ALBERT

Description: Opsin, the ligand-free form of the G-protein-coupled receptor rhodopsin, at low pH adopts a conformationally distinct, active G-protein-binding state known as Ops*. A synthetic peptide derived from the main binding site of the heterotrimeric G protein-the carboxy terminus of the alpha-subunit (GalphaCT)-stabilizes Ops*. Here we present the 3.2 A crystal structure of the bovine Ops*-GalphaCT peptide complex. GalphaCT binds to a site in opsin that is opened by an outward tilt of transmembrane helix (TM) 6, a pairing of TM5 and TM6, and a restructured TM7-helix 8 kink. Contacts along the inner surface of TM5 and TM6 induce an alpha-helical conformation in GalphaCT with a C-terminal reverse turn. Main-chain carbonyl groups in the reverse turn constitute the centre of a hydrogen-bonded network, which links the two receptor regions containing the conserved E(D)RY and NPxxY(x)(5,6)F motifs. On the basis of the Ops*-GalphaCT structure and known conformational changes in Galpha, we discuss signal transfer from the receptor to the G protein nucleotide-binding site.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Scheerer, Patrick -- Park, Jung Hee -- Hildebrand, Peter W -- Kim, Yong Ju -- Krauss, Norbert -- Choe, Hui-Woog -- Hofmann, Klaus Peter -- Ernst, Oliver P -- England -- Nature. 2008 Sep 25;455(7212):497-502. doi: 10.1038/nature07330.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut fur Medizinische Physik und Biophysik (CC2), Charite - Universitatsmedizin Berlin, Chariteplatz 1, D-10117 Berlin, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18818650" target="_blank"〉PubMed〈/a〉

Description: In the G-protein-coupled receptor (GPCR) rhodopsin, the inactivating ligand 11-cis-retinal is bound in the seven-transmembrane helix (TM) bundle and is cis/trans isomerized by light to form active metarhodopsin II. With metarhodopsin II decay, all-trans-retinal is released, and opsin is reloaded with new 11-cis-retinal. Here we present the crystal structure of ligand-free native opsin from bovine retinal rod cells at 2.9 angstrom (A) resolution. Compared to rhodopsin, opsin shows prominent structural changes in the conserved E(D)RY and NPxxY(x)(5,6)F regions and in TM5-TM7. At the cytoplasmic side, TM6 is tilted outwards by 6-7 A, whereas the helix structure of TM5 is more elongated and close to TM6. These structural changes, some of which were attributed to an active GPCR state, reorganize the empty retinal-binding pocket to disclose two openings that may serve the entry and exit of retinal. The opsin structure sheds new light on ligand binding to GPCRs and on GPCR activation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Park, Jung Hee -- Scheerer, Patrick -- Hofmann, Klaus Peter -- Choe, Hui-Woog -- Ernst, Oliver Peter -- England -- Nature. 2008 Jul 10;454(7201):183-7. doi: 10.1038/nature07063. Epub 2008 Jun 18.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut fur Medizinische Physik und Biophysik (CC2), Charite-Universitatsmedizin Berlin, Chariteplatz 1, D-10117 Berlin, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18563085" target="_blank"〉PubMed〈/a〉

Description: G-protein-coupled receptors (GPCRs) are seven transmembrane helix (TM) proteins that transduce signals into living cells by binding extracellular ligands and coupling to intracellular heterotrimeric G proteins (Galphabetagamma). The photoreceptor rhodopsin couples to transducin and bears its ligand 11-cis-retinal covalently bound via a protonated Schiff base to the opsin apoprotein. Absorption of a photon causes retinal cis/trans isomerization and generates the agonist all-trans-retinal in situ. After early photoproducts, the active G-protein-binding intermediate metarhodopsin II (Meta II) is formed, in which the retinal Schiff base is still intact but deprotonated. Dissociation of the proton from the Schiff base breaks a major constraint in the protein and enables further activating steps, including an outward tilt of TM6 and formation of a large cytoplasmic crevice for uptake of the interacting C terminus of the Galpha subunit. Owing to Schiff base hydrolysis, Meta II is short-lived and notoriously difficult to crystallize. We therefore soaked opsin crystals with all-trans-retinal to form Meta II, presuming that the crystal's high concentration of opsin in an active conformation (Ops*) may facilitate all-trans-retinal uptake and Schiff base formation. Here we present the 3.0 A and 2.85 A crystal structures, respectively, of Meta II alone or in complex with an 11-amino-acid C-terminal fragment derived from Galpha (GalphaCT2). GalphaCT2 binds in a large crevice at the cytoplasmic side, akin to the binding of a similar Galpha-derived peptide to Ops* (ref. 7). In the Meta II structures, the electron density from the retinal ligand seamlessly continues into the Lys 296 side chain, reflecting proper formation of the Schiff base linkage. The retinal is in a relaxed conformation and almost undistorted compared with pure crystalline all-trans-retinal. By comparison with early photoproducts we propose how retinal translocation and rotation induce the gross conformational changes characteristic for Meta II. The structures can now serve as models for the large GPCR family.