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Lv T, Jia F, Wang G, Li S, Wan T, Qiu W, Tang Z, Chen H. Sevoflurane causes neurotoxicity and cognitive impairment by regulating Hippo signaling pathway-mediated ferroptosis via upregulating PRKCD. Exp Neurol 2024; 377:114804. [PMID: 38704083 DOI: 10.1016/j.expneurol.2024.114804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 04/25/2024] [Accepted: 04/30/2024] [Indexed: 05/06/2024]
Abstract
BACKGROUND Sevoflurane (SEV) has been found to induce neurotoxicity and cognitive impairment, leading to the development of degenerative diseases. Protein kinase C delta (PRKCD) is upregulated in the hippocampus of SEV-treated mice and may be related to SEV-related neurotoxicity. However, the underlying molecular mechanisms by which SEV mediates neurotoxicity via PRKCD remain unclear. METHODS Normal mice and PRKCD knockout (KO) mice were exposed to SEV. Hippocampal neurons were isolated from mice hippocampal tissues. H&E staining was used for pathological morphology of hippocampal tissues, and NISSL staining was used to analyze the number of hippocampal neurons. The mRNA and protein levels were determined using quantitative real-time PCR, western blot, immunofluorescence staining and immunohistochemical staining. The mitochondrial microstructure was observed by transmission electron microscopy. Cell viability was detected by cell counting kit 8 assay, and ferroptosis was assessed by detecting related marker levels. The cognitive ability of mice was assessed by morris water maze test. And the protein levels of PRKCD, ferroptosis-related markers and Hippo pathway-related markers were examined by western bolt. RESULTS SEV increased PRKCD expression and ferroptosis in hippocampal tissues of mice. Also, SEV promoted mouse hippocampal neuron injury by inducing ferroptosis via upregulating PRKCD expression. Knockout of PRKCD alleviated SEV-induced neurotoxicity and cognitive impairment in mice, and relieved SEV-induced ferroptosis in hippocampal neurons. PRKCD could inhibit the activity of Hippo pathway, and its knockdown also overturned SEV-mediated ferroptosis by activating Hippo pathway. CONCLUSION SEV could induce neurotoxicity and cognitive impairment by promoting ferroptosis via inactivating Hippo pathway through increasing PRKCD expression.
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Affiliation(s)
- Tingmin Lv
- Department of Anesthesiology, Shunde Hospital of Southern Medical University (The First People's Hospital of Shunde), No. 1 Jiazi Road, Lunjiao Street, Shunde District, Foshan City, Guangdong Province 528308, PR China
| | - Feiyu Jia
- Department of Anesthesiology, Shunde Hospital of Southern Medical University (The First People's Hospital of Shunde), No. 1 Jiazi Road, Lunjiao Street, Shunde District, Foshan City, Guangdong Province 528308, PR China
| | - Guanhua Wang
- Department of Anesthesiology, Shunde Hospital of Southern Medical University (The First People's Hospital of Shunde), No. 1 Jiazi Road, Lunjiao Street, Shunde District, Foshan City, Guangdong Province 528308, PR China
| | - Shujia Li
- Department of Anesthesiology, Shunde Hospital of Southern Medical University (The First People's Hospital of Shunde), No. 1 Jiazi Road, Lunjiao Street, Shunde District, Foshan City, Guangdong Province 528308, PR China
| | - Tingting Wan
- Department of Anesthesiology, Shunde Hospital of Southern Medical University (The First People's Hospital of Shunde), No. 1 Jiazi Road, Lunjiao Street, Shunde District, Foshan City, Guangdong Province 528308, PR China
| | - Wenrui Qiu
- Department of Anesthesiology, Shunde Hospital of Southern Medical University (The First People's Hospital of Shunde), No. 1 Jiazi Road, Lunjiao Street, Shunde District, Foshan City, Guangdong Province 528308, PR China
| | - Zhenyu Tang
- Department of Anesthesiology, Shunde Hospital of Southern Medical University (The First People's Hospital of Shunde), No. 1 Jiazi Road, Lunjiao Street, Shunde District, Foshan City, Guangdong Province 528308, PR China
| | - Hanwen Chen
- Department of Anesthesiology, Shunde Hospital of Southern Medical University (The First People's Hospital of Shunde), No. 1 Jiazi Road, Lunjiao Street, Shunde District, Foshan City, Guangdong Province 528308, PR China.
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Lian F, Wang Z, Zhou Z, Xu G. Identification, characterization, and comparison of n-alkanols and anesthetics binding to the C1b subdomain of protein kinase cα: similar function with different binding sites. J Recept Signal Transduct Res 2020; 40:109-116. [PMID: 32054382 DOI: 10.1080/10799893.2020.1726950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Protein kinase C (PKC) is a family of lipid-activated enzymes involved in anesthetic preconditioning signaling pathways. Previously, n-alkanols and general anesthetics have been found to activate PKC by binding to the kinase C1B subdomain. In the present study, we attempt to ascertain the molecular mechanism and interaction mode of human PKCα C1B subdomain with a variety of exogenous n-alkanols and volatile general anesthetics as well as endogenous activator phorbol ester (PE) and co-activator diacylglycerol (DG). Systematic bioinformatics analysis identifies three spatially vicinal sites on the subdomain surface to potentially accommodate small-molecule ligands, where the site 1 is a narrow, amphipathic pocket, the site 2 is a wide, flat and hydrophobic pocket, and the site 3 is a rugged, polar pocket. Further interaction modeling reveals that site 1 is the cognate binding region of natural PE activator, which can moderately simulate the kinase activity in an independent manner. The short-chain n-alkanols are speculated to also bind at the site to competitively inhibit PE-induced kinase activation. The long-chain n-alkanols and co-activator DG are found to target site 2 in a nonspecific manner, while the volatile anesthetics prefer to interact with site 3 in a specific manner. Since the site 1 is composed of two protein loops that are also shared by sites 2 and 3, binding of n-alkanols, DG and anesthetics to sites 2 and 3 can trigger a conformational displacement on the two loops, which enlarges the pocket size and changes the pocket configuration of site 1 through an allosteric mechanism, consequently enhancing kinase activation by improving PE affinity to the site.
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Affiliation(s)
- Fang Lian
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Zhong Wang
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Zhidong Zhou
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Guohai Xu
- Department of Anesthesiology, the Second Affiliated Hospital of Nanchang University, Nanchang, China
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3
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Das J. SNARE Complex-Associated Proteins and Alcohol. Alcohol Clin Exp Res 2019; 44:7-18. [PMID: 31724225 DOI: 10.1111/acer.14238] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 11/07/2019] [Indexed: 12/23/2022]
Abstract
Alcohol addiction causes major health problems throughout the world, causing numerous deaths and incurring a huge economic burden to society. To develop an intervention for alcohol addiction, it is necessary to identify molecular target(s) of alcohol and associated molecular mechanisms of alcohol action. The functions of many central and peripheral synapses are impacted by low concentrations of ethanol (EtOH). While the postsynaptic targets and mechanisms are studied extensively, there are limited studies on the presynaptic targets and mechanisms. This article is an endeavor in this direction, focusing on the effect of EtOH on the presynaptic proteins associated with the neurotransmitter release machinery. Studies on the effects of EtOH at the levels of gene, protein, and behavior are highlighted in this article.
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Affiliation(s)
- Joydip Das
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
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4
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Das J. Identification of alcohol-binding site(s) in proteins using diazirine-based photoaffinity labeling and mass spectrometry. Chem Biol Drug Des 2018; 93:1158-1165. [PMID: 30346111 DOI: 10.1111/cbdd.13403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/03/2018] [Accepted: 09/15/2018] [Indexed: 01/12/2023]
Abstract
Defining molecular targets of alcohol and understanding the molecular mechanism of alcohol actions are necessary to develop effective therapeutics for alcohol use disorder (AUD). Here, we describe a detailed protocol for identifying alcohol-binding site(s) in proteins using diazirine-based azialcohol as photoaffinity labeling agents. Upon photoirradiation, azialcohol photoincorporates into alcohol-binding proteins. The stoichiometry and site of azialcohol photoincorporation can be determined using high-resolution mass spectrometry. Identification of the alcohol-binding residues in protein followed by measuring the biological significance of these residues in regulating alcohol action are important steps in characterizing the molecular targets of alcohol.
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Affiliation(s)
- Joydip Das
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas
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5
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Structural Identification and Systematic Comparison of Phorbol Ester, Dioleoylglycerol, Alcohol and Sevoflurane Binding Sites in PKCδ C1A Domain. Protein J 2018; 37:539-547. [PMID: 30251087 DOI: 10.1007/s10930-018-9793-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Protein kinase C (PKC) is a family of signal transducing enzymes that have been implicated in anesthetic preconditioning signaling cascade. Evidences are emerging that certain exogenous neuromodulators such as n-alkanols and general anesthetics can stimulate PKC activity by binding to regulatory C1A domain of the enzyme. However, the accurate binding sites in C1A domain as well as the molecular mechanism underlying binding-stimulated PKC activation still remain unelucidated. Here, we report a systematic investigation of the intermolecular interaction of human PKCδ C1A domain with its natural activator phorbol ester (PE) and co-activator dioleoylglycerol (DOG) as well as exogenous stimulators butanol, octanol and sevoflurane. The domain is computationally identified to potentially have three spatially vicinal ligand-binding pockets 1, 2 and 3, in which the pockets 1 and 2 have previously been determined as the binding sites of PE and DOG, respectively. Systematic cross-binding analysis reveals that long-chain octanol and DOG are well compatible with the flat, nonpolar pocket 2, where the nonspecific hydrophobic contacts and van der Waals packing are primarily responsible for the binding, while the general anesthetic sevoflurane prefer to interact with the rugged, polar pocket 3 through specific hydrogen bonds and electrostatic forces. Short-chain butanol appears to bind effectively none of the three pockets. In addition, the pocket 1 consists of two angled arms 1 and 2 that are also involved in pockets 2 and 3, respectively. Dynamics characterization imparts that binding of long-chain octanol and DOG to pocket 2 or binding of sevoflurane to pocket 3 can induce a conformational displacement in arm 1 or 2, thus further opening the included angle and enlarging pocket 1, which can improve the pocket 1-PE affinity via an allosteric mechanism, consequently stimulating the PE-induced PKCδ activation.
