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Velazquez EJ, Cress JD, Humpherys TB, Mortimer TO, Bellini DM, Skidmore JR, Smith KR, Robison RA, Weber SK, O’Neill KL. Selection of human single domain antibodies (sdAb) against thymidine kinase 1 and their incorporation into sdAb-Fc antibody constructs for potential use in cancer therapy. PLoS One 2022; 17:e0264822. [PMID: 35239730 PMCID: PMC8893706 DOI: 10.1371/journal.pone.0264822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 02/17/2022] [Indexed: 11/18/2022] Open
Abstract
Thymidine Kinase 1 (TK1) is primarily known as a cancer biomarker with good prognostic capabilities for both hematological and solid malignancies. However, recent studies targeting TK1 at protein and mRNA levels have shown that TK1 may be useful as a therapeutic target. In order to examine the use of TK1 as a therapeutic target, it is necessary to develop therapeutics specific for it. Single domain antibodies (sdAbs), represent an exciting approach for the development of immunotherapeutics due to their cost-effective production and higher tumor penetration than conventional antibodies. In this study, we isolated sdAb fragments specific to human TK1 from a human sdAb library. A total of 400 sdAbs were screened through 5 rounds of selection by monoclonal phage ELISA. The most sensitive sdAb fragments were selected as candidates for preclinical testing. The sdAb fragments showed specificity for human TK1 in phage ELISA, Western blot analysis and had an estimated limit of detection of 3.9 ng/ml for the antibody fragments 4-H-TK1_A1 and 4-H-TK1_D1. The antibody fragments were successfully expressed and used for detection of membrane associated TK1 (mTK1) through flow cytometry on cancer cells [lung (~95%), colon (~87%), breast (~53%)] and healthy human mononuclear cells (MNC). The most sensitive antibody fragments, 4-H-TK1_A1 and 4-H-TK1_D1 were fused to an engineered IgG1 Fc fragment. When added to cancer cells expressing mTK1 co-cultured with human MNCs, the anti-TK1-sdAb-IgG1_A1 and D1 were able to elicit a significant antibody-dependent cell-mediated cytotoxicity (ADCC) response against lung cancer cells compared to isotype controls (P<0.0267 and P<0.0265, respectively). To our knowledge this is the first time that the isolation and evaluation of human anti-TK1 single domain antibodies using phage display technology has been reported. The antibody fragments isolated here may represent a valuable resource for the detection and the targeting of TK1 on tumor cells.
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Affiliation(s)
- Edwin J. Velazquez
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Jordan D. Cress
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Tyler B. Humpherys
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Toni O. Mortimer
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - David M. Bellini
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Jonathan R. Skidmore
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kathryn R. Smith
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Richard A. Robison
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Scott K. Weber
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kim L. O’Neill
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
- * E-mail:
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Li N, Yang H, Yu Z, Li Y, Pan W, Wang H, Tang B. Nuclear-targeted siRNA delivery for long-term gene silencing. Chem Sci 2017; 8:2816-2822. [PMID: 28553519 PMCID: PMC5427680 DOI: 10.1039/c6sc04293g] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 01/19/2017] [Indexed: 02/06/2023] Open
Abstract
Developing effective nonviral siRNA delivery systems for long-term gene silencing remains a great challenge. Here we present a nuclear-targeted siRNA delivery system that can induce long-term gene silencing in cancer cells. The nanocarrier consists of gold nanoparticles modified with a dense shell of synthetic siRNAs and nuclear localization signal (NLS) peptides. The NLS peptide could translocate the nanocarrier into the nucleus and the siRNA was designed to target the promoter of thymidine kinase 1 and trigger the RNA-directed DNA methylation, thereby enabling the nuclear-targeted gene silencing. Compared with traditional gene silencing in cytoplasm, long-lasting gene knockdown could be achieved for the nuclear-targeted nanocarrier, which lasts for more than 30 days. The long-term gene silencing induced by nuclear-targeted siRNA delivery could effectively inhibit the proliferation of cancer cells and prevent the formation of a tumor in a mouse model.
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Affiliation(s)
- Na Li
- College of Chemistry , Chemical Engineering and Materials Science , Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong , Key Laboratory of Molecular and Nano Probes , Ministry of Education , Institute of Molecular and Nano Science , Shandong Normal University , Jinan 250014 , P. R. China .
| | - Huijun Yang
- College of Chemistry , Chemical Engineering and Materials Science , Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong , Key Laboratory of Molecular and Nano Probes , Ministry of Education , Institute of Molecular and Nano Science , Shandong Normal University , Jinan 250014 , P. R. China .
| | - Zhengze Yu
- College of Chemistry , Chemical Engineering and Materials Science , Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong , Key Laboratory of Molecular and Nano Probes , Ministry of Education , Institute of Molecular and Nano Science , Shandong Normal University , Jinan 250014 , P. R. China .
| | - Yanli Li
- College of Chemistry , Chemical Engineering and Materials Science , Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong , Key Laboratory of Molecular and Nano Probes , Ministry of Education , Institute of Molecular and Nano Science , Shandong Normal University , Jinan 250014 , P. R. China .
