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Dong L, Malkowski MG. Defining the Conformational Ensembles Associated with Ligand Binding to Cyclooxygenase-2. Biochemistry 2023; 62:3134-3144. [PMID: 37852627 PMCID: PMC11425902 DOI: 10.1021/acs.biochem.3c00341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
Cyclooxygenases (COX) catalyze the committed step in the production of prostaglandins responsible for the maintenance of physiological homeostasis. While crystal structures of COX in complex with substrates and inhibitors have provided insight into the molecular interactions governing their binding, they have not uncovered specific details related to the protein conformational motions responsible for important aspects of the COX function. We created a cysteine-free COX-2 construct and introduced a free cysteine at position-122 to enable labeling with 3-bromo-1,1,1-trifluoroacetone (BTFA). Placement of the label adjacent to the cyclooxygenase channel entrance permitted the detection of alterations upon ligand binding. 19F-nuclear magnetic resonance spectroscopy (19F-NMR) was then used to probe the conformational ensembles arising from BTFA-labeled COX-2 constructs in the presence and absence of ligands known to allosterically activate or inhibit COX-2. 19F-NMR analyses performed in the presence of the time-dependent inhibitor flurbiprofen, as well as Arg-120, Tyr-355, and Glu-524 mutations, led to the classification of two ensembles as representing the relaxed and tightened states of the cyclooxygenase channel entrance. A third ensemble, generated in the presence of arachidonic acid and the Y355F mutant and modulated by the allosteric potentiators palmitic acid and oleic acid and the nonallosteric substrates 2-arachidonoyl glycerol ether and anandamide, was classified as being related to the allosteric regulation of COX activity. The ensemble-based insight into COX function demonstrated here complements the static information derived from crystal structure analyses, collectively providing a more detailed framework of the dynamics involved in the regulation of COX catalysis and inhibition.
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Affiliation(s)
- Liang Dong
- Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences, University of Buffalo, the State University of New York, Buffalo, NY 14203, USA
| | - Michael G. Malkowski
- Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences, University of Buffalo, the State University of New York, Buffalo, NY 14203, USA
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2
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Lin H. Substrate-selective small-molecule modulators of enzymes: Mechanisms and opportunities. Curr Opin Chem Biol 2023; 72:102231. [PMID: 36455490 PMCID: PMC9870951 DOI: 10.1016/j.cbpa.2022.102231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 10/19/2022] [Accepted: 10/22/2022] [Indexed: 11/29/2022]
Abstract
Small-molecule inhibitors of enzymes are widely used tools in reverse chemical genetics to probe biology and explore therapeutic opportunities. They are often compared with genetic knockdown or knockout and are expected to produce phenotypes similar to the genetic perturbations. This review aims to highlight that small molecule inhibitors of enzymes and genetic perturbations may not necessarily produce the same phenotype due to the possibility of substrate-selective or substrate-dependent effects of the inhibitors. Examples of substrate-selective inhibitors and the mechanisms for the substrate-selective effects are discussed. Substrate-selective modulators of enzymes have distinct advantages and cannot be easily replaced with biologics. Thus, they present an exciting opportunity for chemical biologists and medicinal chemists.
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Affiliation(s)
- Hening Lin
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
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3
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Romero-Estrada A, Boto A, González-Christen J, Romero-Estudillo I, Garduño-Ramírez ML, Razo-Hernández RS, Marquina S, Maldonado-Magaña A, Columba-Palomares MC, Sánchez-Carranza JN, Alvarez L. Synthesis, Biological Evaluation, and Molecular Docking Study of 3-Amino and 3-Hydroxy- seco A Derivatives of α-Amyrin and 3-Epilupeol as Inhibitors of COX-2 Activity and NF-kB Activation. JOURNAL OF NATURAL PRODUCTS 2022; 85:787-803. [PMID: 35175765 DOI: 10.1021/acs.jnatprod.1c00827] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In this study, a series of novel 3-seco-A derivatives of the natural triterpenes α-amyrin (1) and 3-epilupeol (2) were synthesized by a one-pot radical scission-oxidation procedure and evaluated in vitro and in vivo for their capacity to inhibit the inflammatory process. For the in vitro studies, the trans-4-hydroxy-l-proline methyl ester derivatives (1f and 2f) were consistently effective in inhibiting NO, IL-6, and TNF-α secretion, as well as inhibition of NF-κB activation, in RAW cells stimulated by LPS. The further in vivo anti-inflammatory study revealed that the trans-4-hydroxy-l-proline methyl ester derivatives (1f and 2f), together with 1g, were the most effective in inhibiting TPA-induced edema. Interestingly, the α-amyrin derivatives were the most potent inhibitors of COX-2, but inhibited COX-1 only to some extent. The hydroxyl derivative (1c) was selective for COX-2 inhibition (66.3 ± 1.1% at 17.5 μM) without affecting the COX-1 isoform and did not present toxicity. Molecular docking studies revealed that these compounds bind with their polar region in the cavity over Arg-120, and their lipophilic part is orientated to the HEM cofactor similarly to the natural substrate arachidonic acid in the catalytic site of COX-2. These results indicated that seco-A ursane derivatives could be considered promising candidates for the future development of selective NF-κB and COX-2 inhibitors.
