1
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Muñoz-Reyes D, McClelland LJ, Arroyo-Urea S, Sánchez-Yepes S, Sabín J, Pérez-Suárez S, Menendez M, Mansilla A, García-Nafría J, Sprang S, Sanchez-Barrena MJ. The neuronal calcium sensor NCS-1 regulates the phosphorylation state and activity of the Gα chaperone and GEF Ric-8A. eLife 2023; 12:e86151. [PMID: 38018500 PMCID: PMC10732572 DOI: 10.7554/elife.86151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 11/24/2023] [Indexed: 11/30/2023] Open
Abstract
The neuronal calcium sensor 1 (NCS-1), an EF-hand Ca2+ binding protein, and Ric-8A coregulate synapse number and probability of neurotransmitter release. Recently, the structures of Ric-8A bound to Gα have revealed how Ric-8A phosphorylation promotes Gα recognition and activity as a chaperone and guanine nucleotide exchange factor. However, the molecular mechanism by which NCS-1 regulates Ric-8A activity and its interaction with Gα subunits is not well understood. Given the interest in the NCS-1/Ric-8A complex as a therapeutic target in nervous system disorders, it is necessary to shed light on this molecular mechanism of action at atomic level. We have reconstituted NCS-1/Ric-8A complexes to conduct a multimodal approach and determine the sequence of Ca2+ signals and phosphorylation events that promote the interaction of Ric-8A with Gα. Our data show that the binding of NCS-1 and Gα to Ric-8A are mutually exclusive. Importantly, NCS-1 induces a structural rearrangement in Ric-8A that traps the protein in a conformational state that is inaccessible to casein kinase II-mediated phosphorylation, demonstrating one aspect of its negative regulation of Ric-8A-mediated G-protein signaling. Functional experiments indicate a loss of Ric-8A guanine nucleotide exchange factor (GEF) activity toward Gα when complexed with NCS-1, and restoration of nucleotide exchange activity upon increasing Ca2+ concentration. Finally, the high-resolution crystallographic data reported here define the NCS-1/Ric-8A interface and will allow the development of therapeutic synapse function regulators with improved activity and selectivity.
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Affiliation(s)
- Daniel Muñoz-Reyes
- Department of Crystallography and Structural Biology, Institute of Physical-Chemistry 'Blas Cabrera', CSICMadridSpain
| | - Levi J McClelland
- Center for Biomolecular Structure and Dynamics, and Division of Biological Sciences, University of MontanaMissoulaUnited States
| | - Sandra Arroyo-Urea
- Institute for Biocomputation and Physics of Complex Systems (BIFI) and Laboratorio de Microscopías Avanzadas (LMA), University of ZaragozaZaragozaSpain
| | - Sonia Sánchez-Yepes
- Department of Neurobiology, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y CajalMadridSpain
| | - Juan Sabín
- AFFINImeter Scientific & Development team, Software 4 Science DevelopmentsSantiago de CompostelaSpain
- Departamento de Física Aplicada, Universidad de Santiago de CompostelaSantiago de CompostelaSpain
| | - Sara Pérez-Suárez
- Department of Crystallography and Structural Biology, Institute of Physical-Chemistry 'Blas Cabrera', CSICMadridSpain
| | - Margarita Menendez
- Department of Biological Physical-Chemisty, Institute of Physical-Chemistry 'Blas Cabrera', CSICMadridSpain
- Ciber of Respiratory Diseases, ISCIIIMadridSpain
| | - Alicia Mansilla
- Department of Neurobiology, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y CajalMadridSpain
- Department of Systems Biology, Universidad de AlcalaMadridSpain
| | - Javier García-Nafría
- Institute for Biocomputation and Physics of Complex Systems (BIFI) and Laboratorio de Microscopías Avanzadas (LMA), University of ZaragozaZaragozaSpain
| | - Stephen Sprang
- Center for Biomolecular Structure and Dynamics, and Division of Biological Sciences, University of MontanaMissoulaUnited States
| | - Maria Jose Sanchez-Barrena
- Department of Crystallography and Structural Biology, Institute of Physical-Chemistry 'Blas Cabrera', CSICMadridSpain
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2