| | - Wei Pan
- College of Chemistry , Chemical Engineering and Materials Science , Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong , Key Laboratory of Molecular and Nano Probes , Ministry of Education , Institute of Molecular and Nano Science , Shandong Normal University , Jinan 250014 , P. R. China .
| | - Hongyu Wang
- College of Chemistry , Chemical Engineering and Materials Science , Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong , Key Laboratory of Molecular and Nano Probes , Ministry of Education , Institute of Molecular and Nano Science , Shandong Normal University , Jinan 250014 , P. R. China .
| | - Bo Tang
- College of Chemistry , Chemical Engineering and Materials Science , Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong , Key Laboratory of Molecular and Nano Probes , Ministry of Education , Institute of Molecular and Nano Science , Shandong Normal University , Jinan 250014 , P. R. China .
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Valente M, Timm J, Castillo-Acosta VM, Ruiz-Pérez LM, Balzarini T, Nettleship JE, Bird LE, Rada H, Wilson KS, González-Pacanowska D. Cell cycle regulation and novel structural features of thymidine kinase, an essential enzyme in Trypanosoma brucei. Mol Microbiol 2016; 102:365-385. [PMID: 27426054 DOI: 10.1111/mmi.13467] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2016] [Indexed: 11/28/2022]
Abstract
Thymidine kinase (TK) is a key enzyme in the pyrimidine salvage pathway which catalyzes the transfer of the γ-phosphate of ATP to 2'-deoxythymidine (dThd) forming thymidine monophosphate (dTMP). Unlike other type II TKs, the Trypanosoma brucei enzyme (TbTK) is a tandem protein with two TK homolog domains of which only the C-terminal one is active. In this study, we establish that TbTK is essential for parasite viability and cell cycle progression, independently of extracellular pyrimidine concentrations. We show that expression of TbTK is cell cycle regulated and that depletion of TbTK leads to strongly diminished dTTP pools and DNA damage indicating intracellular dThd to be an essential intermediate metabolite for the synthesis of thymine-derived nucleotides. In addition, we report the X-ray structure of the catalytically active domain of TbTK in complex with dThd and dTMP at resolutions up to 2.2 Å. In spite of the high conservation of the active site residues, the structures reveal a widened active site cavity near the nucleobase moiety compared to the human enzyme. Our findings strongly support TbTK as a crucial enzyme in dTTP homeostasis and identify structural differences within the active site that could be exploited in the process of rational drug design.
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Affiliation(s)
- Maria Valente
- Instituto de Parasitología y Biomedicina "López-Neyra", Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Jennifer Timm
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Víctor M Castillo-Acosta
- Instituto de Parasitología y Biomedicina "López-Neyra", Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Luis M Ruiz-Pérez
- Instituto de Parasitología y Biomedicina "López-Neyra", Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Tom Balzarini
- Instituto de Parasitología y Biomedicina "López-Neyra", Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Joanne E Nettleship
- The Oxford Protein Production Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, R92 Harwell, Didcot, Oxfordshire, OX11 0FA, UK
| | - Louise E Bird
- The Oxford Protein Production Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, R92 Harwell, Didcot, Oxfordshire, OX11 0FA, UK
| | - Heather Rada
- The Oxford Protein Production Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, R92 Harwell, Didcot, Oxfordshire, OX11 0FA, UK
| | - Keith S Wilson
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, YO10 5DD, UK.
| | - Dolores González-Pacanowska
- Instituto de Parasitología y Biomedicina "López-Neyra", Consejo Superior de Investigaciones Científicas, Granada, Spain.
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Abstract
Two different strategies have been developed for imaging the proliferative status of solid tumors with the functional imaging technique, Positron Emission Tomography (PET). The first strategy uses carbon-11 labeled thymidine and/or, more recently, fluorine-18 labeled thymidine analogs. These agents are a substrate for the enzyme thymidine kinase-1 (TK-1) and provide a pulse label of the number of cells in S phase. The second method for imaging the proliferative status of a tumor uses radiolabeled ligands that bind to the sigma-2 receptor which has a 10-fold higher density in proliferating (P) tumor cells versus quiescent (Q) tumor cells. This article compares and contrasts the two different strategies for imaging the proliferative status of solid tumors, and describes the strengths and weaknesses of each approach.
