Drug discovery targeting human 5-HT 2C receptors: Residues S3.36 and Y7.43 impact ligand-Binding pocket structure via hydrogen bond formation

Clinton E. Canal, Tania C. Cordova-Sintjago, Nancy Villa, Li Juan Fang, Raymond G. Booth

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Specific activation of serotonin (5-HT) 5-HT 2C G protein-coupled receptors may be therapeutic for obesity and neuropsychiatric disorders. Mutagenesis coupled with computational and molecular modeling experiments based on the human β 2 adrenergic receptor structure was employed to delineate the interactions of different ligands at human 5-HT 2C residues D3.32, S3.36 and Y7.43. No binding of the tertiary amine radioligand ([ 3H]-mesulergine) could be detected when the 5-HT 2C D3.32 residue was mutated to alanine (D3.32A). The S3.36A point-mutation greatly reduced affinity of primary amine ligands, modestly reduced affinity of a secondary amine, and except for the 5-HT 2C-specific agonist N(CH 3) 2-PAT, affinity of tertiary amines was unaffected. Molecular modeling results indicated that the primary amines form hydrogen bonds with the S3.36 residue, whereas, with the exception of N(CH 3) 2-PAT, tertiary amines do not interact considerably with this residue. The Y7.43A point-mutation greatly reduced affinity of 5-HT, yet reduced to a lesser extent the affinity of tryptamine that lacks the 5-hydroxy moiety present in 5-HT; modeling results indicated that the 5-HT 5-hydroxy moiety hydrogen bonds with Y7.43 at the 5-HT 2C receptor. Additional modeling results showed that 5-HT induced a hydrogen bond between Y7.43 and D3.32. Finally, modeling results revealed two low-energy binding modes for 5-HT in the 5-HT 2C binding pocket, supporting the concept that multiple agonist binding modes may stabilize different receptor active conformations to influence signaling. Ligand potencies for modulating WT and point-mutated 5-HT 2C receptor-mediated phospholipase C activity were in accordance with the affinity data. Ligand efficacies, however, were altered considerably by the S3.36A mutation only.

Original languageEnglish (US)
Pages (from-to)1-12
Number of pages12
JournalEuropean Journal of Pharmacology
Volume673
Issue number1-3
DOIs
StatePublished - Dec 30 2011
Externally publishedYes

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Receptor, Serotonin, 5-HT2C
Drug Discovery
Drug Delivery Systems
Hydrogen
Serotonin
Ligands
Amines
Point Mutation
Type C Phospholipases
G-Protein-Coupled Receptors
Mutagenesis
Alanine
Adrenergic Receptors

Keywords

  • G protein-coupled receptor
  • Molecular modeling
  • Mutagenesis
  • Serotonin 2C receptor

ASJC Scopus subject areas

  • Pharmacology

Cite this

Drug discovery targeting human 5-HT 2C receptors : Residues S3.36 and Y7.43 impact ligand-Binding pocket structure via hydrogen bond formation. / Canal, Clinton E.; Cordova-Sintjago, Tania C.; Villa, Nancy; Fang, Li Juan; Booth, Raymond G.

In: European Journal of Pharmacology, Vol. 673, No. 1-3, 30.12.2011, p. 1-12.

Research output: Contribution to journalArticle

Canal, Clinton E. ; Cordova-Sintjago, Tania C. ; Villa, Nancy ; Fang, Li Juan ; Booth, Raymond G. / Drug discovery targeting human 5-HT 2C receptors : Residues S3.36 and Y7.43 impact ligand-Binding pocket structure via hydrogen bond formation. In: European Journal of Pharmacology. 2011 ; Vol. 673, No. 1-3. pp. 1-12.
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AU - Booth, Raymond G.

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AB - Specific activation of serotonin (5-HT) 5-HT 2C G protein-coupled receptors may be therapeutic for obesity and neuropsychiatric disorders. Mutagenesis coupled with computational and molecular modeling experiments based on the human β 2 adrenergic receptor structure was employed to delineate the interactions of different ligands at human 5-HT 2C residues D3.32, S3.36 and Y7.43. No binding of the tertiary amine radioligand ([ 3H]-mesulergine) could be detected when the 5-HT 2C D3.32 residue was mutated to alanine (D3.32A). The S3.36A point-mutation greatly reduced affinity of primary amine ligands, modestly reduced affinity of a secondary amine, and except for the 5-HT 2C-specific agonist N(CH 3) 2-PAT, affinity of tertiary amines was unaffected. Molecular modeling results indicated that the primary amines form hydrogen bonds with the S3.36 residue, whereas, with the exception of N(CH 3) 2-PAT, tertiary amines do not interact considerably with this residue. The Y7.43A point-mutation greatly reduced affinity of 5-HT, yet reduced to a lesser extent the affinity of tryptamine that lacks the 5-hydroxy moiety present in 5-HT; modeling results indicated that the 5-HT 5-hydroxy moiety hydrogen bonds with Y7.43 at the 5-HT 2C receptor. Additional modeling results showed that 5-HT induced a hydrogen bond between Y7.43 and D3.32. Finally, modeling results revealed two low-energy binding modes for 5-HT in the 5-HT 2C binding pocket, supporting the concept that multiple agonist binding modes may stabilize different receptor active conformations to influence signaling. Ligand potencies for modulating WT and point-mutated 5-HT 2C receptor-mediated phospholipase C activity were in accordance with the affinity data. Ligand efficacies, however, were altered considerably by the S3.36A mutation only.

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