1
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Babin KM, Gostynska SE, Karim JA, Pioszak AA. Variable CGRP family peptide signaling durations and the structural determinants thereof. Biochem Pharmacol 2024; 224:116235. [PMID: 38670438 DOI: 10.1016/j.bcp.2024.116235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 03/29/2024] [Accepted: 04/23/2024] [Indexed: 04/28/2024]
Abstract
Calcitonin gene-related peptides alpha and beta (αCGRP, βCGRP), adrenomedullin (AM), and adrenomedullin 2/intermedin (AM2/IMD) function in pain signaling, neuroimmune communication, and regulation of the cardiovascular and lymphatic systems by activating either of two class B GPCRs, CLR and CTR, in complex with a RAMP1, -2, or -3 modulatory subunit. Inspired by our recent discovery that AM2/IMD(1-47) activation of CLR-RAMP3 elicits long duration cAMP signaling, here we used a live-cell cAMP biosensor assay to characterize the signaling kinetics of the two CGRP peptides and several bioactive AM and AM2/IMD fragments with variable N-terminal extensions. Remarkably, AM2/IMD(8-47) and AM2/IMD-53 exhibited even longer duration signaling than the 1-47 fragment. AM2/IMD(8-47) was a striking 8-fold longer acting than AM(13-52) at CLR-RAMP3. In contrast, the N-terminal extension of AM had no effect on signaling duration. AM(1-52) and (13-52) were equally short-acting. Analysis of AM2/IMD-AM mid-region chimeras and AM2/IMD R23 and R33 point mutants showed the importance of these residues for long-duration signaling and identified AM2/IMD peptides that exhibited up to 17-fold diminished signaling duration at CLR-RAMP3, while retaining near wildtype signaling potencies. βCGRP was ∼ 3-fold longer acting than αCGRP at the CGRP (CLR-RAMP1) and the amylin1 (CTR-RAMP1) receptors. Chimeric CGRP peptides showed that the single residue difference near the N-terminus, and the two differences in the mid-region, equally contributed to the longer duration of βCGRP signaling. This work uncovers key temporal differences in cAMP signaling among the CGRP family peptides, elucidates the structural bases thereof, and provides pharmacological tools for studying long-duration AM2/IMD signaling.
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Affiliation(s)
- Katie M Babin
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States
| | - Sandra E Gostynska
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States
| | - Jordan A Karim
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States.
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2
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Babin KM, Karim JA, Gordon PH, Lennon J, Dickson A, Pioszak AA. Adrenomedullin 2/intermedin is a slow off-rate, long-acting endogenous agonist of the adrenomedullin 2 G protein-coupled receptor. J Biol Chem 2023:104785. [PMID: 37146967 DOI: 10.1016/j.jbc.2023.104785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/20/2023] [Accepted: 05/01/2023] [Indexed: 05/07/2023] Open
Abstract
Adrenomedullin 2/intermedin (AM2/IMD), adrenomedullin (AM), and calcitonin gene-related peptide (CGRP) have signaling functions in the cardiovascular, lymphatic, and nervous systems by activating three heterodimeric receptors comprised of the class B GPCR CLR and a RAMP1, -2, or -3 modulatory subunit. CGRP and AM prefer the RAMP1 and RAMP2/3 complexes, respectively, whereas AM2/IMD is thought to be relatively non-selective. Accordingly, AM2/IMD exhibits overlapping actions with CGRP and AM, so the rationale for this third agonist for the CLR-RAMP complexes is unclear. Here, we report that AM2/IMD is kinetically selective for CLR-RAMP3, known as the AM2R, and we define the structural basis for its distinct kinetics. In live cell biosensor assays, AM2/IMD-AM2R elicited substantially longer duration cAMP signaling than the eight other peptide-receptor combinations. AM2/IMD and AM bound the AM2R with similar equilibrium affinities, but AM2/IMD had a much slower off-rate and longer receptor residence time, thus explaining its prolonged signaling capacity. Peptide and receptor chimeras and mutagenesis were used to map the regions responsible for the distinct binding and signaling kinetics to the AM2/IMD mid-region and the RAMP3 extracellular domain (ECD). Molecular dynamics simulations revealed how the former forms stable interactions at the CLR ECD-transmembrane domain interface and how the latter augments the CLR ECD binding pocket to anchor the AM2/IMD C-terminus. These two strong binding components only combine in the AM2R. Our findings uncover AM2/IMD-AM2R as a cognate pair with unique temporal features, reveal how AM2/IMD and RAMP3 collaborate to shape CLR signaling, and have significant implications for AM2/IMD biology.
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Affiliation(s)
- Katie M Babin
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
| | - Jordan A Karim
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
| | - Peyton H Gordon
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
| | - James Lennon
- Departments of Biochemistry and Molecular Biology and Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI 48824
| | - Alex Dickson
- Departments of Biochemistry and Molecular Biology and Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI 48824.
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104.
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3
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Karim JA, Lambert NA, Pioszak AA. Time- and cost-efficient bacterial expression and purification of potato apyrase. Protein Expr Purif 2023; 203:106215. [PMID: 36535546 PMCID: PMC9807108 DOI: 10.1016/j.pep.2022.106215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022]
Abstract
Apyrase from potato (Solanum tuberosum) is a divalent metal ion-dependent enzyme that catalyzes the hydrolysis of nucleoside di- and tri-phosphates with broad substrate specificity. The enzyme is widely used to manipulate nucleotide levels such as in the G protein-coupled receptor (GPCR) field where it is used to deplete guanine nucleotides to stabilize nucleotide-free ternary agonist-GPCR-G protein complexes. Potato apyrase is available commercially as the native enzyme purified from potatoes or as a recombinant protein, but these are prohibitively expensive for some research applications. Here, we report a relatively simple method for the bacterial production of soluble, active potato apyrase. Apyrase has several disulfide bonds, so we co-expressed the enzyme bearing a C-terminal (His)6 tag with the E. coli disulfide isomerase DsbC at low temperature (18 °C) in the oxidizing cytoplasm of E. coli Origami B (DE3). This allowed low level production of soluble apyrase. A two-step purification procedure involving Ni-affinity followed by Cibacron Blue-affinity chromatography yielded highly purified apyrase at a level of ∼0.5 mg per L of bacterial culture. The purified enzyme was functional for ATP hydrolysis in an ATPase assay and for GTP/GDP hydrolysis in a GPCR-G protein coupling assay. This methodology enables the time- and cost-efficient production of recombinant apyrase for various research applications.
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Affiliation(s)
- Jordan A Karim
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Nevin A Lambert
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
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4
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Babin KM, Karim JA, Gordon PH, Lennon J, Dickson A, Pioszak AA. Adrenomedullin 2/intermedin is a slow off-rate, long-acting endogenous agonist of the adrenomedullin 2 G protein-coupled receptor. bioRxiv 2023:2023.01.13.523955. [PMID: 36711519 PMCID: PMC9882245 DOI: 10.1101/2023.01.13.523955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The signaling peptides adrenomedullin 2/intermedin (AM2/IMD), adrenomedullin (AM), and CGRP have overlapping and distinct functions in the cardiovascular, lymphatic, and nervous systems by activating three shared receptors comprised of the class B GPCR CLR in complex with a RAMP1, -2, or -3 modulatory subunit. Here, we report that AM2/IMD, which is thought to be a non-selective agonist, is kinetically selective for CLR-RAMP3, known as the AM 2 R. AM2/IMD-AM 2 R elicited substantially longer duration cAMP signaling than the eight other peptide-receptor combinations due to AM2/IMD slow off-rate binding kinetics. The regions responsible for the slow off-rate were mapped to the AM2/IMD mid-region and the RAMP3 extracellular domain. MD simulations revealed how these bestow enhanced stability to the complex. Our results uncover AM2/IMD-AM 2 R as a cognate pair with unique temporal features, define the mechanism of kinetic selectivity, and explain how AM2/IMD and RAMP3 collaborate to shape the signaling output of a clinically important GPCR.
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Affiliation(s)
- Katie M. Babin
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
| | - Jordan A. Karim
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
| | - Peyton H. Gordon
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
| | - James Lennon
- Departments of Biochemistry and Molecular Biology and Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI 48824
| | - Alex Dickson
- Departments of Biochemistry and Molecular Biology and Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI 48824
| | - Augen A. Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
- Lead contact
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5
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Roehrkasse AM, Karim JA, Pioszak AA. A Native PAGE Assay for the Biochemical Characterization of G Protein Coupling to GPCRs. Bio Protoc 2021; 11:e4266. [PMID: 35087925 PMCID: PMC8720520 DOI: 10.21769/bioprotoc.4266] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 10/07/2021] [Accepted: 10/14/2021] [Indexed: 09/16/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are a large family of membrane-embedded receptors that have diverse roles in physiology and are major drug targets. GPCRs transduce an agonist binding signal across the membrane to activate intracellular heterotrimeric G proteins. The dynamic nature of the receptors and the complexity of their interactions with agonists and G proteins present significant challenges for biochemical studies. Most biochemical/biophysical methods that have been employed to study GPCR-G protein coupling require purified receptors and are technically difficult. Here, we provide a protocol for a relatively simple and time- and cost-effective membrane protein native PAGE assay, to visualize and biochemically characterize agonist-dependent coupling of detergent-solubilized GPCRs to purified G protein surrogate "mini-G" proteins, which stabilize the receptor in an active state. The assay was developed for our studies of the calcitonin receptor-like receptor, a class B GPCR that mediates the actions of calcitonin gene-related peptide and adrenomedullin peptide agonists. It does not require a purified receptor and it can be used in a screening format with transiently-transfected adherent mammalian cell cultures, to quickly identify detergent-stable complexes amenable to study, or in a quantitative format with membrane preparations, to determine apparent affinities of agonists for the mini-G-coupled receptor and apparent affinities of mini-G proteins for the agonist-occupied receptor. The latter provides a partial measure of agonist efficacy. The method should be applicable to other GPCRs, and has the potential to be adapted to the study of other challenging membrane proteins and their complexes with binding partners. Graphic abstract: Visualizing agonist-dependent mini-G protein coupling and determining apparent binding affinities using the native PAGE assay quantitative formats.