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López-Martínez B, Vilchis Ordoñez A, Salazar Garcia M, Klünder-Klünder M, Parra-Ortega I, Dorantes-Acosta E, Angeles-Floriano T. Thymidine Kinase: A Biomarker for Recently Diagnosed Acute Leukemia in Pediatric Patients According to the Cell Line Involved. Arch Med Res 2015; 46:630-4. [PMID: 26656666 DOI: 10.1016/j.arcmed.2015.11.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 11/23/2015] [Indexed: 10/22/2022]
Abstract
BACKGROUND AND AIMS Acute leukemia (AL) is a heterogeneous group of diseases characterized by a disorganized clone proliferation of hematopoietic cells. Thymidine kinase (TK) is a cell enzyme involved in DNA synthesis and is considered a cellular proliferation marker in some solid tumors. METHODS A cross-sectional prospective and comparative study was performed in the Federico Gomez Children's Hospital in Mexico (HIMFG, in Spanish) in 125 samples of patients of the HIMFG with AL and 138 samples of children without leukemia. Serum TK levels were determined for both groups. RESULTS Of the children with AL, 90 presented B-cell acute lymphoblastic leukemia (B-ALL); 13, T-cell acute lymphoblastic leukemia (T-ALL); and 22, acute myeloid leukemia (AML). A median (m) TK level of 23.7 IU (IQR 17-35.7) was observed in the group without AL and 91 IU (IQR 98-392) in the AL group. This difference was statistically significant (p <0.0001). When analyzing TK levels according to the type of leukemia, the m was as follows: 68 IU (IQR 35-118) for B-ALL, 470 IU (IQR 88-750) for AML, and 1678 IU (IQR 288-2108) for T- ALL. CONCLUSION TK is an enzyme showing heterogeneous levels in B-ALL although it is significantly increased in 90% of patients with T-ALL and AML.
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Affiliation(s)
- Briceida López-Martínez
- Division of Auxiliary Diagnostic Services, Hospital Infantil de México Federico Gómez, México, D.F., México
| | - Armando Vilchis Ordoñez
- Department of Clinical Laboratory, Hospital Infantil de México Federico Gómez, México, D.F., México
| | - Marcela Salazar Garcia
- Research Laboratory in Developmental Biology and Experimental Teratogenesis, Hospital Infantil de México Federico Gómez, México, D.F., México
| | - Miguel Klünder-Klünder
- Research Department in Community Health, Hospital Infantil de México Federico Gómez, México, D.F., México
| | - Israel Parra-Ortega
- Department of Clinical Laboratory, Hospital Infantil de México Federico Gómez, México, D.F., México
| | - Elisa Dorantes-Acosta
- Hematology-Oncology Department, Hospital Infantil de México Federico Gómez, México, D.F., México
| | - Tania Angeles-Floriano
- Department of Clinical Laboratory, Hospital Infantil de México Federico Gómez, México, D.F., México.
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Structural and Kinetic Characterization of Thymidine Kinase from Leishmania major. PLoS Negl Trop Dis 2015; 9:e0003781. [PMID: 25978379 PMCID: PMC4433323 DOI: 10.1371/journal.pntd.0003781] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 04/23/2015] [Indexed: 01/17/2023] Open
Abstract
Leishmania spp. is a protozoan parasite and the causative agent of leishmaniasis. Thymidine kinase (TK) catalyses the transfer of the γ-phosphate of ATP to 2’-deoxythymidine (dThd) forming thymidine monophosphate (dTMP). L. major Type II TK (LmTK) has been previously shown to be important for infectivity of the parasite and therefore has potential as a drug target for anti-leishmanial therapy. In this study, we determined the enzymatic properties and the 3D structures of holo forms of the enzyme. LmTK efficiently phosphorylates dThd and dUrd and has high structural homology to TKs from other species. However, it significantly differs in its kinetic properties from Trypanosoma brucei TK since purines are not substrates of the enzyme and dNTPs such as dUTP inhibit LmTK. The enzyme had Km and kcat values for dThd of 1.1 μM and 2.62 s-1 and exhibits cooperative binding for ATP. Additionally, we show that the anti-retroviral prodrug zidovudine (3-azido-3-deoxythymidine, AZT) and 5’-modified dUrd can be readily phosphorylated by LmTK. The production of recombinant enzyme at a level suitable for structural studies was achieved by the construction of C-terminal truncated versions of the enzyme and the use of a baculoviral expression system. The structures of the catalytic core of LmTK in complex with dThd, the negative feedback regulator dTTP and the bi-substrate analogue AP5dT, were determined to 2.74, 3.00 and 2.40 Å, respectively, and provide the structural basis for exclusion of purines and dNTP inhibition. The results will aid the process of rational drug design with LmTK as a potential target for anti-leishmanial drugs. The DNA within the genome of an organism encodes all the information, firstly for reproduction and secondly for translation into proteins—the workhorses of a biological cell. Proteins carry out a host of essential biological activities within the cell. A full understanding of a protein now requires determination of a wide range of its properties in solution in the cell and in vitro in solution, but in addition, its 3D structure usually determined by X-ray crystallography. Leishmania species are a family of protozoan parasites of humans and the causative agent of leishmaniasis, a major health concern in the developing world. Selective inhibition of key enzymes in these parasites is a key route for combating these diseases. We have focused our work on thymidine kinase, an important enzyme from Leishmania major, and a potential target for the development of new drugs. We have carried out kinetic studies of the enzyme’s activity in solution and determined its 3D crystal structure, enabling rational drug design.