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Affiliation(s)
- Antonio Romero-Estrada
- Centro de Investigaciones Químicas-IICBA, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Col. Chamilpa, Cuernavaca 62209, Morelos, México
- Departamento de Madera, Celulosa y Papel, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Km 15.5 Carretera Guadalajara-Nogales, Col. Las Agujas, Zapopan 45100, Jalisco, México
| | - Alicia Boto
- Instituto de Productos Naturales y Agrobiología del CSIC, Avenuda Astrofísico Francisco Sánchez 3, 38206-La Laguna, Tenerife, Spain
| | - Judith González-Christen
- Facultad de Farmacia, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Col. Chamilpa, Cuernavaca 62209 Morelos, México
| | - Ivan Romero-Estudillo
- Centro de Investigaciones Químicas-IICBA, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Col. Chamilpa, Cuernavaca 62209, Morelos, México
- CONACYT-Centro de Investigaciones Químicas-IICBA, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Col. Chamilpa, Cuernavaca 62209 Morelos, México
| | - María Luisa Garduño-Ramírez
- Centro de Investigaciones Químicas-IICBA, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Col. Chamilpa, Cuernavaca 62209, Morelos, México
| | - Rodrigo Said Razo-Hernández
- Centro de Investigación en Dinámica Celular-IICBA, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Col. Chamilpa, Cuernavaca 62209, Morelos, México
| | - Silvia Marquina
- Centro de Investigaciones Químicas-IICBA, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Col. Chamilpa, Cuernavaca 62209, Morelos, México
| | - Amalia Maldonado-Magaña
- Instituto Tecnológico de Milpa Alta. Independencia Sur No. 36, Col. San Salvador Cuauhténco, Alcaldía Milpa Alta CDMX 12300, México
| | - María C Columba-Palomares
- Facultad de Farmacia, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Col. Chamilpa, Cuernavaca 62209 Morelos, México
| | - Jessica Nayelli Sánchez-Carranza
- Facultad de Farmacia, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Col. Chamilpa, Cuernavaca 62209 Morelos, México
| | - Laura Alvarez
- Centro de Investigaciones Químicas-IICBA, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, Col. Chamilpa, Cuernavaca 62209, Morelos, México
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4
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Farah SI, Hilston S, Tran N, Zvonok N, Makriyannis A. 1-, 2- and 3-AG as substrates of the endocannabinoid enzymes and endogenous ligands of the cannabinoid receptor 1. Biochem Biophys Res Commun 2021; 591:31-36. [PMID: 34995983 DOI: 10.1016/j.bbrc.2021.12.105] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/17/2021] [Accepted: 12/25/2021] [Indexed: 11/25/2022]
Abstract
2-Arachidonoylglycerol (2-AG) is the most potent and abundant endocannabinoid that acts as a full agonist at the cannabinoid 1 (CB1) and 2 (CB2) receptors. It serves as a substrate for several serine hydrolases, including monoacylglycerol lipase (MGL), α/β hydrolase domain 6 (ABHD6) and fatty acid amide hydrolase (FAAH). However, 2-AG's rapid conversion to 1-AG (the S stereoisomer) and 3-AG (the R stereoisomer) complicates in vivo signaling. Here, we present the interaction profiles of 2-AG and its isomerization products, 1- and 3-AG, with the endocannabinoid MGL, ABHD6 and FAAH enzymes as well as the CB1 receptor. The 1- and 3-AG enantiomers are less prone to isomerization, and their affinities to endocannabinoid enzymes and potencies at CB1 receptor are quite different compared to 2-AG. Although MGL is the principal hydrolytic enzyme of 2-AG, 3-AG (the R isomer) appears to be the best substrate for hMGL. Contrarily, 1-AG (the S isomer) demonstrates the worst substrate profile, indicating that the stereochemistry of 1(3)-monoacylglycerols is very important for MGL enzyme. On the other hand, both 1- and 3-AG (the sn1 monoacylglycerols) are efficiently hydrolyzed by hABHD6 without preference, while 2-AG (the sn2 monoacylglycerol) has the lowest rate of hydrolysis. FAAH, the principal hydrolytic enzyme for arachidonoylethanolamide (anandamide, AEA), catalyzes the hydrolysis of all three isomers with similar efficiencies. In a functional cAMP assay at CB1 receptor, all three isomers behaved as agonists, with 2-AG being the most potent, followed by 3-AG then 1-AG. The presented data provides stereochemical insights to design chemically stable AG analogs with preferential stability against enzymes of interest.
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Affiliation(s)
- Shrouq I Farah
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, 02115, USA; Center for Drug Discovery, Northeastern University, Boston, MA, 02115, USA
| | - Samantha Hilston
- Center for Drug Discovery, Northeastern University, Boston, MA, 02115, USA; Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115, USA
| | - Ngan Tran
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, 02115, USA; Center for Drug Discovery, Northeastern University, Boston, MA, 02115, USA
| | - Nikolai Zvonok
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, 02115, USA; Center for Drug Discovery, Northeastern University, Boston, MA, 02115, USA.
| | - Alexandros Makriyannis
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, 02115, USA; Center for Drug Discovery, Northeastern University, Boston, MA, 02115, USA; Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115, USA
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5
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Abdul Salam AA, Nayek U, Mathew G, Unnikrishnan M. Structural, CSD, and computational studies of 6b, 11b-Dihydroxy-6b, 11-b-dihydro-7H-indeno[1,2-b]naptho[2,1-d]furan-7-one, a therapeutic potential small molecule. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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6
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Uddin MJ, Xu S, Crews BC, Aleem AM, Ghebreselasie K, Banerjee S, Marnett LJ. Harmaline Analogs as Substrate-Selective Cyclooxygenase-2 Inhibitors. ACS Med Chem Lett 2020; 11:1881-1885. [PMID: 33062168 DOI: 10.1021/acsmedchemlett.9b00555] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 02/14/2020] [Indexed: 11/28/2022] Open
Abstract
We report the design, synthesis, and evaluation of a series of harmaline analogs as selective inhibitors of 2-arachidonylglycerol (2-AG) oxygenation over arachidonic acid (AA) oxygenation by purified cyclooxygenase-2 (COX-2). A fused tricyclic harmaline analog containing a CH3O substituent at C-6 and a CH3 group at the C-1 position of 4,9-dihydro-3H-pyrido[3,4-b]indole (compound 3) was the best substrate-selective COX-2 inhibitor of those evaluated, exhibiting a 2AG-selective COX-2 inhibitory IC50 of 0.022 μM as compared to >1 μM for AA. The 2.66 Å resolution crystal complex of COX-2 with compound 3 revealed that this series of tricyclic indoles binds in the cyclooxygenase channel by flipping the side chain of L531 toward the dimer interface. This novel tricyclic indole series provides the foundation for the development of promising substrate-selective molecules capable of increasing endocannabinoid (EC) levels in the brain to offer new treatments for a variety of diseases, from pain and inflammation to stress and anxiety disorders.
