biology, University of Aarhus, C. F. Møllers Allé, Building 130, Arhus C 8000, Denmark
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32
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Campbell S, Maxwell A. The ATP-operated clamp of human DNA topoisomerase IIalpha: hyperstimulation of ATPase by "piggy-back" binding. J Mol Biol 2002; 320:171-88. [PMID: 12079377 DOI: 10.1016/s0022-2836(02)00461-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We have constructed a series of clones encoding N-terminal fragments of human DNA topoisomerase IIalpha. All fragments exhibit DNA-dependent ATPase activity. Fragment 1-420 shows hyperbolic dependence of ATPase on DNA concentration, whereas fragment 1-453 shows hyperstimulation at low ratios of DNA to enzyme, a phenomenon found previously with the full-length enzyme. The minimum length of DNA found to stimulate the ATPase activity was approximately 10 bp; fragments >or=32 bp manifest the hyperstimulation phenomenon. Molecular mass studies show that fragment 1-453 is a monomer in the absence of nucleotides and a dimer in the presence of nucleotide triphosphate. The results are consistent with the role of the N-terminal domain of topoisomerase II as an ATP-operated clamp that dimerises in the presence of ATP. The hyperstimulation effect can be interpreted in terms of a "piggy-back binding" model for protein-DNA interaction.
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Affiliation(s)
- Spencer Campbell
- Department of Biochemistry, University of Leicester, Leicester LE1 7RH, UK
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33
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Abstract
DNA topoisomerases solve the topological problems associated with DNA replication, transcription, recombination, and chromatin remodeling by introducing temporary single- or double-strand breaks in the DNA. In addition, these enzymes fine-tune the steady-state level of DNA supercoiling both to facilitate protein interactions with the DNA and to prevent excessive supercoiling that is deleterious. In recent years, the crystal structures of a number of topoisomerase fragments, representing nearly all the known classes of enzymes, have been solved. These structures provide remarkable insights into the mechanisms of these enzymes and complement previous conclusions based on biochemical analyses. Surprisingly, despite little or no sequence homology, both type IA and type IIA topoisomerases from prokaryotes and the type IIA enzymes from eukaryotes share structural folds that appear to reflect functional motifs within critical regions of the enzymes. The type IB enzymes are structurally distinct from all other known topoisomerases but are similar to a class of enzymes referred to as tyrosine recombinases. The structural themes common to all topoisomerases include hinged clamps that open and close to bind DNA, the presence of DNA binding cavities for temporary storage of DNA segments, and the coupling of protein conformational changes to DNA rotation or DNA movement. For the type II topoisomerases, the binding and hydrolysis of ATP further modulate conformational changes in the enzymes to effect changes in DNA topology.
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Affiliation(s)
- J J Champoux
- Department of Microbiology, School of Medicine, University of Washington, Seattle, Washington 98195-7242, USA.
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34
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Owen BAL, Sullivan WP, Felts SJ, Toft DO. Regulation of heat shock protein 90 ATPase activity by sequences in the carboxyl terminus. J Biol Chem 2002; 277:7086-91. [PMID: 11751892 DOI: 10.1074/jbc.m111450200] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hsp90, in addition to being an abundant and pivotal cytoplasmic chaperone protein, has been shown to be a weak ATPase. In an effort to characterize the ATPase activity of hsp90, we have observed marked differences in activities among various species of hsp90. Chicken or human hsp90 hydrolyzed ATP with a k(cat) of 0.02 min(-1) and a K(m) greater than 300 microm. In contrast, yeast hsp90 and TRAP1, an hsp90 homologue found in mitochondria, were 10-100-fold more active as ATPases. Sedimentation studies confirmed that all are dimeric proteins. Chicken hsp90 mutants were then analyzed to identify regions within the protein that influence ATPase activity. A truncation mutant of chicken hsp90, N1-573, was found to be monomeric, and yet the catalytic efficiency (k(cat)/K(m)) was greater than 100 times that of the full-length protein (k(cat) of 0.24 min(-1) and K(m) of 60 microm). In contrast, an internal deletion mutant, Delta661-677, was also monomeric but failed to hydrolyze ATP. Finally, deletion of the last 30 amino acids resulted in a dimeric protein with an ATPase activity very similar to full-length hsp90. These data indicate that sequences within the last one-fourth of hsp90 regulate ATP hydrolysis.
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Affiliation(s)
- Barbara A L Owen
- Department of Biochemistry and Molecular Biology, Mayo Clinic Graduate School, 200 First Street SW, Rochester, MN 55905, USA
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35
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Bromberg KD, Osheroff N. DNA cleavage and religation by human topoisomerase II alpha at high temperature. Biochemistry 2001; 40:8410-8. [PMID: 11444988 DOI: 10.1021/bi010681q] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A common DNA religation assay for topoisomerase II takes advantage of the fact that the enzyme can rejoin cleaved nucleic acids but cannot mediate DNA scission at suboptimal temperatures (either high or low). Although temperature-induced DNA religation assays have provided valuable mechanistic information for several type II enzymes, high-temperature shifts have not been examined for human topoisomerase IIalpha. Therefore, the effects of temperature on the DNA cleavage/religation activity of the enzyme were characterized. Human topoisomerase IIalpha undergoes two distinct transitions at high temperatures. The first transition occurs between 45 and 55 degrees C and is accompanied by a 6-fold increase in the level of DNA cleavage at 60 degrees C. It also leads to a loss of DNA strand passage activity, due primarily to an inability of ATP to convert the enzyme to a protein clamp. The enzyme alterations that accompany the first transition appear to be stable and do not revert at lower temperature. The second transition in human topoisomerase IIalpha occurs between 65 and 70 degrees C and correlates with a precipitous drop in the level of DNA scission. At 75 degrees C, cleavage falls well below amounts seen at 37 degrees C. This loss of DNA scission appears to result from a decrease in the forward rate of DNA cleavage rather than an increase in the religation rate. Finally, similar high-temperature alterations were observed for yeast topoisomerase II and human topoisomerase IIbeta, suggesting that parallel heat-induced transitions may be widespread among type II topoisomerases.
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Affiliation(s)
- K D Bromberg
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA
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36
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Viidik A. Experimental gerontology in the Nordic countries. Exp Gerontol 2001; 36:383-401. [PMID: 11250112 DOI: 10.1016/s0531-5565(00)00251-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Research in geriatric medicine developed in the Nordic countries in the 1950s, following the tradition from the United Kingdom. Quite early, longitudinal epidemiological studies of 'normal' ageing emerged. Now there are chairs in geriatric medicine at many of the medical schools. Experimental gerontology came much later, typically scattered in a variety of medical school departments. There is only one chair in gerontology (in Tampere). Two major research undertakings have emerged in recent years, the Danish Centre for Molecular Gerontology, and a cluster of research groups at the Division of Geriatrics at the Karolinska Institutet. Other research groups are found in Denmark at the universities in Aarhus, Copenhagen and Odense; in Finland at the universities in Jyväskylä, Kuopio, Tampere and Turku; and in Norway at the university in Trondheim. These activities are reviewed country-wise.
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Affiliation(s)
- A Viidik
- Institute of Anatomy, University of Aarhus, Universitetsparken, Bygning 230, DK-8000 C, Aarhus, Denmark.
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