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Gao S, Zhu D, Zhu J, Shen L, Zhu M, Ren X. miR-18a-5p Targets FBP1 to Promote Proliferation, Migration, and Invasion of Liver Cancer Cells and Inhibit Cell Apoptosis. Comput Math Methods Med 2021; 2021:3334065. [PMID: 34221105 PMCID: PMC8219440 DOI: 10.1155/2021/3334065] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 06/01/2021] [Indexed: 11/23/2022]
Abstract
Liver cancer is one of the most aggressive malignant tumors. It is significant to understand the molecular mechanism of liver cancer cells to develop new treatment plans. Studies have identified that FBP1 serves as a cancer inhibitor gene. To research the effect mechanism of FBP1 in liver cancer cells, bioinformatics analysis was performed to study its expression in liver cancer tissue. Survival analysis was also performed. Moreover, starBase database was applied to predict upstream regulatory genes of FBP1. Dual-luciferase assay was performed to testify their targeted relationship. The mRNA and protein expression levels of FBP1 in liver cancer cells were detected by qRT-PCR and western blot, respectively. Cell viability was analyzed by CCK-8 assay. The migratory and invasive abilities of cells were analyzed by Transwell assay. The apoptosis of liver cancer cells was detected by flow cytometry. The results showed that the expression of FBP1 was downregulated in liver cancer tissue and cells. FBP1 low expression was correlated with the poor prognosis of patients. miR-18a-5p could inhibit FBP1 expression. Overexpression of FBP1 could inhibit the progression of liver cancer cells and promote cell apoptosis. Overexpressing miR-18a-5p could promote the progression of liver cancer cells and inhibit cell apoptosis. However, overexpressing FBP1 simultaneously could reverse the effect. miR-18a-5p and FBP1 are expected to be candidates for liver cancer treatment.
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Affiliation(s)
- Shan Gao
- Department of General Surgery, The First People's Hospital of Yuhang District, Hangzhou, Zhejiang 311100, China
| | - Dongjie Zhu
- Department of General Surgery, The First People's Hospital of Yuhang District, Hangzhou, Zhejiang 311100, China
| | - Jian Zhu
- Department of General Surgery, The First People's Hospital of Yuhang District, Hangzhou, Zhejiang 311100, China
| | - Lianqiang Shen
- Department of General Surgery, The First People's Hospital of Yuhang District, Hangzhou, Zhejiang 311100, China
| | - Ming Zhu
- Department of General Surgery, The First People's Hospital of Yuhang District, Hangzhou, Zhejiang 311100, China
| | - Xuefeng Ren
- Department of General Surgery, The First People's Hospital of Yuhang District, Hangzhou, Zhejiang 311100, China
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Proença C, Oliveira A, Freitas M, Ribeiro D, Sousa JLC, Ramos MJ, Silva AMS, Fernandes PA, Fernandes E. Structural Specificity of Flavonoids in the Inhibition of Human Fructose 1,6-Bisphosphatase. J Nat Prod 2020; 83:1541-1552. [PMID: 32364726 DOI: 10.1021/acs.jnatprod.0c00014] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Liver fructose 1,6-bisphosphatase (FBPase) is a recognized regulatory enzyme of the gluconeogenesis pathway, which has emerged as a valid target to control gluconeogenesis-mediated overproduction of glucose. As such, the management of diabetes with FBPase inhibitors represents a potential alternative for the currently used antidiabetic agents. In this study, the FBPase inhibition of a panel of 55 structurally related flavonoids was tested, through a microanalysis screening system. Then, a subset of seven active inhibitors and their close chemical relatives were further evaluated by molecular dynamics (MD) simulations using a linear interaction energy (LIE) approach. The results obtained showed that D14 (herbacetin) was the most potent inhibitor, suggesting that the presence of -OH groups at the C-3, C-4', C-5, C-7, and C-8 positions, as well as the double bond between C-2 and C-3 and the 4-oxo function at the pyrone ring, are favorable for the intended effect. Furthermore, D14 (herbacetin) is stabilized by a strong interaction with the Glu30 side chain and the Thr24 backbone of FBPase. This is the first investigation studying the in vitro inhibitory effect of a panel of flavonoids against human liver FBPase, thus representing a potentially important step for the search and design of novel inhibitors of this enzyme.
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Affiliation(s)
- Carina Proença
- LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
| | - Ana Oliveira
- UCIBIO, REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
| | - Marisa Freitas
- LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
| | - Daniela Ribeiro
- LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
| | - Joana L C Sousa
- LAQV-REQUIMTE & QOPNA, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Maria J Ramos
- UCIBIO, REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
| | - Artur M S Silva
- LAQV-REQUIMTE & QOPNA, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Pedro A Fernandes
- UCIBIO, REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
| | - Eduarda Fernandes
- LAQV, REQUIMTE, Laboratory of Applied Chemistry, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
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Iguchi T, Goto K, Watanabe K, Hashimoto K, Suzuki T, Kishino H, Fujimoto K, Mori K. Fluoroquinolones suppress gluconeogenesis by inhibiting fructose 1,6-bisphosphatase in primary monkey hepatocytes. Toxicol In Vitro 2020; 65:104786. [PMID: 32004540 DOI: 10.1016/j.tiv.2020.104786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 01/08/2020] [Accepted: 01/26/2020] [Indexed: 11/17/2022]
Abstract
Dysglycemia is one of the most serious adverse events associated with the clinical use of certain fluoroquinolones. The purpose of this study was to investigate the effects of the representative fluoroquinolones moxifloxacin and gatifloxacin on hepatic gluconeogenesis using primary monkey hepatocytes. Glucose production was induced after the cells were incubated for 4 h with 10 mM sodium lactate and 1 mM sodium pyruvate as gluconeogenic substrates. Under these conditions, moxifloxacin and gatifloxacin dose-dependently suppressed gluconeogenesis at concentrations of 100 μM or higher. Transcriptome analysis of rate-limiting enzymes involved in hepatic gluconeogenesis revealed that moxifloxacin and gatifloxacin at a concentration of 1000 μM did not affect the expression of key gluconeogenic enzymes such as phosphoenolpyruvate carboxykinase, glucose 6-phosphatase, and fructose 1,6-bisphosphatase. Furthermore, metabolome analysis, in vitro glucose production assay using additional gluconeogenic substrates, and fructose 1,6-bisphosphatase assay using the cell extracts showed that fluoroquinolones enzymatically suppressed hepatic gluconeogenesis by inhibiting fructose 1,6-bisphosphatase. These inhibitory effects may involve in the clinically relevant dysglycemia associated with fluoroquinolones in human.
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Affiliation(s)
- Takuma Iguchi
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan.
| | - Koichi Goto
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan.
| | - Kyoko Watanabe
- Biomarker & Translational Research Department, Daiichi Sankyo Co., Ltd., 1-2-58, Hiromachi, Shinagawa-ku, Tokyo 140-0005, Japan.
| | - Kazuyuki Hashimoto
- Biomarker & Translational Research Department, Daiichi Sankyo Co., Ltd., 1-2-58, Hiromachi, Shinagawa-ku, Tokyo 140-0005, Japan.
| | - Takami Suzuki
- Oncology Research Laboratories I, Daiichi Sankyo Co., Ltd., 1-2-58, Hiromachi, Shinagawa-ku, Tokyo 140-0005, Japan.
| | - Hiroyuki Kishino
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan.
| | - Kazunori Fujimoto
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan.
| | - Kazuhiko Mori
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan.
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Chauhan S, Kumar P, Kumar A. Development of prediction model for fructose- 1,6- bisphosphatase inhibitors using the Monte Carlo method. SAR QSAR Environ Res 2019; 30:145-159. [PMID: 30777782 DOI: 10.1080/1062936x.2019.1568299] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Indexed: 06/09/2023]
Abstract
Fructose-1,6-bisphosphatase (FBPase) is an enzyme important for regulation of gluconeogenesis, which is a major process in the liver responsible for glucose production. Inhibition of FBPase enzyme causing blockage of the gluconeogenesis process represents a newer scheme in the progress of anti-diabetic drugs. The current research describes the development of hybrid optimal descriptors-based quantitative structure-activity relationship (QSAR) models intended for a set of 62 FBPase inhibitors with the Monte Carlo method. The molecular structures were expressed by the simplified molecular input line entry system (SMILES) notation. Three splits were prepared by random division of the molecules into training set, calibration set and validation set. Statistical parameters obtained from QSAR modelling were good for various designed splits. The best QSAR model showed the following parameters: the values of r2 for calibration set and validation set of the best model were 0.6837 and 0.8623 and of Q2 were 0.6114 and 0.8036, respectively. Based on the results obtained for correlation weights, different structural attributes were described as promoter of the endpoint. Further, these structural attributes were used in designing of new FBPase inhibitors and a molecular docking study was completed for the determination of interactions of the designed molecules with the enzyme.
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Affiliation(s)
- S Chauhan
- a Department of Pharmaceutical Sciences , Guru Jambheshwar University of Science & Technology , Hisar , India
| | - P Kumar
- b Department of Chemistry , Kurukshetra University , Kurukshetra , India
| | - A Kumar
- a Department of Pharmaceutical Sciences , Guru Jambheshwar University of Science & Technology , Hisar , India
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Yuan M, Vásquez-Valdivieso MG, McNae IW, Michels PAM, Fothergill-Gilmore LA, Walkinshaw MD. Structures of Leishmania Fructose-1,6-Bisphosphatase Reveal Species-Specific Differences in the Mechanism of Allosteric Inhibition. J Mol Biol 2017; 429:3075-3089. [PMID: 28882541 PMCID: PMC5639204 DOI: 10.1016/j.jmb.2017.08.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 08/14/2017] [Accepted: 08/17/2017] [Indexed: 11/29/2022]
Abstract
The gluconeogenic enzyme fructose-1,6-bisphosphatase has been proposed as a potential drug target against Leishmania parasites that cause up to 20,000-30,000 deaths annually. A comparison of three crystal structures of Leishmania major fructose-1,6-bisphosphatase (LmFBPase) along with enzyme kinetic data show how AMP acts as an allosteric inhibitor and provides insight into its metal-dependent reaction mechanism. The crystal structure of the apoenzyme form of LmFBPase is a homotetramer in which the dimer of dimers adopts a planar conformation with disordered "dynamic loops". The structure of LmFBPase, complexed with manganese and its catalytic product phosphate, shows the dynamic loops locked into the active sites. A third crystal structure of LmFBPase complexed with its allosteric inhibitor AMP shows an inactive form of the tetramer, in which the dimer pairs are rotated by 18° relative to each other. The three structures suggest an allosteric mechanism in which AMP binding triggers a rearrangement of hydrogen bonds across the large and small interfaces. Retraction of the "effector loop" required for AMP binding releases the side chain of His23 from the dimer-dimer interface. This is coupled with a flip of the side chain of Arg48 which ties down the key catalytic dynamic loop in a disengaged conformation and also locks the tetramer in an inactive rotated T-state. The structure of the effector site of LmFBPase shows different structural features compared with human FBPases, thereby offering a potential and species-specific drug target.
