title: Spectroscopic analyses of the binding kinetics of 15d-PGJ2 to the PPARgamma ligand-binding domain by multi-wavelength global fitting.
abstract: PPARgamma (peroxisome proliferator-activated receptor gamma) is a nuclear receptor that is activated by natural lipid metabolites, including 15d-PGJ2 (15-deoxy-Delta(12,14)-prostaglandin J2). We previously reported that several oxidized lipid metabolites covalently bind to PPARgamma through a Michael-addition to activate transcription. To separate the ligand-entering (dock) and covalent-binding (lock) steps in PPARgamma activation, we investigated the binding kinetics of 15d-PGJ2 to the PPARgamma LBD (ligand-binding domain) by stopped-flow spectroscopy. We analysed the spectral changes of 15d-PGJ2 by multi-wavelength global fitting based on a two-step chemical reaction model, in which an intermediate state represents the 15d-PGJ2-PPARgamma complex without covalent binding. The extracted spectrum of the intermediate state in wild-type PPARgamma was quite similar to the observed spectrum of 15d-PGJ2 in the C285S mutant, which cannot be activated by 15d-PGJ2, indicating that the complex remains in the inactive, intermediate state in the mutant. Thus 'lock' rather than 'dock' is one of the critical steps in PPARgamma activation by 15d-PGJ2.
authors.affiliation: Department of Molecular Biology, Biomolecular Engineering Research Institute (BERI), 6-2-3 Furuedai, Suita-City, Osaka 565-0874, Japan.
authors.forename: Takuma
authors.initials: T
authors.lastname: Shiraki
authors.forename: Takashi S
authors.initials: TS
authors.lastname: Kodama
authors.forename: Sayaka
authors.initials: S
authors.lastname: Shiki
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Nakagawa
authors.forename: Hisato
authors.initials: H
authors.lastname: Jingami
mesh_terms: D000818:Animals; D002460:Cell Line; D007700:Kinetics; D009154:Mutation; D047495:PPAR gamma / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015230:Prostaglandin D2 / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: C477819:15-deoxyprostaglandin J2; D047495:PPAR gamma; D015230:Prostaglandin D2