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Affiliation(s)
- Md. Jashim Uddin
- A. B. Hancock, Jr., Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology, and Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Shu Xu
- A. B. Hancock, Jr., Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology, and Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Brenda C. Crews
- A. B. Hancock, Jr., Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology, and Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Ansari M. Aleem
- A. B. Hancock, Jr., Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology, and Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Kebreab Ghebreselasie
- A. B. Hancock, Jr., Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology, and Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Surajit Banerjee
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
- Northeastern Collaborative Access Team, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Lawrence J. Marnett
- A. B. Hancock, Jr., Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology, and Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
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7
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Rouzer CA, Marnett LJ. Structural and Chemical Biology of the Interaction of Cyclooxygenase with Substrates and Non-Steroidal Anti-Inflammatory Drugs. Chem Rev 2020; 120:7592-7641. [PMID: 32609495 PMCID: PMC8253488 DOI: 10.1021/acs.chemrev.0c00215] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cyclooxgenases are key enzymes of lipid signaling. They carry out the first step in the production of prostaglandins, important mediators of inflammation, pain, cardiovascular disease, and cancer, and they are the molecular targets for nonsteroidal anti-inflammatory drugs, which are among the oldest and most chemically diverse set of drugs known. Homodimeric proteins that behave as allosterically modulated, functional heterodimers, the cyclooxygenases exhibit complex kinetic behavior, requiring peroxide-dependent activation and undergoing suicide inactivation. Due to their important physiological and pathophysiological roles and keen interest on the part of the pharmaceutical industry, the cyclooxygenases have been the focus of a vast array of structural studies, leading to the publication of over 80 crystal structures of the enzymes in complex with substrates or inhibitors supported by a wealth of functional data generated by site-directed mutation experiments. In this review, we explore the chemical biology of the cyclooxygenases through the lens of this wealth of structural and functional information. We identify key structural features of the cyclooxygenases, break down their active site into regional binding pockets to facilitate comparisons between structures, and explore similarities and differences in the binding modes of the wide variety of ligands (both substrates and inhibitors) that have been characterized in complex with the enzymes. Throughout, we correlate structure with function whenever possible. Finally, we summarize what can and cannot be learned from the currently available structural data and discuss the critical intriguing questions that remain despite the wealth of information that has been amassed in this field.
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Affiliation(s)
- Carol A Rouzer
- A. B. Hancock Jr. Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Lawrence J Marnett
- A. B. Hancock Jr. Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
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8
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Dong L, Anderson AJ, Malkowski MG. Arg-513 and Leu-531 Are Key Residues Governing Time-Dependent Inhibition of Cyclooxygenase-2 by Aspirin and Celebrex. Biochemistry 2019; 58:3990-4002. [PMID: 31469551 DOI: 10.1021/acs.biochem.9b00659] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aspirin and Celebrex are well-known time-dependent inhibitors of the cyclooxygenases (COX). Molecular dynamics simulations suggest that Arg-513 and Leu-531 contribute to the structural mechanisms of COX inhibition. We used mutagenesis and functional analyses to characterize how substitutions at these positions influence time-dependent inhibition by aspirin and Celebrex. We show that substitutions of Leu-531 with asparagine and phenylalanine significantly attenuate time-dependent inhibition of COX-2 by these drugs. The introduction of side chain bulk, rigidity, and charge would disrupt the formation of the initial noncovalent complex, in the case of aspirin, and the "high-affinity" binding state, in the case of Celebrex. Substitution of Arg-513 with histidine (the equivalent residue in COX-1) resulted in a 2-fold potentiation of aspirin inhibition, in support of the hypothesis that the presence of histidine in COX-1 lowers the activation barrier associated with the formation of the initial noncovalent enzyme-inhibitor complex. As a corollary, we previously hypothesized that the flexibility associated with Leu-531 contributes to the binding of arachidonic acid (AA) to acetylated COX-2 to generate 15R-hydroxyeicosatetraenoic acid (15R-HETE). We determined the X-ray crystal structure of AA bound to Co3+-protoporphyrin IX-reconstituted V349I murine COX-2 (muCOX-2). V349I muCOX-2 was utilized as a surrogate to trap AA in a conformation leading to 15R-HETE. AA binds in a C-shaped pose, facilitated by the rotation of the Leu-531 side chain. Ile-349 is positioned to sterically shield antarafacial oxygen addition at carbon-15 in a manner similar to that proposed for the acetylated Ser-530 side chain.
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Affiliation(s)
- Liang Dong
- Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences , University of Buffalo, the State University of New York , Buffalo , New York 14203 , United States
| | - Alyssa J Anderson
- Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences , University of Buffalo, the State University of New York , Buffalo , New York 14203 , United States
| | - Michael G Malkowski
- Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences , University of Buffalo, the State University of New York , Buffalo , New York 14203 , United States
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Shockley EM, Rouzer CA, Marnett LJ, Deeds EJ, Lopez CF. Signal integration and information transfer in an allosterically regulated network. NPJ Syst Biol Appl 2019; 5:23. [PMID: 31341635 PMCID: PMC6639376 DOI: 10.1038/s41540-019-0100-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 06/14/2019] [Indexed: 02/07/2023] Open
Abstract
A biological reaction network may serve multiple purposes, processing more than one input and impacting downstream processes via more than one output. These networks operate in a dynamic cellular environment in which the levels of network components may change within cells and across cells. Recent evidence suggests that protein concentration variability could explain cell fate decisions. However, systems with multiple inputs, multiple outputs, and changing input concentrations have not been studied in detail due to their complexity. Here, we take a systems biochemistry approach, combining physiochemical modeling and information theory, to investigate how cyclooxygenase-2 (COX-2) processes simultaneous input signals within a complex interaction network. We find that changes in input levels affect the amount of information transmitted by the network, as does the correlation between those inputs. This, and the allosteric regulation of COX-2 by its substrates, allows it to act as a signal integrator that is most sensitive to changes in relative input levels.