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Affiliation(s)
- Amanda M. Roehrkasse
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, USA
| | - Jordan A. Karim
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, USA
| | - Augen A. Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, USA
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6
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Booe JM, Warner ML, Pioszak AA. Picomolar Affinity Antagonist and Sustained Signaling Agonist Peptide Ligands for the Adrenomedullin and Calcitonin Gene-Related Peptide Receptors. ACS Pharmacol Transl Sci 2020; 3:759-772. [PMID: 32832875 DOI: 10.1021/acsptsci.0c00031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Indexed: 12/31/2022]
Abstract
The calcitonin receptor-like class B G protein-coupled receptor (CLR) mediates adrenomedullin (AM) and calcitonin gene-related peptide (CGRP) functions including vasodilation, cardioprotection, and nociception. Receptor activity-modifying proteins (RAMP1-3) form heterodimers with CLR and determine its peptide ligand selectivity through an unresolved mechanism. The CGRP (RAMP1:CLR) and AM (RAMP2/3:CLR) receptors are proven or promising drug targets, but short AM and CGRP plasma half-lives limit their therapeutic utility. Here, we used synthetic peptide combinatorial library and rational design approaches to probe the ligand selectivity determinants and develop truncated AM and CGRP antagonist variants with receptor extracellular domain binding affinities that were enhanced ∼1000-fold into the low nanomolar range. Receptor binding studies and a high-resolution crystal structure of a novel library-identified AM variant bound to the RAMP2-CLR extracellular domain complex explained the increased affinities and defined roles for AM Lys46 and RAMP modulation of CLR conformation in the ligand selectivity mechanism. In longer AM and CGRP scaffolds that also bind the CLR transmembrane domain, the variants generated picomolar affinity antagonists, one with an estimated 12.5 h CGRP receptor residence time, and sustained signaling agonists "ss-AM" and "ss-CGRP" that exhibited persistent cAMP signaling after ligand washout. Sustained signaling was demonstrated in primary human umbilical vein endothelial cells and the SK-N-MC cell line, which endogenously express AM and CGRP receptors, respectively. This work clarifies the RAMP-modulated CLR ligand selectivity mechanism and provides AM and CGRP variants that are valuable pharmacological tools and may have potential as long-acting therapeutics.
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Affiliation(s)
- Jason M Booe
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, United States
| | - Margaret L Warner
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, United States
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, United States
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7
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Roehrkasse AM, Warner ML, Booe JM, Pioszak AA. Biochemical characterization of G protein coupling to calcitonin gene-related peptide and adrenomedullin receptors using a native PAGE assay. J Biol Chem 2020; 295:9736-9751. [PMID: 32487746 PMCID: PMC7363127 DOI: 10.1074/jbc.ra120.013854] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 05/27/2020] [Indexed: 11/06/2022] Open
Abstract
Calcitonin gene-related peptide (CGRP), adrenomedullin (AM), and adrenomedullin 2/intermedin (AM2/IMD) have overlapping and unique functions in the nervous and circulatory systems including vasodilation, cardioprotection, and pain transmission. Their actions are mediated by the class B calcitonin-like G protein-coupled receptor (CLR), which heterodimerizes with three receptor activity-modifying proteins (RAMP1-3) that determine its peptide ligand selectivity. How the three agonists and RAMPs modulate CLR binding to transducer proteins remains poorly understood. Here, we biochemically characterized agonist-promoted G protein coupling to each CLR·RAMP complex. We adapted a native PAGE method to assess the formation and thermostabilities of detergent-solubilized fluorescent protein-tagged CLR·RAMP complexes expressed in mammalian cells. Addition of agonist and the purified Gs protein surrogate mini-Gs (mGs) yielded a mobility-shifted agonist·CLR·RAMP·mGs quaternary complex gel band that was sensitive to antagonists. Measuring the apparent affinities of the agonists for the mGs-coupled receptors and of mGs for the agonist-occupied receptors revealed that both ligand and RAMP control mGs coupling and defined how agonist engagement of the CLR extracellular and transmembrane domains affects transducer recruitment. Using mini-Gsq and -Gsi chimeras, we observed a coupling rank order of mGs > mGsq > mGsi for each receptor. Last, we demonstrated the physiological relevance of the native gel assays by showing that they can predict the cAMP-signaling potencies of AM and AM2/IMD chimeras. These results highlight the power of the native PAGE assay for membrane protein biochemistry and provide a biochemical foundation for understanding the molecular basis of shared and distinct signaling properties of CGRP, AM, and AM2/IMD.
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Affiliation(s)
- Amanda M Roehrkasse
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Margaret L Warner
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Jason M Booe
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
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8
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Pioszak AA, Booe JM, Warner ML. Development of Picomolar Affinity Antagonists and Long‐acting Agonists for the Adrenomedullin and CGRP Receptors Using Combinatorial Peptide Library and Structure‐guided Design Approaches. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.06481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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9
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Lee S, Jeong Y, Simms J, Warner ML, Poyner DR, Chung KY, Pioszak AA. Calcitonin Receptor N‐Glycosylation Enhances Peptide Hormone Affinity by Controlling Receptor Dynamics. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.00704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Sangmin Lee
- Fred Wilson School of Pharmacy High Point University
- University of Oklahoma Health Sciences Center
| | | | - John Simms
- School of Life and Health Sciences Aston University
- School of Life Sciences, Faculty of Health and Life Sciences Coventry University
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10
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Hendrikse ER, Liew LP, Bower RL, Bonnet M, Jamaluddin MA, Prodan N, Richards KD, Walker CS, Pairaudeau G, Smith DM, Rujan RM, Sudra R, Reynolds CA, Booe JM, Pioszak AA, Flanagan JU, Hay MP, Hay DL. Identification of Small-Molecule Positive Modulators of Calcitonin-like Receptor-Based Receptors. ACS Pharmacol Transl Sci 2020; 3:305-320. [PMID: 32296770 DOI: 10.1021/acsptsci.9b00108] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Indexed: 11/28/2022]
Abstract
Class B G protein-coupled receptors are highly therapeutically relevant but challenges remain in identifying suitable small-molecule drugs. The calcitonin-like receptor (CLR) in particular is linked to conditions such as migraine, cardiovascular disease, and inflammatory bowel disease. The CLR cannot act as a cell-surface receptor alone but rather must couple to one of three receptor activity-modifying proteins (RAMPs), forming heterodimeric receptors for the peptides adrenomedullin and calcitonin gene-related peptide. These peptides have extended binding sites across their receptors. This is one reason why there are few small-molecule ligands that can modulate these receptors. Here we describe small molecules that are able to positively modulate the signaling of the CLR with all three RAMPs but are not active at the related calcitonin receptor. These compounds were selected from a β-arrestin recruitment screen, coupled with rounds of medicinal chemistry to improve their activity. Translational potential is shown as the compounds can positively modulate cAMP signaling in a vascular cell line model. Binding experiments do not support an extracellular domain binding site; however, molecular modeling reveals potential allosteric binding sites in multiple receptor regions. These are the first small-molecule positive modulators described for the CLR:RAMP complexes.
