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Wińska P, Sobiepanek A, Pawlak K, Staniszewska M, Cieśla J. Phosphorylation of Thymidylate Synthase and Dihydrofolate Reductase in Cancer Cells and the Effect of CK2α Silencing. Int J Mol Sci 2023; 24:ijms24033023. [PMID: 36769342 PMCID: PMC9917831 DOI: 10.3390/ijms24033023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 01/30/2023] [Accepted: 02/01/2023] [Indexed: 02/08/2023] Open
Abstract
Our previous research suggests an important regulatory role of CK2-mediated phosphorylation of enzymes involved in the thymidylate biosynthesis cycle, i.e., thymidylate synthase (TS), dihydrofolate reductase (DHFR), and serine hydroxymethyltransferase (SHMT). The aim of this study was to show whether silencing of the CK2α gene affects TS and DHFR expression in A-549 cells. Additionally, we attempted to identify the endogenous kinases that phosphorylate TS and DHFR in CCRF-CEM and A-549 cells. We used immunodetection, immunofluorescence/confocal analyses, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), in-gel kinase assay, and mass spectrometry analysis. Our results demonstrate that silencing of the CK2α gene in lung adenocarcinoma cells significantly increases both TS and DHFR expression and affects their cellular distribution. Additionally, we show for the first time that both TS and DHFR are very likely phosphorylated by endogenous CK2 in two types of cancer cells, i.e., acute lymphoblastic leukaemia and lung adenocarcinoma. Moreover, our studies indicate that DHFR is phosphorylated intracellularly by CK2 to a greater extent in leukaemia cells than in lung adenocarcinoma cells. Interestingly, in-gel kinase assay results indicate that the CK2α' isoform was more active than the CK2α subunit. Our results confirm the previous studies concerning the physiological relevance of CK2-mediated phosphorylation of TS and DHFR.
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Affiliation(s)
- Patrycja Wińska
- Chair of Drug and Cosmetics Biotechnology, Faculty of Chemistry, Warsaw University of Technology, 00-664 Warsaw, Poland
- Correspondence: (P.W.); (M.S.); Tel.: +48-222-345-573 (P.W.); +48-606-438-241 (M.S.)
| | - Anna Sobiepanek
- Chair of Drug and Cosmetics Biotechnology, Faculty of Chemistry, Warsaw University of Technology, 00-664 Warsaw, Poland
| | - Katarzyna Pawlak
- Chair of Analytical Chemistry, Faculty of Chemistry, Warsaw University of Technology, 00-664 Warsaw, Poland
| | - Monika Staniszewska
- Centre for Advanced Materials and Technologies, Warsaw University of Technology, Poleczki 19, 02-822 Warsaw, Poland
- Correspondence: (P.W.); (M.S.); Tel.: +48-222-345-573 (P.W.); +48-606-438-241 (M.S.)
| | - Joanna Cieśla
- Chair of Drug and Cosmetics Biotechnology, Faculty of Chemistry, Warsaw University of Technology, 00-664 Warsaw, Poland
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Wińska P, Widło Ł, Senkara E, Koronkiewicz M, Cieśla JM, Krzyśko A, Skierka K, Cieśla J. Inhibition of Protein Kinase CK2 Affects Thymidylate Synthesis Cycle Enzyme Level and Distribution in Human Cancer Cells. Front Mol Biosci 2022; 9:847829. [PMID: 35281258 PMCID: PMC8914513 DOI: 10.3389/fmolb.2022.847829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 01/31/2022] [Indexed: 11/13/2022] Open
Abstract
Thymidylate synthase (TS), dihydrofolate reductase (DHFR), and serine hydroxymethyltransferase (SHMT) constitute the thymidylate synthesis cycle providing thymidylate for DNA synthesis and repair. Our previous studies indicated that TS and DHFR are the substrates of protein kinase CK2. This work has been aimed at the elucidation of the effect of CK2 activity on cell cycle progression, thymidylate synthesis enzyme expression and localization, and the role of CK2-mediated TS phosphorylation in in vitro di- and trimolecular complex formation. The results were obtained by means of western blot, confocal microscopy, flow cytometry, quantitative polymerase chain reaction (QPCR), quartz crystal microbalance with dissipation monitoring (QCM-D), and microthermophoresis (MST). Our research indicates that CK2 inhibition does not change the levels of the transcripts; however, it affects the protein levels of DHFR and TS in both tested cell lines, i.e., A549 and CCRF-CEM, and the level of SHMT1 in CCRF-CEM cells. Moreover, we show that CK2-mediated phosphorylation of TS enables the protein (pTS) interaction with SHMT1 and leads to the stability of the tri-complex containing SHMT1, DHFR, and pTS. Our results suggest an important regulatory role of CK2-mediated phosphorylation for inter- and intracellular protein level of enzymes involved in the thymidylate biosynthesis cycle.
