Interactions of the Melanocortin-4 Receptor with the Peptide Agonist NDP-MSH

JOURNAL OF MOLECULAR BIOLOGY

卷:401

Article

Chapman, Kathryn L.¹  Kinsella, Gemma K.²  Cox, Alan¹  Donnelly, Dan¹  Findlay, John B. C.^1,2 

[1] Univ Leeds, Sch Biochem & Mol Biol, Leeds LS2 9JT, W Yorkshire, England

[2] Natl Univ Ireland Maynooth, Dept Biol, Maynooth, Kildare, Ireland

关键词: comparative model;    cysteine cross-linking;    G-protein-coupled receptor (GPCR);    melanocortin-4 receptor (MC4R);    [Nle(4),D-Phe(7)]melanocyte-stimulating hormone (NDP-MSH);   

DOI  :  10.1016/j.jmb.2010.06.028

来源: Elsevier

【 摘 要 】

Melanocortin-4 receptor (MC4R) has an important regulatory role in energy homeostasis and food intake. Peptide agonists of the MC4R are characterized by the conserved sequence His(6)-Phe(7)-Arg(8)-Trp(9), which is crucial for their interaction with the receptor. This investigation utilized the covalent attachment approach to identify receptor residues in close proximity to the bound ligand [Nle(4),D-Phe(7)]melanocyte-stimulating hormone (NDP-MSH), thereby differentiating between residues directly involved in ligand binding and those mutations that compromise ligand binding by inducing conformational changes in the receptor. Also, recent X-ray structures of G-protein-coupled receptors were utilized to refine a model of human MC4R in the active state (R*), which was used to generate a better understanding of the binding mode of the ligand NDP-MSH at the atomic level. The mutation of residues in the human MC4R-such as Leu106 of extracellular loop 1, and Asp122, Ile125, and Asp126 of transmembrane (TM) helix 3, His264 (TM6), and Met292 (TM7)-to Cys residues produced definitive indications of proximity to the side chains of residues in the core region of the peptide ligand. Of particular interest was the contact between D-Phe(7) on the ligand and Ile125 of TIVI3 on the MC4R. Additionally, Met292 (TM7) equivalent to Lys(7.45) (Ballesteros numbering scheme) involved in covalently attaching retinal in rhodopsin is shown to be in close proximity to Trp(9). For the first time, the interactions between the terminal regions of NDP-MSH and the receptor are described. The amino-terminus appears to be adjacent to a series of hydrophilic residues with novel interactions at Cys196 (TM5) and Asp189 (extracellular loop 2). These interactions are reminiscent of sequential ligand binding exhibited by the beta(2)-adrenergic receptor, with the former interaction being equivalent to the known interaction involving Ser204 of the beta(2)-adrenergic receptor. (C) 2010 Published by Elsevier Ltd.

【 授权许可】

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