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Lauciello L, Kappes B, Scapozza L, Perozzo R. Expression, purification and biochemical characterization of recombinant Ca-dependent protein kinase 2 of the malaria parasite Plasmodium falciparum. Protein Expr Purif 2013; 90:170-7. [PMID: 23792132 DOI: 10.1016/j.pep.2013.06.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 06/02/2013] [Accepted: 06/06/2013] [Indexed: 01/17/2023]
Abstract
Calcium-dependent protein kinases (CDPKs) are serine/threonine kinases that react in response to calcium which functions as a trigger for several mechanisms in plants and invertebrates, but not in mammals. Recent structural studies have defined the role of calcium in the activation of CDPKs and have elucidated the important structural changes caused by calcium in order to allow the kinase domain of CDPK to bind and phosphorylate the substrate. However, the role of autophosphorylation in CDPKs is still not fully understood. In Plasmodium falciparum, seven CDPKs have been identified by sequence comparison, and four of them have been characterized and assigned to play a role in parasite motility, gametogenesis and egress from red blood cells. Although PfCDPK2 was already discovered in 1997, little is known about this enzyme and its metabolic role. In this work, we have expressed and purified PfCDPK2 at high purity in its unphosphorylated form and characterized its biochemical properties. Moreover, propositions about putative substrates in P. falciparum are made based on the analysis of the phosphorylation sites on the artificial substrate myelin basic protein (MBP).
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Affiliation(s)
- Leonardo Lauciello
- Pharmaceutical Biochemistry Group, School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland
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Meščić A, Krištafor S, Novaković I, Osmanović A, Müller U, Završnik D, Ametamey SM, Scapozza L, Raić-Malić S. C-5 hydroxyethyl and hydroxypropyl acyclonucleosides as substrates for thymidine kinase of herpes simplex virus type 1 (HSV-1 TK): syntheses and biological evaluation. Molecules 2013; 18:5104-24. [PMID: 23644977 PMCID: PMC6270122 DOI: 10.3390/molecules18055104] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 04/16/2013] [Accepted: 04/25/2013] [Indexed: 11/16/2022] Open
Abstract
The efficient syntheses of 5-(2-hydroxyethyl)- and 5-(3-hydroxypropyl)-substituted pyrimidine derivatives bearing 2,3-dihydroxypropyl, acyclovir-, ganciclovir- and penciclovir-like side chains are reported. A synthetic approach that included the alkylation of an N-anionic-5-substituted pyrimidine intermediate (method A) provided the target acyclonucleosides in significantly higher overall yields in comparison to those obtained by method B using sylilation reaction. The phosphorylation assays of novel compounds as potential substrates for thymidine kinase of herpes simplex virus type 1 (HSV-1 TK) showed that solely pyrimidine 5-substituted acyclonucleosides with a penciclovir-like side chain acted as a fraudulent substrates of HSV-1 TK. Moreover, the uracil derivative with penciclovir-like side chain with less bulky 2-hydroxyethyl substituent at C-5 proved to be a better substrate than the corresponding one with a 3-hydroxypropyl substituent. Therefore, this acyclonucleoside was selected as a lead compound for the development of a positron emission tomography HSV-1 TK activity imaging agent.
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Affiliation(s)
- Andrijana Meščić
- Department of Organic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 20, HR-10000 Zagreb, Croatia; E-Mails: (A.M.); (S.K.)
| | - Svjetlana Krištafor
- Department of Organic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 20, HR-10000 Zagreb, Croatia; E-Mails: (A.M.); (S.K.)
| | - Ivana Novaković
- Pharmaceutical Biochemistry, School of Pharmaceutical Sciences, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva 4, Switzerland; E-Mails: (I.N.); (L.S.)
| | - Amar Osmanović
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Sarajevo, Zmaja od Bosne 8, BIH-71 000 Sarajevo, Bosnia and Herzegovina; E-Mails: (A.O.); (D.Z.)
| | - Ursina Müller
- Center for Radiopharmaceutical Sciences, ETH Zurich (Swiss Federal Institute of Technology), Wolfgang-Pauli Strasse 10, CH-8093 Zurich, Switzerland; E-Mails: (U.M.); (S.M.A.)
| | - Davorka Završnik
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Sarajevo, Zmaja od Bosne 8, BIH-71 000 Sarajevo, Bosnia and Herzegovina; E-Mails: (A.O.); (D.Z.)
| | - Simon M. Ametamey
- Center for Radiopharmaceutical Sciences, ETH Zurich (Swiss Federal Institute of Technology), Wolfgang-Pauli Strasse 10, CH-8093 Zurich, Switzerland; E-Mails: (U.M.); (S.M.A.)
| | - Leonardo Scapozza
- Pharmaceutical Biochemistry, School of Pharmaceutical Sciences, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva 4, Switzerland; E-Mails: (I.N.); (L.S.)
| | - Silvana Raić-Malić
- Department of Organic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 20, HR-10000 Zagreb, Croatia; E-Mails: (A.M.); (S.K.)