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Affiliation(s)
- Erica R Hendrikse
- School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1010, New Zealand
| | - Lydia P Liew
- Auckland Cancer Society Research Centre, University of Auckland, Auckland 1023, New Zealand
| | - Rebekah L Bower
- School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1010, New Zealand
| | - Muriel Bonnet
- Auckland Cancer Society Research Centre, University of Auckland, Auckland 1023, New Zealand
| | - Muhammad A Jamaluddin
- School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1010, New Zealand
| | - Nicole Prodan
- School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand
| | - Keith D Richards
- School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand
| | - Christopher S Walker
- School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1010, New Zealand
| | - Garry Pairaudeau
- Hit Discovery, Discovery Sciences, R&D, AstraZeneca, Cambridge CB2 0SL, United Kingdom
| | - David M Smith
- Emerging Innovations, Discovery Sciences, R&D, AstraZeneca, Cambridge CB2 0SL, United Kingdom
| | - Roxana-Maria Rujan
- School of Life Sciences, University of Essex, Colchester CO4 3SQ, United Kingdom
| | - Risha Sudra
- School of Life Sciences, University of Essex, Colchester CO4 3SQ, United Kingdom
| | | | - Jason M Booe
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, United States
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, United States
| | - Jack U Flanagan
- Auckland Cancer Society Research Centre, University of Auckland, Auckland 1023, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1010, New Zealand
| | - Michael P Hay
- Auckland Cancer Society Research Centre, University of Auckland, Auckland 1023, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1010, New Zealand
| | - Debbie L Hay
- School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1010, New Zealand
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11
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Lee SM, Jeong Y, Simms J, Warner ML, Poyner DR, Chung KY, Pioszak AA. Calcitonin Receptor N-Glycosylation Enhances Peptide Hormone Affinity by Controlling Receptor Dynamics. J Mol Biol 2020; 432:1996-2014. [PMID: 32035902 DOI: 10.1016/j.jmb.2020.01.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Revised: 11/27/2019] [Accepted: 01/27/2020] [Indexed: 02/09/2023]
Abstract
The class B G protein-coupled receptor (GPCR) calcitonin receptor (CTR) is a drug target for osteoporosis and diabetes. N-glycosylation of asparagine 130 in its extracellular domain (ECD) enhances calcitonin hormone affinity with the proximal GlcNAc residue mediating this effect through an unknown mechanism. Here, we present two crystal structures of salmon calcitonin-bound, GlcNAc-bearing CTR ECD at 1.78 and 2.85 Å resolutions and analyze the mechanism of the glycan effect. The N130 GlcNAc does not contact the hormone. Surprisingly, the structures are nearly identical to a structure of hormone-bound, N-glycan-free ECD, which suggested that the GlcNAc might affect CTR dynamics not observed in the static crystallographic snapshots. Hydrogen-deuterium exchange mass spectrometry and molecular dynamics simulations revealed that glycosylation stabilized a β-sheet adjacent to the N130 GlcNAc and the N-terminal α-helix near the peptide-binding site while increasing flexibility of the peptide-binding site turret loop. These changes due to N-glycosylation increased the ligand on-rate and decreased its off-rate. The glycan effect extended to RAMP-CTR amylin receptor complexes and was also conserved in the related CGRP receptor. These results reveal that N-glycosylation can modulate GPCR function by altering receptor dynamics.
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Affiliation(s)
- Sang-Min Lee
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA; Present Address: Department of Basic Pharmaceutical Sciences, Fred Wilson School of Pharmacy, High Point University, High Point, NC, 27268, USA
| | - Yejin Jeong
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - John Simms
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
| | - Margaret L Warner
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - David R Poyner
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
| | - Ka Young Chung
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
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12
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Abstract
Receptor activity-modifying proteins (RAMPs) are a family of three single span transmembrane proteins in humans that interact with many GPCRs and can modulate their function. RAMPs were discovered as key components of the calcitonin gene-related peptide and adrenomedullin receptors. They are required for transport of this class B GPCR, calcitonin receptor-like receptor (CLR), to the cell surface and determine its peptide ligand binding preferences. Soon thereafter RAMPs were shown to modulate the binding of calcitonin and amylin peptides to the related calcitonin receptor (CTR) and in the years since an ever-growing number of RAMP-interacting receptors have been identified including most if not all of the 15 class B GPCRs and several GPCRs from other families. Studies of CLR, CTR, and a handful of other GPCRs revealed that RAMPs are able to modulate various aspects of receptor function including trafficking, ligand binding, and signaling. Here, we review RAMP interactions and functions with an emphasis on class B receptors for which our understanding is most advanced. A key focus is to discuss recent evidence that RAMPs serve as endogenous allosteric modulators of CLR and CTR. We discuss structural studies of RAMP-CLR complexes and CTR and biochemical and pharmacological studies that collectively have significantly expanded our understanding of the mechanistic basis for RAMP modulation of these class B GPCRs. Last, we consider the implications of these findings for drug development targeting RAMP-CLR/CTR complexes.
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Affiliation(s)
- Augen A Pioszak
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.
| | - Debbie L Hay
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
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13
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Roehrkasse AM, Booe JM, Lee SM, Warner ML, Pioszak AA. Structure-function analyses reveal a triple β-turn receptor-bound conformation of adrenomedullin 2/intermedin and enable peptide antagonist design. J Biol Chem 2018; 293:15840-15854. [PMID: 30139742 DOI: 10.1074/jbc.ra118.005062] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 08/20/2018] [Indexed: 12/26/2022] Open
Abstract
The cardioprotective vasodilator peptide adrenomedullin 2/intermedin (AM2/IMD) and the related adrenomedullin (AM) and calcitonin gene-related peptide (CGRP) signal through three heterodimeric receptors comprising the calcitonin receptor-like class B G protein-coupled receptor (CLR) and a variable receptor activity-modifying protein (RAMP1, -2, or -3) that determines ligand selectivity. The CGRP receptor (RAMP1:CLR) favors CGRP binding, whereas the AM1 (RAMP2:CLR) and AM2 (RAMP3:CLR) receptors favor AM binding. How AM2/IMD binds the receptors and how RAMPs modulate its binding is unknown. Here, we show that AM2/IMD binds the three purified RAMP-CLR extracellular domain (ECD) complexes with a selectivity profile that is distinct from those of CGRP and AM. AM2/IMD bound all three ECD complexes but preferred the CGRP and AM2 receptor complexes. A 2.05 Å resolution crystal structure of an AM2/IMD antagonist fragment-bound RAMP1-CLR ECD complex revealed that AM2/IMD binds the complex through a unique triple β-turn conformation that was confirmed by peptide and receptor mutagenesis. Comparisons of the receptor-bound conformations of AM2/IMD, AM, and a high-affinity CGRP analog revealed differences that may have implications for biased signaling. Guided by the structure, enhanced-affinity AM2/IMD antagonist variants were developed, including one that discriminates the AM1 and AM2 receptors with ∼40-fold difference in affinities and one stabilized by an intramolecular disulfide bond. These results reveal differences in how the three peptides engage the receptors, inform development of AM2/IMD-based pharmacological tools and therapeutics, and provide insights into RAMP modulation of receptor pharmacology.
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Affiliation(s)
- Amanda M Roehrkasse
- From the Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Jason M Booe
- From the Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Sang-Min Lee
- From the Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Margaret L Warner
- From the Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Augen A Pioszak
- From the Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
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14
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Bower RL, Yule L, Rees TA, Deganutti G, Hendrikse ER, Harris PWR, Kowalczyk R, Ridgway Z, Wong AG, Swierkula K, Raleigh DP, Pioszak AA, Brimble MA, Reynolds CA, Walker CS, Hay DL. Molecular Signature for Receptor Engagement in the Metabolic Peptide Hormone Amylin. ACS Pharmacol Transl Sci 2018; 1:32-49. [PMID: 32219203 DOI: 10.1021/acsptsci.8b00002] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Indexed: 11/30/2022]
Abstract
The pancreatic peptide hormone, amylin, plays a critical role in the control of appetite, and synergizes with other key metabolic hormones such as glucagon-like peptide 1 (GLP-1). There is opportunity to develop potent and long-acting analogues of amylin or hybrids between these and GLP-1 mimetics for treating obesity. To achieve this, interrogation of how the 37 amino acid amylin peptide engages with its complex receptor system is required. We synthesized an extensive library of peptides to profile the human amylin sequence, determining the role of its disulfide loop, amidated C-terminus and receptor "capture" and "activation" regions in receptor signaling. We profiled four signaling pathways with different ligands at multiple receptor subtypes, in addition to exploring selectivity determinants between related receptors. Distinct roles for peptide subregions in receptor binding and activation were identified, resulting in peptides with greater activity than the native sequence. Enhanced peptide activity was preserved in the brainstem, the major biological target for amylin. Interpretation of our data using full-length active receptor models supported by molecular dynamics, metadynamics, and supervised molecular dynamics simulations guided the synthesis of a potent dual agonist of GLP-1 and amylin receptors. The data offer new insights into the function of peptide amidation, how allostery drives peptide-receptor interactions, and provide a valuable resource for the development of novel amylin agonists for treating diabetes and obesity.