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Fahrenbach VS, Bertaccini EJ. Insights Into Receptor-Based Anesthetic Pharmacophores and Anesthetic-Protein Interactions. Methods Enzymol 2018; 602:77-95. [PMID: 29588042 DOI: 10.1016/bs.mie.2018.01.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
General anesthetics are thought to allosterically bind and potentiate the inhibitory currents of the GABAA receptor through drug-specific binding sites. The physiologically relevant isoform of the GABAA receptor is a transmembrane ligand-gated ion channel consisting of five subunits (γ-α-β-α-β linkage) symmetrically arranged around a central chloride-conducting pore. Although the exact molecular structure of this heteropentameric GABAA receptor remains unknown, molecular modeling has allowed significant advancements in understanding anesthetic binding and action. Using the open-channel conformations of the homologous glycine and glutamate-gated chloride receptors as templates, a homology model of the GABAA receptor was constructed using the Discovery Studio computational chemistry software suite. Consensus structural alignment of the homology templates allowed for the construction of a three-dimensional heteropentameric GABAA receptor model with (γ2-β3-α1-β3-α1) subunit linkage. An anesthetic binding site was identified within the transmembrane α/β intersubunit space by the convergence of three residues shown to be essential for anesthetic activity in previous studies with mutant mice (β3-N265, β3-M286, α1-L232). Propofol derivatives docked into this binding site showed log-linear correlation with experimentally derived GABAA receptor potentiation (EC50) values, suggesting this binding site may be important for receptor activation. The receptor-based pharmacophore was analyzed with surface maps displaying the predominant anesthetic-protein interactions, revealing an amphiphilic binding cavity incorporating the three residues involved in anesthetic modulation. Quantum mechanics calculations of the bonding patterns found in complementary high-resolution receptor systems further elucidated the complex nature of anesthetic-protein interactions.
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Affiliation(s)
- Victoria S Fahrenbach
- Stanford University School of Medicine, Stanford, CA, United States; Palo Alto VA Health Care System, Palo Alto, CA, United States
| | - Edward J Bertaccini
- Stanford University School of Medicine, Stanford, CA, United States; Palo Alto VA Health Care System, Palo Alto, CA, United States.
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Ge SS, Chen B, Wu YY, Long QS, Zhao YL, Wang PY, Yang S. Current advances of carbene-mediated photoaffinity labeling in medicinal chemistry. RSC Adv 2018; 8:29428-29454. [PMID: 35547988 PMCID: PMC9084484 DOI: 10.1039/c8ra03538e] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 07/07/2018] [Indexed: 12/21/2022] Open
Abstract
Photoaffinity labeling (PAL) in combination with a chemical probe to covalently bind its target upon UV irradiation has demonstrated considerable promise in drug discovery for identifying new drug targets and binding sites. In particular, carbene-mediated photoaffinity labeling (cmPAL) has been widely used in drug target identification owing to its excellent photolabeling efficiency, minimal steric interference and longer excitation wavelength. Specifically, diazirines, which are among the precursors of carbenes and have higher carbene yields and greater chemical stability than diazo compounds, have proved to be valuable photolabile reagents in a diverse range of biological systems. This review highlights current advances of cmPAL in medicinal chemistry, with a focus on structures and applications for identifying small molecule–protein and macromolecule–protein interactions and ligand-gated ion channels, coupled with advances in the discovery of targets and inhibitors using carbene precursor-based biological probes developed in recent decades. Photoaffinity labeling (PAL) in combination with a chemical probe to covalently bind its target upon UV irradiation has demonstrated considerable promise in drug discovery for identifying new drug targets and binding sites.![]()
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Affiliation(s)
- Sha-Sha Ge
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering
- Key Laboratory of Green Pesticide and Agricultural Bioengineering
- Ministry of Education
- Center for R&D of Fine Chemicals of Guizhou University
- Guiyang 550025
| | - Biao Chen
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering
- Key Laboratory of Green Pesticide and Agricultural Bioengineering
- Ministry of Education
- Center for R&D of Fine Chemicals of Guizhou University
- Guiyang 550025
| | - Yuan-Yuan Wu
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering
- Key Laboratory of Green Pesticide and Agricultural Bioengineering
- Ministry of Education
- Center for R&D of Fine Chemicals of Guizhou University
- Guiyang 550025
| | - Qing-Su Long
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering
- Key Laboratory of Green Pesticide and Agricultural Bioengineering
- Ministry of Education
- Center for R&D of Fine Chemicals of Guizhou University
- Guiyang 550025
| | - Yong-Liang Zhao
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering
- Key Laboratory of Green Pesticide and Agricultural Bioengineering
- Ministry of Education
- Center for R&D of Fine Chemicals of Guizhou University
- Guiyang 550025
| | - Pei-Yi Wang
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering
- Key Laboratory of Green Pesticide and Agricultural Bioengineering
- Ministry of Education
- Center for R&D of Fine Chemicals of Guizhou University
- Guiyang 550025
| | - Song Yang
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering
- Key Laboratory of Green Pesticide and Agricultural Bioengineering
- Ministry of Education
- Center for R&D of Fine Chemicals of Guizhou University
- Guiyang 550025
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Woll KA, Dailey WP, Brannigan G, Eckenhoff RG. Shedding Light on Anesthetic Mechanisms: Application of Photoaffinity Ligands. Anesth Analg 2017; 123:1253-1262. [PMID: 27464974 DOI: 10.1213/ane.0000000000001365] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Anesthetic photoaffinity ligands have had an increasing presence within anesthesiology research. These ligands mimic parent general anesthetics and allow investigators to study anesthetic interactions with receptors and enzymes; identify novel targets; and determine distribution within biological systems. To date, nearly all general anesthetics used in medicine have a corresponding photoaffinity ligand represented in the literature. In this review, we examine all aspects of the current methodologies, including ligand design, characterization, and deployment. Finally we offer points of consideration and highlight the future outlook as more photoaffinity ligands emerge within the field.
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Affiliation(s)
- Kellie A Woll
- From the Departments of *Anesthesiology and Critical Care and †Pharmacology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania; ‡Department of Chemistry, University of Pennsylvania School of Arts and Sciences, Philadelphia, Pennsylvania; and §Department of Physics, Rutgers University, Camden, New Jersey
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9
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Budelier MM, Cheng WWL, Bergdoll L, Chen ZW, Abramson J, Krishnan K, Qian M, Covey DF, Janetka JW, Evers AS. Click Chemistry Reagent for Identification of Sites of Covalent Ligand Incorporation in Integral Membrane Proteins. Anal Chem 2017; 89:2636-2644. [PMID: 28194953 DOI: 10.1021/acs.analchem.6b05003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Identifying sites of protein-ligand interaction is important for structure-based drug discovery and understanding protein structure-function relationships. Mass spectrometry (MS) has emerged as a useful tool for identifying residues covalently modified by ligands. Current methods use database searches that are dependent on acquiring interpretable fragmentation spectra (MS2) of peptide-ligand adducts. This is problematic for identifying sites of hydrophobic ligand incorporation in integral membrane proteins (IMPs), where poor aqueous solubility and ionization of peptide-ligand adducts and collision-induced adduct loss hinder the acquisition of quality MS2 spectra. To address these issues, we developed a fast ligand identification (FLI) tag that can be attached to any alkyne-containing ligand via Cu(I)-catalyzed cycloaddition. The FLI tag adds charge to increase solubility and ionization, and utilizes stable isotope labeling for MS1 level identification of hydrophobic peptide-ligand adducts. The FLI tag was coupled to an alkyne-containing neurosteroid photolabeling reagent and used to identify peptide-steroid adducts in MS1 spectra via the stable heavy isotope pair. Peptide-steroid adducts were not identified in MS2-based database searches because collision-induced adduct loss was the dominant feature of collision-induced dissociation (CID) fragmentation, but targeted analysis of MS1 pairs using electron transfer dissociation (ETD) markedly reduced adduct loss. Using the FLI tag and ETD, we identified Glu73 as the site of photoincorporation of our neurosteroid ligand in the IMP, mouse voltage-dependent anion channel-1 (mVDAC1), and top-down MS confirmed a single site of photolabeling.