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Campagna CM, McMahon H, Nechipurenko I. The G protein alpha chaperone and guanine-nucleotide exchange factor RIC-8 regulates cilia morphogenesis in Caenorhabditis elegans sensory neurons. PLoS Genet 2023; 19:e1011015. [PMID: 37910589 PMCID: PMC10642896 DOI: 10.1371/journal.pgen.1011015] [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: 08/27/2023] [Revised: 11/13/2023] [Accepted: 10/12/2023] [Indexed: 11/03/2023] Open
Abstract
Heterotrimeric G (αβγ) proteins are canonical transducers of G-protein-coupled receptor (GPCR) signaling and play critical roles in communication between cells and their environment. Many GPCRs and heterotrimeric G proteins localize to primary cilia and modulate cilia morphology via mechanisms that are not well understood. Here, we show that RIC-8, a cytosolic guanine nucleotide exchange factor (GEF) and chaperone for Gα protein subunits, shapes cilia membrane morphology in a subset of Caenorhabditis elegans sensory neurons. Consistent with its role in ciliogenesis, C. elegans RIC-8 localizes to cilia in different sensory neuron types. Using domain mutagenesis, we demonstrate that while the GEF function alone is not sufficient, both the GEF and Gα-interacting chaperone motifs of RIC-8 are required for its role in cilia morphogenesis. We identify ODR-3 as the RIC-8 Gα client and demonstrate that RIC-8 functions in the same genetic pathway with another component of the non-canonical G protein signaling AGS-3 to shape cilia morphology. Notably, despite defects in AWC cilia morphology, ags-3 null mutants exhibit normal chemotaxis toward benzaldehyde unlike odr-3 mutant animals. Collectively, our findings describe a novel function for the evolutionarily conserved protein RIC-8 and non-canonical RIC-8-AGS-3-ODR-3 signaling in cilia morphogenesis and uncouple Gα ODR-3 functions in ciliogenesis and olfaction.
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Affiliation(s)
- Christina M. Campagna
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Hayley McMahon
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Inna Nechipurenko
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
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3
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Campagna CM, McMahon H, Nechipurenko I. The G protein alpha Chaperone and Guanine-Nucleotide Exchange Factor RIC-8 Regulates Cilia Morphogenesis in Caenorhabditis elegans Sensory Neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.25.554856. [PMID: 37662329 PMCID: PMC10473713 DOI: 10.1101/2023.08.25.554856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Heterotrimeric G (αβγ) proteins are canonical transducers of G-protein-coupled receptor (GPCR) signaling and play critical roles in communication between cells and their environment. Many GPCRs and heterotrimeric G proteins localize to primary cilia and modulate cilia morphology via mechanisms that are not well understood. Here, we show that RIC-8, a cytosolic guanine nucleotide exchange factor (GEF) and chaperone for Gα protein subunits, shapes cilia membrane morphology in a subset of Caenorhabditis elegans sensory neurons. Consistent with its role in ciliogenesis, C. elegans RIC-8 localizes to cilia in different sensory neuron types. Using domain mutagenesis, we demonstrate that while the GEF function alone is not sufficient, both the GEF and Gα-interacting chaperone motifs of RIC-8 are required for its role in cilia morphogenesis. We identify ODR-3 as the RIC-8 Gα client and demonstrate that RIC-8 functions in the same genetic pathway with another component of the non-canonical G protein signaling AGS-3 to shape cilia morphology. Notably, despite severe defects in AWC cilia morphology, ags-3 null mutants exhibit normal chemotaxis toward benzaldehyde unlike odr-3 mutant animals. Collectively, our findings describe a novel function for the evolutionarily conserved protein RIC-8 and non-canonical RIC-8-AGS-3-ODR-3 signaling in cilia morphogenesis and uncouple Gα ODR-3 functions in ciliogenesis and olfaction.