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Affiliation(s)
- Erin M. Shockley
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37212 USA
| | - Carol A. Rouzer
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37212 USA
| | | | - Eric J. Deeds
- Center for Computational Biology, University of Kansas, Lawrence, KS 66047 USA
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66047 USA
- Present Address: Institute for Quantitative and Computational Biosciences, University of California, Los Angeles, CA 90095 USA
| | - Carlos F. Lopez
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37212 USA
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN 37212 USA
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10
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Abstract
Omega-6 polyunsaturated fatty acids were identified as essential nutrients in 1930. Their essentiality is largely due to their function as prostaglandin (PG) precursors. I spent most of my career in biochemistry determining how PG biosynthesis is regulated. PGs are lipid mediators formed in response to certain circulating hormones and cytokines. PGs act near their sites of synthesis to signal neighboring cells to coordinate their responses (e.g. when platelets interact with blood vessels). The committed step in PG synthesis is the conversion of a 20-carbon omega-6 fatty acid called arachidonic acid to prostaglandin endoperoxide H2 (PGH2). Depending on the tissue and the hormone or cytokine stimulus, this reaction is catalyzed by either cyclooxygenase-1 or cyclooxygenase-2 (COX-1 or COX-2). Once formed, PGH2 is converted, again depending on the context, to one of several downstream PG subtypes that act via specific G protein-coupled receptors. Nonsteroidal anti-inflammatory drugs (e.g. aspirin, ibuprofen, and naproxen) block PG synthesis by inhibiting COX-1 and COX-2. COX-2 is also inhibited by COX-2-selective inhibitors. Inhibition of COX-1 by low-dose aspirin prevents thrombosis. COX-2 inhibition reduces inflammation and pain. Investigating the mysteries of COXs anchored my scientific career. I attribute my successes to the great good fortune of having been surrounded by people who helped me make the most of my talents. I have written this reflection in a light-hearted fashion as a self-help essay, while highlighting the people and factors that most impacted me during my upbringing and then during my maturation and evolution as a biochemist.
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Affiliation(s)
- William L Smith
- From the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606
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11
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Smith WL, Malkowski MG. Interactions of fatty acids, nonsteroidal anti-inflammatory drugs, and coxibs with the catalytic and allosteric subunits of cyclooxygenases-1 and -2. J Biol Chem 2019; 294:1697-1705. [PMID: 30710016 DOI: 10.1074/jbc.tm118.006295] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Prostaglandin endoperoxide H synthases-1 and -2, commonly called cyclooxygenases-1 and -2 (COX-1 and -2), catalyze the committed step in prostaglandin biosynthesis-the conversion of arachidonic acid to prostaglandin endoperoxide H2 Both COX isoforms are sequence homodimers that function as conformational heterodimers having allosteric (Eallo) and catalytic (Ecat) subunits. At least in the case of COX-2, the enzyme becomes folded into a stable Eallo/Ecat pair. Some COX inhibitors (i.e. nonsteroidal anti-inflammatory drugs and coxibs) and common fatty acids (FAs) modulate Ecat activity by binding Eallo. However, the interactions and outcomes often differ between isoforms. For example, naproxen directly and completely inhibits COX-1 by binding Ecat but indirectly and incompletely inhibits COX-2 by binding Eallo. Additionally, COX-1 is allosterically inhibited up to 50% by common FAs like palmitic acid, whereas COX-2 is allosterically activated 2-fold by palmitic acid. FA binding to Eallo also affects responses to COX inhibitors. Thus, COXs are physiologically and pharmacologically regulated by the FA tone of the milieu in which each operates-COX-1 in the endoplasmic reticulum and COX-2 in the Golgi apparatus. Cross-talk between Eallo and Ecat involves a loop in Eallo immediately downstream of Arg-120. Mutational studies suggest that allosteric modulation requires a direct interaction between the carboxyl group of allosteric effectors and Arg-120 of Eallo; however, structural studies show some allosterically active FAs positioned in COX-2 in a conformation lacking an interaction with Arg-120. Thus, many details about the biological consequences of COX allosterism and how ligand binding to Eallo modulates Ecat remain to be resolved.
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Affiliation(s)
- William L Smith
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109.
| | - Michael G Malkowski
- Department of Structural Biology, Jacobs School of Medicine and Biomedical Sciences, University of Buffalo, Buffalo, New York 14203.
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12
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Liu Y, Ji L, Eno M, Kudalkar S, Li AL, Schimpgen M, Benchama O, Morales P, Xu S, Hurst D, Wu S, Mohammad KA, Wood JT, Zvonok N, Papahatjis DP, Zhou H, Honrao C, Mackie K, Reggio P, Hohmann AG, Marnett LJ, Makriyannis A, Nikas SP. ( R)- N-(1-Methyl-2-hydroxyethyl)-13-( S)-methyl-arachidonamide (AMG315): A Novel Chiral Potent Endocannabinoid Ligand with Stability to Metabolizing Enzymes. J Med Chem 2018; 61:8639-8657. [PMID: 30196704 DOI: 10.1021/acs.jmedchem.8b00611] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The synthesis of potent metabolically stable endocannabinoids is challenging. Here we report a chiral arachidonoyl ethanolamide (AEA) analogue, namely, (13 S,1' R)-dimethylanandamide (AMG315, 3a), a high affinity ligand for the CB1 receptor ( Ki of 7.8 ± 1.4 nM) that behaves as a potent CB1 agonist in vitro (EC50 = 0.6 ± 0.2 nM). (13 S,1' R)-dimethylanandamide is the first potent AEA analogue with significant stability for all endocannabinoid hydrolyzing enzymes as well as the oxidative enzymes COX-2. When tested in vivo using the CFA-induced inflammatory pain model, 3a behaved as a more potent analgesic when compared to endogenous AEA or its hydrolytically stable analogue AM356. This novel analogue will serve as a very useful endocannabinoid probe.