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Affiliation(s)
- Melissa M Budelier
- Department of Anesthesiology, Washington University in St. Louis , St. Louis, Missouri 63110, United States.,Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis , St. Louis, Missouri 63110, United States
| | - Wayland W L Cheng
- Department of Anesthesiology, Washington University in St. Louis , St. Louis, Missouri 63110, United States
| | - Lucie Bergdoll
- Department of Physiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles , Los Angeles, California 90095, United States
| | - Zi-Wei Chen
- Department of Anesthesiology, Washington University in St. Louis , St. Louis, Missouri 63110, United States.,The Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis , St. Louis, Missouri 63110, United States
| | - Jeff Abramson
- Department of Physiology, David Geffen School of Medicine at UCLA, University of California at Los Angeles , Los Angeles, California 90095, United States.,The Institute for Stem Cell Biology and Regenerative Medicine (instem), National Centre for Biological Sciences-Tata Institute of Fundamental Research , Bangalore 560065, Karnataka India
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University in St. Louis , St. Louis, Missouri 63110, United States
| | - Mingxing Qian
- Department of Developmental Biology, Washington University in St. Louis , St. Louis, Missouri 63110, United States
| | - Douglas F Covey
- Department of Anesthesiology, Washington University in St. Louis , St. Louis, Missouri 63110, United States.,The Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis , St. Louis, Missouri 63110, United States.,Department of Developmental Biology, Washington University in St. Louis , St. Louis, Missouri 63110, United States.,Department of Psychiatry, Washington University in St. Louis , St. Louis, Missouri 63110, United States
| | - James W Janetka
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis , St. Louis, Missouri 63110, United States
| | - Alex S Evers
- Department of Anesthesiology, Washington University in St. Louis , St. Louis, Missouri 63110, United States.,The Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis , St. Louis, Missouri 63110, United States.,Department of Developmental Biology, Washington University in St. Louis , St. Louis, Missouri 63110, United States
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Constantinides C, Murphy K. Molecular and Integrative Physiological Effects of Isoflurane Anesthesia: The Paradigm of Cardiovascular Studies in Rodents using Magnetic Resonance Imaging. Front Cardiovasc Med 2016; 3:23. [PMID: 27525256 PMCID: PMC4965459 DOI: 10.3389/fcvm.2016.00023] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 07/04/2016] [Indexed: 12/19/2022] Open
Abstract
To-this-date, the exact molecular, cellular, and integrative physiological mechanisms of anesthesia remain largely unknown. Published evidence indicates that anesthetic effects are multifocal and occur in a time-dependent and coordinated manner, mediated via central, local, and peripheral pathways. Their effects can be modulated by a range of variables, and their elicited end-effect on the integrative physiological response is highly variable. This review summarizes the major cellular and molecular sites of anesthetic action with a focus on the paradigm of isoflurane (ISO) - the most commonly used anesthetic nowadays - and its use in prolonged in vivo rodent studies using imaging modalities, such as magnetic resonance imaging (MRI). It also presents established evidence for normal ranges of global and regional physiological cardiac function under ISO, proposes optimal, practical methodologies relevant to the use of anesthetic protocols for MRI and outlines the beneficial effects of nitrous oxide supplementation.
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Affiliation(s)
- Christakis Constantinides
- Chi Biomedical Ltd., Nicosia, Cyprus; Division of Cardiovascular Medicine, University of Oxford, Oxford, UK
| | - Kathy Murphy
- Division of Biomedical Sciences, University of Oxford , Oxford , UK
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11
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Thangsunan P, Tateing S, Hannongbua S, Suree N. Structural insights into the interactions of phorbol ester and bryostatin complexed with protein kinase C: a comparative molecular dynamics simulation study. J Biomol Struct Dyn 2015; 34:1561-75. [PMID: 26292580 DOI: 10.1080/07391102.2015.1084479] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Protein kinase C (PKC) isozymes are important regulatory enzymes that have been implicated in many diseases, including cancer, Alzheimer's disease, and in the eradication of HIV/AIDS. Given their potential clinical ramifications, PKC modulators, e.g. phorbol esters and bryostatin, are also of great interest in the drug development. However, structural details on the binding between PKC and its modulators, especially bryostatin - the highly potent and non-tumor promoting activator for PKCs, are still lacking. Here, we report the first comparative molecular dynamics study aimed at gaining structural insight into the mechanisms by which the PKC delta cys2 activator domain is used in its binding to phorbol ester and bryostatin-1. As anticipated in the phorbol ester binding, hydrogen bonds are formed through the backbone atoms of Thr242, Leu251, and Gly253 of PKC. However, the opposition of H-bond formation between Thr242 and Gly253 may cause the phorbol ester complex to become less stable when compared with the bryostatin binding. For the PKC delta-bryostatin complex, hydrogen bonds are formed between the Gly253 backbone carbonyl and the C30 carbomethoxy substituent of the ligand. Additionally, the indole Nε1 of the highly homologous Trp252 also forms an H-bond to the C20 ester group on bryostatin. Backbone fluctuations also suggest that this latter H-bond formation may abrogate the transient interaction between Trp252 and His269, thus dampening the fluctuations observed on the nearby Zn(2+)-coordinating residues. This new dynamic fluctuation dampening model can potentially benefit future design of new PKC modulators.
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Affiliation(s)
- Patcharapong Thangsunan
- a Graduate Program in Biotechnology , The Graduate School, Chiang Mai University , 239 Huay Kaew Rd, Suthep, Muang, Chiang Mai 50200 , Thailand.,b Faculty of Science, Department of Chemistry, Division of Biochemistry and Biochemical Technology , Chiang Mai University , 239 Huay Kaew Rd, Suthep, Muang, Chiang Mai 50200 , Thailand
| | - Suriya Tateing
- a Graduate Program in Biotechnology , The Graduate School, Chiang Mai University , 239 Huay Kaew Rd, Suthep, Muang, Chiang Mai 50200 , Thailand.,b Faculty of Science, Department of Chemistry, Division of Biochemistry and Biochemical Technology , Chiang Mai University , 239 Huay Kaew Rd, Suthep, Muang, Chiang Mai 50200 , Thailand
| | - Supa Hannongbua
- c Faculty of Science, Department of Chemistry , Kasetsart University , Bangkok 10900 , Thailand
| | - Nuttee Suree
- b Faculty of Science, Department of Chemistry, Division of Biochemistry and Biochemical Technology , Chiang Mai University , 239 Huay Kaew Rd, Suthep, Muang, Chiang Mai 50200 , Thailand
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Abstract
BACKGROUND Alcohol regulates the expression and function of protein kinase C epsilon (PKCε). In a previous study we identified an alcohol binding site in the C1B, one of the twin C1 subdomains of PKCε (Das et al., Biochem. J., 421, 405-13, 2009). METHODS In this study, we investigated alcohol binding in the entire C1 domain (combined C1A and C1B) of PKCε. Fluorescent phorbol ester, SAPD and fluorescent diacylglycerol (DAG) analog, dansyl-DAG were used to study the effect of ethanol, butanol, and octanol on the ligand binding using fluorescence resonance energy transfer (FRET). To identify alcohol binding site(s), PKCεC1 was photolabeled with 3-azibutanol and 3-azioctanol, and analyzed by mass spectrometry. The effects of alcohols and the azialcohols on PKCε were studied in NG108-15 cells. RESULTS In the presence of alcohol, SAPD and dansyl-DAG showed different extent of FRET, indicating differential effects of alcohol on the C1A and C1B subdomains. Effects of alcohols and azialcohols on PKCε in NG108-15 cells were comparable. Azialcohols labeled Tyr-176 of C1A and Tyr-250 of C1B. Inspection of the model structure of PKCεC1 reveals that these residues are 40Å apart from each other indicating that these residues form two different alcohol binding sites. CONCLUSIONS The present results provide evidence for the presence of multiple alcohol-binding sites on PKCε and underscore the importance of targeting this PKC isoform in developing alcohol antagonists.
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Affiliation(s)
- Satyabrata Pany
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, United States
| | - Joydip Das
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, United States.
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Masuda S, Tomohiro T, Yamaguchi S, Morimoto S, Hatanaka Y. Structure-assisted ligand-binding analysis using fluorogenic photoaffinity labeling. Bioorg Med Chem Lett 2015; 25:1675-1678. [DOI: 10.1016/j.bmcl.2015.03.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 03/02/2015] [Accepted: 03/04/2015] [Indexed: 11/29/2022]
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Weiser BP, Woll KA, Dailey WP, Eckenhoff RG. Mechanisms revealed through general anesthetic photolabeling. CURRENT ANESTHESIOLOGY REPORTS 2013; 4:57-66. [PMID: 24563623 DOI: 10.1007/s40140-013-0040-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
General anesthetic photolabels are used to reveal molecular targets and molecular binding sites of anesthetic ligands. After identification, the relevance of anesthetic substrates or binding sites can be tested in biological systems. Halothane and photoactive analogs of isoflurane, propofol, etomidate, neurosteroids, anthracene, and long chain alcohols have been used in anesthetic photolabeling experiments. Interrogated protein targets include the nicotinic acetylcholine receptor, GABAA receptor, tubulin, leukocyte function-associated antigen-1, and protein kinase C. In this review, we summarize insights revealed by photolabeling these targets, as well as general features of anesthetics, such as their propensity to partition to mitochondria and bind voltage-dependent anion channels. The theory of anesthetic photolabel design and the experimental application of photoactive ligands are also discussed.