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Mutahir Z, Clausen AR, Andersson KM, Wisen SM, Munch-Petersen B, Piškur J. Thymidine kinase 1 regulatory fine-tuning through tetramer formation. FEBS J 2013; 280:1531-41. [PMID: 23351158 DOI: 10.1111/febs.12154] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 01/21/2013] [Accepted: 01/22/2013] [Indexed: 11/30/2022]
Abstract
Thymidine kinase 1 (TK1) provides a crucial precursor, deoxythymidine monophosphate, for nucleic acid synthesis, and the activity of TK1 increases by up to 200-fold during the S-phase of cell division in humans. An important part of the regulatory checkpoints is the ATP and enzyme concentration-dependent transition of TK1 from a dimer with low catalytic efficiency to a tetramer with high catalytic efficiency. This regulatory fine-tuning serves as an additional control to provide a balanced pool of nucleic acid precursors in the cell. We subcloned and over-expressed 10 different TK1s, originating from widely different organisms, and characterized their kinetic and oligomerization properties. Whilst bacteria, plants and Dictyostelium only exhibited dimeric TK1, we found that all animals had a tetrameric TK1. However, a clear ATP-dependent switch between dimer and tetramer was found only in higher vertebrates and was especially pronounced in mammalian and bird TK1s. We suggest that the dimer form is the original form and that the tetramer originated in the animal lineage after the split of Dictyostelium and the lineages leading to invertebrates and vertebrates. The efficient switching mechanism was probably first established in warm-blooded animals when they separated from the rest of the vertebrates.
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Hanan S, Jagarlamudi KK, Liya W, Ellen H, Staffan E. Quaternary structures of recombinant, cellular, and serum forms of thymidine kinase 1 from dogs and humans. BMC BIOCHEMISTRY 2012; 13:12. [PMID: 22741536 PMCID: PMC3411398 DOI: 10.1186/1471-2091-13-12] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 06/28/2012] [Indexed: 12/29/2022]
Abstract
Background Thymidine kinase 1 (TK1) is a salvage enzyme involved in DNA precursor synthesis, and its expression is proliferation dependent. A serum form of TK1 has been used as a biomarker in human medicine for many years and more recently to monitor canine lymphoma. Canine TK1 has not been cloned and studied. Therefore, dog and human TK1 cDNA were cloned and expressed, and the recombinant enzymes characterized. The serum and cellular forms of canine and human TK1 were studied by size-exclusion chromatography and the level of TK1 protein was determined using polyclonal and monoclonal anti-TK1 antibodies. Results Canine TK1 phosphorylated the thymidine (dThd) analog 3'-azido-thymidine (AZT) as efficiently as it did dThd, whereas AZT phosphorylation by human TK1 was less efficient than that of dThd. Dog TK1 was also more thermostable and pH tolerant than the human enzyme. Oligomeric forms were observed with both enzymes in addition to the tetrameric and dimeric forms. Cellular TK1 was predominantly seen in dimeric and tetrameric forms, in the case of both dog TK1 from MDCK cells and human TK1 from CEM cells. Active serum TK1 was found mainly in a high molecular weight form, and treatment with a reducing agent shifted the high molecular weight complex to lower molecular weight forms with reduced total activity. Western blot analysis demonstrated a polypeptide of 26 kDa (dog) and 25 kDa (human) for cellular and serum TK1. There was no direct correlation between serum TK1 activity and protein level. It appears that a substantial fraction of serum TK1 is not enzymatically active. Conclusions These results suggest that the serum TK1 protein differs from cellular or recombinant forms, is more active in high molecular weight complexes, and is sensitive to reducing agents. The results presented here provide important information for the future development and use of serum TK1 as a diagnostic biomarker in human and veterinary medicine.
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Affiliation(s)
- Sharif Hanan
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, BMC, 575, Uppsala, S-751 23, Sweden
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Müller U, Martić M, Kraljević TG, Krištafor S, Ross TL, Ranadheera C, Müller A, Born M, Krämer SD, Raić-Malić S, Ametamey SM. Synthesis and evaluation of a C-6 alkylated pyrimidine derivative for the in vivo imaging of HSV1-TK gene expression. Nucl Med Biol 2012; 39:235-46. [PMID: 21958846 DOI: 10.1016/j.nucmedbio.2011.07.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 06/22/2011] [Accepted: 07/12/2011] [Indexed: 11/30/2022]
Affiliation(s)
- Ursina Müller
- Institute of Pharmaceutical Sciences, ETH Zurich, 8093 Zurich, Switzerland
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Kuettel S, Greenwald J, Kostrewa D, Ahmed S, Scapozza L, Perozzo R. Crystal structures of T. b. rhodesiense adenosine kinase complexed with inhibitor and activator: implications for catalysis and hyperactivation. PLoS Negl Trop Dis 2011; 5:e1164. [PMID: 21629723 PMCID: PMC3101181 DOI: 10.1371/journal.pntd.0001164] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 03/15/2011] [Indexed: 12/02/2022] Open
Abstract
