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Chakraborty S, Kanade M, Gayathri P. Mechanism of GTPase activation of a prokaryotic small Ras-like GTPase MglA by an asymmetrically interacting MglB dimer. J Biol Chem 2024; 300:107197. [PMID: 38508314 PMCID: PMC11016934 DOI: 10.1016/j.jbc.2024.107197] [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: 02/03/2024] [Accepted: 03/04/2024] [Indexed: 03/22/2024] Open
Abstract
Cell polarity oscillations in Myxococcus xanthus motility are driven by a prokaryotic small Ras-like GTPase, mutual gliding protein A (MglA), which switches from one cell pole to the other in response to extracellular signals. MglA dynamics is regulated by MglB, which functions both as a GTPase activating protein (GAP) and a guanine nucleotide exchange factor (GEF) for MglA. With an aim to dissect the asymmetric role of the two MglB protomers in the dual GAP and GEF activities, we generated a functional MglAB complex by coexpressing MglB with a linked construct of MglA and MglB. This strategy enabled us to generate mutations of individual MglB protomers (MglB1 or MglB2 linked to MglA) and delineate their role in GEF and GAP activities. We establish that the C-terminal helix of MglB1, but not MglB2, stimulates nucleotide exchange through a site away from the nucleotide-binding pocket, confirming an allosteric mechanism. Interaction between the N-terminal β-strand of MglB1 and β0 of MglA is essential for the optimal GEF activity of MglB. Specific residues of MglB2, which interact with Switch-I of MglA, partially contribute to its GAP activity. Thus, the role of the MglB2 protomer in the GAP activity of MglB is limited to restricting the conformation of MglA active site loops. The direct demonstration of the allosteric mechanism of GEF action provides us new insights into the regulation of small Ras-like GTPases, a feature potentially present in many uncharacterized GEFs.
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Affiliation(s)
- Sukanya Chakraborty
- Department of Biology, Indian Institute of Science Education and Research Pune, Pune, India
| | - Manil Kanade
- Department of Biology, Indian Institute of Science Education and Research Pune, Pune, India
| | - Pananghat Gayathri
- Department of Biology, Indian Institute of Science Education and Research Pune, Pune, India.
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2
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Koch D, Kho AL, Fukuzawa A, Alexandrovich A, Vanaanen KJ, Beavil A, Pfuhl M, Rees M, Gautel M. Obscurin Rho GEF domains are phosphorylated by MST-family kinases but do not exhibit nucleotide exchange factor activity towards Rho GTPases in vitro. PLoS One 2023; 18:e0284453. [PMID: 37079638 PMCID: PMC10118190 DOI: 10.1371/journal.pone.0284453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 04/01/2023] [Indexed: 04/21/2023] Open
Abstract
Obscurin is a giant muscle protein (>800 kDa) featuring multiple signalling domains, including an SH3-DH-PH domain triplet from the Trio-subfamily of guanosine nucleotide exchange factors (GEFs). While previous research suggests that these domains can activate the small GTPases RhoA and RhoQ in cells, in vitro characterization of these interactions using biophysical techniques has been hampered by the intrinsic instability of obscurin GEF domains. To study substrate specificity, mechanism and regulation of obscurin GEF function by individual domains, we successfully optimized recombinant production of obscurin GEF domains and found that MST-family kinases phosphorylate the obscurin DH domain at Thr5798. Despite extensive testing of multiple GEF domain fragments, we did not detect any nucleotide exchange activity in vitro against 9 representative small GTPases. Bioinformatic analyses show that obscurin differs from other Trio-subfamily GEFs in several important aspects. While further research is necessary to evaluate obscurin GEF activity in vivo, our results indicate that obscurin has atypical GEF domains that, if catalytically active at all, are subject to complex regulation.