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Choe, Hui-Woog -- Kim, Yong Ju -- Park, Jung Hee -- Morizumi, Takefumi -- Pai, Emil F -- Krauss, Norbert -- Hofmann, Klaus Peter -- Scheerer, Patrick -- Ernst, Oliver P -- England -- Nature. 2011 Mar 31;471(7340):651-5. doi: 10.1038/nature09789. Epub 2011 Mar 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut fur Medizinische Physik und Biophysik - CC2, Charite - Universitatsmedizin Berlin, Chariteplatz 1, D-10117 Berlin, Germany. hwchoe@jbnu.ac.kr〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21389988" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ernst, Oliver P -- Sakmar, Thomas P -- England -- Nature. 2012 Feb 15;482(7385):318-9. doi: 10.1038/482318a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22337049" target="_blank"〉PubMed〈/a〉

Description: Arrestins interact with G-protein-coupled receptors (GPCRs) to block interaction with G proteins and initiate G-protein-independent signalling. Arrestins have a bi-lobed structure that is stabilized by a long carboxy-terminal tail (C-tail), and displacement of the C-tail by receptor-attached phosphates activates arrestins for binding active GPCRs. Structures of the inactive state of arrestin are available, but it is not known how C-tail displacement activates arrestin for receptor coupling. Here we present a 3.0 A crystal structure of the bovine arrestin-1 splice variant p44, in which the activation step is mimicked by C-tail truncation. The structure of this pre-activated arrestin is profoundly different from the basal state and gives insight into the activation mechanism. p44 displays breakage of the central polar core and other interlobe hydrogen-bond networks, leading to a approximately 21 degrees rotation of the two lobes as compared to basal arrestin-1. Rearrangements in key receptor-binding loops in the central crest region include the finger loop, loop 139 (refs 8, 10, 11) and the sequence Asp 296-Asn 305 (or gate loop), here identified as controlling the polar core. We verified the role of these conformational alterations in arrestin activation and receptor binding by site-directed fluorescence spectroscopy. The data indicate a mechanism for arrestin activation in which C-tail displacement releases critical central-crest loops from restricted to extended receptor-interacting conformations. In parallel, increased flexibility between the two lobes facilitates a proper fitting of arrestin to the active receptor surface. Our results provide a snapshot of an arrestin ready to bind the active receptor, and give an insight into the role of naturally occurring truncated arrestins in the visual system.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kim, Yong Ju -- Hofmann, Klaus Peter -- Ernst, Oliver P -- Scheerer, Patrick -- Choe, Hui-Woog -- Sommer, Martha E -- England -- Nature. 2013 May 2;497(7447):142-6. doi: 10.1038/nature12133. Epub 2013 Apr 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut fur Medizinische Physik und Biophysik (CC2), Charite-Universitatsmedizin Berlin, Chariteplatz 1, D-10117 Berlin, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23604253" target="_blank"〉PubMed〈/a〉

Description: Conformational selection and induced fit are two prevailing mechanisms to explain the molecular basis for ligand-based activation of receptors. G-protein-coupled receptors are the largest class of cell surface receptors and are important drug targets. A molecular understanding of their activation mechanism is critical for drug discovery and design. However, direct evidence that addresses how agonist binding leads to the formation of an active receptor state is scarce. Here we use (19)F nuclear magnetic resonance to quantify the conformational landscape occupied by the adenosine A2A receptor (A2AR), a prototypical class A G-protein-coupled receptor. We find an ensemble of four states in equilibrium: (1) two inactive states in millisecond exchange, consistent