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Affiliation(s)
- Meng Yuan
- Centre for Translational and Chemical Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Montserrat G Vásquez-Valdivieso
- Centre for Translational and Chemical Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Iain W McNae
- Centre for Translational and Chemical Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Paul A M Michels
- Centre for Translational and Chemical Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Linda A Fothergill-Gilmore
- Centre for Translational and Chemical Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Malcolm D Walkinshaw
- Centre for Translational and Chemical Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK.
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Han X, Huang Y, Zhang R, Xiao S, Zhu S, Qin N, Hong Z, Wei L, Feng J, Ren Y, Feng L, Wan J. New insight into the binding modes of TNP-AMP to human liver fructose-1,6-bisphosphatase. Spectrochim Acta A Mol Biomol Spectrosc 2016; 165:155-160. [PMID: 27137358 DOI: 10.1016/j.saa.2016.04.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 03/13/2016] [Accepted: 04/03/2016] [Indexed: 06/05/2023]
Abstract
Human liver fructose-1,6-bisphosphatase (FBPase) contains two binding sites, a substrate fructose-1,6-bisphosphate (FBP) active site and an adenosine monophosphate (AMP) allosteric site. The FBP active site works by stabilizing the FBPase, and the allosteric site impairs the activity of FBPase through its binding of a nonsubstrate molecule. The fluorescent AMP analogue, 2',3'-O-(2,4,6-trinitrophenyl)adenosine 5'-monophosphate (TNP-AMP) has been used as a fluorescent probe as it is able to competitively inhibit AMP binding to the AMP allosteric site and, therefore, could be used for exploring the binding modes of inhibitors targeted on the allosteric site. In this study, we have re-examined the binding modes of TNP-AMP to FBPase. However, our present enzyme kinetic assays show that AMP and FBP both can reduce the fluorescence from the bound TNP-AMP through competition for FBPase, suggesting that TNP-AMP binds not only to the AMP allosteric site but also to the FBP active site. Mutagenesis assays of K274L (located in the FBP active site) show that the residue K274 is very important for TNP-AMP to bind to the active site of FBPase. The results further prove that TNP-AMP is able to bind individually to the both sites. Our present study provides a new insight into the binding mechanism of TNP-AMP to the FBPase. The TNP-AMP fluorescent probe can be used to exam the binding site of an inhibitor (the active site or the allosteric site) using FBPase saturated by AMP and FBP, respectively, or the K247L mutant FBPase.
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Affiliation(s)
- Xinya Han
- Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China
| | - Yunyuan Huang
- Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China
| | - Rui Zhang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
| | - San Xiao
- Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China
| | - Shuaihuan Zhu
- Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China
| | - Nian Qin
- Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China
| | - Zongqin Hong
- Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China
| | - Lin Wei
- Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China
| | - Jiangtao Feng
- Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China
| | - Yanliang Ren
- Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China
| | - Lingling Feng
- Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China.
| | - Jian Wan
- Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China.
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Bie J, Liu S, Li Z, Mu Y, Xu B, Shen Z. Discovery of novel indole derivatives as allosteric inhibitors of fructose-1,6-bisphosphatase. Eur J Med Chem 2014; 90:394-405. [PMID: 25461330 DOI: 10.1016/j.ejmech.2014.11.049] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Revised: 10/30/2014] [Accepted: 11/24/2014] [Indexed: 11/30/2022]
Abstract
A series of novel indole derivatives was designed and synthesized as inhibitors of fructose-1,6-bisphosphatase (FBPase). The most potent compound 14c was identified with an IC50 value of 0.10 μM by testing the inhibitory activity against recombinant human FBPase. The structure-activity relationships were investigated on the substitution at 4- and 5-position of the indole scaffold. The binding interactions of the title compounds at AMP binding site of FBPase were predicted using CDOCKER algorithm.
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Affiliation(s)
- Jianbo Bie
- Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences&Peking Union Medical College, Beijing 100050, China
| | - Shuainan Liu
- Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences&Peking Union Medical College, Beijing 100050, China
| | - Zhanmei Li
- Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences&Peking Union Medical College, Beijing 100050, China
| | - Yongzhao Mu
- Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences&Peking Union Medical College, Beijing 100050, China
| | - Bailing Xu
- Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences&Peking Union Medical College, Beijing 100050, China.
| | - Zhufang Shen
- Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences&Peking Union Medical College, Beijing 100050, China.
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Rakus D, Gizak A, Kasprzak AA, Zarzycki M, Maciaszczyk-Dziubinska E, Dzugaj A. The mechanism of calcium-induced inhibition of muscle fructose 1,6-bisphosphatase and destabilization of glyconeogenic complex. PLoS One 2013; 8:e76669. [PMID: 24146906 PMCID: PMC3795747 DOI: 10.1371/journal.pone.0076669] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 08/27/2013] [Indexed: 11/18/2022] Open
Abstract
The mechanism by which calcium inhibits the activity of muscle fructose 1,6-bisphosphatase (FBPase) and destabilizes its interaction with aldolase, regulating glycogen synthesis from non-carbohydrates in skeletal muscle is poorly understood. In the current paper, we demonstrate evidence that Ca2+ affects conformation of the catalytic loop 52–72 of muscle FBPase and inhibits its activity by competing with activatory divalent cations, e.g. Mg2+ and Zn2+. We also propose the molecular mechanism of Ca2+-induced destabilization of the aldolase–FBPase interaction, showing that aldolase associates with FBPase in its active form, i.e. with loop 52–72 in the engaged conformation, while Ca2+ stabilizes the disengaged-like form of the loop.
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Affiliation(s)
- Dariusz Rakus
- Department of Animal Molecular Physiology, Wroclaw University, Wroclaw, Poland
- * E-mail:
| | - Agnieszka Gizak
- Department of Animal Molecular Physiology, Wroclaw University, Wroclaw, Poland
| | - Andrzej A. Kasprzak
- Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Marek Zarzycki
- Depatment of Genetics, Wroclaw University, Wroclaw, Poland
| | | | - Andrzej Dzugaj
- Depatment of Genetics, Wroclaw University, Wroclaw, Poland
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Li D, Han X, Tu Q, Feng L, Wu D, Sun Y, Chen H, Li Y, Ren Y, Wan J. Structure-based design and synthesis of novel dual-target inhibitors against cyanobacterial fructose-1,6-bisphosphate aldolase and fructose-1,6-bisphosphatase. J Agric Food Chem 2013; 61:7453-7461. [PMID: 23889687 DOI: 10.1021/jf401939h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Cyanobacteria class II fructose-1,6-bisphoshate aldolase (Cy-FBA-II) and cyanobacteria fructose-1,6-bisphosphatase (Cy-FBPase) are two neighboring key regulatory enzymes in the Calvin cycle of the cyanobacteria photosynthesis system. Each of them might be taken as a potential target for designing novel inhibitors to chemically control harmful algal blooms (HABs). In the present paper, a series of novel inhibitors were rationally designed, synthesized, and optimized based upon the structural and interactional information of both Cy-FBA-II and Cy-FBPase, and their inhibitory activities were examined in vitro and in vivo. The experimental results showed that compounds L19e-L19g exhibited moderate inhibitory activities (IC50 = 28.1-103.2 μM) against both Cy-FBA-II and Cy-FBPase; compounds L19a-L19d, L19h, L20a-L20d exhibited high Cy-FBA-II inhibitory activities (IC50 = 2.3-16.9 μM) and moderate Cy-FBPase inhibitory activities (IC50 = 31.5-141.2 μM); however, compounds L20e-L20h could potently inhibit both Cy-FBA-II and Cy-FBPase with IC50 values less than 30 μM, which demonstrated more or less dual-target inhibitor's feature. Moreover, most of them exhibited potent algicide activity (EC50 = 0.8-22.3 ppm) against cyanobacteria Synechocystis sp. PCC 6803.
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Affiliation(s)
- Ding Li
- Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China
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Hao M, Zhang S, Qiu J. Toward the prediction of FBPase inhibitory activity using chemoinformatic methods. Int J Mol Sci 2012; 13:7015-7037. [PMID: 22837677 PMCID: PMC3397509 DOI: 10.3390/ijms13067015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 05/18/2012] [Accepted: 05/31/2012] [Indexed: 01/08/2023] Open
Abstract
Currently, Chemoinformatic methods are used to perform the prediction for FBPase inhibitory activity. A genetic algorithm-random forest coupled method (GA-RF) was proposed to predict fructose 1,6-bisphosphatase (FBPase) inhibitors to treat type 2 diabetes mellitus using the Mold2 molecular descriptors. A data set of 126 oxazole and thiazole analogs was used to derive the GA-RF model, yielding the significant non-cross-validated correlation coefficient r2ncv and cross-validated r2cv values of 0.96 and 0.67 for the training set, respectively. The statistically significant model was validated by a test set of 64 compounds, producing the prediction correlation coefficient r2pred of 0.90. More importantly, the building GA-RF model also passed through various criteria suggested by Tropsha and Roy with r2o and r2m values of 0.90 and 0.83, respectively. In order to compare with the GA-RF model, a pure RF model developed based on the full descriptors was performed as well for the same data set. The resulting GA-RF model with significantly internal and external prediction capacities is beneficial to the prediction of potential oxazole and thiazole series of FBPase inhibitors prior to chemical synthesis in drug discovery programs.
