scholarly journals Chlorpromazine binding to the PAS domains uncovers the effect of ligand modulation on EAG channel activity

2020 ◽  
Vol 295 (13) ◽  
pp. 4114-4123 ◽  
Author(s):  
Ze-Jun Wang ◽  
Stephanie M. Soohoo ◽  
Purushottam B. Tiwari ◽  
Grzegorz Piszczek ◽  
Tinatin I. Brelidze
Keyword(s):  
Ligand Binding ◽  
Cancer Progression ◽  
Neurological Disorders ◽  
Neuronal Excitability ◽  
Tryptophan Fluorescence ◽  
Structural Similarity ◽  
Pas Domain ◽  
Channel Activity ◽  
Binding Domains ◽  
Eag Channels

Ether-a-go-go (EAG) potassium selective channels are major regulators of neuronal excitability and cancer progression. EAG channels contain a Per–Arnt–Sim (PAS) domain in their intracellular N-terminal region. The PAS domain is structurally similar to the PAS domains in non-ion channel proteins, where these domains frequently function as ligand-binding domains. Despite the structural similarity, it is not known whether the PAS domain can regulate EAG channel function via ligand binding. Here, using surface plasmon resonance, tryptophan fluorescence, and analysis of EAG currents recorded in Xenopus laevis oocytes, we show that a small molecule chlorpromazine (CH), widely used as an antipsychotic medication, binds to the isolated PAS domain of EAG channels and inhibits currents from these channels. Mutant EAG channels that lack the PAS domain show significantly lower inhibition by CH, suggesting that CH affects currents from EAG channels directly through the binding to the PAS domain. Our study lends support to the hypothesis that there are previously unaccounted steps in EAG channel gating that could be activated by ligand binding to the PAS domain. This has broad implications for understanding gating mechanisms of EAG and related ERG and ELK K+ channels and places the PAS domain as a new target for drug discovery in EAG and related channels. Up-regulation of EAG channel activity is linked to cancer and neurological disorders. Our study raises the possibility of repurposing the antipsychotic drug chlorpromazine for treatment of neurological disorders and cancer.

scholarly journals Discovery of a heme-binding domain in a neuronal voltage-gated potassium channel

2020 ◽  
Vol 295 (38) ◽  
pp. 13277-13286
Author(s):  
Mark J. Burton ◽  
Joel Cresser-Brown ◽  
Morgan Thomas ◽  
Nicola Portolano ◽  
Jaswir Basran ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Normal Function ◽  
Pas Domain ◽  
Heme Binding ◽  
Channel Activity ◽  
Action Potential Firing ◽  
Voltage Gated ◽  
Conserved Domain ◽  
Potential Firing ◽  
Eag Channels

The EAG (ether-à-go-go) family of voltage-gated K+ channels are important regulators of neuronal and cardiac action potential firing (excitability) and have major roles in human diseases such as epilepsy, schizophrenia, cancer, and sudden cardiac death. A defining feature of EAG (Kv10–12) channels is a highly conserved domain on the N terminus, known as the eag domain, consisting of a Per–ARNT–Sim (PAS) domain capped by a short sequence containing an amphipathic helix (Cap domain). The PAS and Cap domains are both vital for the normal function of EAG channels. Using heme-affinity pulldown assays and proteomics of lysates from primary cortical neurons, we identified that an EAG channel, hERG3 (Kv11.3), binds to heme. In whole-cell electrophysiology experiments, we identified that heme inhibits hERG3 channel activity. In addition, we expressed the Cap and PAS domain of hERG3 in Escherichia coli and, using spectroscopy and kinetics, identified the PAS domain as the location for heme binding. The results identify heme as a regulator of hERG3 channel activity. These observations are discussed in the context of the emerging role for heme as a regulator of ion channel activity in cells.

Molecular Docking Analysis of Flavonoid Compounds with Matrix Metalloproteinase-8 for the Identification of Potential Effective Inhibitors

2020 ◽  
Vol 17 ◽  
Author(s):  
Amir Taherkhani ◽  
Athena Orangi ◽  
Shirin Moradkhani ◽  
Zahra Khamverdi
Keyword(s):  
Amino Acids ◽  
Molecular Docking ◽  
Amino Acid ◽  
Matrix Metalloproteinase ◽  
Ligand Binding ◽  
Chronic Inflammation ◽  
Cancer Progression ◽  
Dimensional Structure ◽  
Control Test ◽  
Therapeutic Procedures