Background The essential purine salvage pathway of Trypanosoma brucei bears interesting catalytic enzymes for chemotherapeutic intervention of Human African Trypanosomiasis. Unlike mammalian cells, trypanosomes lack de novo purine synthesis and completely rely on salvage from their hosts. One of the key enzymes is adenosine kinase which catalyzes the phosphorylation of ingested adenosine to form adenosine monophosphate (AMP) utilizing adenosine triphosphate (ATP) as the preferred phosphoryl donor. Methods and Findings Here, we present the first structures of Trypanosoma brucei rhodesiense adenosine kinase (TbrAK): the structure of TbrAK in complex with the bisubstrate inhibitor P1,P5-di(adenosine-5′)-pentaphosphate (AP5A) at 1.55 Å, and TbrAK complexed with the recently discovered activator 4-[5-(4-phenoxyphenyl)-2H-pyrazol-3-yl]morpholine (compound 1) at 2.8 Å resolution. Conclusions The structural details and their comparison give new insights into substrate and activator binding to TbrAK at the molecular level. Further structure-activity relationship analyses of a series of derivatives of compound 1 support the observed binding mode of the activator and provide a possible mechanism of action with respect to their activating effect towards TbrAK. Recently, we discovered that 4-[5-(4-phenoxyphenyl)-2H-pyrazol-3-yl]morpholine (compound 1) and its derivatives exhibit specific antitrypanosomal activity toward T. b. rhodesiense, the causative agent of the acute form of HAT. We found that compound 1 would target the parasite adenosine kinase (TbrAK), an important enzyme of the purine salvage pathway, by acting via hyperactivation of the enzyme. This represents a novel and hitherto unexplored strategy for the development of trypanocides. These findings prompted us to investigate the mechanism of action at the molecular level. The present study reports the first three-dimensional crystal structures of TbrAK in complex with the bisubstrate inhibitor AP5A, and in complex with the activator (compound 1). The subsequent structural analysis sheds light on substrate and activator binding, and gives insight into the possible mechanism leading to hyperactivation. Further structure-activity relationships in terms of TbrAK activation properties support the observed binding mode of compound 1 in the crystal structure and may open the field for subsequent optimization of this compound series.
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Affiliation(s)
- Sabine Kuettel
- Pharmaceutical Biochemistry Group, School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Lausanne, Switzerland
| | - Jason Greenwald
- Laboratory of Physical Chemistry, ETH Zurich, Zurich, Switzerland
| | - Dirk Kostrewa
- Gene Center Munich, Department of Biochemistry, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Shaheen Ahmed
- Pharmaceutical Biochemistry Group, School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Lausanne, Switzerland
| | - Leonardo Scapozza
- Pharmaceutical Biochemistry Group, School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Lausanne, Switzerland
- * E-mail: (LS); (RP)
| | - Remo Perozzo
- Pharmaceutical Biochemistry Group, School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Lausanne, Switzerland
- * E-mail: (LS); (RP)
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13
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Munch-Petersen B. Enzymatic regulation of cytosolic thymidine kinase 1 and mitochondrial thymidine kinase 2: a mini review. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2010; 29:363-9. [PMID: 20544521 DOI: 10.1080/15257771003729591] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The central enzyme on the de novo pathway for synthesis of DNA precursors, the deoxyribonucleoside triphosphates, is ribonucleotide reductase (RNR). Deoxythymidine triphosphate (dTTP) has a key role in control of RNR activity shifting the specificity from pyrimidine to purine nucleotide reduction. Apart from the complex de novo synthesis of dTTP through UDP reduction, dTTP is provided through salvage of thymidine catalyzed by the thymidine kinases, the cytosolic and cell cycle regulated TK1 and the mitochondrial and constitutively expressed TK2. The complex enzymatic regulation of TK1 and TK2 and the possible physiological significance of this regulation will be discussed.
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Affiliation(s)
- B Munch-Petersen
- Department of Science, Systems and Models NSM, Roskilde, Denmark.
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14
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Sun XE, Sharling L, Muthalagi M, Mudeppa DG, Pankiewicz KW, Felczak K, Rathod PK, Mead J, Striepen B, Hedstrom L. Prodrug activation by Cryptosporidium thymidine kinase. J Biol Chem 2010; 285:15916-22. [PMID: 20231284 DOI: 10.1074/jbc.m110.101543] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cryptosporidium spp. cause acute gastrointestinal disease that can be fatal for immunocompromised individuals. These protozoan parasites are resistant to conventional antiparasitic chemotherapies and the currently available drugs to treat these infections are largely ineffective. Genomic studies suggest that, unlike other protozoan parasites, Cryptosporidium is incapable of de novo pyrimidine biosynthesis. Curiously, these parasites possess redundant pathways to produce dTMP, one involving thymidine kinase (TK) and the second via thymidylate synthase-dihydrofolate reductase. Here we report the expression and characterization of TK from C. parvum. Unlike other TKs, CpTK is a stable trimer in the presence and absence of substrates and the activator dCTP. Whereas the values of k(cat) = 0.28 s(-1) and K(m)(,ATP) = 140 microm are similar to those of human TK1, the value of K(m)(thymidine) = 48 microm is 100-fold greater, reflecting the abundance of thymidine in the gastrointestinal tract. Surprisingly, the antiparasitic nucleosides AraT, AraC, and IDC are not substrates for CpTK, indicating that Cryptosporidium possesses another deoxynucleoside kinase. Trifluoromethyl thymidine and 5-fluorodeoxyuridine are good substrates for CpTK, and both compounds inhibit parasite growth in an in vitro model of C. parvum infection. Trifluorothymidine is also effective in a mouse model of acute disease. These observations suggest that CpTK-activated pro-drugs may be an effective strategy for treating cryptosporidiosis.