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Affiliation(s)
- Yingpeng Liu
- Center for Drug Discovery and Department of Pharmaceutical Sciences , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Lipin Ji
- Center for Drug Discovery and Department of Pharmaceutical Sciences , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Marsha Eno
- Center for Drug Discovery and Department of Pharmaceutical Sciences , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Shalley Kudalkar
- Departments of Biochemistry, Chemistry, and Pharmacology , Vanderbilt University School of Medicine , Nashville , Tennessee 37232 , United States
| | - Ai-Ling Li
- Department of Biological and Brain Sciences , Indiana University , Bloomington , Indiana 47405 , United States
| | - Marion Schimpgen
- Institute of Organic and Pharmaceutical Chemistry , National Hellenic Research Foundation , 48 Vass. Constantinou , Athens 116-35 , Greece
| | - Othman Benchama
- Center for Drug Discovery and Department of Pharmaceutical Sciences , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Paula Morales
- Center for Drug Discovery, Department of Chemistry and Biochemistry , University of North Carolina at Greensboro , Greensboro , North Carolina 27402 , United States
| | - Shu Xu
- Departments of Biochemistry, Chemistry, and Pharmacology , Vanderbilt University School of Medicine , Nashville , Tennessee 37232 , United States
| | - Dow Hurst
- Center for Drug Discovery, Department of Chemistry and Biochemistry , University of North Carolina at Greensboro , Greensboro , North Carolina 27402 , United States
| | - Simiao Wu
- Center for Drug Discovery and Department of Pharmaceutical Sciences , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Khadijah A Mohammad
- Center for Drug Discovery and Department of Pharmaceutical Sciences , Northeastern University , Boston , Massachusetts 02115 , United States
| | - JodiAnne T Wood
- Center for Drug Discovery and Department of Pharmaceutical Sciences , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Nikolai Zvonok
- Center for Drug Discovery and Department of Pharmaceutical Sciences , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Demetris P Papahatjis
- Institute of Organic and Pharmaceutical Chemistry , National Hellenic Research Foundation , 48 Vass. Constantinou , Athens 116-35 , Greece
| | - Han Zhou
- Center for Drug Discovery and Department of Pharmaceutical Sciences , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Chandrashekhar Honrao
- Center for Drug Discovery and Department of Pharmaceutical Sciences , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Ken Mackie
- Department of Biological and Brain Sciences , Indiana University , Bloomington , Indiana 47405 , United States
| | - Patricia Reggio
- Center for Drug Discovery, Department of Chemistry and Biochemistry , University of North Carolina at Greensboro , Greensboro , North Carolina 27402 , United States
| | - Andrea G Hohmann
- Department of Biological and Brain Sciences , Indiana University , Bloomington , Indiana 47405 , United States
| | - Lawrence J Marnett
- Departments of Biochemistry, Chemistry, and Pharmacology , Vanderbilt University School of Medicine , Nashville , Tennessee 37232 , United States
| | - Alexandros Makriyannis
- Center for Drug Discovery and Department of Pharmaceutical Sciences , Northeastern University , Boston , Massachusetts 02115 , United States.,Departments of Chemistry and Chemical Biology , Northeastern University , Boston , Massachusetts 02115 , United States
| | - Spyros P Nikas
- Center for Drug Discovery and Department of Pharmaceutical Sciences , Northeastern University , Boston , Massachusetts 02115 , United States
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13
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Goodman MC, Xu S, Rouzer CA, Banerjee S, Ghebreselasie K, Migliore M, Piomelli D, Marnett LJ. Dual cyclooxygenase-fatty acid amide hydrolase inhibitor exploits novel binding interactions in the cyclooxygenase active site. J Biol Chem 2018; 293:3028-3038. [PMID: 29326169 DOI: 10.1074/jbc.m117.802058] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 12/13/2017] [Indexed: 12/29/2022] Open
Abstract
The cyclooxygenases COX-1 and COX-2 oxygenate arachidonic acid (AA) to prostaglandin H2 (PGH2). COX-2 also oxygenates the endocannabinoids 2-arachidonoylglycerol (2-AG) and arachidonoylethanolamide (AEA) to the corresponding PGH2 analogs. Both enzymes are targets of nonsteroidal anti-inflammatory drugs (NSAIDs), but NSAID-mediated COX inhibition is associated with gastrointestinal toxicity. One potential strategy to counter this toxicity is to also inhibit fatty acid amide hydrolase (FAAH), which hydrolyzes bioactive fatty acid ethanolamides (FAEs) into fatty acids and ethanolamine. Here, we investigated the mechanism of COX inhibition by ARN2508, an NSAID that inhibits both COXs and FAAH with high potency, target selectivity, and decreased gastrointestinal toxicity in mouse models, presumably due to its ability to increase levels of FAEs. A 2.27-Å-resolution X-ray crystal structure of the COX-2·(S)-ARN2508 complex reveals that ARN2508 adopts a binding pose similar to that of its parent NSAID flurbiprofen. However, ARN2508's alkyl tail is inserted deep into the top channel, an active site region not exploited by any previously reported NSAID. As for flurbiprofen, ARN2508's potency is highly dependent on the configuration of the α-methyl group. Thus, (S)-ARN2508 is more potent than (R)-ARN2508 for inhibition of AA oxygenation by both COXs and 2-AG oxygenation by COX-2. Also, similarly to (R)-flurbiprofen, (R)-ARN2508 exhibits substrate selectivity for inhibition of 2-AG oxygenation. Site-directed mutagenesis confirms the importance of insertion of the alkyl tail into the top channel for (S)-ARN2508's potency and suggests a role for Ser-530 as a determinant of the inhibitor's slow rate of inhibition compared with that of (S)-flurbiprofen.