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Affiliation(s)
- Rebekah L Bower
- School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand
| | - Lauren Yule
- School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand.,School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand.,School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand
| | - Tayla A Rees
- School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand
| | - Giuseppe Deganutti
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, U.K
| | - Erica R Hendrikse
- School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand
| | - Paul W R Harris
- School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand.,School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand.,School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand
| | - Renata Kowalczyk
- School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand.,School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand
| | - Zachary Ridgway
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Amy G Wong
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Katarzyna Swierkula
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, U.K
| | - Daniel P Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States.,Department of Structural and Molecular Biology, University College London, London WC1E 6BT, U.K
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, United States
| | - Margaret A Brimble
- School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand.,School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand
| | - Christopher A Reynolds
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, U.K
| | - Christopher S Walker
- School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand
| | - Debbie L Hay
- School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand.,School of Biological Sciences, School of Chemical Sciences, and Maurice Wilkins Centre, The University of Auckland, Auckland, 1010, New Zealand
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15
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Booe JM, Warner ML, Roehrkasse AM, Hay DL, Pioszak AA. Probing the Mechanism of Receptor Activity-Modifying Protein Modulation of GPCR Ligand Selectivity through Rational Design of Potent Adrenomedullin and Calcitonin Gene-Related Peptide Antagonists. Mol Pharmacol 2018; 93:355-367. [PMID: 29363552 PMCID: PMC5832325 DOI: 10.1124/mol.117.110916] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 01/19/2018] [Indexed: 01/01/2023] Open
Abstract
Binding of the vasodilator peptides adrenomedullin (AM) and calcitonin gene-related peptide (CGRP) to the class B G protein-coupled receptor calcitonin receptor-like receptor (CLR) is modulated by receptor activity-modifying proteins (RAMPs). RAMP1 favors CGRP, whereas RAMP2 and RAMP3 favor AM. Crystal structures of peptide-bound RAMP1/2-CLR extracellular domain (ECD) heterodimers suggested RAMPs alter ligand preference through direct peptide contacts and allosteric modulation of CLR. Here, we probed this dual mechanism through rational structure-guided design of AM and CGRP antagonist variants. Variants were characterized for binding to purified RAMP1/2-CLR ECD and for antagonism of the full-length CGRP (RAMP1:CLR), AM1 (RAMP2:CLR), and AM2 (RAMP3:CLR) receptors. Short nanomolar affinity AM(37-52) and CGRP(27-37) variants were obtained through substitutions including AM S45W/Q50W and CGRP K35W/A36S designed to stabilize their β-turn. K46L and Y52F substitutions designed to exploit RAMP allosteric effects and direct peptide contacts, respectively, yielded AM variants with selectivity for the CGRP receptor over the AM1 receptor. AM(37-52) S45W/K46L/Q50W/Y52F exhibited nanomolar potency at the CGRP receptor and micromolar potency at AM1 A 2.8-Å resolution crystal structure of this variant bound to the RAMP1-CLR ECD confirmed that it bound as designed. CGRP(27-37) N31D/S34P/K35W/A36S exhibited potency and selectivity comparable to the traditional antagonist CGRP(8-37). Giving this variant the ability to contact RAMP2 through the F37Y substitution increased affinity for AM1, but it still preferred the CGRP receptor. These potent peptide antagonists with altered selectivity inform the development of AM/CGRP-based pharmacological tools and support the hypothesis that RAMPs alter CLR ligand selectivity through allosteric effects and direct peptide contacts.
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Affiliation(s)
- Jason M Booe
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (J.M.B., M.L.W., A.M.R., A.A.P.) and School of Biological Sciences, University of Auckland, Auckland, New Zealand (D.L.H.)
| | - Margaret L Warner
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (J.M.B., M.L.W., A.M.R., A.A.P.) and School of Biological Sciences, University of Auckland, Auckland, New Zealand (D.L.H.)
| | - Amanda M Roehrkasse
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (J.M.B., M.L.W., A.M.R., A.A.P.) and School of Biological Sciences, University of Auckland, Auckland, New Zealand (D.L.H.)
| | - Debbie L Hay
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (J.M.B., M.L.W., A.M.R., A.A.P.) and School of Biological Sciences, University of Auckland, Auckland, New Zealand (D.L.H.)
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (J.M.B., M.L.W., A.M.R., A.A.P.) and School of Biological Sciences, University of Auckland, Auckland, New Zealand (D.L.H.)
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16
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Lee SM, Booe JM, Gingell JJ, Sjoelund V, Hay DL, Pioszak AA. N-Glycosylation of Asparagine 130 in the Extracellular Domain of the Human Calcitonin Receptor Significantly Increases Peptide Hormone Affinity. Biochemistry 2017; 56:3380-3393. [PMID: 28614667 DOI: 10.1021/acs.biochem.7b00256] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The calcitonin receptor (CTR) is a class B G protein-coupled receptor that is activated by the peptide hormones calcitonin and amylin. Calcitonin regulates bone remodeling through CTR, whereas amylin regulates blood glucose and food intake by activating CTR in complex with receptor activity-modifying proteins (RAMPs). These receptors are targeted clinically for the treatment of osteoporosis and diabetes. Here, we define the role of CTR N-glycosylation in hormone binding using purified calcitonin and amylin receptor extracellular domain (ECD) glycoforms and fluorescence polarization/anisotropy and isothermal titration calorimetry peptide-binding assays. N-Glycan-free CTR ECD produced in Escherichia coli exhibited ∼10-fold lower peptide affinity than CTR ECD produced in HEK293T cells, which yield complex N-glycans, or in HEK293S GnTI- cells, which yield core N-glycans (Man5GlcNAc2). PNGase F-catalyzed removal of N-glycans at N73, N125, and N130 in the CTR ECD decreased peptide affinity ∼10-fold, whereas Endo H-catalyzed trimming of the N-glycans to single GlcNAc residues had no effect on peptide binding. Similar results were observed for an amylin receptor RAMP2-CTR ECD complex. Characterization of peptide-binding affinities of purified N → Q CTR ECD glycan site mutants combined with PNGase F and Endo H treatment strategies and mass spectrometry to define the glycan species indicated that a single GlcNAc residue at CTR N130 was responsible for the peptide affinity enhancement. Molecular modeling suggested that this GlcNAc functions through an allosteric mechanism rather than by directly contacting the peptide. These results reveal an important role for N-linked glycosylation in the peptide hormone binding of a clinically relevant class B GPCR.
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Affiliation(s)
- Sang-Min Lee
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center , 975 NE 10th Street BRC 462B, Oklahoma City, Oklahoma 73104, United States
| | - Jason M Booe
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center , 975 NE 10th Street BRC 462B, Oklahoma City, Oklahoma 73104, United States
| | | | - Virginie Sjoelund
- Proteomics Division of the Laboratory for Molecular Biology and Cytometry Research, University of Oklahoma Health Sciences Center , 975 NE 10th Street, Oklahoma City, Oklahoma 73104, United States
| | | | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center , 975 NE 10th Street BRC 462B, Oklahoma City, Oklahoma 73104, United States
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17
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Lee SM, Hay DL, Pioszak AA. Calcitonin and amylin receptor peptide interaction mechanisms. INSIGHTS INTO PEPTIDE-BINDING MODES AND ALLOSTERIC MODULATION OF THE CALCITONIN RECEPTOR BY RECEPTOR ACTIVITY-MODIFYING PROTEINS. J Biol Chem 2016; 291:16416. [PMID: 27474777 DOI: 10.1074/jbc.a115.713628] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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18
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Watkins HA, Chakravarthy M, Abhayawardana RS, Gingell JJ, Garelja M, Pardamwar M, McElhinney JMWR, Lathbridge A, Constantine A, Harris PWR, Yuen TY, Brimble MA, Barwell J, Poyner DR, Woolley MJ, Conner AC, Pioszak AA, Reynolds CA, Hay DL. Receptor Activity-modifying Proteins 2 and 3 Generate Adrenomedullin Receptor Subtypes with Distinct Molecular Properties. J Biol Chem 2016; 291:11657-75. [PMID: 27013657 PMCID: PMC4882435 DOI: 10.1074/jbc.m115.688218] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 03/20/2016] [Indexed: 01/28/2023] Open
Abstract
Adrenomedullin (AM) is a peptide hormone with numerous effects in the vascular systems. AM signals through the AM1 and AM2 receptors formed by the obligate heterodimerization of a G protein-coupled receptor, the calcitonin receptor-like receptor (CLR), and receptor activity-modifying proteins 2 and 3 (RAMP2 and RAMP3), respectively. These different CLR-RAMP interactions yield discrete receptor pharmacology and physiological effects. The effective design of therapeutics that target the individual AM receptors is dependent on understanding the molecular details of the effects of RAMPs on CLR. To understand the role of RAMP2 and -3 on the activation and conformation of the CLR subunit of AM receptors, we mutated 68 individual amino acids in the juxtamembrane region of CLR, a key region for activation of AM receptors, and determined the effects on cAMP signaling. Sixteen CLR mutations had differential effects between the AM1 and AM2 receptors. Accompanying this, independent molecular modeling of the full-length AM-bound AM1 and AM2 receptors predicted differences in the binding pocket and differences in the electrostatic potential of the two AM receptors. Druggability analysis indicated unique features that could be used to develop selective small molecule ligands for each receptor. The interaction of RAMP2 or RAMP3 with CLR induces conformational variation in the juxtamembrane region, yielding distinct binding pockets, probably via an allosteric mechanism. These subtype-specific differences have implications for the design of therapeutics aimed at specific AM receptors and for understanding the mechanisms by which accessory proteins affect G protein-coupled receptor function.