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Affiliation(s)
- Christina M. Campagna
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Hayley McMahon
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Inna Nechipurenko
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
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4
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Papasergi-Scott MM, Kwarcinski FE, Yu M, Panova O, Ovrutsky AM, Skiniotis G, Tall GG. Structures of Ric-8B in complex with Gα protein folding clients reveal isoform specificity mechanisms. Structure 2023; 31:553-564.e7. [PMID: 36931277 PMCID: PMC10164081 DOI: 10.1016/j.str.2023.02.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/23/2023] [Accepted: 02/20/2023] [Indexed: 03/18/2023]
Abstract
Mammalian Ric-8 proteins act as chaperones to regulate the cellular abundance of heterotrimeric G protein α subunits. The Ric-8A isoform chaperones Gαi/o, Gα12/13, and Gαq/11 subunits, while Ric-8B acts on Gαs/olf subunits. Here, we determined cryoelectron microscopy (cryo-EM) structures of Ric-8B in complex with Gαs and Gαolf, revealing isoform differences in the relative positioning and contacts between the C-terminal α5 helix of Gα within the concave pocket formed by Ric-8 α-helical repeat elements. Despite the overall architectural similarity with our earlier structures of Ric-8A complexed to Gαq and Gαi1, Ric-8B distinctly accommodates an extended loop found only in Gαs/olf proteins. The structures, along with results from Ric-8 protein thermal stability assays and cell-based Gαolf folding assays, support a requirement for the Gα C-terminal region for binding specificity, and highlight that multiple structural elements impart specificity for Ric-8/G protein binding.
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Affiliation(s)
- Makaía M Papasergi-Scott
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Frank E Kwarcinski
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Maiya Yu
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Ouliana Panova
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Ann M Ovrutsky
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA.
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5
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Guo P, Tai Y, Wang M, Sun H, Zhang L, Wei W, Xiang YK, Wang Q. Gα 12 and Gα 13: Versatility in Physiology and Pathology. Front Cell Dev Biol 2022; 10:809425. [PMID: 35237598 PMCID: PMC8883321 DOI: 10.3389/fcell.2022.809425] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 01/17/2022] [Indexed: 01/14/2023] Open
Abstract
G protein-coupled receptors (GPCRs), as the largest family of receptors in the human body, are involved in the pathological mechanisms of many diseases. Heterotrimeric G proteins represent the main molecular switch and receive cell surface signals from activated GPCRs. Growing evidence suggests that Gα12 subfamily (Gα12/13)-mediated signaling plays a crucial role in cellular function and various pathological processes. The current research on the physiological and pathological function of Gα12/13 is constantly expanding, Changes in the expression levels of Gα12/13 have been found in a wide range of human diseases. However, the mechanistic research on Gα12/13 is scattered. This review briefly describes the structural sequences of the Gα12/13 isoforms and introduces the coupling of GPCRs and non-GPCRs to Gα12/13. The effects of Gα12/13 on RhoA and other signaling pathways and their roles in cell proliferation, migration, and immune cell function, are discussed. Finally, we focus on the pathological impacts of Gα12/13 in cancer, inflammation, metabolic diseases, fibrotic diseases, and circulatory disorders are brought to focus.
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Affiliation(s)
- Paipai Guo
- Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Medical University, Hefei, China
| | - Yu Tai
- Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Medical University, Hefei, China
| | - Manman Wang
- Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Medical University, Hefei, China
| | - Hanfei Sun
- Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Medical University, Hefei, China
| | - Lingling Zhang
- Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Medical University, Hefei, China
| | - Wei Wei
- Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Medical University, Hefei, China
| | - Yang K Xiang
- Department of Pharmacology, University of California, Davis, Davis, CA, United States.,VA Northern California Health Care System, Mather, CA, United States
| | - Qingtong Wang
- Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Medical University, Hefei, China
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6
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Lechler T, Mapelli M. Spindle positioning and its impact on vertebrate tissue architecture and cell fate. Nat Rev Mol Cell Biol 2021; 22:691-708. [PMID: 34158639 PMCID: PMC10544824 DOI: 10.1038/s41580-021-00384-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2021] [Indexed: 12/18/2022]
Abstract
In multicellular systems, oriented cell divisions are essential for morphogenesis and homeostasis as they determine the position of daughter cells within the tissue and also, in many cases, their fate. Early studies in invertebrates led to the identification of conserved core mechanisms of mitotic spindle positioning centred on the Gαi-LGN-NuMA-dynein complex. In recent years, much has been learnt about the way this complex functions in vertebrate cells. In particular, studies addressed how the Gαi-LGN-NuMA-dynein complex dynamically crosstalks with astral microtubules and the actin cytoskeleton, and how it is regulated to orient the spindle according to cellular and tissue-wide cues. We have also begun to understand how dynein motors and actin regulators interact with mechanosensitive adhesion molecules sensing extracellular mechanical stimuli, such as cadherins and integrins, and with signalling pathways so as to respond to extracellular cues instructing the orientation of the division axis in vivo. In this Review, with the focus on epithelial tissues, we discuss the molecular mechanisms of mitotic spindle orientation in vertebrate cells, and how this machinery is regulated by epithelial cues and extracellular signals to maintain tissue cohesiveness during mitosis. We also outline recent knowledge of how spindle orientation impacts tissue architecture in epithelia and its emerging links to the regulation of cell fate decisions. Finally, we describe how defective spindle orientation can be corrected or its effects eliminated in tissues under physiological conditions, and the pathological implications associated with spindle misorientation.