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Affiliation(s)
- Michael C Goodman
- From the A. B. Hancock, Jr. Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology and Center in Molecular Toxicology, Vanderbilt Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Shu Xu
- From the A. B. Hancock, Jr. Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology and Center in Molecular Toxicology, Vanderbilt Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Carol A Rouzer
- From the A. B. Hancock, Jr. Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology and Center in Molecular Toxicology, Vanderbilt Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Surajit Banerjee
- the Northeastern Collaborative Access Team, Argonne National Laboratory, Argonne, Illinois 60439
| | - Kebreab Ghebreselasie
- From the A. B. Hancock, Jr. Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology and Center in Molecular Toxicology, Vanderbilt Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Marco Migliore
- the Department of Drug Discovery and Development, Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Daniele Piomelli
- the Department of Drug Discovery and Development, Istituto Italiano di Tecnologia, 16163 Genoa, Italy.,the Departments of Anatomy, Neurobiology, Pharmacology, and Biological Chemistry, University of California, Irvine, California 92697, and
| | - Lawrence J Marnett
- From the A. B. Hancock, Jr. Memorial Laboratory for Cancer Research, Departments of Biochemistry, Chemistry, and Pharmacology, Vanderbilt Institute of Chemical Biology and Center in Molecular Toxicology, Vanderbilt Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232,
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14
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Liao X, Wang W, Fan C, Yang N, Zhao J, Zhang Y, Gao R, Shen G, Xia S, Li G. Prokaryotic expression, purification and characterization of human cyclooxygenase-2. Int J Mol Med 2017; 40:75-82. [PMID: 28560423 PMCID: PMC5466394 DOI: 10.3892/ijmm.2017.3007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 05/26/2017] [Indexed: 01/06/2023] Open
Abstract
Cyclooxygenase-2 (COX-2) is a key enzyme which catalyzes the conversion of arachidonic acid (AA) into prostaglandins (PGs). It plays an important role in pathophysiological processes, such as tumorigenesis, angiogenesis, inflammation and tumor cell drug resistance. Therefore, COX-2 has been viewed as an important target for cancer therapy. The preparation of COX-2 protein is an important initial step for the subsequent development of COX-2 inhibitors. In this study, we report a strategy to heterologously express truncated human COX-2 (trCOX-2) in Escherichia coli (E. coli) BL21(DE3) host cells. Following denaturation, purification and renaturation, we successfully obtained enzymatically active trCOX-2 containing 257 residues of the C-terminus. Homology modeling and molecular docking analyses revealed that trCOX-2 retained the predicted 3D catalytic domain structure and AA could still bind to its hydrophobic groove. Western blot analysis and ELISA indicated that the trCOX-2 still retained its characteristic antigenicity and binding activity, while COX assays revealed that trCOX-2 maintained its enzyme activity. On the whole, in this study, we provided a novel method to isolate trCOX-2 possessing AA binding and catalytic activities. This study thus lays a foundation to facilitate further investigations of COX-2 and offers a valuable method with which to achieve the prokaryotic expression of a eukaryotic membrane protein.
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Affiliation(s)
- Xiangzhi Liao
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, College of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Wenhan Wang
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, College of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Chuanxi Fan
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, College of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Ning Yang
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, College of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Jialiang Zhao
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, College of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Ying Zhang
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, College of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Ruijuan Gao
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, College of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Guannan Shen
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, College of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Simin Xia
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, College of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Guiying Li
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, College of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
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15
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Dong L, Yuan C, Orlando BJ, Malkowski MG, Smith WL. Fatty Acid Binding to the Allosteric Subunit of Cyclooxygenase-2 Relieves a Tonic Inhibition of the Catalytic Subunit. J Biol Chem 2016; 291:25641-25655. [PMID: 27756840 DOI: 10.1074/jbc.m116.757310] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 10/13/2016] [Indexed: 01/24/2023] Open
Abstract
Prostaglandin endoperoxide H synthase-2 (PGHS-2), also called cyclooxygenase-2 (COX-2), converts arachidonic acid to PGH2 PGHS-2 is a conformational heterodimer composed of allosteric (Eallo) and catalytic (Ecat) subunits. Fatty acids (FAs) bind to Arg-120 of Eallo increasing to different degrees, depending on the FA, the Vmax of its Ecat partner. We report here that movement of helical residues 120-122 and loop residues 123-129 of Eallo underlies the allosteric effects of FAs and allosteric COX-2 inhibitors, including naproxen and flurbiprofen. An S121P substitution in both PGHS-2 monomers yields a variant (S121P/S121P PGHS-2) that has 1.7-1.8 times the Vmax of native PGHS-2 and is relatively insensitive to activation by FAs or inhibition by allosteric inhibitors. The S121P substitution in Eallo is primarily responsible for these effects. In X-ray crystal structures, the Cα atoms of helical residues 119-122 of S121P/S121P PGHS-2 are displaced from their normal positions. Additionally, the S121P/S121P PGHS-2 variants in which Pro-127 and Ser-541 are replaced by cysteines spontaneously forms Cys-127 to Cys-541 cross-links between monomers. This is unlike the corresponding native PGHS-2 variant and suggests that S121P substitutions also unhinge the loop involving residues 123-129. We conclude the following: (a) the region involving residues 120-129 of unoccupied Eallo tonically inhibits Ecat; (b) binding of an activating FA (e.g. arachidonic, palmitic, or oleic acid) to Eallo or an S121P substitution in Eallo repositions this region to increase Ecat activity; and (c) allosteric COX inhibitors act by preventing FA binding to Eallo and additionally by relocating Eallo residues to inhibit Ecat.
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Affiliation(s)
- Liang Dong
- From the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109 and
| | - Chong Yuan
- From the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109 and
| | - Benjamin J Orlando
- the Department of Structural Biology, University at Buffalo, The State University of New York, and the Hauptman-Woodward Medical Research Institute, Buffalo, New York 14203
| | - Michael G Malkowski
- the Department of Structural Biology, University at Buffalo, The State University of New York, and the Hauptman-Woodward Medical Research Institute, Buffalo, New York 14203
| | - William L Smith
- From the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109 and
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16
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Orlando BJ, Malkowski MG. Substrate-selective Inhibition of Cyclooxygeanse-2 by Fenamic Acid Derivatives Is Dependent on Peroxide Tone. J Biol Chem 2016; 291:15069-81. [PMID: 27226593 DOI: 10.1074/jbc.m116.725713] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Indexed: 12/13/2022] Open
Abstract
Cyclooxygenase-2 (COX-2) catalyzes the oxygenation of arachidonic acid (AA) and endocannabinoid substrates, placing the enzyme at a unique junction between the eicosanoid and endocannabinoid signaling pathways. COX-2 is a sequence homodimer, but the enzyme displays half-of-site reactivity, such that only one monomer of the dimer is active at a given time. Certain rapid reversible, competitive nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to inhibit COX-2 in a substrate-selective manner, with the binding of inhibitor to a single monomer sufficient to inhibit the oxygenation of endocannabinoids but not arachidonic acid. The underlying mechanism responsible for substrate-selective inhibition has remained elusive. We utilized structural and biophysical methods to evaluate flufenamic acid, meclofenamic acid, mefenamic acid, and tolfenamic acid for their ability to act as substrate-selective inhibitors. Crystal structures of each drug in complex with human COX-2 revealed that the inhibitor binds within the cyclooxygenase channel in an inverted orientation, with the carboxylate group interacting with Tyr-385 and Ser-530 at the top of the channel. Tryptophan fluorescence quenching, continuous-wave electron spin resonance, and UV-visible spectroscopy demonstrate that flufenamic acid, mefenamic acid, and tolfenamic acid are substrate-selective inhibitors that bind rapidly to COX-2, quench tyrosyl radicals, and reduce higher oxidation states of the heme moiety. Substrate-selective inhibition was attenuated by the addition of the lipid peroxide 15-hydroperoxyeicosatertaenoic acid. Collectively, these studies implicate peroxide tone as an important mechanistic component of substrate-selective inhibition by flufenamic acid, mefenamic acid, and tolfenamic acid.