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Affiliation(s)
- Harriet A Watkins
- From the School of Biological Sciences, the Maurice Wilkins Centre for Molecular Biodiscovery, and
| | | | | | - Joseph J Gingell
- From the School of Biological Sciences, the Maurice Wilkins Centre for Molecular Biodiscovery, and
| | | | - Meenakshi Pardamwar
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - James M W R McElhinney
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - Alex Lathbridge
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - Arran Constantine
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - Paul W R Harris
- the Maurice Wilkins Centre for Molecular Biodiscovery, and the School of Chemical Sciences, University of Auckland, Auckland 1010, New Zealand
| | - Tsz-Ying Yuen
- the Maurice Wilkins Centre for Molecular Biodiscovery, and the School of Chemical Sciences, University of Auckland, Auckland 1010, New Zealand
| | - Margaret A Brimble
- the Maurice Wilkins Centre for Molecular Biodiscovery, and the School of Chemical Sciences, University of Auckland, Auckland 1010, New Zealand
| | - James Barwell
- the School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, United Kingdom
| | - David R Poyner
- the School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, United Kingdom
| | - Michael J Woolley
- the School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Alex C Conner
- the School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Augen A Pioszak
- the Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Christopher A Reynolds
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom,
| | - Debbie L Hay
- From the School of Biological Sciences, the Maurice Wilkins Centre for Molecular Biodiscovery, and
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19
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J Gingell J, Simms J, Barwell J, Poyner DR, Watkins HA, Pioszak AA, Sexton PM, Hay DL. An allosteric role for receptor activity-modifying proteins in defining GPCR pharmacology. Cell Discov 2016; 2:16012. [PMID: 27462459 PMCID: PMC4869360 DOI: 10.1038/celldisc.2016.12] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 02/24/2016] [Indexed: 12/15/2022] Open
Abstract
G protein-coupled receptors are allosteric proteins that control transmission of external signals to regulate cellular response. Although agonist binding promotes canonical G protein signalling transmitted through conformational changes, G protein-coupled receptors also interact with other proteins. These include other G protein-coupled receptors, other receptors and channels, regulatory proteins and receptor-modifying proteins, notably receptor activity-modifying proteins (RAMPs). RAMPs have at least 11 G protein-coupled receptor partners, including many class B G protein-coupled receptors. Prototypic is the calcitonin receptor, with altered ligand specificity when co-expressed with RAMPs. To gain molecular insight into the consequences of this protein–protein interaction, we combined molecular modelling with mutagenesis of the calcitonin receptor extracellular domain, assessed in ligand binding and functional assays. Although some calcitonin receptor residues are universally important for peptide interactions (calcitonin, amylin and calcitonin gene-related peptide) in calcitonin receptor alone or with receptor activity-modifying protein, others have RAMP-dependent effects, whereby mutations decreased amylin/calcitonin gene-related peptide potency substantially only when RAMP was present. Remarkably, the key residues were completely conserved between calcitonin receptor and AMY receptors, and between subtypes of AMY receptor that have different ligand preferences. Mutations at the interface between calcitonin receptor and RAMP affected ligand pharmacology in a RAMP-dependent manner, suggesting that RAMP may allosterically influence the calcitonin receptor conformation. Supporting this, molecular dynamics simulations suggested that the calcitonin receptor extracellular N-terminal domain is more flexible in the presence of receptor activity-modifying protein 1. Thus, RAMPs may act in an allosteric manner to generate a spectrum of unique calcitonin receptor conformational states, explaining the pharmacological preferences of calcitonin receptor-RAMP complexes. This provides novel insight into our understanding of G protein-coupled receptor-protein interaction that is likely broadly applicable for this receptor class.
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Affiliation(s)
- Joseph J Gingell
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
| | - John Simms
- School of Life and Health Sciences, Aston University , Birmingham, UK
| | - James Barwell
- School of Life and Health Sciences, Aston University , Birmingham, UK
| | - David R Poyner
- School of Life and Health Sciences, Aston University , Birmingham, UK
| | - Harriet A Watkins
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center , Oklahoma City, OK, USA
| | - Patrick M Sexton
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, VIC, Australia
| | - Debbie L Hay
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
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20
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Lee SM, Hay DL, Pioszak AA. Calcitonin and Amylin Receptor Peptide Interaction Mechanisms: INSIGHTS INTO PEPTIDE-BINDING MODES AND ALLOSTERIC MODULATION OF THE CALCITONIN RECEPTOR BY RECEPTOR ACTIVITY-MODIFYING PROTEINS. J Biol Chem 2016; 291:8686-700. [PMID: 26895962 DOI: 10.1074/jbc.m115.713628] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Indexed: 12/12/2022] Open
Abstract
Receptor activity-modifying proteins (RAMP1-3) determine the selectivity of the class B G protein-coupled calcitonin receptor (CTR) and the CTR-like receptor (CLR) for calcitonin (CT), amylin (Amy), calcitonin gene-related peptide (CGRP), and adrenomedullin (AM) peptides. RAMP1/2 alter CLR selectivity for CGRP/AM in part by RAMP1 Trp-84 or RAMP2 Glu-101 contacting the distinct CGRP/AM C-terminal residues. It is unclear whether RAMPs use a similar mechanism to modulate CTR affinity for CT and Amy, analogs of which are therapeutics for bone disorders and diabetes, respectively. Here, we reproduced the peptide selectivity of intact CTR, AMY1 (CTR·RAMP1), and AMY2 (CTR·RAMP2) receptors using purified CTR extracellular domain (ECD) and tethered RAMP1- and RAMP2-CTR ECD fusion proteins and antagonist peptides. All three proteins bound salmon calcitonin (sCT). Tethering RAMPs to CTR enhanced binding of rAmy, CGRP, and the AMY antagonist AC413. Peptide alanine-scanning mutagenesis and modeling of receptor-bound sCT and AC413 supported a shared non-helical CGRP-like conformation for their TN(T/V)G motif prior to the C terminus. After this motif, the peptides diverged; the sCT C-terminal Pro was crucial for receptor binding, whereas the AC413/rAmy C-terminal Tyr had little or no influence on binding. Accordingly, mutant RAMP1 W84A- and RAMP2 E101A-CTR ECD retained AC413/rAmy binding. ECD binding and cell-based signaling assays with antagonist sCT/AC413/rAmy variants with C-terminal residue swaps indicated that the C-terminal sCT/rAmy residue identity affects affinity more than selectivity. rAmy(8-37) Y37P exhibited enhanced antagonism of AMY1 while retaining selectivity. These results reveal unexpected differences in how RAMPs determine CTR and CLR peptide selectivity and support the hypothesis that RAMPs allosterically modulate CTR peptide affinity.
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Affiliation(s)
- Sang-Min Lee
- From the Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104 and
| | - Debbie L Hay
- the School of Biological Sciences and Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1142, New Zealand
| | - Augen A Pioszak
- From the Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104 and
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21
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Abstract
It is now recognized that G protein-coupled receptors (GPCRs), once considered largely independent functional units, have a far more diverse molecular architecture. Receptor activity-modifying proteins (RAMPs) provide an important example of proteins that interact with GPCRs to modify their function. RAMPs are able to act as pharmacological switches and chaperones, and they can regulate signaling and/or trafficking in a receptor-dependent manner. This review covers recent discoveries in the RAMP field and summarizes the known GPCR partners and functions of RAMPs. We also discuss the first peptide-bound structures of RAMP-GPCR complexes, which give insight into the molecular mechanisms that enable RAMPs to alter the pharmacology and signaling of GPCRs.
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Affiliation(s)
- Debbie L Hay
- School of Biological Sciences and Maurice Wilkins Center, University of Auckland, Auckland 1142, New Zealand;
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104;
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22
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Lee SM, Booe JM, Pioszak AA. Structural insights into ligand recognition and selectivity for classes A, B, and C GPCRs. Eur J Pharmacol 2015; 763:196-205. [PMID: 25981303 DOI: 10.1016/j.ejphar.2015.05.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 05/05/2015] [Accepted: 05/12/2015] [Indexed: 01/14/2023]
Abstract
The G protein-coupled receptor (GPCR) superfamily constitutes the largest collection of cell surface signaling proteins with approximately 800 members in the human genome. GPCRs regulate virtually all aspects of physiology and they are an important class of drug targets with ~30% of drugs on the market targeting a GPCR. Breakthroughs in GPCR structural biology in recent years have significantly expanded our understanding of GPCR structure and function and ushered in a new era of structure-based drug design for GPCRs. Crystal structures for nearly thirty distinct GPCRs are now available including receptors from each of the major classes, A, B, C, and F. These structures provide a foundation for understanding the molecular basis of GPCR pharmacology. Here, we review structural mechanisms of ligand recognition and selectivity of GPCRs with a focus on selected examples from classes A, B, and C, and we highlight major unresolved questions for future structural studies.
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Affiliation(s)
- Sang-Min Lee
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Jason M Booe
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
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23
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Abstract
Secreted R-spondin proteins (RSPOs1-4) function as adult stem cell growth factors by potentiating Wnt signaling. Simultaneous binding of distinct regions of the RSPO Fu1-Fu2 domain module to the extracellular domains (ECDs) of the LGR4 G protein-coupled receptor and the ZNRF3 transmembrane E3 ubiquitin ligase regulates Wnt receptor availability. Here, we examine the molecular basis for the differing signaling strengths of RSPOs1-4 using purified RSPO Fu1-Fu2, LGR4 ECD, and ZNRF3 ECD proteins in Wnt signaling and receptor binding assays, and we engineer novel high-potency RSPOs. RSPO2/3/4 had similar signaling potencies that were stronger than that of RSPO1, whereas RSPO1/2/3 had similar efficacies that were greater than that of RSPO4. The RSPOs bound LGR4 with affinity rank order RSPO4 > RSPO2/3 > RSPO1 and ZNRF3 with affinity rank order RSPO2/3 > > RSPO1 > RSPO4. An RSPO2-4 chimera combining RSPO2 ZNRF3 binding with RSPO4 LGR4 binding was a "Superspondin" that exhibited enhanced ternary complex formation and 10-fold stronger signaling potency than RSPO2 and efficacy equivalent to RSPO2. An RSPO4-1 chimera combining RSPO4 ZNRF3 binding with RSPO1 LGR4 binding was a "Poorspondin" that exhibited signaling potency similar to RSPO1 and efficacy equivalent to RSPO4. Conferring increased ZNRF3 binding upon RSPO4 with amino acid substitutions L56F, I58L, and I63M enhanced its signaling potency and efficacy. Our results reveal the molecular basis for RSPOs1-4 activity differences and suggest that signaling potency is determined by ternary complex formation ability, whereas efficacy depends on ZNRF3 recruitment. High-potency RSPOs may be of value for regenerative medicine and/or therapeutic applications.