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Affiliation(s)
- Terry Lechler
- Department of Dermatology, Duke University Medical Center, Durham, NC, USA.
- Department of Cell Biology, Duke University Medical Center, Durham, NC, USA.
| | - Marina Mapelli
- Department of Experimental Oncology, European Institute of Oncology IRCCS, Milan, Italy.
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7
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Seven AB, Hilger D, Papasergi-Scott MM, Zhang L, Qu Q, Kobilka BK, Tall GG, Skiniotis G. Structures of Gα Proteins in Complex with Their Chaperone Reveal Quality Control Mechanisms. Cell Rep 2020; 30:3699-3709.e6. [PMID: 32126208 PMCID: PMC7192526 DOI: 10.1016/j.celrep.2020.02.086] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 01/31/2020] [Accepted: 02/24/2020] [Indexed: 01/14/2023] Open
Abstract
Many chaperones promote nascent polypeptide folding followed by substrate release through ATP-dependent conformational changes. Here we show cryoEM structures of Gα subunit folding intermediates in complex with full-length Ric-8A, a unique chaperone-client system in which substrate release is facilitated by guanine nucleotide binding to the client G protein. The structures of Ric-8A-Gαi and Ric-8A-Gαq complexes reveal that the chaperone employs its extended C-terminal region to cradle the Ras-like domain of Gα, positioning the Ras core in contact with the Ric-8A core while engaging its switch2 nucleotide binding region. The C-terminal α5 helix of Gα is held away from the Ras-like domain through Ric-8A core domain interactions, which critically depend on recognition of the Gα C terminus by the chaperone. The structures, complemented with biochemical and cellular chaperoning data, support a folding quality control mechanism that ensures proper formation of the C-terminal α5 helix before allowing GTP-gated release of Gα from Ric-8A.
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Affiliation(s)
- Alpay Burak Seven
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Daniel Hilger
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Makaía M Papasergi-Scott
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Li Zhang
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Qianhui Qu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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8
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Srivastava D, Artemyev NO. Ric-8A, a GEF, and a Chaperone for G Protein α-Subunits: Evidence for the Two-Faced Interface. Bioessays 2020; 42:e1900208. [PMID: 31967346 PMCID: PMC7034654 DOI: 10.1002/bies.201900208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/30/2019] [Indexed: 12/21/2022]
Abstract
Resistance to inhibitors of cholinesterase 8A (Ric-8A) is a prominent non-receptor GEF and a chaperone of G protein α-subunits (Gα). Recent studies shed light on the structure of Ric-8A, providing insights into the mechanisms underlying its interaction with Gα. Ric-8A is composed of a core armadillo-like domain and a flexible C-terminal tail. Interaction of a conserved concave surface of its core domain with the Gα C-terminus appears to mediate formation of the initial Ric-8A/GαGDP intermediate, followed by the formation of a stable nucleotide-free complex. The latter event involves a large-scale dislocation of the Gα α5-helix that produces an extensive primary interface and disrupts the nucleotide-binding site of Gα. The distal portion of the C-terminal tail of Ric-8A forms a smaller secondary interface, which ostensibly binds the switch II region of Gα, facilitating binding of GTP. The two-site Gα interface of Ric-8A is distinct from that of GPCRs, and might have evolved to support the chaperone function of Ric-8A.