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Affiliation(s)
- Patrycja Wińska
- Chair of Drug and Cosmetics Biotechnology, Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland
- *Correspondence: Patrycja Wińska, ; Joanna Cieśla,
| | - Łukasz Widło
- Chair of Drug and Cosmetics Biotechnology, Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland
| | - Elżbieta Senkara
- Chair of Drug and Cosmetics Biotechnology, Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland
| | | | - Jarosław M. Cieśla
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Alicja Krzyśko
- Chair of Drug and Cosmetics Biotechnology, Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland
| | - Katarzyna Skierka
- Chair of Drug and Cosmetics Biotechnology, Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland
| | - Joanna Cieśla
- Chair of Drug and Cosmetics Biotechnology, Faculty of Chemistry, Warsaw University of Technology, Warsaw, Poland
- *Correspondence: Patrycja Wińska, ; Joanna Cieśla,
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Lee GY, Bong JH, Jung J, Kang MJ, Jose J, Pyun JC. Application of a thermophoretic immunoassay in the diagnosis of lupus using outer membrane particles from E. coli. Biosens Bioelectron 2020; 156:112110. [PMID: 32174550 DOI: 10.1016/j.bios.2020.112110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 02/02/2020] [Accepted: 02/18/2020] [Indexed: 10/24/2022]
Abstract
Thermophoresis is the physical diffusion of molecules from hot to cold induced by a thermal gradient. Thermophoresis has been used to evaluate the interaction of biomolecules in solution. In this study, the outer membrane from E. coli was isolated and used to produce OM particles with a diameter of approximately 100 nm. These prepared OM particles were applied in a thermophoretic immunoassay. First, outer membrane (OM) particles with lipopolysaccharides (LPS) and anti-LPS antibodies were used as a model to demonstrate proof of concept and the difference in E. coli thermophoresis was explained by the changes in the molecular surface area (A) and effective charge (σeff). The hydrodynamic size of the molecules was measured as a changing parameter, molecular surface area (A), by dynamic laser scattering (DLS), and the zeta potential was measured as a changing parameter of effective charge (σeff) and then evaluated by the Soret equation. Using the hydrodynamic size and zeta potential values, the interaction between the antigen (OM particle with LPS) and antibody (anti-LPS antibodies) could be monitored and the results were fitted to the thermophoretic immunoassay using the Soret coefficient and equation. Finally, this OM-based immunoassay was applied to the medical diagnosis of systemic lupus erythematosus. Here, OM particles with Ro and La proteins were used to analyze the autoantibodies in patient and control sera. Thermophoretic immunoassay results were also compared to the fitted analysis using hydrodynamic size and zeta potential values and the Soret coefficient and equation.
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Affiliation(s)
- Ga-Yeon Lee
- Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749, South Korea
| | - Ji-Hong Bong
- Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749, South Korea
| | - Jaeyong Jung
- Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749, South Korea
| | - Min-Jung Kang
- Korea Institute of Science and Technology, Seoul, South Korea
| | - Joachim Jose
- Institute of Pharmaceutical and Medical Chemistry, University of Münster, Münster, Germany
| | - Jae-Chul Pyun
- Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749, South Korea.
