title: Identification of critical structural determinants responsible for octopamine binding to the alpha-adrenergic-like Bombyx mori octopamine receptor.
abstract: Octopamine (OA) is a biogenic amine with a widespread distribution in the insect nervous system. OA modulates and/or regulates various behavioral patterns of insects as a neurotransmitter, neuromodulator, and neurohormone. OA receptors (OARs) belong to one of the families of G protein-coupled receptors (GPCRs). The binding of OA to OARs is coupled to the activation of the specific G proteins, which induces the release of intracellular second messengers such as cAMP and/or calcium. We previously reported the isolation of an OAR (BmOAR1) from Bombyx mori. In the study presented here, five mutated BmOAR1s were constructed with a point mutation in the putative binding crevice and expressed in HEK-293 cells. The S202A mutant receptor was found to retain the cAMP response to OA as does the wild-type receptor, but such function was impaired in the other four mutants (D103A, S198A, Y412F, and S198A/S202A). Furthermore, competition binding assays using [3H]OA and calcium mobilization assays gave results that were approximately consistent with those of the cAMP assays. Taken together, the results indicate that D103 and S198 are involved in the binding and activation of BmOAR1 with OA through electrostatic or hydrogen bond interactions, but S202 does not appear to participate in this process. Y412 seems to be involved in one of the active forms of BmOAR1. These findings should prove helpful in designing new pest control chemicals.
authors.affiliation: Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan.
authors.forename: Jia
authors.initials: J
authors.lastname: Huang
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Hamasaki
authors.forename: Fumiyo
authors.initials: F
authors.lastname: Ozoe
authors.forename: Hiroto
authors.initials: H
authors.lastname: Ohta
authors.forename: Koh-ichi
authors.initials: K
authors.lastname: Enomoto
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kataoka
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sawa
authors.forename: Akihiko
authors.initials: A
authors.lastname: Hirota
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Ozoe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001224:Aspartic Acid / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D012831:Bombyx / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D006801:Humans; D006860:Hydrogen Bonding; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009655:Octopamine / Q000737:chemistry* / Q000378:metabolism*; D011942:Receptors, Adrenergic, alpha / Q000737:chemistry / Q000378:metabolism*; D017982:Receptors, Biogenic Amine / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000235:genetics / Q000378:metabolism; D055672:Static Electricity; D013329:Structure-Activity Relationship
chemical_list: D011942:Receptors, Adrenergic, alpha; D017982:Receptors, Biogenic Amine; C027604:norsynephrine receptor; D009655:Octopamine; D001224:Aspartic Acid; D012694:Serine