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Affiliation(s)
- Margaret L Warner
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Tufica Bell
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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Moad HE, Pioszak AA. Selective CGRP and adrenomedullin peptide binding by tethered RAMP-calcitonin receptor-like receptor extracellular domain fusion proteins. Protein Sci 2013; 22:1775-85. [PMID: 24115156 DOI: 10.1002/pro.2377] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 09/07/2013] [Accepted: 09/10/2013] [Indexed: 11/12/2022]
Abstract
Calcitonin gene-related peptide (CGRP) and adrenomedullin (AM) are related peptides that are potent vasodilators. The CGRP and AM receptors are heteromeric protein complexes comprised of a shared calcitonin receptor-like receptor (CLR) subunit and a variable receptor activity modifying protein (RAMP) subunit. RAMP1 enables CGRP binding whereas RAMP2 confers AM specificity. How RAMPs determine peptide selectivity is unclear and the receptor stoichiometries are a topic of debate with evidence for 1:1, 2:2, and 2:1 CLR:RAMP stoichiometries. Here, we describe bacterial production of recombinant tethered RAMP-CLR extracellular domain (ECD) fusion proteins and biochemical characterization of their peptide binding properties. Tethering the two ECDs ensures complex stability and enforces defined stoichiometry. The RAMP1-CLR ECD fusion purified as a monomer, whereas the RAMP2-CLR ECD fusion purified as a dimer. Both proteins selectively bound their respective peptides with affinities in the low micromolar range. Truncated CGRP(27-37) and AM(37-52) fragments were identified as the minimal ECD complex binding regions. The CGRP C-terminal amide group contributed to, but was not required for, ECD binding, whereas the AM C-terminal amide group was essential for ECD binding. Alanine-scan experiments identified CGRP residues T30, V32, and F37 and AM residues P43, K46, I47, and Y52 as critical for ECD binding. Our results identify CGRP and AM determinants for receptor ECD complex binding and suggest that the CGRP receptor functions as a 1:1 heterodimer. In contrast, the AM receptor may function as a 2:2 dimer of heterodimers, although our results cannot rule out 2:1 or 1:1 stoichiometries.
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Affiliation(s)
- Heather E Moad
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, 73104
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Moad HE, Pioszak AA. Reconstitution of R-spondin:LGR4:ZNRF3 adult stem cell growth factor signaling complexes with recombinant proteins produced in Escherichia coli. Biochemistry 2013; 52:7295-304. [PMID: 24050775 DOI: 10.1021/bi401090h] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
R-Spondins are secreted glycoproteins (RSPO1-RSPO4) that have proliferative effects on adult stem cells by potentiating Wnt signaling. RSPO actions are mediated by the leucine-rich repeat (LRR)-containing seven-transmembrane receptors LGR4-LGR6 and the transmembrane E3 ubiquitin ligases ZNRF3 and RNF43. Here, we present a methodology for the bacterial expression and purification of the signaling competent, cysteine-rich Fu1-Fu2 domains of the four human RSPOs, a fragment of the human LGR4 extracellular domain (ECD) containing LRR1-14, and the human ZNRF3 ECD. In a cell-based signaling assay, the nonglycosylated RSPOs enhanced low-dose Wnt3a signaling with potencies comparable to those of mammalian cell-produced RSPOs and RSPO2 and -3 were more potent than RSPO1 and -4. LGR4 LRR1-14 and ZNRF3 ECD inhibited RSPO2-enhanced Wnt3a signaling. The RSPOs bound LGR4 LRR1-14 with nanomolar affinities that decreased in the following order in a time-resolved fluorescence resonance energy transfer (TR-FRET) assay: RSPO4 > RSPO2 > RSPO3 > RSPO1. RSPO-receptor interactions were further characterized with a native gel electrophoretic mobility shift assay, which corroborated the RSPO-LGR4 TR-FRET results and indicated that RSPOs weakly bound ZNRF3 with affinities that decreased in the following order: RSPO2 > RSPO3 > RSPO1. RSPO4:ZNRF3 complexes were not detected. Lastly, ternary RSPO:LGR4:ZNRF3 complexes were detected for RSPO2 and -3. Our results indicate that RSPO and LGR4 N-glycans are dispensable for function, demonstrate RSPO-mediated ternary complex formation, and suggest that the stronger signaling potencies of RSPO2 and -3 result from their strong binding of both receptors. Our unique protein production methodology may provide a cost-effective source of recombinant RSPOs for regenerative medicine applications.
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Affiliation(s)
- Heather E Moad
- Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center , Oklahoma City, Oklahoma 73104, United States
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Pal K, Swaminathan K, Xu HE, Pioszak AA. Structural basis for hormone recognition by the Human CRFR2{alpha} G protein-coupled receptor. J Biol Chem 2010; 285:40351-61. [PMID: 20966082 DOI: 10.1074/jbc.m110.186072] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The mammalian corticotropin releasing factor (CRF)/urocortin (Ucn) peptide hormones include four structurally similar peptides, CRF, Ucn1, Ucn2, and Ucn3, that regulate stress responses, metabolism, and cardiovascular function by activating either of two related class B G protein-coupled receptors, CRFR1 and CRFR2. CRF and Ucn1 activate both receptors, whereas Ucn2 and Ucn3 are CRFR2-selective. The molecular basis for selectivity is unclear. Here, we show that the purified N-terminal extracellular domains (ECDs) of human CRFR1 and the CRFR2α isoform are sufficient to discriminate the peptides, and we present three crystal structures of the CRFR2α ECD bound to each of the Ucn peptides. The CRFR2α ECD forms the same fold observed for the CRFR1 and mouse CRFR2β ECDs but contains a unique N-terminal α-helix formed by its pseudo signal peptide. The CRFR2α ECD peptide-binding site architecture is similar to that of CRFR1, and binding of the α-helical Ucn peptides closely resembles CRF binding to CRFR1. Comparing the electrostatic surface potentials of the ECDs suggests a charge compatibility mechanism for ligand discrimination involving a single amino acid difference in the receptors (CRFR1 Glu104/CRFR2α Pro-100) at a site proximate to peptide residue 35 (Arg in CRF/Ucn1, Ala in Ucn2/3). CRFR1 Glu-104 acts as a selectivity filter preventing Ucn2/3 binding because the nonpolar Ala-35 is incompatible with the negatively charged Glu-104. The structures explain the mechanisms of ligand recognition and discrimination and provide a molecular template for the rational design of therapeutic agents selectively targeting these receptors.
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Affiliation(s)
- Kuntal Pal
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA
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Pioszak AA, Harikumar KG, Parker NR, Miller LJ, Xu HE. Dimeric arrangement of the parathyroid hormone receptor and a structural mechanism for ligand-induced dissociation. J Biol Chem 2010; 285:12435-44. [PMID: 20172855 DOI: 10.1074/jbc.m109.093138] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The parathyroid hormone receptor (PTH1R) is a class B G protein-coupled receptor that is activated by parathyroid hormone (PTH) and PTH-related protein (PTHrP). Little is known about the oligomeric state of the receptor and its regulation by hormone. The crystal structure of the ligand-free PTH1R extracellular domain (ECD) reveals an unexpected dimer in which the C-terminal segment of both ECD protomers forms an alpha-helix that mimics PTH/PTHrP by occupying the peptide binding groove of the opposing protomer. ECD-mediated oligomerization of intact PTH1R was confirmed in living cells by bioluminescence and fluorescence resonance energy transfer experiments. As predicted by the structure, PTH binding disrupted receptor oligomerization. A receptor rendered monomeric by mutations in the ECD retained wild-type PTH binding and cAMP signaling ability. Our results are consistent with the hypothesis that PTH1R forms constitutive dimers that are dissociated by ligand binding and that monomeric PTH1R is capable of activating G protein.
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Affiliation(s)
- Augen A Pioszak
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA.
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Pioszak AA, Parker NR, Gardella TJ, Xu HE. Structural basis for parathyroid hormone-related protein binding to the parathyroid hormone receptor and design of conformation-selective peptides. J Biol Chem 2009; 284:28382-28391. [PMID: 19674967 DOI: 10.1074/jbc.m109.022905] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Parathyroid hormone (PTH) and PTH-related protein (PTHrP) are two related peptides that control calcium/phosphate homeostasis and bone development, respectively, through activation of the PTH/PTHrP receptor (PTH1R), a class B G protein-coupled receptor. Both peptides hold clinical interest for their capacities to stimulate bone formation. PTH and PTHrP display different selectivity for two distinct PTH1R conformations, but how their binding to the receptor differs is unclear. The high resolution crystal structure of PTHrP bound to the extracellular domain (ECD) of PTH1R reveals that PTHrP binds as an amphipathic alpha-helix to the same hydrophobic groove in the ECD as occupied by PTH, but in contrast to a straight, continuous PTH helix, the PTHrP helix is gently curved and C-terminally "unwound." The receptor accommodates the altered binding modes by shifting the side chain conformations of two residues within the binding groove: Leu-41 and Ile-115, the former acting as a rotamer toggle switch to accommodate PTH/PTHrP sequence divergence, and the latter adapting to the PTHrP curvature. Binding studies performed with PTH/PTHrP hybrid ligands having reciprocal exchanges of residues involved in different contacts confirmed functional consequences for the altered interactions and enabled the design of altered PTH and PTHrP peptides that adopt the ECD-binding mode of the opposite peptide. Hybrid peptides that bound the ECD poorly were selective for the G protein-coupled PTH1R conformation. These results establish a molecular model for better understanding of how two biologically distinct ligands can act through a single receptor and provide a template for designing better PTH/PTHrP therapeutics.