with a formed (state S1) and a broken (state S2) salt bridge (known as 'ionic lock') between transmembrane helices 3 and 6; and (2) two active states, S3 and S3', as identified by binding of a G-protein-derived peptide. In contrast to a recent study of the beta2-adrenergic receptor, the present approach allowed identification of a second active state for A2AR. Addition of inverse agonist (ZM241385) increases the population of the inactive states, while full agonists (UK432097 or NECA) stabilize the active state, S3', in a manner consistent with conformational selection. In contrast, partial agonist (LUF5834) and an allosteric modulator (HMA) exclusively increase the population of the S3 state. Thus, partial agonism is achieved here by conformational selection of a distinct active state which we predict will have compromised coupling to the G protein. Direct observation of the conformational equilibria of ligand-dependent G-protein-coupled receptor and deduction of the underlying mechanisms of receptor activation will have wide-reaching implications for our understanding of the function of G-protein-coupled receptor in health and disease.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ye, Libin -- Van Eps, Ned -- Zimmer, Marco -- Ernst, Oliver P -- Prosser, R Scott -- England -- Nature. 2016 May 4;533(7602):265-8. doi: 10.1038/nature17668.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Toronto, UTM, 3359 Mississauga Road North, Mississauga, Ontario L5L 1C6, Canada. ; Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada. ; Department of Technical Biochemistry, University of Stuttgart, 31 Allmandring, Stuttgart, Baden-Wurttemberg, D-70569, Germany. ; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27144352" target="_blank"〉PubMed〈/a〉

Description: G-protein-coupled receptors (GPCRs) signal primarily through G proteins or arrestins. Arrestin binding to GPCRs blocks G protein interaction and redirects signalling to numerous G-protein-independent pathways. Here we report the crystal structure of a constitutively active form of human rhodopsin bound to a pre-activated form of the mouse visual arrestin, determined by serial femtosecond X-ray laser crystallography. Together with extensive biochemical and mutagenesis data, the structure reveals an overall architecture of the rhodopsin-arrestin assembly in which rhodopsin uses distinct structural elements, including transmembrane helix 7 and helix 8, to recruit arrestin. Correspondingly, arrestin adopts the pre-activated conformation, with a approximately 20 degrees rotation between the amino and carboxy domains, which opens up a cleft in arrestin to accommodate a short helix formed by the second intracellular loop of rhodopsin. This structure provides a basis for understanding GPCR-mediated arrestin-biased signalling and demonstrates the power of X-ray lasers for advancing the frontiers of structural biology.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4521999/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4521999/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kang, Yanyong -- Zhou, X Edward -- Gao, Xiang -- He, Yuanzheng -- Liu, Wei -- Ishchenko, Andrii -- Barty, Anton -- White, Thomas A -- Yefanov, Oleksandr -- Han, Gye Won -- Xu, Qingping -- de Waal, Parker W -- Ke, Jiyuan -- Tan, M H Eileen -- Zhang, Chenghai -- Moeller, Arne -- West, Graham M -- Pascal, Bruce D -- Van Eps, Ned -- Caro, Lydia N -- Vishnivetskiy, Sergey A -- Lee, Regina J -- Suino-Powell, Kelly M -- Gu, Xin -- Pal, Kuntal -- Ma, Jinming -- Zhi, Xiaoyong -- Boutet, Sebastien -- Williams, Garth J -- Messerschmidt, Marc -- Gati, Cornelius -- Zatsepin, Nadia A -- Wang, Dingjie -- James, Daniel -- Basu, Shibom -- Roy-Chowdhury, Shatabdi -- Conrad, Chelsie E -- Coe, Jesse -- Liu, Haiguang -- Lisova, Stella -- Kupitz, Christopher -- Grotjohann, Ingo -- Fromme, Raimund -- Jiang, Yi -- Tan, Minjia -- Yang, Huaiyu -- Li, Jun -- Wang, Meitian -- Zheng, Zhong -- Li, Dianfan -- Howe, Nicole -- Zhao, Yingming -- Standfuss, Jorg -- Diederichs, Kay -- Dong, Yuhui -- Potter, Clinton S -- Carragher, Bridget -- Caffrey, Martin -- Jiang, Hualiang -- Chapman, Henry N -- Spence, John C H -- Fromme, Petra -- Weierstall, Uwe -- Ernst, Oliver P -- Katritch, Vsevolod -- Gurevich, Vsevolod V -- Griffin, Patrick R -- Hubbell, Wayne L -- Stevens, Raymond C -- Cherezov, Vadim -- Melcher, Karsten -- Xu, H Eric -- DK071662/DK/NIDDK NIH HHS/ -- EY005216/EY/NEI NIH HHS/ -- EY011500/EY/NEI NIH HHS/ -- GM073197/GM/NIGMS NIH HHS/ -- GM077561/GM/NIGMS NIH HHS/ -- GM095583/GM/NIGMS NIH HHS/ -- GM097463/GM/NIGMS NIH HHS/ -- GM102545/GM/NIGMS NIH HHS/ -- GM103310/GM/NIGMS NIH HHS/ -- GM104212/GM/NIGMS NIH HHS/ -- GM108635/GM/NIGMS NIH HHS/ -- P30EY000331/EY/NEI NIH HHS/ -- P41 GM103310/GM/NIGMS NIH HHS/ -- P41GM103393/GM/NIGMS NIH HHS/ -- P41RR001209/RR/NCRR NIH HHS/ -- P50 GM073197/GM/NIGMS NIH HHS/ -- P50 GM073210/GM/NIGMS NIH HHS/ -- R01 DK066202/DK/NIDDK NIH HHS/ -- R01 DK071662/DK/NIDDK NIH HHS/ -- R01 EY011500/EY/NEI NIH HHS/ -- R01 GM087413/GM/NIGMS NIH HHS/ -- R01 GM109955/GM/NIGMS NIH HHS/ -- S10 RR027270/RR/NCRR NIH HHS/ -- U54 GM094586/GM/NIGMS NIH HHS/ -- U54 GM094599/GM/NIGMS NIH HHS/ -- U54 GM094618/GM/NIGMS NIH HHS/ -- England -- Nature. 