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Broza YY, Zhou X, Yuan M, Qu D, Zheng Y, Vishinkin R, Khatib M, Wu W, Haick H. Disease Detection with Molecular Biomarkers: From Chemistry of Body Fluids to Nature-Inspired Chemical Sensors. Chem Rev 2019; 119:11761-11817. [DOI: 10.1021/acs.chemrev.9b00437] [Citation(s) in RCA: 164] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Yoav Y. Broza
- Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa 3200003, Israel
| | - Xi Zhou
- School of Natural and Applied Sciences, Northwestern Polytechnical University, Xi’an 710072, P.R. China
| | - Miaomiao Yuan
- The Eighth Affiliated Hospital, Sun Yat-sen University, Shenzhen, Guangdong 518033, P.R. China
| | - Danyao Qu
- School of Advanced Materials and Nanotechnology, Interdisciplinary Research Center of Smart Sensors, Xidian University, Shaanxi 710126, P.R. China
| | - Youbing Zheng
- Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa 3200003, Israel
| | - Rotem Vishinkin
- Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa 3200003, Israel
| | - Muhammad Khatib
- Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa 3200003, Israel
| | - Weiwei Wu
- School of Advanced Materials and Nanotechnology, Interdisciplinary Research Center of Smart Sensors, Xidian University, Shaanxi 710126, P.R. China
| | - Hossam Haick
- Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa 3200003, Israel
- School of Advanced Materials and Nanotechnology, Interdisciplinary Research Center of Smart Sensors, Xidian University, Shaanxi 710126, P.R. China
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Human dihydrofolate reductase is a substrate of protein kinase CK2α. Biochem Biophys Res Commun 2019; 513:368-373. [PMID: 30961929 DOI: 10.1016/j.bbrc.2019.03.186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 03/27/2019] [Indexed: 11/22/2022]
Abstract
Dihydrofolate reductase (DHFR) is a prominent molecular target in antitumor, antibacterial, antiprotozoan, and immunosuppressive chemotherapies, and CK2 protein kinase is an ubiquitous enzyme involved in many processes, such as tRNA and rRNA synthesis, apoptosis, cell cycle or oncogenic transformation. We show for the first time that CK2α subunit strongly interacted with and phosphorylated DHFR in vitro. Using quartz crystal microbalance with dissipation monitoring (QCM-D) we determined DHFR-CK2α binding kinetic parameters (Kd below 0.5 μM, kon = 10.31 × 104 M-1s-1 and koff = 1.40 × 10-3s-1) and calculated Gibbs free energy (-36.4 kJ/mol). In order to identify phosphorylation site(s) we used site-directed mutagenesis to obtain several DHFR mutants with predicted CK2-phosphorylable serine or threonine residues substituted with alanines. All enzyme forms were subjected to CK2α subunit catalytic activity and the results pointed to serine 168 as a phosphorylation site. Mass spectrometry analyses confirmed the presence of phosphoserine 168 and revealed additionally the presence of phosphoserine 145, although the latter phosphorylation was on a very low level.
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Lee GY, Bong JH, Kim JY, Yoo G, Park M, Kang MJ, Jose J, Pyun JC. Thermophoretic diagnosis of autoimmune diseases based on Escherichia coli with autodisplayed autoantigens. Anal Chim Acta 2019; 1055:106-114. [DOI: 10.1016/j.aca.2018.12.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 12/10/2018] [Accepted: 12/18/2018] [Indexed: 12/19/2022]
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Lin D, Lopez-Sanchez P, Selway N, Gidley MJ. Viscoelastic properties of pectin/cellulose composites studied by QCM-D and oscillatory shear rheology. Food Hydrocoll 2018. [DOI: 10.1016/j.foodhyd.2017.12.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors.