Background: Matrix metalloproteinase-8 (MMP-8) participates in degradation of different types of collagens in the extracellular matrix and basement membrane. Up-regulation of the MMP-8 has been demonstrated in many of disorders including cancer development, tooth caries, periodontal/peri-implant soft and hard tissue degeneration, and acute/chronic inflammation. Therefore, MMP-8 has become an encouraging target for therapeutic procedures for scientists. We carried out molecular docking approach to study the binding affinity of 29 flavonoids, as drug candidates, with the MMP-8. Pharmacokinetic and toxicological properties of the compounds were also studied. Moreover, it was attempted to identify the most important amino acids participating in ligand binding based on degree of each of the amino acids in the ligand-amino acid interaction network for MMP-8. Methods: Three-dimensional structure of the protein was gained from the RCSB database (PDB ID: 4QKZ). AutoDock version 4.0 and Cytoscape 3.7.2 were used for molecular docking and network analysis, respectively. Notably, the inhibitor of the protein in the crystalline structure of the 4QKZ was considered as a control test. Pharmacokinetic and toxicological features of compounds were predicted using bioinformatic web tools. Post-docking analyses were performed using BIOVIA Discovery Studio Visualizer version 19.1.0.18287. Results and Discussions: According to results, 24 of the studied compounds considered to be top potential inhibitors for MMP-8 based on their salient estimated free energy of binding and inhibition constant as compared with the control test: Apigenin-7-glucoside, nicotiflorin, luteolin, glabridin, taxifolin, apigenin, licochalcone A, quercetin, isorhamnetin, myricetin, herbacetin, kaemferol, epicatechin, chrysin, amentoflavone, rutin, orientin, epiafzelechin, quercetin-3-rhamnoside, formononetin, isoliquiritigenin, vitexin, catechine, isoquercitrin. Moreover, His-197 was found to be the most important amino acid involved in the ligand binding for the enzyme. Conclusion: The results of the current study could be used in the prevention and therapeutic procedures of a number of disorders such as cancer progression and invasion, oral diseases, and acute/chronic inflammation. Although, in vitro and in vivo tests are inevitable in the future.

scholarly journals PKA-RIIβ autophosphorylation modulates PKA activity and seizure phenotypes in mice

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Jingliang Zhang ◽  
Chenyu Zhang ◽  
Xiaoling Chen ◽  
Bingwei Wang ◽  
Weining Ma ◽  
...  
Keyword(s):  
Therapeutic Target ◽  
Neurological Disorders ◽  
Neuronal Excitability ◽  
Granule Cells ◽  
Critical Role ◽  
Intrinsic Excitability ◽  
Seizure Susceptibility ◽  
Seizure Onset ◽  
Potential Therapeutic Target ◽  
Seizure Model

AbstractTemporal lobe epilepsy (TLE) is one of the most common and intractable neurological disorders in adults. Dysfunctional PKA signaling is causally linked to the TLE. However, the mechanism underlying PKA involves in epileptogenesis is still poorly understood. In the present study, we found the autophosphorylation level at serine 114 site (serine 112 site in mice) of PKA-RIIβ subunit was robustly decreased in the epileptic foci obtained from both surgical specimens of TLE patients and seizure model mice. The p-RIIβ level was negatively correlated with the activities of PKA. Notably, by using a P-site mutant that cannot be autophosphorylated and thus results in the released catalytic subunit to exert persistent phosphorylation, an increase in PKA activities through transduction with AAV-RIIβ-S112A in hippocampal DG granule cells decreased mIPSC frequency but not mEPSC, enhanced neuronal intrinsic excitability and seizure susceptibility. In contrast, a reduction of PKA activities by RIIβ knockout led to an increased mIPSC frequency, a reduction in neuronal excitability, and mice less prone to experimental seizure onset. Collectively, our data demonstrated that the autophosphorylation of RIIβ subunit plays a critical role in controlling neuronal and network excitabilities by regulating the activities of PKA, providing a potential therapeutic target for TLE.

scholarly journals Cryptic-site binding mechanism of medium-sized Bcl-xL inhibiting compounds elucidated by McMD-based dynamic docking simulations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gert-Jan Bekker ◽  
Ikuo Fukuda ◽  
Junichi Higo ◽  
Yoshifumi Fukunishi ◽  
Narutoshi Kamiya
Keyword(s):  
Ligand Binding ◽  
Cancer Progression ◽  
Hydrophobic Interactions ◽  
Binding Mechanism ◽  
Docking Simulations ◽  
Large Conformational Change ◽  
Binding Pockets ◽  
Dynamic Docking ◽  
Site Binding ◽  
Apo State