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Affiliation(s)
- Brian P Weiser
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104 ; Department of Pharmacology, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104
| | - Kellie A Woll
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104 ; Department of Pharmacology, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104
| | - William P Dailey
- Department of Chemistry, University of Pennsylvania School of Arts and Sciences, 231 S. 34th Street, Philadelphia, PA 19104
| | - Roderic G Eckenhoff
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104
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Shanmugasundararaj S, Das J, Sandberg WS, Zhou X, Wang D, Messing RO, Bruzik KS, Stehle T, Miller KW. Structural and functional characterization of an anesthetic binding site in the second cysteine-rich domain of protein kinase Cδ*. Biophys J 2013; 103:2331-40. [PMID: 23283232 DOI: 10.1016/j.bpj.2012.10.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 10/24/2012] [Accepted: 10/26/2012] [Indexed: 01/04/2023] Open
Abstract
Elucidating the principles governing anesthetic-protein interactions requires structural determinations at high resolutions not yet achieved with ion channels. Protein kinase C (PKC) activity is modulated by general anesthetics. We solved the structure of the phorbol-binding domain (C1B) of PKCδ complexed with an ether (methoxymethylcycloprane) and with an alcohol (cyclopropylmethanol) at 1.36-Å resolution. The cyclopropane rings of both agents displace a single water molecule in a surface pocket adjacent to the phorbol-binding site, making van der Waals contacts with the backbone and/or side chains of residues Asn-237 to Ser-240. Surprisingly, two water molecules anchored in a hydrogen-bonded chain between Thr-242 and Lys-260 impart elasticity to one side of the binding pocket. The cyclopropane ring takes part in π-acceptor hydrogen bonds with the amide of Met-239. There is a crucial hydrogen bond between the oxygen atoms of the anesthetics and the hydroxyl of Tyr-236. A Tyr-236-Phe mutation results in loss of binding. Thus, both van der Waals interactions and hydrogen-bonding are essential for binding to occur. Ethanol failed to bind because it is too short to benefit from both interactions. Cyclopropylmethanol inhibited phorbol-ester-induced PKCδ activity, but failed to do so in PKCδ containing the Tyr-236-Phe mutation.
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16
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Das J, Xu S, Pany S, Guillory A, Shah V, Roman GW. The pre-synaptic Munc13-1 binds alcohol and modulates alcohol self-administration in Drosophila. J Neurochem 2013; 126:715-26. [PMID: 23692447 DOI: 10.1111/jnc.12315] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 05/09/2013] [Accepted: 05/17/2013] [Indexed: 11/30/2022]
Abstract
Munc13-1 is a pre-synaptic active-zone protein essential for neurotransmitter release and involved in pre-synaptic plasticity in brain. Ethanol, butanol, and octanol quenched the intrinsic fluorescence of the C1 domain of Munc13-1 with EC₅₀ s of 52 mM, 26 mM, and 0.7 mM, respectively. Photoactive azialcohols photolabeled Munc13-1 C1 exclusively at Glu-582, which was identified by mass spectrometry. Mutation of Glu-582 to alanine, leucine, and histidine reduced the alcohol binding two- to five-fold. Circular dichroism studies suggested that binding of alcohol increased the stability of the wild-type Munc13-1 compared with the mutants. If Munc13-1 plays some role in the neural effects of alcohol in vivo, changes in the activity of this protein should produce differences in the behavioral responses to ethanol. We tested this prediction with a loss-of-function mutation in the conserved Dunc-13 in Drosophila melanogaster. The Dunc-13(P84200) /+ heterozygotes have 50% wild-type levels of Dunc-13 mRNA and display a very robust increase in ethanol self-administration. This phenotype is reversed by the expression of the rat Munc13-1 protein within the Drosophila nervous system. The present studies indicate that Munc13-1 C1 has binding site(s) for alcohols and Munc13-1 activity is sufficient to restore normal self-administration to Drosophila mutants deficient in Dunc-13 activity. The pre-synaptic Mun13-1 protein is a critical regulator of synaptic vesicle fusion and may be involved in processes that lead to ethanol abuse and addiction. We studied its interaction with alcohol and identified Glu-582 as a critical residue for ethanol binding. Munc13-1 can functionally complement the Dunc13 haploinsufficient ethanol self-administration phenotype in Drosophila melanogaster, indicating that this protein participates in alcohol-induced behavioral plasticity.
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Affiliation(s)
- Joydip Das
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas 77204, USA.
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17
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Sourbier C, Scroggins BT, Ratnayake R, Prince TL, Lee S, Lee MJ, Nagy PL, Lee YH, Trepel JB, Beutler JA, Linehan WM, Neckers L. Englerin A stimulates PKCθ to inhibit insulin signaling and to simultaneously activate HSF1: pharmacologically induced synthetic lethality. Cancer Cell 2013; 23:228-37. [PMID: 23352416 PMCID: PMC3574184 DOI: 10.1016/j.ccr.2012.12.007] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 10/19/2012] [Accepted: 12/18/2012] [Indexed: 12/31/2022]
Abstract
The natural product englerin A (EA) binds to and activates protein kinase C-θ (PKCθ). EA-dependent activation of PKCθ induces an insulin-resistant phenotype, limiting the access of tumor cells to glucose. At the same time, EA causes PKCθ-mediated phosphorylation and activation of the transcription factor heat shock factor 1, an inducer of glucose dependence. By promoting glucose addiction, while simultaneously starving cells of glucose, EA proves to be synthetically lethal to highly glycolytic tumors.
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Affiliation(s)
- Carole Sourbier
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892
| | - Bradley T. Scroggins
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892
| | - Ranjala Ratnayake
- Molecular Targets Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702
| | - Thomas L. Prince
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892
| | - Sunmin Lee
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892
| | - Min-Jung Lee
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892
| | | | - Young H. Lee
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892
| | - Jane B. Trepel
- Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892
| | - John A. Beutler
- Molecular Targets Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702
| | - W. Marston Linehan
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892
| | - Len Neckers
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892
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18
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PKC activation by resveratrol derivatives with unsaturated aliphatic chain. PLoS One 2012; 7:e52888. [PMID: 23285216 PMCID: PMC3528653 DOI: 10.1371/journal.pone.0052888] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 11/22/2012] [Indexed: 01/04/2023] Open
Abstract
Resveratrol (1) is a naturally occurring phytoalexin that affects a variety of human disease models, including cardio- and neuroprotection, immune regulation, and cancer chemoprevention. One of the possible mechanisms by which resveratrol affects these disease states is by affecting the cellular signaling network involving protein kinase C (PKC). PKC is the family of serine/threonine kinases, whose activity is inhibited by resveratrol. To develop PKC isotype selective molecules on the resveratrol scaffold, several analogs (2–5) of resveratrol with a long aliphatic chain varying with number of unsaturated doubled bonds have been synthesized, their cytotoxic effects on CHO-K1 cells are measured and their effects on the membrane translocation properties of PKCα and PKCε have been determined. The analogs showed less cytotoxic effects on CHO-K1 cells. Analog 4 with three unsaturated double bonds in its aliphatic chain activated PKCα, but not PKCε. Analog 4 also activated ERK1/2, the downstream proteins in the PKC signaling pathway. Resveratrol analogs 2–5, however, did not show any inhibition of the phorbol ester-induced membrane translocation for either PKCα or PKCε. Molecular docking of 4 into the activator binding site of PKCα revealed that the resveratrol moiety formed hydrogen bonds with the activator binding residues and the aliphatic chain capped the activator binding loops making its surface hydrophobic to facilitate its interaction with the plasma membrane. The present study shows that subtle changes in the resveratrol structure can have profound impact on the translocation properties of PKCs. Therefore, resveratrol scaffold can be used to develop PKC selective modulators for regulating associated disease states.
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Weiser BP, Kelz MB, Eckenhoff RG. In vivo activation of azipropofol prolongs anesthesia and reveals synaptic targets. J Biol Chem 2012. [PMID: 23184948 DOI: 10.1074/jbc.m112.413989] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
General anesthetic photolabels have been instrumental in discovering and confirming protein binding partners and binding sites of these promiscuous ligands. We report the in vivo photoactivation of meta-azipropofol, a potent analog of propofol, in Xenopus laevis tadpoles. Covalent adduction of meta-azipropofol in vivo prolongs the primary pharmacologic effect of general anesthetics in a behavioral phenotype we termed "optoanesthesia." Coupling this behavior with a tritiated probe, we performed unbiased, time-resolved gel proteomics to identify neuronal targets of meta-azipropofol in vivo. We have identified synaptic binding partners, such as synaptosomal-associated protein 25, as well as voltage-dependent anion channels as potential facilitators of the general anesthetic state. Pairing behavioral phenotypes elicited by the activation of efficacious photolabels in vivo with time-resolved proteomics provides a novel approach to investigate molecular mechanisms of general anesthetics.
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Affiliation(s)
- Brian P Weiser
- Department of Anesthesia and Critical Care, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, USA
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20
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Stahelin RV, Kong KF, Raha S, Tian W, Melowic HR, Ward KE, Murray D, Altman A, Cho W. Protein kinase Cθ C2 domain is a phosphotyrosine binding module that plays a key role in its activation. J Biol Chem 2012; 287:30518-28. [PMID: 22787157 DOI: 10.1074/jbc.m112.391557] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Protein kinase Cθ (PKCθ) is a novel PKC that plays a key role in T lymphocyte activation. To understand how PKCθ is regulated in T cells, we investigated the properties of its N-terminal C2 domain that functions as an autoinhibitory domain. Our measurements show that a Tyr(P)-containing peptide derived from CDCP1 binds the C2 domain of PKCθ with high affinity and activates the enzyme activity of the intact protein. The Tyr(P) peptide also binds the C2 domain of PKCδ tightly, but no enzyme activation was observed with PKCδ. Mutations of PKCθ-C2 residues involved in Tyr(P) binding abrogated the enzyme activation and association of PKCθ with Tyr-phosphorylated full-length CDCP1 and severely inhibited the T cell receptor/CD28-mediated activation of a PKCθ-dependent reporter gene in T cells. Collectively, these studies establish the C2 domain of PKCθ as a Tyr(P)-binding domain and suggest that the domain may play a major role in PKCθ activation via its Tyr(P) binding.
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Affiliation(s)
- Robert V Stahelin
- Department of Chemistry, University of Illinois, Chicago, IL 60607, USA.