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Antosiewicz A, Jarmuła A, Przybylska D, Mosieniak G, Szczepanowska J, Kowalkowska A, Rode W, Cieśla J. Human dihydrofolate reductase and thymidylate synthase form a complex in vitro and co-localize in normal and cancer cells. J Biomol Struct Dyn 2016; 35:1474-1490. [PMID: 27187663 DOI: 10.1080/07391102.2016.1186560] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Enzymes involved in thymidylate biosynthesis, thymidylate synthase (TS), and dihydrofolate reductase (DHFR) are well-known targets in cancer chemotherapy. In this study, we demonstrated for the first time, that human TS and DHFR form a strong complex in vitro and co-localize in human normal and colon cancer cell cytoplasm and nucleus. Treatment of cancer cells with methotrexate or 5-fluorouracil did not affect the distribution of either enzyme within the cells. However, 5-FU, but not MTX, lowered the presence of DHFR-TS complex in the nucleus by 2.5-fold. The results may suggest the sequestering of TS by FdUMP in the cytoplasm and thereby affecting the translocation of DHFR-TS complex to the nucleus. Providing a strong likelihood of DHFR-TS complex formation in vivo, the latter complex is a potential new drug target in cancer therapy. In this paper, known 3D structures of human TS and human DHFR, and some protozoan bifunctional DHFR-TS structures as templates, are used to build an in silico model of human DHFR-TS complex structure, consisting of one TS dimer and two DHFR monomers. This complex structure may serve as an initial 3D drug target model for prospective inhibitors targeting interfaces between the DHFR and TS enzymes.
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Affiliation(s)
- Anna Antosiewicz
- a Faculty of Chemistry , Warsaw University of Technology , Noakowskiego 3, 00-664 Warsaw , Poland
| | - Adam Jarmuła
- b Nencki Institute of Experimental Biology , Polish Academy of Sciences , Pasteura 3, 02-093 , Warsaw , Poland
| | - Dorota Przybylska
- b Nencki Institute of Experimental Biology , Polish Academy of Sciences , Pasteura 3, 02-093 , Warsaw , Poland
| | - Grażyna Mosieniak
- b Nencki Institute of Experimental Biology , Polish Academy of Sciences , Pasteura 3, 02-093 , Warsaw , Poland
| | - Joanna Szczepanowska
- b Nencki Institute of Experimental Biology , Polish Academy of Sciences , Pasteura 3, 02-093 , Warsaw , Poland
| | - Anna Kowalkowska
- a Faculty of Chemistry , Warsaw University of Technology , Noakowskiego 3, 00-664 Warsaw , Poland
| | - Wojciech Rode
- b Nencki Institute of Experimental Biology , Polish Academy of Sciences , Pasteura 3, 02-093 , Warsaw , Poland
| | - Joanna Cieśla
- a Faculty of Chemistry , Warsaw University of Technology , Noakowskiego 3, 00-664 Warsaw , Poland
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Huang CH, Chen TH, Ng KL. Graph theory and stability analysis of protein complex interaction networks. IET Syst Biol 2016; 10:64-75. [PMID: 26997661 DOI: 10.1049/iet-syb.2015.0007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Protein complexes play an essential role in many biological processes. Complexes can interact with other complexes to form protein complex interaction network (PCIN) that involves in important cellular processes. There are relatively few studies on examining the interaction topology among protein complexes; and little is known about the stability of PCIN under perturbations. We employed graph theoretical approach to reveal hidden properties and features of four species PCINs. Two main issues are addressed, (i) the global and local network topological properties, and (ii) the stability of the networks under 12 types of perturbations. According to the topological parameter classification, we identified some critical protein complexes and validated that the topological analysis approach could provide meaningful biological interpretations of the protein complex systems. Through the Kolmogorov-Smimov test, we showed that local topological parameters are good indicators to characterise the structure of PCINs. We further demonstrated the effectiveness of the current approach by performing the scalability and data normalization tests. To measure the robustness of PCINs, we proposed to consider eight topological-based perturbations, which are specifically applicable in scenarios of targeted, sustained attacks. We found that the degree-based, betweenness-based and brokering-coefficient-based perturbations have the largest effect on network stability.
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Affiliation(s)
- Chien-Hung Huang
- Department of Computer Science and Information Engineering, National Formosa University, Yun-Lin 63205, Taiwan
| | - Teng-Hung Chen
- Department of Computer Science and Information Engineering, National Formosa University, Yun-Lin 63205, Taiwan
| | - Ka-Lok Ng
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 40402, Taiwan.