AbstractWe have performed multicanonical molecular dynamics (McMD) based dynamic docking simulations to study and compare the binding mechanism between two medium-sized inhibitors (ABT-737 and WEHI-539) that bind to the cryptic site of Bcl-xL, by exhaustively sampling the conformational and configurational space. Cryptic sites are binding pockets that are transiently formed in the apo state or are induced upon ligand binding. Bcl-xL, a pro-survival protein involved in cancer progression, is known to have a cryptic site, whereby the shape of the pocket depends on which ligand is bound to it. Starting from the apo-structure, we have performed two independent McMD-based dynamic docking simulations for each ligand, and were able to obtain near-native complex structures in both cases. In addition, we have also studied their interactions along their respective binding pathways by using path sampling simulations, which showed that the ligands form stable binding configurations via predominantly hydrophobic interactions. Although the protein started from the apo state, both ligands modulated the pocket in different ways, shifting the conformational preference of the sub-pockets of Bcl-xL. We demonstrate that McMD-based dynamic docking is a powerful tool that can be effectively used to study binding mechanisms involving a cryptic site, where ligand binding requires a large conformational change in the protein to occur.

scholarly journals Intracellular ATP Increases Capsaicin-Activated Channel Activity by Interacting with Nucleotide-Binding Domains

2000 ◽  
Vol 20 (22) ◽  
pp. 8298-8304 ◽  
Author(s):  
Jiyeon Kwak ◽  
Myeong Hyeon Wang ◽  
Sun Wook Hwang ◽  
Tae-Yoon Kim ◽  
Soon-Youl Lee ◽  
...  
Keyword(s):  
Nucleotide Binding ◽  
Channel Activity ◽  
Intracellular Atp ◽  
Binding Domains

scholarly journals Paired opposing leukocyte receptors recognizing rapidly evolving ligands are subject to homogenization of their ligand binding domains

2011 ◽  
Vol 63 (12) ◽  
pp. 809-820 ◽  
Author(s):  
Sigbjørn Fossum ◽  
Per Christian Saether ◽  
John Torgils Vaage ◽  
Michael Rory Daws ◽  
Erik Dissen
Keyword(s):  
Ligand Binding ◽  
Binding Domains ◽  
Leukocyte Receptors

scholarly journals Biochemical and NMR Mapping of the Interface between CREB-binding Protein and Ligand Binding Domains of Nuclear Receptor

2004 ◽  
Vol 280 (7) ◽  
pp. 5682-5692 ◽  
Author(s):  
Fabrice A. C. Klein ◽  
R. Andrew Atkinson ◽  
Noelle Potier ◽  
Dino Moras ◽  
Jean Cavarelli
Keyword(s):  
Ligand Binding ◽  
Nuclear Receptor ◽  
Binding Protein ◽  
Creb Binding Protein ◽  
Binding Domains

Ligand modulates the conversion of DNA-bound vitamin D3 receptor (VDR) homodimers into VDR-retinoid X receptor heterodimers

1994 ◽  
Vol 14 (5) ◽  
pp. 3329-3338
Author(s):  
B Cheskis ◽  
L P Freedman
Keyword(s):  
Ligand Binding ◽  
Vitamin D3 ◽  
Hormone Receptors ◽  
Steroid Receptors ◽  
Dependent Manner ◽  
D3 Receptor ◽  
Vitamin D3 Receptor ◽  
Binding Domains

Protein dimerization facilitates cooperative, high-affinity interactions with DNA. Nuclear hormone receptors, for example, bind either as homodimers or as heterodimers with retinoid X receptors (RXR) to half-site repeats that are stabilized by protein-protein interactions mediated by residues within both the DNA- and ligand-binding domains. In vivo, ligand binding among the subfamily of steroid receptors unmasks the nuclear localization and DNA-binding domains from a complex with auxiliary factors such as the heat shock proteins. However, the role of ligand is less clear among nuclear receptors, since they are constitutively localized to the nucleus and are presumably associated with DNA in the absence of ligand. In this study, we have begun to explore the role of the ligand in vitamin D3 receptor (VDR) function by examining its effect on receptor homodimer and heterodimer formation. Our results demonstrate that VDR is a monomer in solution; VDR binding to a specific DNA element leads to the formation of a homodimeric complex through a monomeric intermediate. We find that 1,25-dihydroxyvitamin D3, the ligand for VDR, decreases the amount of the DNA-bound VDR homodimer complex. It does so by significantly decreasing the rate of conversion of DNA-bound monomer to homodimer and at the same time enhancing the dissociation of the dimeric complex. This effectively stabilizes the bound monomeric species, which in turn serves to favor the formation of a VDR-RXR heterodimer. The ligand for RXR, 9-cis retinoic acid, has the opposite effect of destabilizing the heterodimeric-DNA complex. These results may explain how a nuclear receptor can bind DNA constitutively but still act to regulate transcription in a fully hormone-dependent manner.

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