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Affiliation(s)
| | | | - Jieshan Qiu
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +86-411-84986024; Fax: +86-411-84986080
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11
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Visinoni S, Khalid NFI, Joannides CN, Shulkes A, Yim M, Whitehead J, Tiganis T, Lamont BJ, Favaloro JM, Proietto J, Andrikopoulos S, Fam BC. The role of liver fructose-1,6-bisphosphatase in regulating appetite and adiposity. Diabetes 2012; 61:1122-32. [PMID: 22517657 PMCID: PMC3331739 DOI: 10.2337/db11-1511] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Liver fructose-1,6-bisphosphatase (FBPase) is a regulatory enzyme in gluconeogenesis that is elevated by obesity and dietary fat intake. Whether FBPase functions only to regulate glucose or has other metabolic consequences is not clear; therefore, the aim of this study was to determine the importance of liver FBPase in body weight regulation. To this end we performed comprehensive physiologic and biochemical assessments of energy balance in liver-specific transgenic FBPase mice and negative control littermates of both sexes. In addition, hepatic branch vagotomies and pharmacologic inhibition studies were performed to confirm the role of FBPase. Compared with negative littermates, liver-specific FBPase transgenic mice had 50% less adiposity and ate 15% less food but did not have altered energy expenditure. The reduced food consumption was associated with increased circulating leptin and cholecystokinin, elevated fatty acid oxidation, and 3-β-hydroxybutyrate ketone levels, and reduced appetite-stimulating neuropeptides, neuropeptide Y and Agouti-related peptide. Hepatic branch vagotomy and direct pharmacologic inhibition of FBPase in transgenic mice both returned food intake and body weight to the negative littermates. This is the first study to identify liver FBPase as a previously unknown regulator of appetite and adiposity and describes a novel process by which the liver participates in body weight regulation.
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Affiliation(s)
- Sherley Visinoni
- Department of Medicine, University of Melbourne, Heidelberg, Victoria, Australia
| | | | | | - Arthur Shulkes
- Department of Surgery, Austin Health, University of Melbourne, Heidelberg, Victoria, Australia
| | - Mildred Yim
- Department of Surgery, Austin Health, University of Melbourne, Heidelberg, Victoria, Australia
| | - Jon Whitehead
- Mater Medical Research Institute, Brisbane, Queensland, Australia
| | - Tony Tiganis
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Benjamin J. Lamont
- Department of Medicine, University of Melbourne, Heidelberg, Victoria, Australia
| | - Jenny M. Favaloro
- Department of Medicine, University of Melbourne, Heidelberg, Victoria, Australia
| | - Joseph Proietto
- Department of Medicine, University of Melbourne, Heidelberg, Victoria, Australia
| | | | - Barbara C. Fam
- Department of Medicine, University of Melbourne, Heidelberg, Victoria, Australia
- Corresponding author: Barbara C. Fam,
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12
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Hao M, Zhang X, Ren H, Li Y, Zhang S, Luo F, Ji M, Li G, Yang L. In silico identification of structure requirement for novel thiazole and oxazole derivatives as potent fructose 1,6-bisphosphatase inhibitors. Int J Mol Sci 2011; 12:8161-80. [PMID: 22174657 PMCID: PMC3233463 DOI: 10.3390/ijms12118161] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2011] [Revised: 11/10/2011] [Accepted: 11/16/2011] [Indexed: 12/12/2022] Open
Abstract
Fructose 1,6-bisphosphatase (FBPase) has been identified as a drug discovery target for lowering glucose in type 2 diabetes mellitus. In this study, a large series of 105 FBPase inhibitors were studied using a combinational method by 3D-QSAR, molecular docking and molecular dynamics simulations for a further improvement in potency. The optimal 3D models exhibit high statistical significance of the results, especially for the CoMFA results with rncv2, q2 values of 0.986, 0.514 for internal validation, and rpred2, rm2 statistics of 0.902, 0.828 statistics for external validation. Graphic representation of the results, as contoured 3D coefficient plots, also provides a clue to the reasonable modification of molecules. (1) Substituents with a proper length and size at the C5 position of the thiazole core are required to enhance the potency; (2) A small and electron-withdrawing group at the C2 position linked to the thiazole core is likely to help increase the FBPase inhibition; (3) Substituent groups as hydrogen bond acceptors at the C2 position of the furan ring are favored. In addition, the agreement between 3D-QSAR, molecular docking and molecular dynamics simulation proves the rationality of the developed models. These results, we hope, may be helpful in designing novel and potential FBPase inhibitors.
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Affiliation(s)
- Ming Hao
- Department of Materials Science and Chemical Engineering, Dalian University of Technology, Dalian, Liaoning, 116023, China; E-Mails: (M.H.); (S.Z.)
| | - Xiaole Zhang
- Department of Mathematical Sciences, Dalian University of Technology, Dalian, Liaoning, 116023, China; E-Mail:
| | - Hong Ren
- Department of Ophthalmology, Qi Lu Hospital, Medical School of Shandong University, Jinan, 250012, China; E-Mail:
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China; E-Mail:
| | - Yan Li
- Department of Materials Science and Chemical Engineering, Dalian University of Technology, Dalian, Liaoning, 116023, China; E-Mails: (M.H.); (S.Z.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +86-411-84986062; Fax: +86-411-84986063
| | - Shuwei Zhang
- Department of Materials Science and Chemical Engineering, Dalian University of Technology, Dalian, Liaoning, 116023, China; E-Mails: (M.H.); (S.Z.)
| | - Fang Luo
- College of Chemistry and Chemical Engineering, Graduate School of the Chinese Academy of Sciences, Beijing, 100049, China; E-Mails: (F.L.); (M.J.)
| | - Mingjuan Ji
- College of Chemistry and Chemical Engineering, Graduate School of the Chinese Academy of Sciences, Beijing, 100049, China; E-Mails: (F.L.); (M.J.)
| | - Guohui Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China; E-Mail:
| | - Ling Yang
- Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Graduate School of the Chinese Academy of Sciences, Dalian, Liaoning, 116023, China; E-Mail:
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13
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Li ZM, Bie JB, Song HR, Xu BL. [Recent advance in the discovery of allosteric inhibitors binding to the AMP site of fructose-1,6-bisphosphatase]. Yao Xue Xue Bao 2011; 46:1291-1300. [PMID: 22260018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Fructose-1, 6-bisphosphatase (FBPase), a rate-limiting enzyme involved in the pathway of gluconeogenesis, can catalyze the hydrolysis of fructose-1, 6-bisphosphate to fructose-6-phosphate. Upon inhibiting the activity of FBPase, the production of endogenous glucose can be decreased and the level of blood glucose lowered. Therefore, inhibitors of FBPase are expected to be novel potential therapeutics for the treatment of type II diabetes. Recent research efforts were reviewed in the field of developing allosteric inhibitors interacting with the AMP binding site of FBPase.
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Affiliation(s)
- Zhan-mei Li
- Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
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14
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Abstract
Pancreatic β-cells can precisely sense glucose stimulation and accordingly adjust their insulin secretion. Fructose-1,6-bisphosphatase (FBPase) is a gluconeogenic enzyme, but its physiological significance in β-cells is not established. Here we determined its physiological role in regulating glucose sensing and insulin secretion of β-cells. Considerable FBPase mRNA was detected in normal mouse islets and β-cell lines, although their protein levels appeared to be quite low. Down-regulation of FBP1 in MIN6 cells by small interfering RNA could enhance the glucose-stimulated insulin secretion (GSIS), whereas FBP1-overexpressing MIN6 cells exhibited decreased GSIS. Inhibition of FBPase activity in islet β-cells by its specific inhibitor MB05032 led to significant increase of their glucose utilization and cellular ATP to ADP ratios and consequently enhanced GSIS in vitro. Pretreatment of mice with the MB05032 prodrug MB06322 could potentiate GSIS in vivo and improve their glucose tolerance. Therefore, FBPase plays an important role in regulating glucose sensing and insulin secretion of β-cells and serves a promising target for diabetes treatment.
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Affiliation(s)
- Ye Zhang
- Center for Obesity & Diabetes Research and Innovation, Department of Pathophysiology, Second Military Medical University, 800 Xiangyin Road, Shanghai 200433, China
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15
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Brown G, Singer A, Lunin VV, Proudfoot M, Skarina T, Flick R, Kochinyan S, Sanishvili R, Joachimiak A, Edwards AM, Savchenko A, Yakunin AF. Structural and biochemical characterization of the type II fructose-1,6-bisphosphatase GlpX from Escherichia coli. J Biol Chem 2009; 284:3784-92. [PMID: 19073594 PMCID: PMC2635049 DOI: 10.1074/jbc.m808186200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2008] [Revised: 12/08/2008] [Indexed: 11/06/2022] Open
Abstract
Gluconeogenesis is an important metabolic pathway, which produces glucose from noncarbohydrate precursors such as organic acids, fatty acids, amino acids, or glycerol. Fructose-1,6-bisphosphatase, a key enzyme of gluconeogenesis, is found in all organisms, and five different classes of these enzymes have been identified. Here we demonstrate that Escherichia coli has two class II fructose-1,6-bisphosphatases, GlpX and YggF, which show different catalytic properties. We present the first crystal structure of a class II fructose-1,6-bisphosphatase (GlpX) determined in a free state and in the complex with a substrate (fructose 1,6-bisphosphate) or inhibitor (phosphate). The crystal structure of the ligand-free GlpX revealed a compact, globular shape with two alpha/beta-sandwich domains. The core fold of GlpX is structurally similar to that of Li+-sensitive phosphatases implying that they have a common evolutionary origin and catalytic mechanism. The structure of the GlpX complex with fructose 1,6-bisphosphate revealed that the active site is located between two domains and accommodates several conserved residues coordinating two metal ions and the substrate. The third metal ion is bound to phosphate 6 of the substrate. Inorganic phosphate strongly inhibited activity of both GlpX and YggF, and the crystal structure of the GlpX complex with phosphate demonstrated that the inhibitor molecule binds to the active site. Alanine replacement mutagenesis of GlpX identified 12 conserved residues important for activity and suggested that Thr(90) is the primary catalytic residue. Our data provide insight into the molecular mechanisms of the substrate specificity and catalysis of GlpX and other class II fructose-1,6-bisphosphatases.