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Affiliation(s)
- Benjamin J Orlando
- From the Department of Structural Biology, The State University of New York at Buffalo and
| | - Michael G Malkowski
- From the Department of Structural Biology, The State University of New York at Buffalo and the Hauptman-Woodward Medical Research Institute, Buffalo, New York 14203
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17
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Dong L, Zou H, Yuan C, Hong YH, Uhlson CL, Murphy RC, Smith WL. Interactions of 2-O-arachidonylglycerol ether and ibuprofen with the allosteric and catalytic subunits of human COX-2. J Lipid Res 2016; 57:1043-50. [PMID: 27059979 DOI: 10.1194/jlr.m067512] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Indexed: 11/20/2022] Open
Abstract
Prostaglandin (PG) endoperoxide H synthase (PGHS)-2, also known as cyclooxygenase (COX)-2, can convert arachidonic acid (AA) to PGH2 in the committed step of PG synthesis. PGHS-2 functions as a conformational heterodimer composed of an allosteric (Eallo) and a catalytic (Ecat) monomer. Here we investigated the interplay between human (hu)PGHS-2 and an alternative COX substrate, the endocannabinoid, 2-arachidonoylglycerol (2-AG), as well as a stable analog, 2-O-arachidonylglycerol ether (2-AG ether). We also compared the inhibition of huPGHS-2-mediated oxygenation of AA, 2-AG, and 2-AG ether by the well-known COX inhibitor, ibuprofen. When tested with huPGHS-2, 2-AG and 2-AG ether exhibit very similar kinetic parameters, responses to stimulation by FAs that are not COX substrates, and modes of inhibition by ibuprofen. The 2-AG ether binds Ecat more tightly than Eallo and, thus, can be used as a stable Ecat-specific substrate to examine certain Eallo-dependent responses. Ibuprofen binding to Eallo of huPGHS-2 completely blocks 2-AG or 2-AG ether oxygenation; however, inhibition by ibuprofen of huPGHS-2-mediated oxygenation of AA engages a combination of both allosteric and competitive mechanisms.
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Affiliation(s)
- Liang Dong
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109
| | - Hechang Zou
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109
| | - Chong Yuan
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109
| | - Yu H Hong
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109
| | - Charis L Uhlson
- Department of Pharmacology, University of Colorado-Denver, Aurora, CO 80045
| | - Robert C Murphy
- Department of Pharmacology, University of Colorado-Denver, Aurora, CO 80045
| | - William L Smith
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109
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18
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Lucido MJ, Orlando BJ, Vecchio AJ, Malkowski MG. Crystal Structure of Aspirin-Acetylated Human Cyclooxygenase-2: Insight into the Formation of Products with Reversed Stereochemistry. Biochemistry 2016; 55:1226-38. [PMID: 26859324 DOI: 10.1021/acs.biochem.5b01378] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Aspirin and other nonsteroidal anti-inflammatory drugs target the cyclooxygenase enzymes (COX-1 and COX-2) to block the formation of prostaglandins. Aspirin is unique in that it covalently modifies each enzyme by acetylating Ser-530 within the cyclooxygenase active site. Acetylation of COX-1 leads to complete loss of activity, while acetylation of COX-2 results in the generation of the monooxygenated product 15(R)-hydroxyeicosatetraenoic acid (15R-HETE). Ser-530 has also been shown to influence the stereochemistry for the addition of oxygen to the prostaglandin product. We determined the crystal structures of S530T murine (mu) COX-2, aspirin-acetylated human (hu) COX-2, and huCOX-2 in complex with salicylate to 1.9, 2.0, and 2.4 Å, respectively. The structures reveal that (1) the acetylated Ser-530 completely blocks access to the hydrophobic groove, (2) the observed binding pose of salicylate is reflective of the enzyme-inhibitor complex prior to acetylation, and (3) the observed Thr-530 rotamer in the S530T muCOX-2 crystal structure does not impede access to the hydrophobic groove. On the basis of these structural observations, along with functional analysis of the S530T/G533V double mutant, we propose a working hypothesis for the generation of 15R-HETE by aspirin-acetylated COX-2. We also observe differential acetylation of COX-2 purified in various detergent systems and nanodiscs, indicating that detergent and lipid binding within the membrane-binding domain of the enzyme alters the rate of the acetylation reaction in vitro.
