Identification of an efficacy switch region in the ghrelin receptor responsible for interchange between agonism and inverse agonism

Birgitte Holst; Jacek Mokrosinski; Manja Lang; Erik Brandt; Rie Nygaard; Thomas M Frimurer; Annette G Beck-Sickinger; Thue W Schwartz

doi:10.1074/jbc.M609796200

Identification of an efficacy switch region in the ghrelin receptor responsible for interchange between agonism and inverse agonism

Birgitte Holst, Jacek Mokrosinski, Manja Lang, Erik Brandt, Rie Nygaard, Thomas M Frimurer, Annette G Beck-Sickinger, Thue W Schwartz

Department of Neuroscience

72 Citations (Scopus)

Abstract

The carboxyamidated wFwLL peptide was used as a core ligand to probe the structural basis for agonism versus inverse agonism in the constitutively active ghrelin receptor. In the ligand, an efficacy switch could be built at the N terminus, as exemplified by AwFwLL, which functioned as a high potency agonist, whereas KwFwLL was an equally high potency inverse agonist. The wFw-containing peptides, agonists as well as inverse agonists, were affected by receptor mutations covering the whole main ligand-binding pocket with key interaction sites being an aromatic cluster in transmembrane (TM)-VI and -VII and residues on the opposing face of TM-III. Gain-of-function in respect of either increased agonist or inverse agonist potency or swap between high potency versions of these properties was obtained by substitutions at a number of positions covering a broad area of the binding pocket on TM-III, -IV, and -V. However, in particular, space-generating substitutions at position III:04 shifted the efficacy of the ligands from inverse agonism toward agonism, whereas similar substitutions at position III: 08, one helical turn below, shifted the efficacy from agonism toward inverse agonism. It is suggested that the relative position of the ligand in the binding pocket between this "efficacy shift region" on TM-III and the opposing aromatic cluster on TM-VI and TM-VII leads either to agonism, i.e. in a superficial binding mode, or it leads to inverse agonism, i.e. in a more profound binding mode. This relationship between different binding modes and opposite efficacy is in accordance with the Global Toggle Switch model for 7TM receptor activation.

Original language	English
Journal	Journal of Biological Chemistry
Volume	282
Issue number	21
Pages (from-to)	15799-811
Number of pages	12
ISSN	0021-9258
DOIs	https://doi.org/10.1074/jbc.M609796200
Publication status	Published - 2007

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10.1074/jbc.M609796200

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title = "Identification of an efficacy switch region in the ghrelin receptor responsible for interchange between agonism and inverse agonism",

abstract = "The carboxyamidated wFwLL peptide was used as a core ligand to probe the structural basis for agonism versus inverse agonism in the constitutively active ghrelin receptor. In the ligand, an efficacy switch could be built at the N terminus, as exemplified by AwFwLL, which functioned as a high potency agonist, whereas KwFwLL was an equally high potency inverse agonist. The wFw-containing peptides, agonists as well as inverse agonists, were affected by receptor mutations covering the whole main ligand-binding pocket with key interaction sites being an aromatic cluster in transmembrane (TM)-VI and -VII and residues on the opposing face of TM-III. Gain-of-function in respect of either increased agonist or inverse agonist potency or swap between high potency versions of these properties was obtained by substitutions at a number of positions covering a broad area of the binding pocket on TM-III, -IV, and -V. However, in particular, space-generating substitutions at position III:04 shifted the efficacy of the ligands from inverse agonism toward agonism, whereas similar substitutions at position III: 08, one helical turn below, shifted the efficacy from agonism toward inverse agonism. It is suggested that the relative position of the ligand in the binding pocket between this {"}efficacy shift region{"} on TM-III and the opposing aromatic cluster on TM-VI and TM-VII leads either to agonism, i.e. in a superficial binding mode, or it leads to inverse agonism, i.e. in a more profound binding mode. This relationship between different binding modes and opposite efficacy is in accordance with the Global Toggle Switch model for 7TM receptor activation.",

author = "Birgitte Holst and Jacek Mokrosinski and Manja Lang and Erik Brandt and Rie Nygaard and Frimurer, {Thomas M} and Beck-Sickinger, {Annette G} and Schwartz, {Thue W}",

note = "Keywords: Amino Acid Substitution; Animals; Binding Sites; COS Cells; Cercopithecus aethiops; Humans; Ligands; Models, Molecular; Mutation, Missense; Peptides; Protein Binding; Protein Structure, Secondary; Receptors, G-Protein-Coupled; Receptors, Ghrelin; Structure-Activity Relationship",

year = "2007",

doi = "10.1074/jbc.M609796200",

language = "English",

volume = "282",

pages = "15799--811",

journal = "Journal of Biological Chemistry",

issn = "0021-9258",

publisher = "American Society for Biochemistry and Molecular Biology, Inc.",

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T1 - Identification of an efficacy switch region in the ghrelin receptor responsible for interchange between agonism and inverse agonism