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Affiliation(s)
- Greg Brown
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario M5G 1L6, Canada
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16
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Abstract
Type-2 diabetes is associated with impaired glucose clearance by the liver in the postprandial state, and with elevated glucose production in the post-absorptive state. New targets within the liver are currently being investigated for development of antihyperglycaemic drugs for type-2 diabetes. They include glucokinase, which catalyses the first step in glucose metabolism, the glucagon receptor, and enzymes of gluconeogenesis and/or glycogenolysis such as glucose 6-phosphatase, fructose 1,6-bisphosphatase and glycogen phosphorylase. Preclinical studies with candidate drugs on animal models or cell-based assays suggest that these targets have the potential for pharmacological glycaemic control. Data from clinical studies is awaited. Further work is required for better understanding of the implications of targeting these sites in terms of possible side-effects or tachyphylaxis. The advantage of combined targeting of two or more sites within the liver for minimizing side-effects and tachyphylaxis caused by single-site targeting is discussed.
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Affiliation(s)
- Loranne Agius
- Institute of Cellular Medicine, School of Clinical Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
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17
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Rabasseda X. Insight into antidiabetic therapies: a report from the 43rd annual meeting of the European Association for the Study of Diabetes. Timely Top Med Cardiovasc Dis 2007; 11:E28. [PMID: 18297140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Affiliation(s)
- X Rabasseda
- Prous Science Medical Information Department
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18
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Wang Y, Tomlinson B. Managlinat dialanetil, a fructose-1,6-bisphosphatase inhibitor for the treatment of type 2 diabetes. Curr Opin Investig Drugs 2007; 8:849-58. [PMID: 17907062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Metabasis Therapeutics Inc (formerly Gensia Sicor Inc, which became SICOR Inc), in collaboration with Daiichi Sankyo Co Ltd (formerly Sankyo Co Ltd) is developing the fructose-1,6-bisphosphatase inhibitor managlinat dialanetil, a low-molecular weight purine nucleotide analog that inhibits gluconeogenesis, for the potential treatment of type 2 diabetes. Phase II clinical trials of the compound are underway in Europe and the US.
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Affiliation(s)
- Ying Wang
- Division of Clinical Pharmacology, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong
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19
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Reddy MR, Erion MD. Relative binding affinities of fructose-1,6-bisphosphatase inhibitors calculated using a quantum mechanics-based free energy perturbation method. J Am Chem Soc 2007; 129:9296-7. [PMID: 17616196 DOI: 10.1021/ja072905j] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M Rami Reddy
- Metabasis Therapeutics Inc, La Jolla, CA 92037, USA.
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20
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Hines JK, Kruesel CE, Fromm HJ, Honzatko RB. Structure of inhibited fructose-1,6-bisphosphatase from Escherichia coli: distinct allosteric inhibition sites for AMP and glucose 6-phosphate and the characterization of a gluconeogenic switch. J Biol Chem 2007; 282:24697-706. [PMID: 17567577 DOI: 10.1074/jbc.m703580200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Allosteric activation of fructose-1,6-bisphosphatase (FBPase) from Escherichia coli by phosphoenolpyruvate implies rapid feed-forward activation of gluconeogenesis in heterotrophic bacteria. But how do such bacteria rapidly down-regulate an activated FBPase in order to avoid futile cycling? Demonstrated here is the allosteric inhibition of E. coli FBPase by glucose 6-phosphate (Glc-6-P), the first metabolite produced upon glucose transport into the cell. FBPase undergoes a quaternary transition from the canonical R-state to a T-like state in response to Glc-6-P and AMP ligation. By displacing Phe(15), AMP binds to an allosteric site comparable with that of mammalian FBPase. Relative movements in helices H1 and H2 perturb allosteric activator sites for phosphoenolpyruvate. Glc-6-P binds to allosteric sites heretofore not observed in previous structures, perturbing subunits that in pairs form complete active sites of FBPase. Glc-6-P and AMP are synergistic inhibitors of E. coli FBPase, placing AMP/Glc-6-P inhibition in bacteria as a possible evolutionary predecessor to AMP/fructose 2,6-bisphosphate inhibition in mammalian FBPases. With no exceptions, signature residues of allosteric activation appear in bacterial sequences along with key residues of the Glc-6-P site. FBPases in such organisms may be components of metabolic switches that allow rapid changeover between gluconeogenesis and glycolysis in response to nutrient availability.
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Affiliation(s)
- Justin K Hines
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA
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21
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Mutyala R, Reddy RN, Sumakanth M, Reddanna P, Reddy MR. Calculation of relative binding affinities of fructose 1,6-bisphosphatase mutants with adenosine monophosphate using free energy perturbation method. J Comput Chem 2007; 28:932-7. [PMID: 17253638 DOI: 10.1002/jcc.20617] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The free energy perturbation (FEP) methodology is the most accurate means of estimating relative binding affinities between inhibitors and protein variants. In this article, the importance of hydrophobic and hydrophilic residues to the binding of adenosine monophosphate (AMP) to the fructose 1,6-bisphosphatase (FBPase), a target enzyme for type-II diabetes, was examined by FEP method. Five mutations were made to the FBPase enzyme with AMP inhibitor bound: 113Tyr --> 113Phe, 31Thr --> 31Ala, 31Thr --> 31Ser, 177Met --> 177Ala, and 30Leu --> 30Phe. These mutations test the strength of hydrogen bonds and van der Waals interactions between the ligand and enzyme. The calculated relative free energies indicated that: 113Tyr and 31Thr play an important role, each via two hydrogen bonds affecting the binding affinity of inhibitor AMP to FBPase, and any changes in these hydrogen bonds due to mutations on the protein will have significant effect on the binding affinity of AMP to FBPase, consistent to experimental results. Also, the free energy calculations clearly show that the hydrophilic interactions are more important than the hydrophobic interactions of the binding pocket of FBPase.
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22
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Zarzycki M, Maciaszczyk E, Dzugaj A. Glu 69 is essential for the high sensitivity of muscle fructose-1,6-bisphosphatase inhibition by calcium ions. FEBS Lett 2007; 581:1347-50. [PMID: 17350621 DOI: 10.1016/j.febslet.2007.02.051] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 02/15/2007] [Accepted: 02/22/2007] [Indexed: 11/18/2022]
Abstract
Muscle fructose-1,6-bisphosphatase (FBPase) is highly sensitive toward inhibition by AMP and calcium ions. In allosteric inhibition by AMP, a loop 52-72 plays a decisive role. This loop is a highly conservative region in muscle and liver FBPases. It is feasible that the same region is involved in the inhibition by calcium ions. To test this hypothesis, chemical modification, limited proteolysis and site directed mutagenesis Glu(69)/Gln were employed. The chemical modification of Lys(71-72) and the proteolytic cleavage of the loop resulted in the significant decrease of the muscle FBPase sensitivity toward inhibition by calcium ions. The mutation of Glu(69)-->Gln resulted in a 500-fold increase of muscle isozyme I(0.5) vs. calcium ions. These results demonstrate the key role that the 52-72 amino acid loop plays in determining the sensitivity of FBPase to inhibition by AMP and calcium ions.
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Affiliation(s)
- Marek Zarzycki
- Department of Animal Physiology, Zoological Institute, University of Wroclaw, Cybulskiego 30, 50-205 Wroclaw, Poland
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23
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Rosini M, Mancini F, Tarozzi A, Colizzi F, Andrisano V, Bolognesi ML, Hrelia P, Melchiorre C. Design, synthesis, and biological evaluation of substituted 2,3-dihydro-1H-cyclopenta[b]quinolin-9-ylamine related compounds as fructose-1,6-bisphosphatase inhibitors. Bioorg Med Chem 2006; 14:7846-53. [PMID: 16908175 DOI: 10.1016/j.bmc.2006.07.059] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Revised: 07/26/2006] [Accepted: 07/28/2006] [Indexed: 10/24/2022]
Abstract
In a search for structurally new inhibitors of fructose-1,6-bisphosphatase (F16BPase), substituted 2,3-dihydro-1H-cyclopenta[b]quinoline derivatives were synthesized. It has been shown that the 2,3-dihydro-1H-cyclopenta[b]quinoline moiety may represent a suitable scaffold for the synthesis of potent F16BPase inhibitors endowed with significantly lower EGFR tyrosine kinase inhibitory activity.
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Affiliation(s)
- Michela Rosini
- Department of Pharmaceutical Sciences, Alma Mater Studiorum, University of Bologna, Via Belmeloro 6, 40126 Bologna, Italy
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24
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25
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Dougherty MJ, Boyd JM, Downs DM. Inhibition of fructose-1,6-bisphosphatase by aminoimidazole carboxamide ribotide prevents growth of Salmonella enterica purH mutants on glycerol. J Biol Chem 2006; 281:33892-9. [PMID: 16987812 DOI: 10.1074/jbc.m604429200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The enzyme fructose-1,6-bisphosphatase (FBP) is key regulatory point in gluconeogenesis. Mutants of Salmonella enterica lacking purH accumulate 5-amino-4-imidazole carboxamide ribotide (AICAR) and are unable to utilize glycerol as sole carbon and energy sources. The work described here demonstrates this lack of growth is due to inhibition of FBP by AICAR. Mutant alleles of fbp that restore growth on glycerol encode proteins resistant to inhibition by AICAR and the allosteric regulator AMP. This is the first report of biochemical characterization of substitutions causing AMP resistance in a bacterial FBP. Inhibition of FBP activity by AICAR occurs at physiologically relevant concentrations and may represent a form of regulation of gluconeogenic flux in Salmonella enterica.