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Affiliation(s)
- Xin E Sun
- Brandeis University, Waltham, Massachusetts 02454, USA
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15
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Radivoyevitch T. Mass action models versus the Hill model: an analysis of tetrameric human thymidine kinase 1 positive cooperativity. Biol Direct 2009; 4:49. [PMID: 20003201 PMCID: PMC2799445 DOI: 10.1186/1745-6150-4-49] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Accepted: 12/09/2009] [Indexed: 11/15/2022] Open
Abstract
Background The Hill coefficient characterizes the extent to which an enzyme exhibits positive or negative cooperativity, but it provides no information regarding the mechanism of cooperativity. In contrast, models based on the equilibrium concept of mass action can suggest mechanisms of cooperativity, but there are often many such models and often many with too many parameters. Results Mass action models of tetrameric human thymidine kinase 1 (TK1) activity data were formed as pairs of plausible hypotheses that per site activities and binary dissociation constants are equal within contiguous stretches of the number of substrates bound. Of these, six 3-parameter models were fitted to 5 different datasets. Akaike's Information Criterion was then used to form model probability weighted averages. The literature average of the 5 model averages was K = (0.85, 0.69, 0.65, 0.51) μM and k = (3.3, 3.9, 4.1, 4.1) sec-1 where K and k are per-site binary dissociation constants and activities indexed by the number of substrates bound to the tetrameric enzyme. Conclusion The TK1 model presented supports both K and k positive cooperativity. Three-parameter mass action models can and should replace the 3-parameter Hill model. Reviewers This article was reviewed by Philip Hahnfeldt, Fangping Mu (nominated by William Hlavacek) and Rainer Sachs.
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Affiliation(s)
- Tomas Radivoyevitch
- Department of Epidemiology and Biostatistics, Case Western Reserve University, Cleveland, Ohio 44106, USA.
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16
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Hazra S, Sabini E, Ort S, Konrad M, Lavie A. Extending thymidine kinase activity to the catalytic repertoire of human deoxycytidine kinase. Biochemistry 2009; 48:1256-63. [PMID: 19159229 DOI: 10.1021/bi802062w] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Salvage of nucleosides in the cytosol of human cells is carried out by deoxycytidine kinase (dCK) and thymidine kinase 1 (TK1). Whereas TK1 is only responsible for thymidine phosphorylation, dCK is capable of converting dC, dA, and dG into their monophosphate forms. Using structural data on dCK, we predicted that select mutations at the active site would, in addition to making the enzyme faster, expand the catalytic repertoire of dCK to include thymidine. Specifically, we hypothesized that steric repulsion between the methyl group of the thymine base and Arg104 is the main factor preventing the phosphorylation of thymidine by wild-type dCK. Here we present kinetic data on several dCK variants where Arg104 has been replaced by select residues, all performed in combination with the mutation of Asp133 to an alanine. We show that several hydrophobic residues at position 104 endow dCK with thymidine kinase activity. Depending on the exact nature of the mutations, the enzyme's substrate preference is modified. The R104M-D133A double mutant is a pyrimidine-specific enzyme due to large K(m) values with purines. The crystal structure of the double mutant R104M-D133A in complex with the L-form of thymidine supplies a structural explanation for the ability of this variant to phosphorylate thymidine and thymidine analogs. The replacement of Arg104 by a smaller residue allows L-dT to bind deeper into the active site, making space for the C5-methyl group of the thymine base. The unique catalytic properties of several of the mutants make them good candidates for suicide-gene/protein-therapy applications.
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Affiliation(s)
- Saugata Hazra
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, 900 S. Ashland (M/C 669), Chicago, Illinois 60607, USA
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17
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Production of recombinant proteins in the lon-deficient BL21(DE3) strain of Escherichia coli in the absence of the DnaK chaperone. Appl Environ Microbiol 2009; 75:3803-7. [PMID: 19346357 DOI: 10.1128/aem.00255-09] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To eliminate unavoidable contamination of purified recombinant proteins by DnaK, we present a unique approach employing a BL21(DE3) DeltadnaK strain of Escherichia coli. Selected representative purified proteins remained soluble, correctly assembled, and active. This finding establishes DnaK dispensability for protein production in BL21(DE3), which is void of Lon protease, key to eliminating unfolded proteins.