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Affiliation(s)
- Daniel Koch
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Ay Lin Kho
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Atsushi Fukuzawa
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Alexander Alexandrovich
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Kutti J. Vanaanen
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Andrew Beavil
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Mark Pfuhl
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Martin Rees
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Mathias Gautel
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
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Zhang M, Yang B, Zhang J, Song Y, Wang W, Li N, Wang Y, Li W, Wang J. Monitoring the Dynamic Regulation of the Mitochondrial GTP‐to‐GDP Ratio with a Genetically Encoded Fluorescent Biosensor. Angew Chem Int Ed Engl 2022; 61:e202201266. [DOI: 10.1002/anie.202201266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Indexed: 11/07/2022]
Affiliation(s)
- Meiqi Zhang
- State Key Laboratory of Natural and Biomimetic Drugs and Department of Chemical Biology Department of Chemical Biology School of Pharmaceutical Sciences Peking University Peking University Beijing 100191 China
| | - Bo Yang
- State Key Laboratory of Natural and Biomimetic Drugs and Department of Chemical Biology Department of Chemical Biology School of Pharmaceutical Sciences Peking University Peking University Beijing 100191 China
| | - Jiayuan Zhang
- State Key Laboratory of Natural and Biomimetic Drugs and Department of Chemical Biology Department of Chemical Biology School of Pharmaceutical Sciences Peking University Peking University Beijing 100191 China
- Wellcome Centre for Human Genetics University of Oxford Roosevelt Dr, Headington Oxford OX3 7BN UK
| | - Yuxin Song
- State Key Laboratory of Natural and Biomimetic Drugs and Department of Chemical Biology Department of Chemical Biology School of Pharmaceutical Sciences Peking University Peking University Beijing 100191 China
| | - Weibo Wang
- State Key Laboratory of Natural and Biomimetic Drugs and Department of Chemical Biology Department of Chemical Biology School of Pharmaceutical Sciences Peking University Peking University Beijing 100191 China
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education International Joint Research Center for Intelligent Biosensor Technology and Health College of Chemistry Central China Normal University Wuhan 430079 China
| | - Na Li
- State Key Laboratory of Natural and Biomimetic Drugs and Department of Chemical Biology Department of Chemical Biology School of Pharmaceutical Sciences Peking University Peking University Beijing 100191 China
| | - Yuan Wang
- State Key Laboratory of Natural and Biomimetic Drugs and Department of Chemical Biology Department of Chemical Biology School of Pharmaceutical Sciences Peking University Peking University Beijing 100191 China
| | - Wenzhe Li
- State Key Laboratory of Natural and Biomimetic Drugs and Department of Chemical Biology Department of Chemical Biology School of Pharmaceutical Sciences Peking University Peking University Beijing 100191 China
| | - Jing Wang
- State Key Laboratory of Natural and Biomimetic Drugs and Department of Chemical Biology Department of Chemical Biology School of Pharmaceutical Sciences Peking University Peking University Beijing 100191 China
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4
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Zhang M, Yang B, Zhang J, Song Y, Wang W, Li N, Wang Y, Li W, Wang J. Monitoring the Dynamic Regulation of the Mitochondrial GTP‐to‐GDP Ratio with a Genetically Encoded Fluorescent Biosensor. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202201266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Meiqi Zhang
- Peking University School of Pharmaceutical Sciences Department of Chemical Biology CHINA
| | - Bo Yang
- Peking University School of Pharmaceutical Sciences Department of Chemical Biology CHINA
| | - Jiayuan Zhang
- University of Oxford Wellcome Centre for Human Genetics UNITED KINGDOM
| | - Yuxin Song
- Peking University School of Pharmaceutical Sciences Department of Chemical Biology CHINA
| | - Weibo Wang
- Peking University School of Pharmaceutical Sciences Chemical Biology CHINA
| | - Na Li
- Peking University School of Pharmaceutical Sciences Chemical Biology CHINA
| | - Yuan Wang
- Peking University School of Pharmaceutical Sciences Chemical Biology CHINA
| | - Wenzhe Li
- Peking University School of Pharmaceutical Sciences Chemical Biology CHINA
| | - Jing Wang
- Peking University School of Pharmaceutical Sciences Chemical Biology 38 Xueyuan Rd, Haidian Distict 100191 Beijing CHINA
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In silico and saturation transfer difference NMR approaches to unravel the binding mode of an andrographolide derivative to K-Ras oncoprotein. Future Med Chem 2020; 12:1611-1631. [PMID: 32892640 DOI: 10.4155/fmc-2020-0104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background: Andrographolide and its benzylidene derivatives, SRJ09 and SRJ23, potentially bind oncogenic K-Ras to exert anticancer activity. Their molecular interactions with K-Ras oncoproteins that lead to effective biological activity are of major interest. Methods & results: In silico docking and molecular dynamics simulation were performed using Glide and Desmond, respectively; while saturation transfer difference NMR was performed using GDP-bound K-RasG12V. SRJ23 was found to bind strongly and selectively to K-RasG12V, by anchoring to a binding pocket (namely p2) principally via hydrogen bond and hydrophobic interactions. The saturation transfer difference NMR analysis revealed the proximity of protons of functional moieties in SRJ23 to K-RasG12V, suggesting positive binding. Conclusion: SRJ23 binds strongly and interacts stably with K-RasG12V to exhibit its inhibitory activity.
