Beta(1)-selective agonist (-)-1-(3,4-dimethoxyphenetylamino)-3-(3,4-dihydroxy)-2-propanol [(-)-RO363] differentially interacts with key amino acids responsible for beta(1)-selective binding in resting and active states

• Published in: The Journal of pharmacology and experimental therapeutics Vol. 301; no. 1; pp. 51 - 58
• Main Authors: Sugimoto, Yoshiyuki, Fujisawa, Reiko, Tanimura, Ryuji, Lattion, Anne Laure, Cotecchia, Susanna, Tsujimoto, Gozoh, Nagao, Taku, Kurose, Hitoshi
• Format: Journal Article
• Language: English
• Published: United States 01.04.2002
• Subjects: Adrenergic beta-1 Receptor Agonists; Adrenergic beta-2 Receptor Agonists; Adrenergic beta-Agonists - pharmacology; Amino Acid Sequence; Amino Acids - drug effects; Catechols - pharmacology; Gene Expression Regulation; Humans; Kinetics; Models, Molecular; Molecular Sequence Data; Mutation - physiology; Plasmids - genetics; Propanolamines - pharmacology; Radioligand Assay; Receptors, Adrenergic, beta-1 - genetics; Receptors, Adrenergic, beta-1 - metabolism; Receptors, Adrenergic, beta-2 - genetics; Receptors, Adrenergic, beta-2 - metabolism; Recombinant Fusion Proteins - biosynthesis; Recombinant Fusion Proteins - genetics
• ISSN: 0022-3565
• DOI: 10.1124/jpet.301.1.51

(-)-1-(3,4-Dimethoxyphenetylamino)-3-(3,4-dihydroxy)-2-propanol [(-)-RO363] is a highly selective beta(1)-adrenergic receptor (beta(1)AR) agonist. To study the binding site of beta(1)-selective agonist, chimeric beta(1)/beta(2)ARs and Ala-substituted beta(1)ARs were constructed. Several key residues of beta(1)AR [Leu(110) and Thr(117) in transmembrane domain (TMD) 2], and Phe(359) in TMD 7] were found to be responsible for beta(1)-selective binding of (-)-RO363, as determined by competitive binding. Based on these results, we built a three-dimensional model of the binding domain for (-)-RO363. The model indicated that TMD 2 and TMD 7 of beta(1)AR form a binding pocket; the methoxyphenyl group of N-substituent of (-)-RO363 seems to locate within the cavity surrounded by Leu(110), Thr(117), and Phe(359). The amino acids Leu(110) and Phe(359) interact with the phenyl ring of (-)-RO363, whereas Thr(117) forms hydrogen bond with the methoxy group of (-)-RO363. To examine the interaction of these residues with beta(1)AR in an active state, each of the amino acids was changed to Ala in a constitutively active (CA)-beta(1)AR mutant. The degree of decrease in the affinity of CA-beta(1)AR for (-)-RO363 was essentially the same as that of wild-type beta(1)AR when mutated at Leu(110) and Thr(117). However, the affinity was decreased in Ala-substituted mutant of Phe(359) compared with that of wild-type beta(1)AR. These results indicated that Leu(110) and Thr(117) are necessary for the initial binding of (-)-RO363 with beta(1)-selectivity, and interaction of Phe(359) with the N-substituent of (-)-RO363 in an active state is stronger than in the resting state.