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21
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Mamidi N, Gorai S, Sahoo J, Manna D. Alkyl cinnamates as regulator for the C1 domain of protein kinase C isoforms. Chem Phys Lipids 2012; 165:320-30. [DOI: 10.1016/j.chemphyslip.2012.02.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Revised: 02/22/2012] [Accepted: 02/24/2012] [Indexed: 12/11/2022]
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22
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Ziemba BP, Booth JC, Jones DNM. 1H, 13C and 15N NMR assignments of the C1A and C1B subdomains of PKC-delta. BIOMOLECULAR NMR ASSIGNMENTS 2011; 5:125-129. [PMID: 21132404 PMCID: PMC4396712 DOI: 10.1007/s12104-010-9283-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Accepted: 11/04/2010] [Indexed: 05/30/2023]
Abstract
The Protein Kinase C family of enzymes is a group of serine/threonine kinases that play central roles in cell-cycle regulation, development and cancer. A key step in the activation of PKC is translocation to membranes and binding of membrane-associated activators including diacylglycerol (DAG). Interaction of novel and conventional isotypes of PKC with DAG and phorbol esters occurs through the two C1 regulatory domains (C1A and C1B), which exhibit distinct ligand binding selectivity that likely controls enzyme activation by different co-activators. PKC has also been implicated in physiological responses to alcohol consumption and it has been proposed that PKCα (Slater et al. J Biol Chem 272(10):6167-6173, 1997; Slater et al. Biochemistry 43(23):7601-7609, 2004), PKCε (Das et al. Biochem J 421(3):405-413, 2009) and PKCδ (Das et al. J Biol Chem 279(36):37964-37972, 2004; Das et al. Protein Sci 15(9):2107-2119, 2006) contain specific alcohol-binding sites in their C1 domains. We are interested in understanding how ethanol affects signal transduction processes through its affects on the structure and function of the C1 domains of PKC. Here we present the (1)H, (15)N and (13)C NMR chemical shift assignments for the Rattus norvegicus PKCδ C1A and C1B proteins.
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Affiliation(s)
- Brian P Ziemba
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
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23
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Das J, Pany S, Panchal S, Majhi A, Rahman GM. Binding of isoxazole and pyrazole derivatives of curcumin with the activator binding domain of novel protein kinase C. Bioorg Med Chem 2011; 19:6196-202. [PMID: 21975067 DOI: 10.1016/j.bmc.2011.09.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Accepted: 09/08/2011] [Indexed: 11/26/2022]
Abstract
The protein kinase C (PKC) family of serine/threonine kinases is an attractive drug target because of its involvement in the regulation of various cellular functions, including cell growth, differentiation, metabolism, and apoptosis. The endogenous PKC activator diacylglycerol contains two long carbon chains, which are attached to the glycerol moiety via ester linkage. Natural product curcumin (1), the active constituent of Curcuma L., contains two carbonyl and two hydroxyl groups. It modulates PKC activity and binds to the activator binding site (Majhi et al., Bioorg. Med. Chem.2010, 18, 1591). To investigate the role of the carbonyl and hydroxyl groups of curcumin in PKC binding and to develop curcumin derivatives as effective PKC modulators, we synthesized several isoxazole and pyrazole derivatives of curcumin (2-6), characterized their absorption and fluorescence properties, and studied their interaction with the activator-binding second cysteine-rich C1B subdomain of PKCδ, PKCε and PKCθ. The EC(50)s of the curcumin derivatives for protein fluorescence quenching varied in the range of 3-25 μM. All the derivatives showed higher binding with the PKCθC1B compared with PKCδC1B and PKCεC1B. Fluorescence emission maxima of 2-5 were blue shifted in the presence of the C1B domains, confirming their binding to the protein. Molecular docking revealed that hydroxyl, carbonyl and pyrazole ring of curcumin (1), pyrazole (2), and isoxazole (4) derivatives form hydrogen bonds with the protein residues. The present result shows that isoxazole and pyrazole derivatives bind to the activator binding site of novel PKCs and both carbonyl and hydroxy groups of curcumin play roles in the binding process, depending on the nature of curcumin derivative and the PKC isotype used.
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Affiliation(s)
- Joydip Das
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, United States.
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24
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Das J, Pany S, Majhi A. Chemical modifications of resveratrol for improved protein kinase C alpha activity. Bioorg Med Chem 2011; 19:5321-33. [PMID: 21880495 DOI: 10.1016/j.bmc.2011.08.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 07/28/2011] [Accepted: 08/03/2011] [Indexed: 12/20/2022]
Abstract
Resveratrol (1) is a naturally occurring phytoalexin that affects a variety of human disease models, including cardio- and neuroprotection, immune regulation, and cancer chemoprevention. One of the possible mechanisms by which resveratrol affects these disease states is by affecting the cellular signaling network involving protein kinase C alpha (PKCα). PKCα is a member of the family of serine/threonine kinases, whose activity is inhibited by resveratrol. To study the structure-activity relationship, several monoalkoxy, dialkoxy and hydroxy analogs of resveratrol have been synthesized, tested for their cytotoxic effects on HEK293 cells, measured their effects on the membrane translocation properties of PKCα in the presence and absence of the PKC activator TPA, and studied their binding with the activator binding domain of PKCα. The analogs showed less cytotoxic effects on HEK293 cells and caused higher membrane translocation (activation) than that of resveratrol. Among all the analogs, 3, 16 and 25 showed significantly higher activation than resveratrol. Resveratrol analogs, however, inhibited phorbol ester-induced membrane translocation, and the inhibition was less than that of resveratrol. Binding studies using steady state fluorescence spectroscopy indicated that resveratrol and the analogs bind to the second cysteine-rich domain of PKCα. The molecular docking studies indicated that resveratrol and the analogs interact with the protein by forming hydrogen bonds through its hydroxyl groups. These results signify that molecules developed on a resveratrol scaffold can attenuate PKCα activity and this strategy can be used to regulate various disease states involving PKCα.
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Affiliation(s)
- Joydip Das
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, United States.
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25
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Howard RJ, Slesinger PA, Davies DL, Das J, Trudell JR, Harris RA. Alcohol-binding sites in distinct brain proteins: the quest for atomic level resolution. Alcohol Clin Exp Res 2011; 35:1561-73. [PMID: 21676006 DOI: 10.1111/j.1530-0277.2011.01502.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Defining the sites of action of ethanol on brain proteins is a major prerequisite to understanding the molecular pharmacology of this drug. The main barrier to reaching an atomic-level understanding of alcohol action is the low potency of alcohols, ethanol in particular, which is a reflection of transient, low-affinity interactions with their targets. These mechanisms are difficult or impossible to study with traditional techniques such as radioligand binding or spectroscopy. However, there has been considerable recent progress in combining X-ray crystallography, structural modeling, and site-directed mutagenesis to define the sites and mechanisms of action of ethanol and related alcohols on key brain proteins. We review such insights for several diverse classes of proteins including inwardly rectifying potassium, transient receptor potential, and neurotransmitter-gated ion channels, as well as protein kinase C epsilon. Some common themes are beginning to emerge from these proteins, including hydrogen bonding of the hydroxyl group and van der Waals interactions of the methylene groups of ethanol with specific amino acid residues. The resulting binding energy is proposed to facilitate or stabilize low-energy state transitions in the bound proteins, allowing ethanol to act as a "molecular lubricant" for protein function. We discuss evidence for characteristic, discrete alcohol-binding sites on protein targets, as well as evidence that binding to some proteins is better characterized by an interaction region that can accommodate multiple molecules of ethanol.
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Affiliation(s)
- Rebecca J Howard
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Texas 77812, USA.
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26
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Das J. Aliphatic diazirines as photoaffinity probes for proteins: recent developments. Chem Rev 2011; 111:4405-17. [PMID: 21466226 DOI: 10.1021/cr1002722] [Citation(s) in RCA: 199] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Joydip Das
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas 77204, USA.
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27
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Bertaccini EJ. The Molecular Mechanisms of Anesthetic Action: Updates and Cutting Edge Developments from the Field of Molecular Modeling. Pharmaceuticals (Basel) 2010; 3:2178-2196. [PMID: 27713348 PMCID: PMC4036663 DOI: 10.3390/ph3072178] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Revised: 06/10/2010] [Accepted: 07/06/2010] [Indexed: 12/01/2022] Open
Abstract
For over 160 years, general anesthetics have been given for the relief of pain and suffering. While many theories of anesthetic action have been purported, it has become increasingly apparent that a significant molecular focus of anesthetic action lies within the family of ligand-gated ion channels (LGIC’s). These protein channels have a transmembrane region that is composed of a pentamer of four helix bundles, symmetrically arranged around a central pore for ion passage. While initial and some current models suggest a possible cavity for binding within this four helix bundle, newer calculations postulate that the actual cavity for anesthetic binding may exist between four helix bundles. In either scenario, these cavities have a transmembrane mode of access and may be partially bordered by lipid moieties. Their physicochemical nature is amphiphilic. Anesthetic binding may alter the overall motion of a ligand-gated ion channel by a “foot-in-door” motif, resulting in the higher likelihood of and greater time spent in a specific channel state. The overall gating motion of these channels is consistent with that shown in normal mode analyses carried out both in vacuo as well as in explicitly hydrated lipid bilayer models. Molecular docking and large scale molecular dynamics calculations may now begin to show a more exact mode by which anesthetic molecules actually localize themselves and bind to specific protein sites within LGIC’s, making the design of future improvements to anesthetic ligands a more realizable possibility.