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Affiliation(s)
- Augen A Pioszak
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan 49503.
| | - Naomi R Parker
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan 49503
| | - Thomas J Gardella
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02144
| | - H Eric Xu
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan 49503.
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Pioszak AA, Parker NR, Suino-Powell K, Xu HE. Molecular recognition of corticotropin-releasing factor by its G-protein-coupled receptor CRFR1. J Biol Chem 2008; 283:32900-12. [PMID: 18801728 DOI: 10.1074/jbc.m805749200] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The bimolecular interaction between corticotropin-releasing factor (CRF), a neuropeptide, and its type 1 receptor (CRFR1), a class B G-protein-coupled receptor (GPCR), is crucial for activation of the hypothalamic-pituitary-adrenal axis in response to stress, and has been a target of intense drug design for the treatment of anxiety, depression, and related disorders. As a class B GPCR, CRFR1 contains an N-terminal extracellular domain (ECD) that provides the primary ligand binding determinants. Here we present three crystal structures of the human CRFR1 ECD, one in a ligand-free form and two in distinct CRF-bound states. The CRFR1 ECD adopts the alpha-beta-betaalpha fold observed for other class B GPCR ECDs, but the N-terminal alpha-helix is significantly shorter and does not contact CRF. CRF adopts a continuous alpha-helix that docks in a hydrophobic surface of the ECD that is distinct from the peptide-binding site of other class B GPCRs, thereby providing a basis for the specificity of ligand recognition between CRFR1 and other class B GPCRs. The binding of CRF is accompanied by clamp-like conformational changes of two loops of the receptor that anchor the CRF C terminus, including the C-terminal amide group. These structural studies provide a molecular framework for understanding peptide binding and specificity by the CRF receptors as well as a template for designing potent and selective CRFR1 antagonists for therapeutic applications.
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Affiliation(s)
- Augen A Pioszak
- Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA.
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30
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Abstract
Parathyroid hormone (PTH) is central to calcium homeostasis and bone maintenance in vertebrates, and as such it has been used for treating osteoporosis. It acts primarily by binding to its receptor, PTH1R, a member of the class B G protein-coupled receptor (GPCR) family that also includes receptors for glucagon, calcitonin, and other therapeutically important peptide hormones. Despite considerable interest and much research, determining the structure of the receptor-hormone complex has been hindered by difficulties in purifying the receptor and obtaining diffraction-quality crystals. Here, we present a method for expression and purification of the extracellular domain (ECD) of human PTH1R engineered as a maltose-binding protein (MBP) fusion that readily crystallizes. The 1.95-A structure of PTH bound to the MBP-PTH1R-ECD fusion reveals that PTH docks as an amphipathic helix into a central hydrophobic groove formed by a three-layer alpha-beta-betaalpha fold of the PTH1R ECD, resembling a hot dog in a bun. Conservation in the ECD scaffold and the helical structure of peptide hormones emphasizes this hot dog model as a general mechanism of hormone recognition common to class B GPCRs. Our findings reveal critical insights into PTH actions and provide a rational template for drug design that targets this hormone signaling pathway.
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MESH Headings
- Amino Acid Sequence
- Animals
- Cattle
- Conserved Sequence
- Crystallography, X-Ray
- Gene Expression
- Humans
- Models, Molecular
- Molecular Sequence Data
- Parathyroid Hormone/chemistry
- Parathyroid Hormone/metabolism
- Protein Binding
- Protein Structure, Quaternary
- Receptor, Parathyroid Hormone, Type 1/chemistry
- Receptor, Parathyroid Hormone, Type 1/genetics
- Receptor, Parathyroid Hormone, Type 1/isolation & purification
- Receptor, Parathyroid Hormone, Type 1/metabolism
- Sensitivity and Specificity
- Sequence Alignment
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Affiliation(s)
- Augen A. Pioszak
- Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Avenue, N.E., Grand Rapids, MI 49503
| | - H. Eric Xu
- Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Avenue, N.E., Grand Rapids, MI 49503
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Jiang P, Pioszak AA, Ninfa AJ. Structure-function analysis of glutamine synthetase adenylyltransferase (ATase, EC 2.7.7.49) of Escherichia coli. Biochemistry 2007; 46:4117-32. [PMID: 17355124 DOI: 10.1021/bi0620508] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glutamine synthetase adenylyltransferase (ATase) regulates the activity of glutamine synthetase by adenylylation and deadenylylation in response to signals of nitrogen and carbon status: glutamine, alpha-ketoglutarate, and the uridylylated and unmodified forms of the PII signal transduction protein. ATase consists of two conserved nucleotidyltransferase (NT) domains linked by a central region of approximately 200 amino acids. Here, we study the activities and regulation of mutated and truncated forms of ATase. Our results indicate the following. (i) The N-terminal NT domain contained the adenylyl-removing (AR) active site, and the C-terminal NT domain contained the adenylyltransferase (AT) active site. (ii) The enzyme contained a glutamine binding site, and glutamine increased the affinity for PII. (iii) The enzyme appeared to contain multiple sites for the binding of PII and PII-UMP. (iv) Truncated versions of ATase missing the C-terminal (NT) domain lacked both AT and AR activity, suggesting a role for the C-terminal NT domain in both activities. (v) The purified C-terminal NT domain and larger polypeptides containing this domain had significant basal AT activity, which was stimulated by glutamine. These polypeptides were indifferent to PII and PII-UMP, or their ATase activity was inhibited by either PII or PII-UMP. (vi) Certain point mutations in the central region or an internal deletion removing most of this part of the protein eliminated the AR activity and eliminated activation of the AT activity by PII, while not eliminating the binding of PII or PII-UMP. That is, these mutations in the central region appeared to destroy the communication between the PII and PII-UMP binding sites and the AT and AR active sites. (vii) Certain mutations in the central region of ATase appeared to dramatically improve the binding of glutamine to the enzyme. (viii) While the isolated AT and AR domains of ATase bound poorly to PII and PII-UMP, these domains bound PII and PII-UMP significantly better when linked to the central region of ATase. Together, our results indicate a highly coordinated enzyme, in which the AT and AR domains participate in each other's regulation and distant regulatory sites are in communication with each other. A model for the regulation of ATase by glutamine, PII, and PII-UMP consistent with all data is presented.
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Affiliation(s)
- Peng Jiang
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606, USA
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Pioszak AA, Murayama K, Nakagawa N, Ebihara A, Kuramitsu S, Shirouzu M, Yokoyama S. Structures of a putative RNA 5-methyluridine methyltransferase, Thermus thermophilus TTHA1280, and its complex with S-adenosyl-L-homocysteine. Acta Crystallogr Sect F Struct Biol Cryst Commun 2005; 61:867-74. [PMID: 16511182 PMCID: PMC1991318 DOI: 10.1107/s1744309105029842] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Accepted: 09/20/2005] [Indexed: 01/22/2023]
Abstract
The Thermus thermophilus hypothetical protein TTHA1280 belongs to a family of predicted S-adenosyl-L-methionine (AdoMet) dependent RNA methyltransferases (MTases) present in many bacterial and archaeal species. Inspection of amino-acid sequence motifs common to class I Rossmann-fold-like MTases suggested a specific role as an RNA 5-methyluridine MTase. Selenomethionine (SeMet) labelled and native versions of the protein were expressed, purified and crystallized. Two crystal forms of the SeMet-labelled apoprotein were obtained: SeMet-ApoI and SeMet-ApoII. Cocrystallization of the native protein with S-adenosyl-L-homocysteine (AdoHcy) yielded a third crystal form, Native-AdoHcy. The SeMet-ApoI structure was solved by the multiple anomalous dispersion method and refined at 2.55 A resolution. The SeMet-ApoII and Native-AdoHcy structures were solved by molecular replacement and refined at 1.80 and 2.60 A, respectively. TTHA1280 formed a homodimer in the crystals and in solution. Each subunit folds into a three-domain structure composed of a small N-terminal PUA domain, a central alpha/beta-domain and a C-terminal Rossmann-fold-like MTase domain. The three domains form an overall clamp-like shape, with the putative active site facing a deep cleft. The architecture of the active site is consistent with specific recognition of uridine and catalysis of methyl transfer to the 5-carbon position. The cleft is suitable in size and charge distribution for binding single-stranded RNA.