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Affiliation(s)
- Michael J Dougherty
- Department of Bacteriology, University of Wisconsin, Madison, Wisconsin 53706, USA
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26
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Kirchner S, Kwon E, Muduli A, Cerqueira C, Cui XL, Ferraris RP. Vanadate but not tungstate prevents the fructose-induced increase in GLUT5 expression and fructose uptake by neonatal rat intestine. J Nutr 2006; 136:2308-13. [PMID: 16920846 DOI: 10.1093/jn/136.9.2308] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Intermediary signals, precociously enhancing GLUT5 transcription in response to perfusion of its substrate, fructose, in the small intestine of neonatal rats, are not known. Because glucose-6-phosphatase (G6Pase), glucose-6-phosphate translocase (G6PT), and fructose-1,6-bisphosphatase (FBPase) expression increases parallel to or precedes that of GLUT5, we investigated the link between these gluconeogenic genes and GLUT5 by using vanadate or tungstate, potent inhibitors of gluconeogenesis. Small intestinal perfusions of 20-d-old rats were performed with fructose alone, fructose + vanadate or tungstate, glucose alone, and glucose + vanadate or tungstate. As expected, fructose, but not glucose nor glucose + inhibitor perfusion, increased GLUT5 mRNA abundance and fructose transport. Fructose perfusion dramatically increased G6Pase mRNA abundance but had no effect on G6Pase activity. In sharp contrast, fructose perfusion did not increase FBPase gene expression but stimulated FBPase activity. Both vanadate and tungstate significantly inhibited G6Pase activity but did not prevent the fructose-induced increases in G6Pase and G6PT gene expression. Perfusion with fructose + vanadate prevented the fructose-induced increases in fructose transport and GLUT5 mRNA abundance, whereas perfusion with fructose + tungstate did not. Interestingly, vanadate, but not tungstate, inhibited the fructose-induced increase in FBPase activity. Thus, vanadate inhibition of fructose-induced increases in FBPase activity paralleled exactly vanadate inhibition of fructose-induced increases in GLUT5 mRNA abundance and activity. Fructose-induced changes in FBPase activity may regulate changes in GLUT5 expression and activity in the small intestine of neonatal rats. The marked increases in intestinal G6Pase and GLUT5 mRNA abundance may be a parallel response to different factors released during fructose perfusion.
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Affiliation(s)
- Séverine Kirchner
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, Newark, NJ 07103-2714, USA
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27
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van Poelje PD, Potter SC, Chandramouli VC, Landau BR, Dang Q, Erion MD. Inhibition of fructose 1,6-bisphosphatase reduces excessive endogenous glucose production and attenuates hyperglycemia in Zucker diabetic fatty rats. Diabetes 2006; 55:1747-54. [PMID: 16731838 DOI: 10.2337/db05-1443] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Gluconeogenesis is increased in type 2 diabetes and contributes significantly to fasting and postprandial hyperglycemia. We recently reported the discovery of the first potent and selective inhibitors of fructose 1,6-bisphosphatase (FBPase), a rate-controlling enzyme of gluconeogenesis. Herein we describe acute and chronic effects of the lead inhibitor, MB06322 (CS-917), in rodent models of type 2 diabetes. In fasting male ZDF rats with overt diabetes, a single dose of MB06322 inhibited gluconeogenesis by 70% and overall endogenous glucose production by 46%, leading to a reduction in blood glucose of >200 mg/dl. Chronic treatment of freely feeding 6-week-old male Zucker diabetic fatty (ZDF) rats delayed the development of hyperglycemia and preserved pancreatic function. Elevation of lactate ( approximately 1.5-fold) occurred after 4 weeks of treatment, as did the apparent shunting of precursors into triglycerides. Profound glucose lowering ( approximately 44%) and similar metabolic ramifications were associated with 2-week intervention therapy of 10-week-old male ZDF rats. In high-fat diet-fed female ZDF rats, MB06322 treatment for 2 weeks fully attenuated hyperglycemia without evidence of metabolic perturbation other than a modest reduction in glycogen stores ( approximately 20%). The studies confirm that excessive gluconeogenesis plays an integral role in the pathophysiology of type 2 diabetes and suggest that FBPase inhibitors may provide a future treatment option.
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Affiliation(s)
- Paul D van Poelje
- Department of Biochemistry, Metabasis Therapeutics, 11119 North Torrey Pines Rd., La Jolla, CA 92037, USA.
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28
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Lai C, Gum RJ, Daly M, Fry EH, Hutchins C, Abad-Zapatero C, von Geldern TW. Benzoxazole benzenesulfonamides as allosteric inhibitors of fructose-1,6-bisphosphatase. Bioorg Med Chem Lett 2006; 16:1807-10. [PMID: 16446092 DOI: 10.1016/j.bmcl.2006.01.014] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Revised: 01/04/2006] [Accepted: 01/05/2006] [Indexed: 11/17/2022]
Abstract
A series of novel benzoxazole benzenesulfonamides was synthesized as inhibitors of fructose-1,6-bisphosphatase (FBPase-1). Extensive SAR studies led to a potent inhibitor, 53, with an IC(50) of 0.57microM. Compound 17 exhibited excellent bioavailability and a good pharmacokinetic profile in rats.
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Affiliation(s)
- Chunqiu Lai
- Metabolic Disease Research, GPRD, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064, USA.
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von Geldern TW, Lai C, Gum RJ, Daly M, Sun C, Fry EH, Abad-Zapatero C. Benzoxazole benzenesulfonamides are novel allosteric inhibitors of fructose-1,6-bisphosphatase with a distinct binding mode. Bioorg Med Chem Lett 2006; 16:1811-5. [PMID: 16442285 DOI: 10.1016/j.bmcl.2006.01.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Revised: 01/04/2006] [Accepted: 01/05/2006] [Indexed: 10/25/2022]
Abstract
We have identified benzoxazole benzenesulfonamide 1 as a novel allosteric inhibitor of fructose-1,6-bisphosphatase (FBPase-1). X-ray crystallographic and biological studies of 1 indicate a distinct binding mode that recapitulates features of several previously reported FBPase-1 inhibitor classes.
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Affiliation(s)
- Thomas W von Geldern
- Metabolic Disease Research, GPRD, Abbott Laboratories, Abbott Park, IL 60064, USA.
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30
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Rakus D, Maciaszczyk E, Wawrzycka D, Ułaszewski S, Eschrich K, Dzugaj A. The origin of the high sensitivity of muscle fructose 1,6-bisphosphatase towards AMP. FEBS Lett 2005; 579:5577-81. [PMID: 16213487 DOI: 10.1016/j.febslet.2005.09.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 07/13/2005] [Accepted: 09/13/2005] [Indexed: 11/27/2022]
Abstract
Adenosine 5'-monophosphate (AMP) inhibits muscle fructose 1,6-bisphosphatase (FBPase) about 44 times stronger than the liver isozyme. The key role in strong AMP binding to muscle isozyme play K20, T177 and Q179. Muscle FBPase which has been mutated towards the liver enzyme (K20E/T177M/Q179C) is inhibited by AMP about 26 times weaker than the wild-type muscle enzyme, but it binds the fluorescent AMP analogue, 2',3'-O-(2,4,6-trinitrophenyl)adenosine 5'-monophosphate (TNP-AMP), similarly to the wild-type liver enzyme. The reverse mutation of liver FBPase towards the muscle isozyme significantly increases the affinity of the mutant to TNP-AMP. High affinity to the inhibitor but low sensitivity to AMP of the liver triple mutant suggest differences between the isozymes in the mechanism of allosteric signal transmission.
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Affiliation(s)
- D Rakus
- Department of Animal Physiology, Institute of Zoology, Wroclaw University, Poland
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31
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Erion MD, van Poelje PD, Dang Q, Kasibhatla SR, Potter SC, Reddy MR, Reddy KR, Jiang T, Lipscomb WN. MB06322 (CS-917): A potent and selective inhibitor of fructose 1,6-bisphosphatase for controlling gluconeogenesis in type 2 diabetes. Proc Natl Acad Sci U S A 2005; 102:7970-5. [PMID: 15911772 PMCID: PMC1138262 DOI: 10.1073/pnas.0502983102] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
In type 2 diabetes, the liver produces excessive amounts of glucose through the gluconeogenesis (GNG) pathway and consequently is partly responsible for the elevated glucose levels characteristic of the disease. In an effort to find safe and efficacious GNG inhibitors, we targeted the AMP binding site of fructose 1,6-bisphosphatase (FBPase). The hydrophilic nature of AMP binding sites and their widespread use for allosteric regulation of enzymes in metabolic pathways has historically made discovery of AMP mimetics suitable for drug development difficult. By using a structure-based drug design strategy, we discovered a series of compounds that mimic AMP but bear little structural resemblance. The lead compound, MB05032, exhibited high potency and specificity for human FBPase. Oral delivery of MB05032 was achieved by using the bisamidate prodrug MB06322 (CS-917), which is converted to MB05032 in two steps through the action of an esterase and a phosphoramidase. MB06322 inhibited glucose production from a variety of GNG substrates in rat hepatocytes and from bicarbonate in male Zucker diabetic fatty rats. Analysis of liver GNG pathway intermediates confirmed FBPase as the site of action. Oral administration of MB06322 to Zucker diabetic fatty rats led to a dose-dependent decrease in plasma glucose levels independent of insulin levels and nutritional status. Glucose lowering occurred without signs of hypoglycemia or significant elevations in plasma lactate or triglyceride levels. The findings suggest that potent and specific FBPase inhibitors represent a drug class with potential to treat type 2 diabetes through inhibition of GNG.
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Affiliation(s)
- Mark D Erion
- Department of Biochemistry, Metabasis Therapeutics, Inc., 9390 Towne Centre Drive, Building 300, San Diego, CA 92121, USA.