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18
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Munch-Petersen B. Reversible tetramerization of human TK1 to the high catalytic efficient form is induced by pyrophosphate, in addition to tripolyphosphates, or high enzyme concentration. FEBS J 2008; 276:571-80. [DOI: 10.1111/j.1742-4658.2008.06804.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Segura-Peña D, Lutz S, Monnerjahn C, Konrad M, Lavie A. Binding of ATP to TK1-like enzymes is associated with a conformational change in the quaternary structure. J Mol Biol 2007; 369:129-41. [PMID: 17407781 PMCID: PMC1899836 DOI: 10.1016/j.jmb.2007.02.104] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Revised: 01/30/2007] [Accepted: 02/21/2007] [Indexed: 11/28/2022]
Abstract
Human thymidine kinase 1 (hTK1) and structurally related TKs from other organisms catalyze the initial phosphorylation step in the thymidine salvage pathway. Though ATP is known to be the preferred phosphoryl donor for TK1-like enzymes, its exact binding mode and effect on the oligomeric state has not been analyzed. Here we report the structures of hTK1 and of the Thermotoga maritima thymidine kinase (TmTK) in complex with the bisubstrate inhibitor TP4A. The TmTK-TP4A structure reveals that the adenosine moiety of ATP binds at the subunit interface of the homotetrameric enzyme and that the majority of the ATP-enzyme interactions occur between the phosphate groups and the P-loop. In the hTK1 structure the adenosine group of TP4A exhibited no electron density. This difference between hTK1 and TmTK is rationalized by a difference in the conformation of their quaternary structure. A more open conformation, as seen in the TmTK-TP4A complex structure, is required to provide space for the adenosine moiety. Our analysis supports the formation of an analogous open conformation in hTK1 upon ATP binding.
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Affiliation(s)
- Dario Segura-Peña
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, 900 South Ashland Avenue, Chicago, IL 60607, USA
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20
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Smith RF, Freyer MW, Lewis EA. Biophysical characterization of vaccinia virus thymidine kinase substrate utilization. J Virol Methods 2007; 142:151-8. [PMID: 17335913 DOI: 10.1016/j.jviromet.2007.01.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Revised: 01/15/2007] [Accepted: 01/23/2007] [Indexed: 11/18/2022]
Abstract
To provide information for the development of new antiviral compounds that inhibit orthopoxviruses, further characterization of the kinetics and thermodynamics that underlie substrate utilization reactions of vaccinia virus thymidine kinase (VVTK) has been undertaken. The kinetics of 2'deoxythymidine phosphorylation by VVTK and the thermodynamics of complex formation between VVTK and the substrate 2' deoxythymidine were determined using spectroscopic and calorimetric techniques. These studies demonstrated that kinetic parameters for 2' deoxythymidine phosphorylation by VVTK were 25 microM and 0.2s(-1) for K(m) and k(cat), respectively. The enthalpy change, Delta H, for the enzyme catalyzed reaction is -18.1 kcal/mol. Thermodynamic studies for the formation of the enzyme substrate complex demonstrated a binding affinity (K(a)) of 4 x 10(4)M(-1), an enthalpy change for binding (Delta H) of -17.4 kcal/mol, and a reaction stoichiometry of two molecules of substrate binding to each enzyme tetramer. Kinetic and thermodynamic data were in agreement (K(a) approximately 1/K(m)) and showed similarities to literature values reported for herpes simplex virus thymidine kinase (HSV-TK) and human thymidine kinase 1 (hTK1) with respect to k(cat) but not with respect to K(m). The K(m) value found for VVTK in this study is nearly two orders of magnitude larger than the values reported for the hTK1 and the HSV TK enzymes.
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Affiliation(s)
- Robert F Smith
- Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, AZ 86011-5698, USA
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21
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Kosinska U, Carnrot C, Sandrini MPB, Clausen AR, Wang L, Piskur J, Eriksson S, Eklund H. Structural studies of thymidine kinases from Bacillus anthracis and Bacillus cereus provide insights into quaternary structure and conformational changes upon substrate binding. FEBS J 2006; 274:727-37. [PMID: 17288553 DOI: 10.1111/j.1742-4658.2006.05617.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Thymidine kinase (TK) is the key enzyme in salvaging thymidine to produce thymidine monophosphate. Owing to its ability to phosphorylate nucleoside analogue prodrugs, TK has gained attention as a rate-limiting drug activator. We describe the structures of two bacterial TKs, one from the pathogen Bacillus anthracis in complex with the substrate dT, and the second from the food-poison-associated Bacillus cereus in complex with the feedback inhibitor dTTP. Interestingly, in contrast with previous structures of TK in complex with dTTP, in this study dTTP occupies the phosphate donor site and not the phosphate acceptor site. This results in several conformational changes compared with TK structures described previously. One of the differences is the way tetramers are formed. Unlike B. anthracis TK, B. cereus TK shows a loose tetramer. Moreover, the lasso-domain is in open conformation in B. cereus TK without any substrate in the active site, whereas in B. anthracis TK the loop conformation is closed and thymidine occupies the active site. Another conformational difference lies within a region of 20 residues that we refer to as phosphate-binding beta-hairpin. The phosphate-binding beta-hairpin seems to be a flexible region of the enzyme which becomes ordered upon formation of hydrogen bonds to the alpha-phosphate of the phosphate donor, dTTP. In addition to descriptions of the different conformations that TK may adopt during the course of reaction, the oligomeric state of the enzyme is investigated.
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Affiliation(s)
- Urszula Kosinska
- Department of Molecular Biology, Swedish University of Agricultural Sciences, Uppsala Biomedical Centre, Sweden
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