2015 Jul 30;523(7562):561-7. doi: 10.1038/nature14656. Epub 2015 Jul 22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Structural Sciences, Center for Structural Biology and Drug Discovery, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA. ; Department of Chemistry and Biochemistry, and Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, Arizona 85287-1604, USA. ; Department of Chemistry, Bridge Institute, University of Southern California, Los Angeles, California 90089, USA. ; Center for Free Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany. ; Joint Center for Structural Genomics, Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA. ; 1] Laboratory of Structural Sciences, Center for Structural Biology and Drug Discovery, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA [2] Department of Obstetrics &Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. ; The National Resource for Automated Molecular Microscopy, New York Structural Biology Center, New York, New York 10027, USA. ; Department of Molecular Therapeutics, The Scripps Research Institute, Scripps Florida, Jupiter, Florida 33458, USA. ; Jules Stein Eye Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA. ; Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada. ; Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, USA. ; Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA. ; 1] Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA [2] BioXFEL, NSF Science and Technology Center, 700 Ellicott Street, Buffalo, New York 14203, USA. ; 1] Department of Chemistry and Biochemistry, and Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, Arizona 85287-1604, USA [2] Department of Physics, Arizona State University, Tempe, Arizona 85287, USA. ; 1] Department of Chemistry and Biochemistry, and Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, Arizona 85287-1604, USA [2] Beijing Computational Science Research Center, Haidian District, Beijing 10084, China. ; 1] Department of Chemistry and Biochemistry, and Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, Arizona 85287-1604, USA [2] Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA. ; State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China. ; Department of Obstetrics &Gynecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. ; Swiss Light Source at Paul Scherrer Institute, CH-5232 Villigen, Switzerland. ; Department of Biological Sciences, Bridge Institute, University of Southern California, Los Angeles, California 90089, USA. ; School of Medicine and School of Biochemistry and Immunology, Trinity College, Dublin 2, Ireland. ; 1] BioXFEL, NSF Science and Technology Center, 700 Ellicott Street, Buffalo, New York 14203, USA [2] Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois 60637, USA. ; Laboratory of Biomolecular Research at Paul Scherrer Institute, CH-5232 Villigen, Switzerland. ; Department of Biology, Universitat Konstanz, 78457 Konstanz, Germany. ; Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China. ; 1] Center for Free Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany [2] Centre for Ultrafast Imaging, 22761 Hamburg, Germany. ; 1] Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada [2] Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada. ; 1] Department of Chemistry, Bridge Institute, University of Southern California, Los Angeles, California 90089, USA [2] Department of Biological Sciences, Bridge Institute, University of Southern California, Los Angeles, California 90089, USA [3] iHuman Institute, ShanghaiTech University, 2F Building 6, 99 Haike Road, Pudong New District, Shanghai 201210, China. ; 1] Laboratory of Structural Sciences, Center for Structural Biology and Drug Discovery, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA [2] VARI-SIMM Center, Center for Structure and Function of Drug Targets, CAS-Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26200343" target="_blank"〉PubMed〈/a〉