Novel computational model for the interaction of dopamine with the D2 receptor.
With the use of molecular modelling and computational chemistry, two models were obtained showing the binding of dopamine to part of the D2 receptor. These models consist of a molecular complex containing dopamine, the transmembrane domains (TM) 3, 4 and 5, a small part of the extracellular loop just before TM3 and a larger part of the loop connecting TM4 and TM5. The models are further characterized by the presence of two disulphide bonds: one between TM3 and TM4 and a second linking the Cys residue before TM3 with the Cys residue in the loop between TM4 and TM5. In the first model, the beta-adrenergic receptor is used as a reference with the catechol moieties of dopamine interacting with two Ser residues in TM5, and the Asp residue in TM3 interacting with the protonated nitrogen of dopamine. In the second model, dopamine is positioned between the TM without interaction assumptions. In both models the TM positions are close to the arrangement of the alpha-helix ordering as found in bacteriorhodopsin. Energy minimization was accomplished using these two starting structures. The two minimized complexes show different molecular interactions that make good chemical sense and are in agreement with reported X-ray data of different proteins. The disulphide bond between TM3 and 4 is apparently unique to the D2 and D3 receptors. The first minimized complex revealed that not Ser194, as in the beta-receptor, but Ser 193 interacted with the meta-hydroxyl of dopamine, although a proper hydrogen bond with Ser194 was initially present in the starting structure. The para-hydroxyl group interacted with Ser197.(ABSTRACT TRUNCATED AT 250 WORDS)
Moereels
H
H
Department of Theoretical Medicinal Chemistry, Janssen Research Foundation, Beerse, Belgium.
Leysen
J E
JE
D000595:Amino Acid Sequence; D001665:Binding Sites; D004220:Disulfides / Q000737:chemistry; D004298:Dopamine / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D006860:Hydrogen Bonding; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D017433:Protein Structure, Secondary; D017448:Receptors, Dopamine D2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013816:Thermodynamics
D004220:Disulfides; D017448:Receptors, Dopamine D2; D004298:Dopamine