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Affiliation(s)
- Dhiraj Srivastava
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | - Nikolai O. Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, IA 52242
- Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242
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9
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McClelland LJ, Zhang K, Mou TC, Johnston J, Yates-Hansen C, Li S, Thomas CJ, Doukov TI, Triest S, Wohlkonig A, Tall GG, Steyaert J, Chiu W, Sprang SR. Structure of the G protein chaperone and guanine nucleotide exchange factor Ric-8A bound to Gαi1. Nat Commun 2020; 11:1077. [PMID: 32103024 PMCID: PMC7044438 DOI: 10.1038/s41467-020-14943-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Accepted: 02/10/2020] [Indexed: 12/24/2022] Open
Abstract
Ric-8A is a cytosolic Guanine Nucleotide exchange Factor (GEF) that activates heterotrimeric G protein alpha subunits (Gα) and serves as an essential Gα chaperone. Mechanisms by which Ric-8A catalyzes these activities, which are stimulated by Casein Kinase II phosphorylation, are unknown. We report the structure of the nanobody-stabilized complex of nucleotide-free Gα bound to phosphorylated Ric-8A at near atomic resolution by cryo-electron microscopy and X-ray crystallography. The mechanism of Ric-8A GEF activity differs considerably from that employed by G protein-coupled receptors at the plasma membrane. Ric-8A engages a specific conformation of Gα at multiple interfaces to form a complex that is stabilized by phosphorylation within a Ric-8A segment that connects two Gα binding sites. The C-terminus of Gα is ejected from its beta sheet core, thereby dismantling the GDP binding site. Ric-8A binds to the exposed Gα beta sheet and switch II to stabilize the nucleotide-free state of Gα.
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Affiliation(s)
- Levi J McClelland
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA
| | - Kaiming Zhang
- Department of Bioengineering and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA
| | - Tung-Chung Mou
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Jake Johnston
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Cindee Yates-Hansen
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA
| | - Shanshan Li
- Department of Bioengineering and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA
| | - Celestine J Thomas
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA
- Regeneron Pharmaceutical, Inc., Tarrytown, NY, USA
| | - Tzanko I Doukov
- Macromolecular Crystallography Group, Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA, 94025, USA
| | - Sarah Triest
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Alexandre Wohlkonig
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Wah Chiu
- Department of Bioengineering and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA.
- Biosciences Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, 94025, USA.
| | - Stephen R Sprang
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA.
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA.
- Graduate Program in Biochemistry and Biophysics, University of Montana, Missoula, MT, 59812, USA.
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10
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Structural underpinnings of Ric8A function as a G-protein α-subunit chaperone and guanine-nucleotide exchange factor. Nat Commun 2019; 10:3084. [PMID: 31300652 PMCID: PMC6625990 DOI: 10.1038/s41467-019-11088-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 06/21/2019] [Indexed: 02/03/2023] Open
Abstract
Resistance to inhibitors of cholinesterase 8A (Ric8A) is an essential regulator of G protein α-subunits (Gα), acting as a guanine nucleotide exchange factor and a chaperone. We report two crystal structures of Ric8A, one in the apo form and the other in complex with a tagged C-terminal fragment of Gα. These structures reveal two principal domains of Ric8A: an armadillo-fold core and a flexible C-terminal tail. Additionally, they show that the Gα C-terminus binds to a highly-conserved patch on the concave surface of the Ric8A armadillo-domain, with selectivity determinants residing in the Gα sequence. Biochemical analysis shows that the Ric8A C-terminal tail is critical for its stability and function. A model of the Ric8A/Gα complex derived from crosslinking mass spectrometry and molecular dynamics simulations suggests that the Ric8A C-terminal tail helps organize the GTP-binding site of Gα. This study lays the groundwork for understanding Ric8A function at the molecular level. Ric8A regulates G protein α-subunits (Gα) by acting as a guanine nucleotide exchange factor (GEF) and a Gα chaperone. Here, the authors solve the crystal structures of free and Gα fragment bound Ric8A, and provide insights into the structural basis for Ric8A’s GEF and chaperone functions.