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32
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Mackonochie M, Chan D. American Chemical Society - 229th National Meeting: general oral and poster sessions. IDrugs 2005; 8:392-4. [PMID: 15883919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
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33
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Iancu CV, Mukund S, Fromm HJ, Honzatko RB. R-state AMP complex reveals initial steps of the quaternary transition of fructose-1,6-bisphosphatase. J Biol Chem 2005; 280:19737-45. [PMID: 15767255 DOI: 10.1074/jbc.m501011200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AMP transforms fructose-1,6-bisphosphatase from its active R-state to its inactive T-state; however, the mechanism of that transformation is poorly understood. The mutation of Ala(54) to leucine destabilizes the T-state of fructose-1,6-bisphosphatase. The mutant enzyme retains wild-type levels of activity, but the concentration of AMP that causes 50% inhibition increases 50-fold. In the absence of AMP, the Leu(54) enzyme adopts an R-state conformation nearly identical to that of the wild-type enzyme. The mutant enzyme, however, grows in two crystal forms in the presence of saturating AMP. In one form, the AMP-bound tetramer is in a T-like conformation, whereas in the other form, the AMP-bound tetramer is in a R-like conformation. The latter reveals conformational changes in two helices due to the binding of AMP. Helix H1 moves toward the center of the tetramer and displaces Ile(10) from a hydrophobic pocket. The displacement of Ile(10) exposes a hydrophobic surface critical to interactions that stabilize the T-state. Helix H2 moves away from the center of the tetramer, breaking hydrogen bonds with a buried loop (residues 187-195) in an adjacent subunit. The same hydrogen bonds reform but only after the quaternary transition to the T-state. Proposed here is a model that accounts for the quaternary transition and cooperativity in the inhibition of catalysis by AMP.
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Affiliation(s)
- Cristina V Iancu
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, 50011, USA
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34
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Abstract
Computational assessment of the binding affinity of enzyme inhibitors prior to synthesis is an important component of computer-aided drug design (CADD) paradigms. The free energy perturbation (FEP) methodology is the most accurate means of estimating relative binding affinities between two inhibitors. However, due to its complexity and computation-intensive nature, practical applications are restricted to analysis of structurally-related inhibitors. Accordingly, there is a need for methods that enable rapid assessment of a large number of structurally-unrelated molecules in a suitably accurate manner. In this review, the FEP method is compared with molecular mechanics (MM) methods to assess the advantages of each in the estimation of relative binding affinities of inhibitors to an enzyme. Qualitative predictions of relative binding free energies of fructose 1, 6-bisphosphatase inhibitors using MM methods are discussed and compared with the corresponding FEP results. The results indicate that the MM based methods and the FEP method are useful in the qualitative and quantitative assessment of relative binding affinities of enzyme inhibitors, respectively, prior to synthesis.
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Affiliation(s)
- M Rami Reddy
- Metabasis Therapeutics, Inc, 9390 Towne Centre Drive, San Diego, CA 92121, USA. E-mail:
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35
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Rakus D, Pasek M, Krotkiewski H, Dzugaj A. Interaction between muscle aldolase and muscle fructose 1,6-bisphosphatase results in the substrate channeling. Biochemistry 2005; 43:14948-57. [PMID: 15554702 DOI: 10.1021/bi048886x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Fructose 1,6-bisphosphatase (FBPase) is known to form a supramolecular complex with alpha-actinin and aldolase on both sides of the Z-line in skeletal muscle cells. It has been proposed that association of aldolase with FBPase not only desensitizes muscle FBPase toward AMP inhibition but it also might enable the channeling of intermediates between the enzymes [Rakus et al. (2003) FEBS Lett. 547, 11-14]. In the present paper, we tested the possibility of fructose 1,6-bisphosphate (F1,6-P(2)) channeling between aldolase and FBPase using the approach in which an inactive form of FBPase competed with active FBPase for binding to aldolase and thus decreased the rate of aldolase-FBPase reaction. The results showed that F1,6-P(2) is transferred directly from aldolase to FBPase without mixing with the bulk phase. Further evidence that F1,6-P(2) is channeled from aldolase to FBPase comes from the experiments investigating the inhibitory effect of a high concentration of magnesium ions on aldolase-FBPase activity. FBPase in a complex with aldolase, contrary to free muscle FBPase, was not inhibited by high Mg(2+) concentrations, which suggests that free F1,6-P(2) was not present in the assay mixture during the reaction. A real-time interaction analysis between aldolase and FBPase revealed a dual role of Mg(2+) in the regulation of the aldolase-FBPase complex stability. A physiological concentration of Mg(2+) increased the affinity of muscle FBPase to muscle aldolase, whereas higher concentrations of the cation decreased the concentration of the complex. We hypothesized that the presence of Mg(2+) stabilizes a positively charged cavity within FBPase and that it might enable an interaction with aldolase. Because magnesium decreased the binding constant (K(a)) between aldolase and FBPase in a manner similar to the decrease of K(a) caused by monovalent cations, it is postulated that electrostatic attraction might be a driving force for the complex formation. It is presumed that the biological relevance of F1,6-P(2) channeling between aldolase and FBPase is protection of this glyconeogenic, as well as glycolytic, intermediate against degradation by cytosolic aldolase, which is one of the most abundant enzyme of glycolysis.
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Affiliation(s)
- Darek Rakus
- Department of Animal Physiology, Zoological Institute, Wroclaw University, Cybulskiego 30, 50-205 Wroclaw, Poland
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36
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Gizak A, Majkowski M, Dus D, Dzugaj A. Calcium inhibits muscle FBPase and affects its intracellular localization in cardiomyocytes. FEBS Lett 2004; 576:445-8. [PMID: 15498578 DOI: 10.1016/j.febslet.2004.09.050] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2004] [Revised: 09/17/2004] [Accepted: 09/24/2004] [Indexed: 11/24/2022]
Abstract
As our recent investigation revealed, in mammalian heart muscle, fructose 1,6-bisphosphatase (FBPase)--a key enzyme of glyconeogenesis--is located around the Z-line, inside cells' nuclei and, as we demonstrate here for the first time, it associates with intercalated discs. Since the degree of association of numerous enzymes with subcellular structures depends on the metabolic state of the cell, we studied the effect of elevated Ca2+ concentration on localization of FBPase in cardiomyocytes. In such conditions, FBPase dissociated from the Z-line, but no visible effect on FBPase associated with intercalated discs or on the nuclear localization of the enzyme was observed. Additionally, Ca2+ appeared to be a strong inhibitor of muscle FBPase.
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Affiliation(s)
- A Gizak
- Department of Animal Physiology, Institute of Zoology, Wroclaw University, Cybulskiego 30, 50-205 Wroclaw, Poland
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37
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Dziewulska-Szwajkowska D, Zmojdzian M, Dobryszycki P, Kochman M, Dzugaj A. The interaction of FBPase with aldolase: a kinetic and fluorescence investigation on chicken muscle enzymes. Comp Biochem Physiol B Biochem Mol Biol 2004; 137:115-29. [PMID: 14698918 DOI: 10.1016/j.cbpc.2003.10.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Fructose-1,6-bisphosphatase (FBPase; EC 3.1.3.11) is strongly inhibited by AMP in vitro and, therefore, at physiological concentrations of substrate and AMP, FBPase should be completely inhibited. Desensitization of rabbit muscle FBPase against AMP inhibition was previously observed in the presence of rabbit muscle aldolase. In this study, we analysed the kinetics of an FBPase catalyzed reaction and interaction between chicken muscle FBPase and chicken muscle aldolase. The initial rate of FBPase reaction vs. substrate concentration shows a maximum activity at a concentration of 20 microM Fru-1,6P2 and then decreases. Assuming rapid equilibrium kinetics, the enzyme-catalyzed reaction was described by the substrate inhibition model, with Ks approximately 5 microM and Ksi approximately 39 microM and factor beta approximately 0.2, describing change in the rate constant (k) of product formation from the ES and ESSi complexes. Based on ultracentrifugation studies, aldolase and FBPase form a hetero-complex with approximately 1:1 stoichiometry with a dissociation constant (Kd) of 3.8 microM. The FBPase-aldolase interaction was confirmed via fluorescence investigation. The aldolase-FBPase interaction results in aldolase fluorescence quenching and its maximum emission spectrum shifting from 344 to 356 nm. The Kd of the FBPase-aldolase complex, determined on the basis of fluorescence changes, is 0.4 microM at 25 degrees C with almost 1:1 stoichiometry. This interaction increases the I(0.5) for the AMP inhibition of FBPase threefold, and slightly affects FBPase affinity to magnesium ions, increasing the Ka and Hill coefficient (n). No effect of aldolase on the FBPase pH optimum was observed. Thus, the decrease in FBPase sensitivity to AMP inhibition enables FBPase to function in vivo thanks to aldolase.
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Affiliation(s)
- Daria Dziewulska-Szwajkowska
- Department of Animal Physiology, Zoological Institute, Wroclaw University, Cybulskiego 30, 50-205 Wroclaw, Poland
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38
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Obiadalla-Ali H, Fernie AR, Lytovchenko A, Kossmann J, Lloyd JR. Inhibition of chloroplastic fructose 1,6-bisphosphatase in tomato fruits leads to decreased fruit size, but only small changes in carbohydrate metabolism. Planta 2004; 219:533-40. [PMID: 15060828 DOI: 10.1007/s00425-004-1257-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2003] [Accepted: 02/03/2004] [Indexed: 05/06/2023]
Abstract
A potato (Solanum tuberosum L.) cDNA coding for the chloroplastic isoform of fructose 1,6-bisphosphatase (cp-FBPase) was utilized to repress its activity in tomatoes (Lycopersicon esculentum Mill.) using antisense techniques. The patatin B33 promoter was used to ensure fruit specificity of the antisense effect. Transgenic plants were isolated in which fructose 1,6-bisphosphatase activity was reduced by more than 50% of the control in green fruits. Immunoblots indicated that the plastidial isoform was almost completely eliminated in the most strongly inhibited lines. Fruits of the transgenic plants were analyzed for levels of metabolites during fruit development. Glucose and fructose concentrations were increased in green fruits in the transgenic lines, but unchanged at later stages of development. The sucrose concentration was low, and was not significantly altered in the transgenic lines. There was net degradation of starch over the developmental period, but the starch content was not decreased. In green fruit the levels of hexose phosphates were unchanged, whilst the level of 3-phosphoglyceric acid was significantly increased in one line. Most importantly the deduced ratio of hexose phosphate to 3-phosphoglyceric acid decreased, consistent with an in vivo inhibition of fructose 1,6-bisphosphatase activity. One consequence of this reduction of in vivo activity of cp-FBPase was that the average weight of fully ripe fruits was significantly decreased by up to 20% in all transgenic lines in comparison with the control.