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Chutshela A, Masamba P, Oyinloye BE, Kappo AP. Molecular Context of ADP-ribosylation in Schistosomes for Drug Discovery and Vaccine Development. Curr Drug Discov Technol 2020; 18:473-484. [PMID: 32767945 DOI: 10.2174/1570163817666200806170654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 07/06/2020] [Accepted: 07/06/2020] [Indexed: 11/22/2022]
Abstract
Schistosome infection is regarded as one of the most important and neglected tropical diseases associated with poor sanitation. Like other living organisms, schistosomes employ multiple biological processes, of which some are regulated by a post-translational modification called Adenosine Diphosphate-ribosylation (ADP-ribosylation), catalyzed by ADP-ribosyltransferases. ADP-ribosylation is the addition of ADP-ribose moieties from Nicotinamide Adenine Dinucleotide (NAD+) to various targets, which include proteins and nucleotides. It is crucial in biological processes such as DNA repair, apoptosis, carbohydrate metabolism and catabolism. In the absence of a vaccine against schistosomiasis, this becomes a promising pathway in the identification of drug targets against various forms of this infection. The tegument of the worm is an encouraging immunogenic target for anti-schistosomal vaccine development. Vaccinology, molecular modeling and target-based drug discovery strategies have been used for years in drug discovery and for vaccine development. In this paper, we outline ADP-ribosylation and other different approaches to drug discovery and vaccine development against schistosomiasis.
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Affiliation(s)
- Amandla Chutshela
- Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa 3886, South Africa
| | - Priscilla Masamba
- Molecular Biophysics and Structural Biology Group, Department of Biochemistry, University of Johannesburg, Kingsway Campus, Auckland Park 2006, South Africa
| | | | - Abidemi Paul Kappo
- Molecular Biophysics and Structural Biology Group, Department of Biochemistry, University of Johannesburg, Kingsway Campus, Auckland Park 2006, South Africa
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Affiliation(s)
- Oliver Einsle
- Institute for Biochemistry, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany
| | - Douglas C. Rees
- Division of Chemistry and Chemical Engineering, Howard Hughes Medical Institute, California Institute of Technology, Pasadena California 91125, United States
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Ehrmann A, Nguyen B, Seifert U. Interlinked GTPase cascades provide a motif for both robust switches and oscillators. J R Soc Interface 2019; 16:20190198. [PMID: 31387482 DOI: 10.1098/rsif.2019.0198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
GTPases regulate a wide range of cellular processes, such as intracellular vesicular transport, signal transduction and protein translation. These hydrolase enzymes operate as biochemical switches by toggling between an active guanosine triphosphate (GTP)-bound state and an inactive guanosine diphosphate (GDP)-bound state. We compare two network motifs, a single-species switch and an interlinked cascade that consists of two species coupled through positive and negative feedback loops. We find that interlinked cascades are closer to the ideal all-or-none switch and are more robust against fluctuating signals. While the single-species switch can only achieve bistability, interlinked cascades can be converted into oscillators by tuning the cofactor concentrations, which catalyse the activity of the cascade. These regimes can only be achieved with sufficient chemical driving provided by GTP hydrolysis. In this study, we present a thermodynamically consistent model that can achieve bistability and oscillations with the same feedback motif.
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Affiliation(s)
- Andreas Ehrmann
- II. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart, Germany
| | - Basile Nguyen
- II. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart, Germany
| | - Udo Seifert
- II. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart, Germany
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The guanine nucleotide exchange factor, Spata13, influences social behaviour and nocturnal activity. Mamm Genome 2019; 30:54-62. [PMID: 31020388 PMCID: PMC6491400 DOI: 10.1007/s00335-019-09800-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/08/2019] [Indexed: 11/08/2022]
Abstract
Spermatogenesis-associated protein 13 (Spata13) is a guanine nucleotide exchange factor (GEF) enriched in discrete brain regions in the adult, with pronounced expression in the extended central amygdala (CeA). Loss of Spata13, also known as the adenomatous polyposis coli exchange factor Asef2, has no identifiable phenotype although it has been shown to reduce the number and size of intestinal tumours in Apc (Min/+) mice. Nevertheless, its brain-related functions have not been investigated. To pursue this, we have generated a Spata13 knockout mouse line using CRISPR-mediated deletion of an exon containing the GTPase domain that is common to multiple isoforms. Homozygous mutants were viable and appeared normal. We subjected both male and female cohorts to a comprehensive battery of behavioural tests designed to investigate particular CeA-related functions. Here, we show that Spata13 modulates social behaviour with homozygous mutants being subordinate to wildtype controls. Furthermore, female homozygotes show increased activity in home cages during the dark phase of the light–dark cycle. In summary, Spata13 modulates social hierarchy in both male and female mice in addition to affecting voluntary activity in females.