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Affiliation(s)
| | | | - Noriko Nakagawa
- RIKEN Harima Institute at SPring-8, Hyogo, Japan
- Graduate School of Science, Osaka University, Osaka, Japan
| | - Akio Ebihara
- RIKEN Harima Institute at SPring-8, Hyogo, Japan
- Graduate School of Science, Osaka University, Osaka, Japan
| | - Seiki Kuramitsu
- RIKEN Genomic Sciences Center, Yokohama, Japan
- RIKEN Harima Institute at SPring-8, Hyogo, Japan
- Graduate School of Science, Osaka University, Osaka, Japan
| | - Mikako Shirouzu
- RIKEN Genomic Sciences Center, Yokohama, Japan
- RIKEN Harima Institute at SPring-8, Hyogo, Japan
| | - Shigeyuki Yokoyama
- RIKEN Harima Institute at SPring-8, Hyogo, Japan
- Graduate School of Science, University of Tokyo, Tokyo, Japan
- Correspondence e-mail:
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Pioszak AA, Ninfa AJ. Mutations altering the N-terminal receiver domain of NRI (NtrC) That prevent dephosphorylation by the NRII-PII complex in Escherichia coli. J Bacteriol 2004; 186:5730-40. [PMID: 15317778 PMCID: PMC516846 DOI: 10.1128/jb.186.17.5730-5740.2004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The phosphorylated form of NRI is the transcriptional activator of nitrogen-regulated genes in Escherichia coli. NRI approximately P displays a slow autophosphatase activity and is rapidly dephosphorylated by the complex of the NRII and PII signal transduction proteins. Here we describe the isolation of two mutations, causing the alterations DeltaD10 and K104Q in the receiver domain of NRI, that were selected as conferring resistance to dephosphorylation by the NRII-PII complex. The mutations, which alter highly conserved residues near the D54 site of phosphorylation in the NRI receiver domain, resulted in elevated expression of nitrogen-regulated genes under nitrogen-rich conditions. The altered NRI receiver domains were phosphorylated by NRII in vitro but were defective in dephosphorylation. The DeltaD10 receiver domain retained normal autophosphatase activity but was resistant to dephosphorylation by the NRII-PII complex. The K104Q receiver domain lacked both the autophosphatase activity and the ability to be dephosphorylated by the NRII-PII complex. The properties of these altered proteins are consistent with the hypothesis that the NRII-PII complex is not a true phosphatase but rather collaborates with NRI approximately P to bring about its dephosphorylation.
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Affiliation(s)
- Augen A Pioszak
- Department of Biological Chemistry, University of Michigan Medical School, 1301 E. Catherine, Ann Arbor, MI 48109-0606, USA
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Song Y, Peisach D, Pioszak AA, Xu Z, Ninfa AJ. Crystal structure of the C-terminal domain of the two-component system transmitter protein nitrogen regulator II (NRII; NtrB), regulator of nitrogen assimilation in Escherichia coli. Biochemistry 2004; 43:6670-8. [PMID: 15157101 DOI: 10.1021/bi049474r] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The kinase/phosphatase nitrogen regulator II (NRII, NtrB) is a member of the transmitter protein family of conserved two-component signal transduction systems. The kinase activity of NRII brings about the phosphorylation of the transcription factor nitrogen regulator I (NRI, NtrC), causing the activation of Ntr gene transcription. The phosphatase activity of NRII results in the inactivation of NRI-P. The activities of NRII are regulated by the signal transduction protein encoded by glnB, PII protein, which upon binding to NRII inhibits the kinase and activates the phosphatase activity. The C-terminal ATP-binding domain of NRII is required for both the kinase and phosphatase activities and contains the PII binding site. Here, we present the crystal structure of the C-terminal domain of a mutant form of NRII, NRII-Y302N, at 1.6 A resolution and compare this structure to the analogous domains of other two-component system transmitter proteins. While the C-terminal domain of NRII shares the general tertiary structure seen in CheA, PhoQ, and EnvZ transmitter proteins, it contains a distinct beta-hairpin projection that is absent in these related proteins. This projection is near the site of a well-characterized mutation that reduces the binding of PII and near other less-characterized mutations that affect the phosphatase activity of NRII. Sequence alignment suggests that the beta-hairpin projection is present in NRII proteins from various organisms, and absent in other transmitter proteins from Escherichia coliK-12. This unique structural element in the NRII C-terminal domain may play a role in binding PII or in intramolecular signal transduction.
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Affiliation(s)
- Yuanda Song
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606, USA
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35
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Pioszak AA, Ninfa AJ. Mechanism of the PII-activated phosphatase activity of Escherichia coli NRII (NtrB): how the different domains of NRII collaborate to act as a phosphatase. Biochemistry 2003; 42:8885-99. [PMID: 12873150 DOI: 10.1021/bi030065p] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The phosphatase activity of the homodimeric NRII protein of Escherichia coli is activated by the PII protein and requires all three domains of NRII. Mutations in the N-terminal domain (L16R), central domain (A129T), C-terminal domain PII-binding site (S227R), and C-terminal domain ATP-lid (Y302N) of NRII result in diminished phosphatase activity. Here, we used heterodimers formed in vitro from purified homodimeric proteins to study the phosphatase activity. A129T, S227R, and Y302N mutant subunits and A129T/S227R, A129T/Y302N, and S227R/Y302N double-mutant subunits formed stable heterodimers and were amenable to analysis; heterodimers containing these mutant subunits in various combinations were formed and their activities assessed. Complementation of the PII-activated phosphatase activity was observed in heterodimers containing S227R and Y302N subunits and in heterodimers containing A129T and Y302N subunits, but not in heterodimers containing A129T and S227R subunits. Complementation of the PII-activated phosphatase activity was also observed in heterodimers containing A129T/S227R and Y302N subunits, but not in heterodimers containing A129T/Y302N and S227R subunits. Finally, inclusion of an S227R/Y302N subunit in a heterodimer with a subunit having wild-type phosphatase activity resulted in a dramatic decrease in phosphatase activity, while inclusion of an A129T/S227R subunit did not. These results suggest that the phosphatase activity of NRII requires the collaboration of the PII-binding site from one subunit of the dimer, the central domain from the same subunit, and the ATP-lid from the opposing subunit, in addition to the undefined N-terminal domain requirement(s).
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Affiliation(s)
- Augen A Pioszak
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606, USA
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Pioszak AA, Ninfa AJ. Genetic and biochemical analysis of phosphatase activity of Escherichia coli NRII (NtrB) and its regulation by the PII signal transduction protein. J Bacteriol 2003; 185:1299-315. [PMID: 12562801 PMCID: PMC142841 DOI: 10.1128/jb.185.4.1299-1315.2003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mutant forms of Escherichia coli NRII (NtrB) were isolated that retained wild-type NRII kinase activity but were defective in the PII-activated phosphatase activity of NRII. Mutant strains were selected as mimicking the phenotype of a strain (strain BK) that lacks both of the related PII and GlnK signal transduction proteins and thus has no mechanism for activation of the NRII phosphatase activity. The selection and screening procedure resulted in the isolation of numerous mutants that phenotypically resembled strain BK to various extents. Mutations mapped to the glnL (ntrB) gene encoding NRII and were obtained in all three domains of NRII. Two distinct regions of the C-terminal, ATP-binding domain were identified by clusters of mutations. One cluster, including the Y302N mutation, altered a lid that sits over the ATP-binding site of NRII. The other cluster, including the S227R mutation, defined a small surface on the "back" or opposite side of this domain. The S227R and Y302N proteins were purified, along with the A129T (NRII2302) protein, which has reduced phosphatase activity due to a mutation in the central domain of NRII, and the L16R protein, which has a mutation in the N-terminal domain of NRII. The S227R, Y302N, and L16R proteins were specifically defective in the PII-activated phosphatase activity of NRII. Wild-type NRII, Y302N, A129T, and L16R proteins bound to PII, while the S227R protein was defective in binding PII. This suggests that the PII-binding site maps to the "back" of the C-terminal domain and that mutation of the ATP-lid, central domain, and N-terminal domain altered functions necessary for the phosphatase activity after PII binding.
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Affiliation(s)
- Augen A Pioszak
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606, USA
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Pioszak AA, Jiang P, Ninfa AJ. The Escherichia coli PII signal transduction protein regulates the activities of the two-component system transmitter protein NRII by direct interaction with the kinase domain of the transmitter module. Biochemistry 2000; 39:13450-61. [PMID: 11063581 DOI: 10.1021/bi000795m] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The PII signal transduction protein regulates the transcription of nitrogen-regulated genes by controlling the kinase and phosphatase activities of NRII. We used a cross-linking approach to study the interaction of the T-loop of the PII protein with NRII. Cross-linking of PII to NRII required ATP and 2-ketoglutarate, allosteric effectors known to control PII activity, and was not affected by the presence of excess nonspecific proteins such as bovine serum albumin. The purified cross-linked species appeared to consist mainly of PII trimers in which one of the three subunits was cross-linked to a single subunit of the NRII dimer; this complex had the phosphatase activity characteristic of the un-cross-linked PII-NRII complex, and had significant phosphatase activity in the absence of 2-ketoglutarate, suggesting that once PII was tethered to NRII the active conformation was stabilized. Studies with truncated forms of NRII indicated that the purified N-terminal "sensory" domain of NRII was not cross-linked to PII, nor was a polypeptide consisting of NRII residues 1-189. In contrast, polypeptides containing the kinase domain of the transmitter module of NRII (residues 190-349) were cross-linked to PII in an ATP- and 2-ketoglutarate-dependent reaction. These results indicate that PII controls NRII by interaction with the conserved kinase domain of the transmitter module.
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Affiliation(s)
- A A Pioszak
- Department of Biological Chemistry and Human Genetics Training Program, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606, USA
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