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Affiliation(s)
- Edward J Bertaccini
- Department of Anesthesia, Stanford University School of Medicine, Co-Director of Operating Room and Intensive Care Services, Palo Alto VA Health Care System, 112A, PAVAHCS, 3801 Miranda Avenue, Palo Alto, CA 94304, USA.
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28
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Majhi A, Rahman GM, Panchal S, Das J. Binding of curcumin and its long chain derivatives to the activator binding domain of novel protein kinase C. Bioorg Med Chem 2010; 18:1591-8. [PMID: 20100661 PMCID: PMC2843403 DOI: 10.1016/j.bmc.2009.12.075] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 12/24/2009] [Accepted: 12/31/2009] [Indexed: 01/08/2023]
Abstract
Protein kinase C (PKC) is a family of serine/threonine kinases that play a central role in cellular signal transduction. The second messenger diacylglycerol having two long carbon chains acts as the endogenous ligand for the PKCs. Polyphenol curcumin, the active constituent of Curcuma longa is an anti-cancer agent and modulates PKC activity. To develop curcumin derivatives as effective PKC activators, we synthesized several long chain derivatives of curcumin, characterized their absorption and fluorescence properties and studied their interaction with the activator binding second cysteine-rich C1B subdomain of PKCdelta, PKCepsilon and PKCtheta. Curcumin (1) and its C16 long chain analog (4) quenched the intrinsic fluorescence of PKCdeltaC1B, PKCepsilonC1B and PKCthetaC1B in a manner similar to that of PKC activator 12-O-tetradecanoylphorbol 13-acetate (TPA). The EC(50)s of the curcumin derivatives for fluorescence quenching varied in the range of 4-11 microM, whereas, EC(50)s for TPA varied in the range of 3-6 microM. Fluorescence emission maxima of 1 and 4 were blue shifted and the fluorescence anisotropy values were increased in the presence of the C1B domains in a manner similar to that shown by the fluorescent analog of TPA, sapintoxin-D, confirming that they were bound to the proteins. Molecular docking of 1 and 4 with novel PKC C1B revealed that both the molecules form hydrogen bonds with the protein residues. The present result shows that curcumin and its long chain derivatives bind to the C1B subdomain of novel PKCs and can be further modified structurally to improve its binding and activity.
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Affiliation(s)
- Anjoy Majhi
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204
| | - Ghazi M. Rahman
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204
| | - Shyam Panchal
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204
| | - Joydip Das
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204
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29
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Abstract
BACKGROUND Myocardial protection by anesthetics is known to involve activation of protein kinase C epsilon (PKC epsilon). A key step in the activation process is autophosphorylation of the enzyme at serine 729. This study's objectives were to identify the extent to which propofol interacts with PKC epsilon and to identify the molecular mechanism(s) of interaction. METHODS Immunoblot analysis of recombinant PKC epsilon was used to assess autophosphorylation of PKC epsilon at serine 729 before and after exposure to propofol. An enzyme-linked immunosorbant assay kit was used for measuring PKC epsilon activity. Spectral shifts in fluorescence emission maxima of the C1B subdomain of PKC epsilon in combination with the fluorescent phorbol ester, sapintoxin D, was used to identify molecular interactions between propofol and the phorbol ester/diacylglycerol binding site on the enzyme. RESULTS Propofol (1 microM) caused a sixfold increase in immunodetectable serine 729 phosphorylated PKC epsilon and increased catalytic activity of the enzyme in a dose-dependent manner. Dioctanoylglycerol-induced or phorbol myristic acetate-induced activation of recombinant PKC epsilon activity was enhanced by preincubation with propofol. Both propofol and phorbol myristic acetate quenched the intrinsic fluorescence spectra of the PKC epsilon C1B subdomain in a dose-dependent manner, and propofol caused a further leftward-shift in the fluorescence emission maxima of sapintoxin D after addition of the C1B subdomain. CONCLUSIONS These results demonstrate that propofol interacts with recombinant PKC epsilon causing autophosphorylation and activation of the enzyme. Moreover, propofol enhances phorbol ester-induced catalytic activity, suggesting that propofol binds to a region near the phorbol ester binding site allowing for allosteric modulation of PKC epsilon catalytic activity.
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Abstract
Alcohols regulate the expression and function of PKC (protein kinase C), and it has been proposed that an alcohol-binding site is present in PKCα in its C1 domain, which consists of two cysteine-rich subdomains, C1A and C1B. A PKCϵ-knockout mouse showed a significant decrease in alcohol consumption compared with the wild-type. The aim of the present study was to investigate whether an alcohol-binding site could be present in PKCϵ. Here we show that ethanol inhibited PKCϵ activity in a concentration-dependent manner with an EC50 (equilibrium ligand concentration at half-maximum effect) of 43 mM. Ethanol, butanol and octanol increased the binding affinity of a fluorescent phorbol ester SAPD (sapintoxin-D) to PKCϵC1B in a concentration-dependent manner with EC50 values of 78 mM, 8 mM and 340 μM respectively, suggesting the presence of an allosteric alcohol-binding site in this subdomain. To identify this site, PKCϵC1B was photolabelled with 3-azibutanol and 3-azioctanol and analysed by MS. Whereas azibutanol preferentially labelled His236, Tyr238 was the preferred site for azioctanol. Inspection of the model structure of PKCϵC1B reveals that these residues are 3.46 Å (1 Å=0.1 nm) apart from each other and form a groove where His236 is surface-exposed and Tyr238 is buried inside. When these residues were replaced by alanine, it significantly decreased alcohol binding in terms of both photolabelling and alcohol-induced SAPD binding in the mutant H236A/Y238A. Whereas Tyr238 was labelled in mutant H236A, His236 was labelled in mutant Y238A. The present results provide direct evidence for the presence of an allosteric alcohol-binding site on protein kinase Cϵ and underscore the role of His236 and Tyr238 residues in alcohol binding.
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31
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Das J. Photoincorporation of azialcohol to the C1B domain of PKCdelta is buffer dependent. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2009; 95:185-8. [PMID: 19359193 DOI: 10.1016/j.jphotobiol.2009.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 03/10/2009] [Accepted: 03/11/2009] [Indexed: 11/25/2022]
Abstract
Protein kinase C (PKC) is a signal transducing protein that has been implicated in binding alcohol and anesthetics. The alcohol and anesthetic binding of protein kinase C delta C1B domain has been determined previously by photolabeling and mass spectrometry [J. Das, G.H. Addona, W.S. Sandberg, S.S. Husain, T. Stehle, K.W. Miller, Identiffcation of a general anesthetic binding site in the diacylglycerol-binding domain of protein kinase C delta, J. Biol. Chem. 279 (2004) 37964-37972]. Here we studied photoincorporation of 3-azioctanol, a photoactive analog of octanol into PKC delta C1B in two buffer systems containing tris and hepes. The extent of photoincorporation was higher in hepes compared to tris as determined by high performance liquid chromatography and mass spectrometric analysis. The results are explained on the basis of the presence of number of primary hydroxyl and amino groups in tris and hepes molecules that could affect the binding of alcohol molecules to protein. This observation will be useful in selecting buffer system for biochemical studies on PKC.
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Affiliation(s)
- Joydip Das
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, TX 77204, United States.
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Ho C, Shanmugasundararaj S, Miller KW, Malinowski SA, Cook AC, Slater SJ. Interaction of anesthetics with the Rho GTPase regulator Rho GDP dissociation inhibitor. Biochemistry 2008; 47:9540-52. [PMID: 18702520 DOI: 10.1021/bi800544d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The physiological effects of anesthetics have been ascribed to their interaction with hydrophobic sites within functionally relevant CNS proteins. Studies have shown that volatile anesthetics compete for luciferin binding to the hydrophobic substrate binding site within firefly luciferase and inhibit its activity (Franks, N. P., and Lieb, W. R. (1984) Nature 310, 599-601). To assess whether anesthetics also compete for ligand binding to a mammalian signal transduction protein, we investigated the interaction of the volatile anesthetic, halothane, with the Rho GDP dissociation inhibitor (RhoGDIalpha), which binds the geranylgeranyl moiety of GDP-bound Rho GTPases. Consistent with the existence of a discrete halothane binding site, the intrinsic tryptophan fluorescence of RhoGDIalpha was quenched by halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) in a saturable, concentration-dependent manner. Bromine quenching of tryptophan fluorescence is short-range and W192 and W194 of the RhoGDIalpha are located within the geranylgeranyl binding pocket, suggesting that halothane binds within this region. Supporting this, N-acetyl-geranylgeranyl cysteine reversed tryptophan quenching by halothane. Short chain n-alcohols ( n < 6) also reversed tryptophan quenching, suggesting that RhoGDIalpha may also bind n-alkanols. Consistent with this, E193 was photolabeled by 3-azibutanol. This residue is located in the vicinity of, but outside, the geranylgeranyl chain binding pocket, suggesting that the alcohol binding site is distinct from that occupied by halothane. Supporting this, N-acetyl-geranylgeranyl cysteine enhanced E193 photolabeling by 3-azibutanol. Overall, the results suggest that halothane binds to a site within the geranylgeranyl chain binding pocket of RhoGDIalpha, whereas alcohols bind to a distal site that interacts allosterically with this pocket.