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Husein A, Jamal A, Ahmed MZ, Arish M, Ali R, Tabrez S, Rasool F, Rub A. Leishmania donovani infection differentially regulates small G-proteins. J Cell Biochem 2018; 119:7844-7854. [PMID: 29943842 DOI: 10.1002/jcb.27186] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 05/24/2018] [Indexed: 01/28/2023]
Abstract
Leishmania is a protozoan parasite that resides and replicates in macrophages and causes leishmaniasis. The parasite alters the signaling cascade in host macrophages and evades the host machinery. Small G-proteins are GTPases, grouped in 5 different families that play a crucial role in the regulation of cell proliferation, cell survival, apoptosis, intracellular trafficking, and transport. In particular, the Ras family of small G-proteins has been identified to play a significant role in the cellular functions mentioned before. Here, we studied the differential expression of the most important small G-proteins during Leishmania infection. We found major changes in the expression of different isoforms of Ras, mainly in N-Ras. We observed that Leishmania donovani infection led to enhanced N-Ras expression, whereas it inhibited K-Ras and H-Ras expression. Furthermore, an active N-Ras pull-down assay showed enhanced N-Ras activity. L donovani infection also increased extracellular signal-regulated kinase 1/2 phosphorylation and simultaneously decreased p38 phosphorylation. In contrast, pharmacological inhibition of Ras led to reduction in the phosphorylation of extracellular signal-regulated kinase 1/2 and enhanced the phosphorylation of p38 in Leishmania-infected cells, which could lead to increased interleukin-12 expression and decreased interleukin-10 expression. Indeed, farnesylthiosalicyclic acid (a Ras inhibitor), when used at the effective level in L donovani-infected macrophages, reduced amastigotes in the host macrophages. Thus, upregulated N-Ras expression during L donovani infection could be a novel immune evasion strategy of Leishmania and would be a potential target for antileishmanial immunotherapy.
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Affiliation(s)
- Atahar Husein
- Infection and Immunity Lab (Lab No. 414), Department of Biotechnology, Jamia Millia Islamia, New Delhi, India
| | - Azfar Jamal
- Virology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Mohammad Zulfazal Ahmed
- Infection and Immunity Lab (Lab No. 414), Department of Biotechnology, Jamia Millia Islamia, New Delhi, India
| | - Mohammad Arish
- Infection and Immunity Lab (Lab No. 414), Department of Biotechnology, Jamia Millia Islamia, New Delhi, India
| | - Rahat Ali
- Infection and Immunity Lab (Lab No. 414), Department of Biotechnology, Jamia Millia Islamia, New Delhi, India
| | - Shams Tabrez
- Infection and Immunity Lab (Lab No. 414), Department of Biotechnology, Jamia Millia Islamia, New Delhi, India
| | - Fayyaz Rasool
- Infection and Immunity Lab (Lab No. 414), Department of Biotechnology, Jamia Millia Islamia, New Delhi, India
| | - Abdur Rub
- Infection and Immunity Lab (Lab No. 414), Department of Biotechnology, Jamia Millia Islamia, New Delhi, India.,Department of Medical Laboratory Sciences, College of Applied Medical Sciences, Majmaah University, Al Majmaah, Saudi Arabia
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Trade-off and flexibility in the dynamic regulation of the cullin-RING ubiquitin ligase repertoire. PLoS Comput Biol 2017; 13:e1005869. [PMID: 29149173 PMCID: PMC5711038 DOI: 10.1371/journal.pcbi.1005869] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 12/01/2017] [Accepted: 11/02/2017] [Indexed: 11/19/2022] Open
Abstract
Cullin-RING ubiquitin ligases (CRLs) catalyze the ubiquitylation of substrates many of which are degraded by the 26S proteasome. Their modular architecture enables recognition of numerous substrates via exchangeable substrate receptors that competitively bind to a cullin scaffold with high affinity. Due to the plasticity of these interactions there is ongoing uncertainty how cells maintain a flexible CRL repertoire in view of changing substrate loads. Based on a series of in vivo and in vitro studies, different groups proposed that the exchange of substrate receptors is mediated by a protein exchange factor named Cand1. Here, we have performed mathematical modeling to provide a quantitative underpinning of this hypothesis. First we show that the exchange activity of Cand1 necessarily leads to a trade-off between high ligase activity and fast receptor exchange. Supported by measurements we argue that this trade-off yields an optimal Cand1 concentration in cells where the time scale for substrate degradation becomes minimal. In a second step we show through simulations that (i) substrates bias the CRL repertoire leading to preferential assembly of ligases for which substrates are available and (ii) differences in binding affinities or substrate receptor abundances create a temporal hierarchy for the degradation of substrates. Finally, we