AU - Holst, Birgitte

AU - Mokrosinski, Jacek

AU - Lang, Manja

AU - Brandt, Erik

AU - Nygaard, Rie

AU - Frimurer, Thomas M

AU - Beck-Sickinger, Annette G

AU - Schwartz, Thue W

N1 - Keywords: Amino Acid Substitution; Animals; Binding Sites; COS Cells; Cercopithecus aethiops; Humans; Ligands; Models, Molecular; Mutation, Missense; Peptides; Protein Binding; Protein Structure, Secondary; Receptors, G-Protein-Coupled; Receptors, Ghrelin; Structure-Activity Relationship

PY - 2007

Y1 - 2007

N2 - The carboxyamidated wFwLL peptide was used as a core ligand to probe the structural basis for agonism versus inverse agonism in the constitutively active ghrelin receptor. In the ligand, an efficacy switch could be built at the N terminus, as exemplified by AwFwLL, which functioned as a high potency agonist, whereas KwFwLL was an equally high potency inverse agonist. The wFw-containing peptides, agonists as well as inverse agonists, were affected by receptor mutations covering the whole main ligand-binding pocket with key interaction sites being an aromatic cluster in transmembrane (TM)-VI and -VII and residues on the opposing face of TM-III. Gain-of-function in respect of either increased agonist or inverse agonist potency or swap between high potency versions of these properties was obtained by substitutions at a number of positions covering a broad area of the binding pocket on TM-III, -IV, and -V. However, in particular, space-generating substitutions at position III:04 shifted the efficacy of the ligands from inverse agonism toward agonism, whereas similar substitutions at position III: 08, one helical turn below, shifted the efficacy from agonism toward inverse agonism. It is suggested that the relative position of the ligand in the binding pocket between this "efficacy shift region" on TM-III and the opposing aromatic cluster on TM-VI and TM-VII leads either to agonism, i.e. in a superficial binding mode, or it leads to inverse agonism, i.e. in a more profound binding mode. This relationship between different binding modes and opposite efficacy is in accordance with the Global Toggle Switch model for 7TM receptor activation.

AB - The carboxyamidated wFwLL peptide was used as a core ligand to probe the structural basis for agonism versus inverse agonism in the constitutively active ghrelin receptor. In the ligand, an efficacy switch could be built at the N terminus, as exemplified by AwFwLL, which functioned as a high potency agonist, whereas KwFwLL was an equally high potency inverse agonist. The wFw-containing peptides, agonists as well as inverse agonists, were affected by receptor mutations covering the whole main ligand-binding pocket with key interaction sites being an aromatic cluster in transmembrane (TM)-VI and -VII and residues on the opposing face of TM-III. Gain-of-function in respect of either increased agonist or inverse agonist potency or swap between high potency versions of these properties was obtained by substitutions at a number of positions covering a broad area of the binding pocket on TM-III, -IV, and -V. However, in particular, space-generating substitutions at position III:04 shifted the efficacy of the ligands from inverse agonism toward agonism, whereas similar substitutions at position III: 08, one helical turn below, shifted the efficacy from agonism toward inverse agonism. It is suggested that the relative position of the ligand in the binding pocket between this "efficacy shift region" on TM-III and the opposing aromatic cluster on TM-VI and TM-VII leads either to agonism, i.e. in a superficial binding mode, or it leads to inverse agonism, i.e. in a more profound binding mode. This relationship between different binding modes and opposite efficacy is in accordance with the Global Toggle Switch model for 7TM receptor activation.

U2 - 10.1074/jbc.M609796200

DO - 10.1074/jbc.M609796200

M3 - Journal article

C2 - 17371869

SN - 0021-9258

VL - 282

SP - 15799

EP - 15811

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

IS - 21

ER -

Identification of an efficacy switch region in the ghrelin receptor responsible for interchange between agonism and inverse agonism

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