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Affiliation(s)
- Cojen Ho
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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Sudhahar C, Haney R, Xue Y, Stahelin R. Cellular membranes and lipid-binding domains as attractive targets for drug development. Curr Drug Targets 2008; 9:603-13. [PMID: 18691008 PMCID: PMC5975357 DOI: 10.2174/138945008785132420] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Interdisciplinary research focused on biological membranes has revealed them as signaling and trafficking platforms for processes fundamental to life. Biomembranes harbor receptors, ion channels, lipid domains, lipid signals, and scaffolding complexes, which function to maintain cellular growth, metabolism, and homeostasis. Moreover, abnormalities in lipid metabolism attributed to genetic changes among other causes are often associated with diseases such as cancer, arthritis and diabetes. Thus, there is a need to comprehensively understand molecular events occurring within and on membranes as a means of grasping disease etiology and identifying viable targets for drug development. A rapidly expanding field in the last decade has centered on understanding membrane recruitment of peripheral proteins. This class of proteins reversibly interacts with specific lipids in a spatial and temporal fashion in crucial biological processes. Typically, recruitment of peripheral proteins to the different cellular sites is mediated by one or more modular lipid-binding domains through specific lipid recognition. Structural, computational, and experimental studies of these lipid-binding domains have demonstrated how they specifically recognize their cognate lipids and achieve subcellular localization. However, the mechanisms by which these modular domains and their host proteins are recruited to and interact with various cell membranes often vary drastically due to differences in lipid affinity, specificity, penetration as well as protein-protein and intramolecular interactions. As there is still a paucity of predictive data for peripheral protein function, these enzymes are often rigorously studied to characterize their lipid-dependent properties. This review summarizes recent progress in our understanding of how peripheral proteins are recruited to biomembranes and highlights avenues to exploit in drug development targeted at cellular membranes and/or lipid-binding proteins.
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Affiliation(s)
- C.G. Sudhahar
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46656, USA
- Walther Center for Cancer Research, University of Notre Dame, Notre Dame, IN 46656, USA
| | - R.M. Haney
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine-South Bend, South Bend, IN 46617
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46656, USA
| | - Y. Xue
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine-South Bend, South Bend, IN 46617
| | - R.V. Stahelin
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine-South Bend, South Bend, IN 46617
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46656, USA
- Walther Center for Cancer Research, University of Notre Dame, Notre Dame, IN 46656, USA
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Eckenhoff R, Zheng W, Kelz M. From anesthetic mechanisms research to drug discovery. Clin Pharmacol Ther 2008; 84:144-8. [PMID: 18449184 DOI: 10.1038/clpt.2008.77] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ability to render patients insensible and amnesic to remarkably invasive procedures that are uncomfortable to watch, let alone experience, has been rightly designated as one of the greatest medical discoveries of all time. General anesthesia, introduced formally in the mid-nineteenth century, is now delivered to approximately 40 million patients every year in the United States alone. Given its central role in health care, it is indeed extraordinary how poorly we understand anesthesia and anesthetics. In fact, definitions are at best operational and convey little understanding of the underlying neurobiology, while the hypothetical mechanisms are surprisingly superficial. Worse, there is growing concern that the anesthetic drugs in current use, especially the inhaled anesthetics, have durable adverse effects on cognition.
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Affiliation(s)
- Rg Eckenhoff
- Department of Anesthesiology and Critical Care, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
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Thode AB, Kruse SW, Nix JC, Jones DNM. The role of multiple hydrogen-bonding groups in specific alcohol binding sites in proteins: insights from structural studies of LUSH. J Mol Biol 2008; 376:1360-76. [PMID: 18234222 PMCID: PMC2293277 DOI: 10.1016/j.jmb.2007.12.063] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Revised: 12/21/2007] [Accepted: 12/21/2007] [Indexed: 11/16/2022]
Abstract
It is now generally accepted that many of the physiological effects of alcohol consumption are a direct result of binding to specific sites in neuronal proteins such as ion channels or other components of neuronal signaling cascades. Binding to these targets generally occurs in water-filled pockets and leads to alterations in protein structure and dynamics. However, the precise interactions required to confer alcohol sensitivity to a particular protein remain undefined. Using information from the previously solved crystal structures of the Drosophila melanogaster protein LUSH in complexes with short-chain alcohols, we have designed and tested the effects of specific amino acid substitutions on alcohol binding. The effects of these substitutions, specifically S52A, T57S, and T57A, were examined using a combination of molecular dynamics, X-ray crystallography, fluorescence spectroscopy, and thermal unfolding. These studies reveal that the binding of ethanol is highly sensitive to small changes in the composition of the alcohol binding site. We find that T57 is the most critical residue for binding alcohols; the T57A substitution completely abolishes binding, while the T57S substitution differentially affects ethanol binding compared to longer-chain alcohols. The additional requirement for a potential hydrogen-bond acceptor at position 52 suggests that both the presence of multiple hydrogen-bonding groups and the identity of the hydrogen-bonding residues are critical for defining an ethanol binding site. These results provide new insights into the detailed chemistry of alcohol's interactions with proteins.
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Affiliation(s)
- Anna B. Thode
- Program in Biomolecular Structure, University of Colorado, Denver School of Medicine, 12801 East 17 Avenue, MS 8303, PO Box 6511, Aurora, CO 80045
| | - Schoen W Kruse
- Department of Pharmacology, University of Colorado Denver School of Medicine, 12801 East 17 Avenue, MS 8303, PO Box 6511, Aurora, CO 80045
| | - Jay C. Nix
- Molecular Biology Consortium, Advanced Light Source Beamline 4.2.2, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - David N. M. Jones
- Department of Pharmacology, University of Colorado Denver School of Medicine, 12801 East 17 Avenue, MS 8303, PO Box 6511, Aurora, CO 80045
- Program in Biomolecular Structure, University of Colorado, Denver School of Medicine, 12801 East 17 Avenue, MS 8303, PO Box 6511, Aurora, CO 80045
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Abstract
Prenatal ethanol exposure causes fetal alcohol spectrum disorders (FASD) in part by disrupting the neural cell adhesion molecule L1. L1 gene mutations cause neuropathological abnormalities similar to those of FASD. Ethanol and 1-butanol inhibit L1-mediated cell-cell adhesion (L1 adhesion), whereas 1-octanol antagonizes this action. To test the hypothesis that there are alcohol binding sites on L1, we used 3-azibutanol and 3-azioctanol, the photoactivatable analogs of 1-butanol and 1-octanol, to photolabel the purified Ig1-4 domain of human L1 (hL1 Ig1-4). 3-Azibutanol (11 mM), like ethanol, inhibited L1 adhesion in NIH/3T3 cells stably transfected with hL1, whereas subanesthetic concentrations of 3-azioctanol (14 microM) antagonized ethanol inhibition of L1 adhesion. 3-Azibutanol (100-1,000 microM) and 3-azioctanol (10-100 microM) photoincorporated into Tyr-418 on Ig4 and into two adjacent regions in the N terminus, Glu-33 and Glu-24 to Glu-27. A homology model of hL1 Ig1-4 (residues 33-422), based on the structure of the Ig1-4 domains of axonin-1, suggests that Glu-33 and Tyr-418 hydrogen-bond at the interface of Ig1 and Ig4 to stabilize a horseshoe conformation of L1 that favors homophilic binding. Furthermore, this alcohol binding pocket lies within 7 A of Leu-120 and Gly-121, residues in which missense mutations cause neurological disorders similar to FASD. These data suggest that ethanol or selected mutations produce neuropathological abnormalities by disrupting the domain interface between Ig1 and Ig4. Characterization of alcohol agonist and antagonist binding sites on L1 will aid in understanding the molecular basis for FASD and might accelerate the development of ethanol antagonists.
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An evolutionarily conserved presynaptic protein is required for isoflurane sensitivity in Caenorhabditis elegans. Anesthesiology 2007; 107:971-82. [PMID: 18043066 DOI: 10.1097/01.anes.0000291451.49034.b8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Volatile general anesthetics inhibit neurotransmitter release by an unknown mechanism. A mutation in the presynaptic soluble NSF attachment protein receptor (SNARE) protein syntaxin 1A was previously shown to antagonize the anesthetic isoflurane in Caenorhabditis elegans. The mechanism underlying this antagonism may identify presynaptic anesthetic targets relevant to human anesthesia. METHODS Sensitivity to isoflurane concentrations in the human clinical range was measured in locomotion assays on adult C. elegans. Sensitivity to the acetylcholinesterase inhibitor aldicarb was used as an assay for the global level of C. elegans neurotransmitter release. Comparisons of isoflurane sensitivity (measured by the EC50) were made by simultaneous curve fitting and F test as described by Waud. RESULTS Expression of a truncated syntaxin fragment (residues 1-106) antagonized isoflurane sensitivity in C. elegans. This portion of syntaxin interacts with the presynaptic protein UNC-13, suggesting the hypothesis that truncated syntaxin binds to UNC-13 and antagonizes an inhibitory effect of isoflurane on UNC-13 function. Consistent with this hypothesis, overexpression of UNC-13 suppressed the isoflurane resistance of the truncated syntaxins, and unc-13 loss-of-function mutants were highly isoflurane resistant. Normal anesthetic sensitivity was restored by full-length UNC-13, by a shortened form of UNC-13 lacking a C2 domain, but not by a membrane-targeted UNC-13 that might bypass isoflurane inhibition of membrane translocation of UNC-13. Isoflurane was found to inhibit synaptic localization of UNC-13. CONCLUSIONS These data show that UNC-13, an evolutionarily conserved protein that promotes neurotransmitter release, is necessary for isoflurane sensitivity in C. elegans and suggest that its vertebrate homologs may be a component of the general anesthetic mechanism.