compare the Cand1-mediated exchange cycle with an alternative architecture lacking Cand1 which indicates superiority of a system with exchange factor if substrate receptors bind substrates and the cullin scaffold in a random order. Together, our results provide general constraints for the operating regimes of molecular exchange systems and suggest that Cand1 endows the CRL network with the properties of an “on demand” system allowing cells to dynamically adjust their CRL repertoire to fluctuating substrate abundances. Cullin-RING ubiquitin ligases (CRLs) are multisubunit protein complexes where exchangeable substrate receptors (SRs) assemble on a cullin scaffold to mediate ubiquitylation and subsequent degradation of a large variety of substrates. In humans there are hundreds of different CRLs having potentially thousands of substrates. Due to the high affinity of cullin-SR interactions, it has long been a mystery how cells would maintain flexibility to sample the entire SR repertoire in order to match fluctuating substrate loads. Recent experiments indicate that the exchange of different SRs is mediated by a novel protein exchange factor (Cand1). However, the proposed biochemical function of Cand1 as a promoter of CRL activity remained difficult to reconcile with previous reports of Cand1 acting as an inhibitor of CRL activity in vitro. Here we show that these two findings are not contradictory, but that the exchange activity of Cand1 necessarily leads to a trade-off between high ligase activity and fast receptor exchange which leads us to predict an optimal Cand1 concentration and a temporal hierarchy for substrate degradation. Our results support the view that Cand1 endows the CRL network with the flexibility of an “on demand” system where relative CRL abundances are dictated by substrate availability.
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Senarath K, Ratnayake K, Siripurapu P, Payton JL, Karunarathne A. Reversible G Protein βγ9 Distribution-Based Assay Reveals Molecular Underpinnings in Subcellular, Single-Cell, and Multicellular GPCR and G Protein Activity. Anal Chem 2016; 88:11450-11459. [PMID: 27778511 DOI: 10.1021/acs.analchem.6b02512] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Current assays to measure the activation of G protein coupled receptors (GPCRs) and G proteins are time-consuming, indirect, and expensive. Therefore, an efficient method which directly measures the ability of a ligand to govern GPCR-G protein interactions can help to understand the molecular underpinnings of the associated signaling. A live cell imaging-based approach is presented here to directly measure ligand-induced GPCR and G protein activity in real time. The number of active GPCRs governs G protein heterotrimer (αβγ) dissociation, thereby controlling the concentration of free βγ subunits. The described γ9 assay measures the GPCR activation-induced extent of the reversible βγ9 subunit exchange between the plasma membrane (PM) and internal membranes (IMs). Confocal microscopy-based γ9 assay quantitatively determines the concentration dependency of ligands on GPCR activation. Demonstrating the high-throughput screening (HTS) adaptability, the γ9 assay performed using an imaging plate reader measures the ligand-induced GPCR activation. This suggests that the γ9 assay can be employed to screen libraries of compounds for their ability to activate GPCRs. Together with subcellular optogenetics, the spatiotemporal sensitivity of the γ9 assay permits experimental determination of the limits of spatially restricted activation of GPCRs and G proteins in subcellular regions of single cells. This assay works effectively for GPCRs coupled to αi/o and αs heterotrimers, including light-sensitive GPCRs. In addition, computational modeling of experimental data from the assay is used to decipher intricate molecular details of the GPCR-G protein activation process. Overall, the γ9 assay provides a robust strategy for quantitative as well as qualitative determination of GPCR and G protein function on a single-cell, multicell, and subcellular level. This assay not only provides information about the inner workings of the signaling pathway, but it also strengthens GPCR deorphanization as well as drug discovery efforts.
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Affiliation(s)
- Kanishka Senarath
- Department of Chemistry and Biochemistry, The University of Toledo , Toledo, Ohio 43606, United States
| | - Kasun Ratnayake
- Department of Chemistry and Biochemistry, The University of Toledo , Toledo, Ohio 43606, United States
| | - Praneeth Siripurapu
- Department of Chemistry and Biochemistry, The University of Toledo , Toledo, Ohio 43606, United States
| | - John L Payton
- Department of Chemistry and Biochemistry, The University of Toledo , Toledo, Ohio 43606, United States
| | - Ajith Karunarathne
- Department of Chemistry and Biochemistry, The University of Toledo , Toledo, Ohio 43606, United States
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