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Fei Z, Gao Y, Qiu M, Qi X, Dai Y, Wang S, Quan Z, Liu Y, Ou J. Down-regulation of dihydrofolate reductase inhibits the growth of endothelial EA.hy926 cell through induction of G1 cell cycle arrest via up-regulating p53 and p21(waf1/cip1) expression. J Clin Biochem Nutr 2016; 58:105-13. [PMID: 27013776 PMCID: PMC4788405 DOI: 10.3164/jcbn.15-64] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 09/15/2015] [Indexed: 01/10/2023] Open
Abstract
Folic acid supplementation may meliorate cardiovascular disease risk by improving vascular endothelial structure and function. However, the underlying mechanisms are still lack of a global understanding. To be used, folic acid must be converted to 7,8-dihydrofolate by dihydrofolate reductase to generate one-carbon derivatives serving as important cellular cofactors in the synthesis of nucleotides and amino acids required for cell growth. Therefore, this study explored the effect of dihydrofolate reductase knockdown on endothelial EA.hy926 cell growth and the mechanism involved. We found that down-regulation of dihydrofolate reductase inhibited EA.hy926 cell proliferation, and induced G1 phase arrest. Meanwhile, the expression of regulators necessary for G1/S phase transition, such as cyclin-dependent kinases CDK2, CDK4 and CDK6, were remarkably down-regulated; by contrast, the cell cycle inhibitors p21waf/cip1, p27Kip1 and p53 were significantly up-regulated after dihydrofolate reductase knockdown. Furthermore, supplementation of 5-methyltetrahydrofolate to the dihydrofolate reductase knockdown cells could weaken the inhibitory effect of dihydrofolate reductase knockdown on cell proliferation, simultaneously, inducing the expression of p53 and p21waf/cip1 falling back moderately. Our findings suggest that attenuating dihydrofolate reductase may cause imbalanced expression of cell cycle regulators, especially up-regulation of p53-p21waf/cip1 pathway, leading to G1 cell cycle arrest, thereby inhibiting the growth of endothelial EA.hy926 cells.
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Affiliation(s)
- Zhewei Fei
- Department of General Surgery, Xinhua Hospital (Chong Ming) affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 202150, China
| | - Yong Gao
- Department of Vascular Surgery, The First Affiliated Hospital of Bengbu Medical College, An Hui Province 233003, China
| | - Mingke Qiu
- Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
| | - Xianqin Qi
- Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
| | - Yuxin Dai
- Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
| | - Shuqing Wang
- Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
| | - Zhiwei Quan
- Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
| | - Yingbin Liu
- Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
| | - Jingmin Ou
- Department of General Surgery, Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
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Wang N, McCammon JA. Substrate channeling between the human dihydrofolate reductase and thymidylate synthase. Protein Sci 2015; 25:79-86. [PMID: 26096018 DOI: 10.1002/pro.2720] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 06/02/2015] [Accepted: 06/05/2015] [Indexed: 12/17/2022]
Abstract
In vivo, as an advanced catalytic strategy, transient non-covalently bound multi-enzyme complexes can be formed to facilitate the relay of substrates, i. e. substrate channeling, between sequential enzymatic reactions and to enhance the throughput of multi-step enzymatic pathways. The human thymidylate synthase and dihydrofolate reductase catalyze two consecutive reactions in the folate metabolism pathway, and experiments have shown that they are very likely to bind in the same multi-enzyme complex in vivo. While reports on the protozoa thymidylate synthase-dihydrofolate reductase bifunctional enzyme give substantial evidences of substrate channeling along a surface "electrostatic highway," attention has not been paid to whether the human thymidylate synthase and dihydrofolate reductase, if they are in contact with each other in the multi-enzyme complex, are capable of substrate channeling employing surface electrostatics. This work utilizes protein-protein docking, electrostatics calculations, and Brownian dynamics to explore the existence and mechanism of the substrate channeling between the human thymidylate synthase and dihydrofolate reductase. The results show that the bound human thymidylate synthase and dihydrofolate reductase are capable of substrate channeling and the formation of the surface "electrostatic highway." The substrate channeling efficiency between the two can be reasonably high and comparable to that of the protozoa.
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Affiliation(s)
- Nuo Wang
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, 92037
| | - J Andrew McCammon
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, 92037.,Department of Pharmacology, University of California San Diego, La Jolla, California, 92037.,Howard Hughes Medical Institute, University of California San Diego, La Jolla, California, 92037
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