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Affiliation(s)
- Hazem Obiadalla-Ali
- Willmitzer Department, Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Golm, Germany
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39
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Zhou R, Cheng L. Biochemical characterization of cytosolic fructose-1,6-bisphosphatase from apple (Malus domestica) leaves. Plant Cell Physiol 2004; 45:879-86. [PMID: 15295071 DOI: 10.1093/pcp/pch096] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Cytosolic fructose-1,6-bisphosphatase was purified to apparent homogeneity from the leaves of apple, a sorbitol synthesizing species. The enzyme was a homotetramer with a subunit mass of 37 kDa, and was highly specific for fructose 1,6-bisphosphate (F1,6BP) with a Km of 3.1 micro M and a Vmax of 48 units (mg protein)(-1). Either Mg2+ or Mn2+ was required for its activity with a Km of 0.59 mM and 62 micro M, respectively. Li+, Ca2+, Zn2+, Cu2+ and Hg2+ inhibited whereas Mn2+ enhanced the Mg2+ activated enzyme activity. Fructose 6-phosphate (F6P) was found to be a mixed type inhibitor with a Ki of 0.47 mM. Fructose 2,6-bisphosphate (F2,6BP) competitively inhibited the enzyme activity and changed the substrate saturation curve from hyperbolic to sigmoidal. AMP was a non-competitive inhibitor for the enzyme. F6P interacted with F2,6BP and AMP in a synergistic way to inhibit the enzyme activity. Dihydroxyacetone phosphate slightly inhibited the enzyme activity in the presence or absence of F2,6BP. Sorbitol increased the susceptibility of the enzyme to the inhibition by high concentrations of F1,6BP. High concentrations of sorbitol in the reaction mixture led to a reduction in the enzyme activity.
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Affiliation(s)
- Rui Zhou
- Department of Horticulture, Cornell University, Ithaca, NY 14853, USA
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40
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Choe JY, Nelson SW, Arienti KL, Axe FU, Collins TL, Jones TK, Kimmich RDA, Newman MJ, Norvell K, Ripka WC, Romano SJ, Short KM, Slee DH, Fromm HJ, Honzatko RB. Inhibition of fructose-1,6-bisphosphatase by a new class of allosteric effectors. J Biol Chem 2003; 278:51176-83. [PMID: 14530289 DOI: 10.1074/jbc.m308396200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A highly constrained pseudo-tetrapeptide (OC252-324) further defines a new allosteric binding site located near the center of fructose-1,6-bisphosphatase. In a crystal structure, pairs of inhibitory molecules bind to opposite faces of the enzyme tetramer. Each ligand molecule is in contact with three of four subunits of the tetramer, hydrogen bonding with the side chain of Asp187 and the backbone carbonyl of residue 71, and electrostatically interacting with the backbone carbonyl of residue 51. The ligated complex adopts a quaternary structure between the canonical R- and T-states of fructose-1,6-bisphosphatase, and yet a dynamic loop essential for catalysis (residues 52-72) is in a conformation identical to that of the T-state enzyme. Inhibition by the pseudo-tetrapeptide is cooperative (Hill coefficient of 2), synergistic with both AMP and fructose 2,6-bisphosphate, noncompetitive with respect to Mg2+, and uncompetitive with respect to fructose 1,6-bisphosphate. The ligand dramatically lowers the concentration at which substrate inhibition dominates the kinetics of fructose-1,6-bisphosphatase. Elevated substrate concentrations employed in kinetic screens may have facilitated the discovery of this uncompetitive inhibitor. Moreover, the inhibitor could mimic an unknown natural effector of fructose-1,6-bisphosphatase, as it interacts strongly with a conserved residue of undetermined functional significance.
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Affiliation(s)
- Jun-Young Choe
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA
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Abstract
Real-time interaction analysis, using the BIAcore biosensor, of rabbit muscle FBPase-aldolase complex revealed apparent binding constant [K(Aapp)] values of about 4.4x10(8) M(-1). The stability of the complex was down-regulated by the glycolytic intermediates dihydroxyacetone phosphate and fructose 6-phosphate, and by the regulator of glycolysis and glyconeogenesis--fructose 2,6-bisphosphate. FBPase in a complex with aldolase was entirely insensitive to inhibition by physiological concentrations of AMP (I(0.5) was 1.35 mM) and the cooperativity of the inhibition was not observed. The existence of an FBPase-aldolase complex that is insensitive to AMP inhibition explains the possibility of glycogen synthesis from carbohydrate precursors in vertebrates' myocytes.
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Affiliation(s)
- D Rakus
- Department of Animal Physiology, Institute of Zoology, Wroclaw University, Cybulskiego 30, 50-205, Wroclaw, Poland
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Wright SW, Carlo AA, Danley DE, Hageman DL, Karam GA, Mansour MN, McClure LD, Pandit J, Schulte GK, Treadway JL, Wang IK, Bauer PH. 3-(2-carboxyethyl)-4,6-dichloro-1H-indole-2-carboxylic acid: an allosteric inhibitor of fructose-1,6-bisphosphatase at the AMP site. Bioorg Med Chem Lett 2003; 13:2055-8. [PMID: 12781194 DOI: 10.1016/s0960-894x(03)00310-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
3-(2-Carboxyethyl)-4,6-dichloro-1H-indole-2-carboxylic acid (MDL-29951), an antagonist of the glycine site of the NMDA receptor, has been found to be an allosteric inhibitor of the enzyme fructose 1,6-bisphosphatase. The compound binds at the AMP regulatory site by X-ray crystallography. This represents a new approach to inhibition of fructose 1,6-bisphosphatase and serves as a lead for further drug design.
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Affiliation(s)
- Stephen W Wright
- Pfizer Central Research, Eastern Point Road, Box 8220-3141, Groton, CT 06340, USA.
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Link JT. Pharmacological regulation of hepatic glucose production. Curr Opin Investig Drugs 2003; 4:421-9. [PMID: 12808881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
The discovery of antidiabetic agents that inhibit hepatic glucose production is a popular and potentially fruitful research area for the pharmaceutical research community. Metformin, a marketed agent with this mechanism of action, is widely used for the treatment of type 2 diabetes, however, more efficacious agents are sought. A number of promising proteins are being targeted for modulation by new compounds, including the glucagon receptor, glycogen phosphorylase, glucocorticoid receptor, 11 beta-hydroxysteroid dehydrogenase-1, fructose-1,6-bisphosphatase, carnitine palmitoyltransferase-1, glycogen synthase kinase-3, glucose-6-phosphate T1 translocase and the A2B receptor. Compounds designed to work against these targets are at the early clinical or preclinical phase of study. Glucagon receptor antagonists, glycogen phosphorylase inhibitors, 11 beta-hydroxysteroid dehydrogenase-1 inhibitors, carnitine palmitoyltransferase-1 inhibitors and fructose-1,6-bisphosphatase inhibitors are, or have been, clinically evaluated. Preclinical studies against the other targets have yielded compounds that demonstrate efficacy in diabetic animal models and clinical activity will continue.
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Affiliation(s)
- James T Link
- Abbott Laboratories, 100 Abbott Park Road, IL 60064-6098, USA.
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44
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Rakus D, Tillmann H, Wysocki R, Ulaszewski S, Eschrich K, Dzugaj A. Different sensitivities of mutants and chimeric forms of human muscle and liver fructose-1,6-bisphosphatases towards AMP. Biol Chem 2003; 384:51-8. [PMID: 12674499 DOI: 10.1515/bc.2003.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AMP is an allosteric inhibitor of human muscle and liver fructose-1,6-bisphosphatase (FBPase). Despite strong similarity of the nucleotide binding domains, the muscle enzyme is inhibited by AMP approximately 35 times stronger than liver FBPase: I0.5 for muscle and for liver FBPase are 0.14 microM and 4.8 microM, respectively. Chimeric human muscle (L50M288) and chimeric human liver enzymes (M50L288), in which the N-terminal residues (1-50) were derived from the human liver and human muscle FBPases, respectively, were inhibited by AMP 2-3 times stronger than the wild-type liver enzyme. An amino acid exchange within the N-terminal region of the muscle enzyme towards liver FBPase (Lys20-->Glu) resulted in 13-fold increased I0.5 values compared to the wild-type muscle enzyme. However, the opposite exchanges in the liver enzyme (Glu20-->Lys and double mutation Glu19-->Asp/Glu20-->Lys) did not change the sensitivity for AMP inhibition of the liver mutant (I0.5 value of 4.9 microM). The decrease of sensitivity for AMP of the muscle mutant Lys20-->Glu, as well as the lack of changes in the inhibition by AMP of liver mutants Glu20-->Lys and Glu19-->Asp/Glu20-->Lys, suggest a different mechanism of AMP binding to the muscle and liver enzyme.