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11
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Zeng B, Mou TC, Doukov TI, Steiner A, Yu W, Papasergi-Scott M, Tall GG, Hagn F, Sprang SR. Structure, Function, and Dynamics of the Gα Binding Domain of Ric-8A. Structure 2019; 27:1137-1147.e5. [PMID: 31155309 DOI: 10.1016/j.str.2019.04.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 04/01/2019] [Accepted: 04/23/2019] [Indexed: 10/26/2022]
Abstract
Ric-8A is a 530-amino acid cytoplasmic molecular chaperone and guanine nucleotide exchange factor (GEF) for i, q, and 12/13 classes of heterortrimeric G protein alpha subunits (Gα). We report the 2.2-Å crystal structure of the Ric-8A Gα-binding domain with GEF activity, residues 1-452, and is phosphorylated at Ser435 and Thr440. Residues 1-429 adopt a superhelical fold comprised of Armadillo (ARM) and HEAT repeats, and the C terminus is disordered. One of the phosphorylated residues potentially binds to a basic cluster in an ARM motif. Amino acid sequence conservation and published hydrogen-deuterium exchange data indicate repeats 3 through 6 to be a putative Gα-binding surface. Normal mode modeling of small-angle X-ray scattering data indicates that phosphorylation induces relative rotation between repeats 1-4, 5-6, and 7-9. 2D 1H-15N-TROSY spectra of [2H,15N]-labeled Gαi1 in the presence of R452 reveals chemical shift perturbations of the C terminus and Gαi1 residues involved in nucleotide binding.
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Affiliation(s)
- Baisen Zeng
- Graduate Program in Biochemistry and Biophysics, University of Montana, Missoula, MT 59812, USA
| | - Tung-Chung Mou
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT 59812, USA; Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Tzanko I Doukov
- Macromolecular Crystallography Group, Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94309, USA
| | - Andrea Steiner
- Bavarian NMR Center at the Department of Chemistry and Institute for Advanced Study, Technical University of Munich, Ernst-Otto-Fischer-Strasse 2, 85748 Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
| | - Wenxi Yu
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Makaia Papasergi-Scott
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Franz Hagn
- Bavarian NMR Center at the Department of Chemistry and Institute for Advanced Study, Technical University of Munich, Ernst-Otto-Fischer-Strasse 2, 85748 Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
| | - Stephen R Sprang
- Graduate Program in Biochemistry and Biophysics, University of Montana, Missoula, MT 59812, USA; Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT 59812, USA; Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA.
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Yu W, Yu M, Papasergi-Scott MM, Tall GG. Production of Phosphorylated Ric-8A proteins using protein kinase CK2. Protein Expr Purif 2018; 154:98-103. [PMID: 30290220 DOI: 10.1016/j.pep.2018.10.002] [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] [Received: 07/06/2018] [Revised: 09/26/2018] [Accepted: 10/01/2018] [Indexed: 01/13/2023]
Abstract
Resistance to Inhibitors of Cholinesterase-8 (Ric-8) proteins are molecular chaperones that fold heterotrimeric G protein α subunits shortly after biosynthesis. Ric-8 proteins also act as test tube guanine nucleotide exchange factors (GEF) that promote Gα subunit GDP for GTP exchange. The GEF and chaperoning activities of Ric-8A are regulated by phosphorylation of five serine and threonine residues within protein kinase CK2 consensus sites. The traditional way that Ric-8A proteins have been purified is from Spodoptera frugiperda (Sf9) or Trichoplusia ni (Tni) insect cells. Endogenous insect cell kinases do phosphorylate the critical regulatory sites of recombinant Ric-8A reasonably well, but there is batch-to-batch variability among recombinant Ric-8A preparations. Additionally, insect cell-production of some Ric-8 proteins with phosphosite alanine substitution mutations is proscribed as there seems to be interdependency of multi-site phosphorylation for functional protein production. Here, we present a method to produce wild type and phosphosite mutant Ric-8A proteins that are fully occupied with bound phosphate at each of the regulatory positions. Ric-8A proteins were expressed and purified from E. coli. Purified Ric-8A was phosphorylated in vitro with protein kinase CK2 and then re-isolated to remove kinase. The phosphorylated Ric-8A proteins were ∼99% pure and the completeness of phosphorylation was verified by chromatography, phos-tag SDS-PAGE mobility shifts, immunoblotting using phospho-site specific antibodies, and mass spectrometry analysis. E. coli-produced Ric-8A that was phosphorylated using this method promoted a faster rate of Gα subunit guanine nucleotide exchange than Ric-8A that was variably phosphorylated during production in insect cells.
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Affiliation(s)
- Wenxi Yu
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Maiya Yu
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | | | - Gregory G Tall
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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