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38
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Solodukhin AS, Kretsinger RH, Sando JJ. Initial three-dimensional reconstructions of protein kinase C δ from two-dimensional crystals on lipid monolayers. Cell Signal 2007; 19:2035-45. [PMID: 17604605 DOI: 10.1016/j.cellsig.2007.05.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Revised: 05/22/2007] [Accepted: 05/25/2007] [Indexed: 01/06/2023]
Abstract
Two-dimensional crystals of protein kinase C delta (PKCdelta) and of its regulatory domain (RDdelta) were grown on lipid monolayers and analyzed by electron microscopy at tilt angles varying from -50 degrees to +55 degrees. Although the crystals exhibit pseudo-3-fold symmetry, analysis of difference phase residuals indicates that there is only one way to align the crystals for merging so the data were processed in plane group P1. Three-dimensional reconstructions generated for several two-dimensional crystals each of PKCdelta and RDdelta show good agreement and are consistent with membrane attachment via a single C1 subdomain, a small surface contact by one or two loops from the C2 domain, and, in intact PKCdelta, a small appendage from the catalytic domain, probably V5. Two-dimensional crystallography with three-dimensional reconstruction should be suitable for examination of additional PKC isozymes and for analysis of the enzymes bound to substrates and other proteins.
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39
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Bright DP, Adham SD, Lemaire LCJM, Benavides R, Gruss M, Taylor GW, Smith EH, Franks NP. Identification of anesthetic binding sites on human serum albumin using a novel etomidate photolabel. J Biol Chem 2007; 282:12038-47. [PMID: 17311911 DOI: 10.1074/jbc.m700479200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We have synthesized a novel analog of the general anesthetic etomidate in which the ethoxy group has been replaced by an azide group, and which can be used as a photolabel to identify etomidate binding sites. This acyl azide analog is a potent general anesthetic in both rats and tadpoles and, as with etomidate, is stereoselective in its actions, with the R(+) enantiomer being significantly more potent than the S(-) enantiomer. Its effects on alpha1beta2gamma2s GABA(A) receptors expressed in HEK-293 cells are virtually indistinguishable from the parent compound etomidate, showing stereoselective potentiation of GABA-induced currents, as well as direct mimetic effects at higher concentrations. In addition, a point mutation (beta2 N265M), which is known to attenuate the potentiating actions of etomidate, also blocks the effects of the acyl azide analog. We have investigated the utility of the analog to identify etomidate binding sites by using it to photolabel human serum albumin, a protein that binds approximately 75% of etomidate in human plasma and which is thought to play a major role in its pharmacokinetics. Using HPLC/mass spectrometry we have identified two anesthetic binding sites on HSA. One site is the well-characterized drug binding site I, located in HSA subdomain IIA, and the second site is also an established drug binding site located in subdomain IIIB, which also binds propofol. The acyl azide etomidate may prove to be a useful new photolabel to identify anesthetic binding sites on the GABA(A) receptor or other putative targets.
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Affiliation(s)
- Damian P Bright
- Biophysics Section, Blackett Laboratory, Imperial College, South Kensington, London SW7 2AZ, United Kingdom
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40
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Li GD, Chiara DC, Sawyer GW, Husain SS, Olsen RW, Cohen JB. Identification of a GABAA receptor anesthetic binding site at subunit interfaces by photolabeling with an etomidate analog. J Neurosci 2006; 26:11599-605. [PMID: 17093081 PMCID: PMC6674783 DOI: 10.1523/jneurosci.3467-06.2006] [Citation(s) in RCA: 257] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
General anesthetics, including etomidate, act by binding to and enhancing the function of GABA type A receptors (GABA(A)Rs), which mediate inhibitory neurotransmission in the brain. Here, we used a radiolabeled, photoreactive etomidate analog ([(3)H]azietomidate), which retains anesthetic potency in vivo and enhances GABA(A)R function in vitro, to identify directly, for the first time, amino acids that contribute to a GABA(A)R anesthetic binding site. For GABA(A)Rs purified by affinity chromatography from detergent extracts of bovine cortex, [(3)H]azietomidate photoincorporation was increased by GABA and inhibited by etomidate in a concentration-dependent manner (IC(50) = 30 microm). Protein microsequencing of fragments isolated from proteolytic digests established photolabeling of two residues: one within the alphaM1 transmembrane helix at alpha1Met-236 (and/or the homologous methionines in alpha2,3,5), not previously implicated in etomidate function, and one within the betaM3 transmembrane helix at beta3Met-286 (and/or the homologous methionines in beta1,2), an etomidate sensitivity determinant. The pharmacological specificity of labeling indicates that these methionines contribute to a single binding pocket for etomidate located in the transmembrane domain at the interface between beta and alpha subunits, in what is predicted by structural models based on homology with the nicotinic acetylcholine receptor to be a water-filled pocket approximately 50 A below the GABA binding site. The localization of the etomidate binding site to an intersubunit, not an intrasubunit, binding pocket is a novel conclusion that suggests more generally that the localization of drug binding sites to subunit interfaces may be a feature not only for GABA and benzodiazepines but also for etomidate and other intravenous and volatile anesthetics.
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Affiliation(s)
- Guo-Dong Li
- Department of Molecular and Medical Pharmacology, Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095
| | - David C. Chiara
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, and
| | - Gregory W. Sawyer
- Department of Molecular and Medical Pharmacology, Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095
| | - S. Shaukat Husain
- Department of Anesthesia and Critical Care, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Richard W. Olsen
- Department of Molecular and Medical Pharmacology, Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095
| | - Jonathan B. Cohen
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, and
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Das J, Zhou X, Miller KW. Identification of an alcohol binding site in the first cysteine-rich domain of protein kinase Cdelta. Protein Sci 2006; 15:2107-19. [PMID: 16943444 PMCID: PMC2242605 DOI: 10.1110/ps.062237606] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Protein kinase C (PKC) is an important signal transduction protein whose cysteine-rich regulatory domain C1 has been proposed to interact with general anesthetics in both of its diacylglycerol/phorbol ester-binding subdomains, the tandem repeats C1A and C1B. Previously, we identified an allosteric binding site on one of the two cysteine-rich domains, PKCdelta C1B. To test the hypothesis that there is an additional anesthetic site on the other cysteine-rich subdomain, C1A, we subcloned, expressed in Escherichia coli, purified, and characterized mouse PKCdelta C1A. Octanol and butanol both quenched the intrinsic fluorescence of PKCdelta C1A in a saturable manner, suggesting the presence of a binding site. To locate this site, PKCdelta C1A was photolabeled with three diazirine-containing alkanols, 3-azioctanol, 7-azioctanol, and 3-azibutanol. Mass spectrometry revealed that at low concentrations all three photoincorporated into PKCdelta C1A with a stoichiometry of 1:1 in the labeled fraction, but higher stoichiometries occurred at higher concentrations, particularly with azibutanol. Photocomplexes of PKCdelta C1A with azioctanols were separated from the unlabeled protein by HPLC, reduced, alkylated, digested with trypsin, and sequenced by mass spectrometry. All the azioctanols photolabeled PKCdelta C1A at residue Tyr-29, corresponding to Tyr-187 of the full-length PKCdelta, and at a neighboring residue, Lys-40, suggesting there is an alcohol site in this vicinity. In addition, Glu-2 was photolabeled more efficiently by 3-azibutanol than by the azioctanols, suggesting the existence of a second, smaller site.
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Affiliation(s)
- Joydip Das
- Department of Anesthesia and Critical Care, Massachusetts General Hospital, Boston, MA 02114, USA.
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Blencowe A, Hayes W. Development and application of diazirines in biological and synthetic macromolecular systems. SOFT MATTER 2005; 1:178-205. [PMID: 32646075 DOI: 10.1039/b501989c] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Many different reagents and methodologies have been utilised for the modification of synthetic and biological macromolecular systems. In addition, an area of intense research at present is the construction of hybrid biosynthetic polymers, comprised of biologically active species immobilised or complexed with synthetic polymers. One of the most useful and widely applicable techniques available for functionalisation of macromolecular systems involves indiscriminate carbene insertion processes. The highly reactive and non-specific nature of carbenes has enabled a multitude of macromolecular structures to be functionalised without the need for specialised reagents or additives. The use of diazirines as stable carbene precursors has increased dramatically over the past twenty years and these reagents are fast becoming the most popular photophors for photoaffinity labelling and biological applications in which covalent modification of macromolecular structures is the basis to understanding structure-activity relationships. This review reports the synthesis and application of a diverse range of diazirines in macromolecular systems.
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Affiliation(s)
- Anton Blencowe
- School of Chemistry, The University of Reading, Whiteknights, Reading, Berkshire, UKRG6 6AD.
| | - Wayne Hayes
- School of Chemistry, The University of Reading, Whiteknights, Reading, Berkshire, UKRG6 6AD.
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Abstract
Research in the past decade has revealed that many cytosolic proteins are recruited to different cellular membranes to form protein-protein and lipid-protein interactions during cell signaling and membrane trafficking. Membrane recruitment of these peripheral proteins is mediated by a growing number of modular membrane-targeting domains, including C1, C2, PH, FYVE, PX, ENTH, ANTH, BAR, FERM, and tubby domains, that recognize specific lipid molecules in the membranes. Structural studies of these membrane-targeting domains demonstrate how they specifically recognize their cognate lipid ligands. However, the mechanisms by which these domains and their host proteins are recruited to and interact with various cell membranes are only beginning to unravel with recent computational studies, in vitro membrane binding studies using model membranes, and cellular translocation studies using fluorescent protein-tagged proteins. This review summarizes the recent progress in our understanding of how the kinetics and energetics of membrane-protein interactions are regulated during the cellular membrane targeting and activation of peripheral proteins.
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Affiliation(s)
- Wonhwa Cho
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607-7061, USA.
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