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Affiliation(s)
- Michael J Lucido
- Department of Structural Biology, The State University of New York at Buffalo and Hauptman-Woodward Medical Research Institute , Buffalo, New York 14203, United States
| | - Benjamin J Orlando
- Department of Structural Biology, The State University of New York at Buffalo and Hauptman-Woodward Medical Research Institute , Buffalo, New York 14203, United States
| | - Alex J Vecchio
- Department of Structural Biology, The State University of New York at Buffalo and Hauptman-Woodward Medical Research Institute , Buffalo, New York 14203, United States
| | - Michael G Malkowski
- Department of Structural Biology, The State University of New York at Buffalo and Hauptman-Woodward Medical Research Institute , Buffalo, New York 14203, United States
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19
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Konkle ME, Blobaum AL, Moth CW, Prusakiewicz JJ, Xu S, Ghebreselasie K, Akingbade D, Jacobs AT, Rouzer CA, Lybrand TP, Marnett LJ. Conservative Secondary Shell Substitution In Cyclooxygenase-2 Reduces Inhibition by Indomethacin Amides and Esters via Altered Enzyme Dynamics. Biochemistry 2015; 55:348-59. [PMID: 26704937 PMCID: PMC4721528 DOI: 10.1021/acs.biochem.5b01222] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The cyclooxygenase enzymes (COX-1 and COX-2) are the therapeutic targets of nonsteroidal anti-inflammatory drugs (NSAIDs). Neutralization of the carboxylic acid moiety of the NSAID indomethacin to an ester or amide functionality confers COX-2 selectivity, but the molecular basis for this selectivity has not been completely revealed through mutagenesis studies and/or X-ray crystallographic attempts. We expressed and assayed a number of divergent secondary shell COX-2 active site mutants and found that a COX-2 to COX-1 change at position 472 (Leu in COX-2, Met in COX-1) reduced the potency of enzyme inhibition by a series of COX-2-selective indomethacin amides and esters. In contrast, the potencies of indomethacin, arylacetic acid, propionic acid, and COX-2-selective diarylheterocycle inhibitors were either unaffected or only mildly affected by this mutation. Molecular dynamics simulations revealed identical equilibrium enzyme structures around residue 472; however, calculations indicated that the L472M mutation impacted local low-frequency dynamical COX constriction site motions by stabilizing the active site entrance and slowing constriction site dynamics. Kinetic analysis of inhibitor binding is consistent with the computational findings.
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Affiliation(s)
- Mary E Konkle
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Anna L Blobaum
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Christopher W Moth
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Jeffery J Prusakiewicz
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Shu Xu
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Kebreab Ghebreselasie
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Dapo Akingbade
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Aaron T Jacobs
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Carol A Rouzer
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Terry P Lybrand
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
| | - Lawrence J Marnett
- Departments of Biochemistry, ‡Chemistry, and §Pharmacology, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville Tennessee 37232-0146, United States
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20
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Dong L, Zou H, Yuan C, Hong YH, Kuklev DV, Smith WL. Different Fatty Acids Compete with Arachidonic Acid for Binding to the Allosteric or Catalytic Subunits of Cyclooxygenases to Regulate Prostanoid Synthesis. J Biol Chem 2015; 291:4069-78. [PMID: 26703471 DOI: 10.1074/jbc.m115.698001] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Indexed: 12/20/2022] Open
Abstract
Prostaglandin endoperoxide H synthases (PGHSs), also called cyclooxygenases (COXs), convert arachidonic acid (AA) to PGH2. PGHS-1 and PGHS-2 are conformational heterodimers, each composed of an (Eallo) and a catalytic (Ecat) monomer. Previous studies suggested that the binding to Eallo of saturated or monounsaturated fatty acids (FAs) that are not COX substrates differentially regulate PGHS-1 versus PGHS-2. Here, we substantiate and expand this concept to include polyunsaturated FAs known to modulate COX activities. Non-substrate FAs like palmitic acid bind Eallo of PGHSs stimulating human (hu) PGHS-2 but inhibiting huPGHS-1. We find the maximal effects of non-substrate FAs on both huPGHSs occurring at the same physiologically relevant FA/AA ratio of ∼20. This inverse allosteric regulation likely underlies the ability of PGHS-2 to operate at low AA concentrations, when PGHS-1 is effectively latent. Unlike FAs tested previously, we observe that C-22 FAs, including ω-3 fish oil FAs, have higher affinities for Ecat than Eallo subunits of PGHSs. Curiously, C-20 ω-3 eicosapentaenoate preferentially binds Ecat of huPGHS-1 but Eallo of huPGHS-2. PGE2 production decreases 50% when fish oil consumption produces tissue EPA/AA ratios of ≥0.2. However, 50% inhibition of huPGHS-1 itself is only seen with ω-3 FA/AA ratios of ≥5.0. This suggests that fish oil-enriched diets disfavor AA oxygenation by altering the composition of the FA pool in which PGHS-1 functions. The distinctive binding specificities of PGHS subunits permit different combinations of non-esterified FAs, which can be manipulated dietarily, to regulate AA binding to Eallo and/or Ecat thereby controlling COX activities.
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Affiliation(s)
- Liang Dong
- From the Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Hechang Zou
- From the Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Chong Yuan
- From the Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Yu H Hong
- From the Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Dmitry V Kuklev
- From the Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - William L Smith
- From the Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109
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21
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Competition and allostery govern substrate selectivity of cyclooxygenase-2. Proc Natl Acad Sci U S A 2015; 112:12366-71. [PMID: 26392530 DOI: 10.1073/pnas.1507307112] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cyclooxygenase-2 (COX-2) oxygenates arachidonic acid (AA) and its ester analog, 2-arachidonoylglycerol (2-AG), to prostaglandins (PGs) and prostaglandin glyceryl esters (PG-Gs), respectively. Although the efficiency of oxygenation of these substrates by COX-2 in vitro is similar, cellular biosynthesis of PGs far exceeds that of PG-Gs. Evidence that the COX enzymes are functional heterodimers suggests that competitive interaction of AA and 2-AG at the allosteric site of COX-2 might result in differential regulation of the oxygenation of the two substrates when both are present. Modulation of AA levels in RAW264.7 macrophages uncovered an inverse correlation between cellular AA levels and PG-G biosynthesis. In vitro kinetic analysis using purified protein demonstrated that the inhibition of 2-AG oxygenation by high concentrations of AA far exceeded the inhibition of AA oxygenation by high concentrations of 2-AG. An unbiased systems-based mechanistic model of the kinetic data revealed that binding of AA or 2-AG at the allosteric site of COX-2 results in a decreased catalytic efficiency of the enzyme toward 2-AG, whereas 2-AG binding at the allosteric site increases COX-2's efficiency toward AA. The results suggest that substrates interact with COX-2 via multiple potential complexes involving binding to both the catalytic and allosteric sites. Competition between AA and 2-AG for these sites, combined with differential allosteric modulation, gives rise to a complex interplay between the substrates, leading to preferential oxygenation of AA.
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