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Affiliation(s)
- Dariusz Rakus
- Department of Animal Physiology, Zoological Institute, Wroclaw University, Cybulskiego 30, 50-205 Wroclaw, Poland
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45
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Wright SW, Carlo AA, Carty MD, Danley DE, Hageman DL, Karam GA, Levy CB, Mansour MN, Mathiowetz AM, McClure LD, Nestor NB, McPherson RK, Pandit J, Pustilnik LR, Schulte GK, Soeller WC, Treadway JL, Wang IK, Bauer PH. Anilinoquinazoline inhibitors of fructose 1,6-bisphosphatase bind at a novel allosteric site: synthesis, in vitro characterization, and X-ray crystallography. J Med Chem 2002; 45:3865-77. [PMID: 12190310 DOI: 10.1021/jm010496a] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis and in vitro structure-activity relationships (SAR) of a novel series of anilinoquinazolines as allosteric inhibitors of fructose-1,6-bisphosphatase (F16Bpase) are reported. The compounds have a different SAR as inhibitors of F16Bpase than anilinoquinazolines previously reported. Selective inhibition of F16Bpase can be attained through the addition of appropriate polar functional groups at the quinazoline 2-position, thus separating the F16Bpase inhibitory activity from the epidermal growth factor receptor tyrosine kinase inhibitory activity previously observed with similar structures. The compounds have been found to bind at a symmetry-repeated novel allosteric site at the subunit interface of the enzyme. Inhibition is brought about by binding to a loop comprised of residues 52-72, preventing the necessary participation of these residues in the assembly of the catalytic site. Mutagenesis studies have identified the key amino acid residues in the loop that are required for inhibitor recognition and binding.
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Affiliation(s)
- Stephen W Wright
- Pfizer Central Research, Eastern Point Road, Groton, Connecticut 06340, USA.
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Nelson SW, Honzatko RB, Fromm HJ. Hybrid tetramers of porcine liver fructose-1,6-bisphosphatase reveal multiple pathways of allosteric inhibition. J Biol Chem 2002; 277:15539-45. [PMID: 11854289 DOI: 10.1074/jbc.m112304200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fructose-1,6-bisphosphatase is a square planar tetramer of identical subunits, which exhibits cooperative allosteric inhibition of catalysis by AMP. Protocols for in vitro subunit exchange provide three of five possible hybrid tetramers of fructose-1,6-bisphosphatase in high purity. The two hybrid types with different subunits in the top and bottom halves of the tetramer co-purify. Hybrid tetramers, formed from subunits unable to bind AMP and subunits with wild-type properties, differ from the wild-type enzyme only in regard to their properties of AMP inhibition. Hybrid tetramers exhibit cooperative, potent, and complete (100%) AMP inhibition if at least one functional AMP binding site exists in the top and bottom halves of the tetramer. Furthermore, titrations of hybrid tetramers with AMP, monitored by a tryptophan reporter group, reveal cooperativity and fluorescence changes consistent with an R- to T-state transition, provided that again at least one functional AMP site exists in the top and bottom halves of the tetramer. In contrast, hybrid tetramers, which have functional AMP binding sites in only one half (top/bottom), exhibit an R- to T-state transition and complete AMP inhibition, but without cooperativity. Evidently, two pathways of allosteric inhibition of fructose-1,6-bisphosphatase are possible, only one of which is cooperative.
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Affiliation(s)
- Scott W Nelson
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA
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47
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Abstract
Lys-112 and Tyr-113 in pig kidney fructose-1,6-bisphosphatase (FBPase) make direct interactions with AMP in the allosteric binding site. Both residues interact with the phosphate moiety of AMP while Tyr-113 also interacts with the 3'-hydroxyl of the ribose ring. The role of these two residues in AMP binding and allosteric inhibition was investigated. Site-specific mutagenesis was used to convert Lys-112 to glutamine (K112Q) and Tyr-113 to phenylalanine (Y113F). These amino acid substitutions result in small alterations in k(cat) and increases in K(m). However, both the K112Q and Y113F enzymes show alterations in Mg(2+) affinity and dramatic reductions in AMP affinity. For both mutant enzymes, the AMP concentration required to reduced the enzyme activity by one-half, [AMP](0.5), was increased more than a 1000-fold as compared to the wild-type enzyme. The K112Q enzyme also showed a 10-fold reduction in affinity for Mg(2+). Although the allosteric site is approximately 28 A from the metal binding sites, which comprise part of the active site, these site-specific mutations in the AMP site influence metal binding and suggest a direct connection between the allosteric and the active sites.
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Affiliation(s)
- N Kelley-Loughnane
- Department of Chemistry, Boston College, Merkert Chemistry Center, Chestnut Hill, MA 02467, USA
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48
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Reddy MR, Erion MD. Calculation of relative binding free energy differences for fructose 1,6-bisphosphatase inhibitors using the thermodynamic cycle perturbation approach. J Am Chem Soc 2001; 123:6246-52. [PMID: 11427047 DOI: 10.1021/ja0103288] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An iterative, computer-assisted, drug design strategy that combines molecular design, molecular mechanics, molecular dynamics (MD), and free energy perturbation (FEP) calculations with compound synthesis, biochemical testing of inhibitors, and crystallographic structure determination of protein-inhibitor complexes was successfully used to predict the rank order of a series of nucleoside monophosphate analogues as fructose 1,6-bisphosphatase (FBPase) inhibitors. The X-ray structure of FBPase complexed with 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranosyl 5'-monophosphate (ZMP) provided structural information used for subsequent analogue design and free energy calculations. The FEP protocol was validated by calculating the free energy differences for the mutation of ZMP (1) to AMP (2). The calculated results showed a net gain of 1.7 kcal/mol, which agreed with the experimental result of 1.3 kcal/mol. FEP calculations were performed for 18 other AMP analogues. Inhibition constants were determined for over half of these analogues, usually after completion of the calculation, and were consistent with the predictions. Solvation free energy differences between AMP and various AMP analogues proved to be an important factor in binding free energies, suggesting that increased desolvation costs associated with the addition of polar groups to an inhibitor must be overcome by stronger ligand-protein interactions if the structural modification is to enhance inhibitor potency. The results indicate that FEP calculations predict relative binding affinities with high accuracy and provide valuable insight into the factors that influence inhibitor binding and therefore should greatly aid efforts to optimize initial lead compounds and reduce the time required for the discovery of new drug candidates.
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Affiliation(s)
- M R Reddy
- Metabasis Therapeutics, Inc., 9390 Towne Centre Drive, San Diego, CA 92121, USA.
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McIninch JK, Kantrowitz ER. Use of silicate sol-gels to trap the R and T quaternary conformational states of pig kidney fructose-1,6-bisphosphatase. Biochim Biophys Acta 2001; 1547:320-8. [PMID: 11410288 DOI: 10.1016/s0167-4838(01)00203-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Encapsulation of the homotetrameric pig kidney fructose-1,6-bisphosphatase (FBPase) in tetramethyl orthosilicate sol-gels was used to dramatically reduce the rate of the allosteric transition of the enzyme between the T and R allosteric states. When assayed in the absence of the allosteric inhibitor AMP, the enzyme encapsulated in the T-state exhibited little activity. The enzyme encapsulated in the R-state exhibited a 4-fold lower k(cat) and V(max) than the enzyme in solution, and the apparent K(m) for this enzyme was 350-fold higher than the corresponding value for the enzyme in solution. The [Mg(2+)](0.5) for the encapsulated enzyme was only 0.1 mM, compared to 0.54 mM for the normal enzyme. Magnesium activation, under both sets of conditions, was cooperative with a Hill coefficient of approximately 2. The activity of enzyme encapsulated in the R-state decreased to about 70% of initial activity within 1 min of adding AMP, it then decreased slowly to about 40% of initial activity over the following 7 h. Under the conditions tested, the encapsulated enzyme never became completely inactivated and AMP inhibition was no longer cooperative. For enzyme encapsulated in the T-state, activity was restored over approximately 7 h after removal of the AMP. The biphasic and slow responses to changing AMP levels suggest that encapsulated enzyme can be used to study the effects of local conformational changes distinct from the global quaternary conformational changes by slowing down the ability of the enzyme to carry out global rotations. The response to AMP exhibited by the encapsulated enzyme is consistent with the ability of AMP, at least partially, to directly influence the activity of the active site within each subunit.
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Affiliation(s)
- J K McIninch
- Department of Chemistry, Boston College, Merkert Chemistry Center, Chestnut Hill, MA 02467, USA
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Becker A, Liewald JF, Stypa H, Wegener G. Antagonistic effects of hypertrehalosemic neuropeptide on the activities of 6-phosphofructo-1-kinase and fructose-1,6-bisphosphatase in cockroach fat body. Insect Biochem Mol Biol 2001; 31:381-392. [PMID: 11222947 DOI: 10.1016/s0965-1748(00)00131-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Hypertrehalosemic neuropeptides from the corpora cardiaca such as the decapeptide Bld HrTH bring about a profound switch in the metabolic activity of cockroach fat body during which production of the blood sugar trehalose is stimulated while the catabolism of carbohydrate (glycolysis) is inhibited. The mechanisms of the metabolic switch are not fully understood. Incubation of isolated fat body from the cockroach Blaptica dubia with 10(-8) M Bld HrTH, for 10-60 min, stimulated glycogen breakdown and increased the content of the substrates of both the glycolytic enzyme 6-phosphofructo-1-kinase (PFK, EC 2.7.1.11) and the gluconeogenic enzyme fructose-1,6-bisphosphatase (FBPase, EC 3.1.3.11) in the tissue. The glycolytic signal fructose 2,6-bisphosphate was markedly decreased in fat body on incubation with Bld HrTH. The content of ATP was slightly reduced, while the contents of ADP and AMP were increased after incubation with the hormone. Fructose 2,6-bisphosphate is a potent activator of PFK and a strong inhibitor of FBPase purified from fat body. The activity of PFK was decreased by about 90% when the hormone-dependent changes in effectors and substrates in fat body were simulated in vitro. FBPase, in contrast, was activated about 25-fold under these conditions, suggesting the hormone to stimulate gluconeogenesis in fat body. The data support the view that fructose 2,6-bisphosphate is a pivotal intracellular messenger in the hormone-induced metabolic switch from carbohydrate degradation to trehalose production in cockroach fat body.
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Affiliation(s)
- A Becker
- Institut für Zoologie, Johannes Gutenberg-Universität, Saarstrasse 21, 55099, Mainz, Germany
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