scholarly journals Spectroscopic analyses of the binding kinetics of 15d-PGJ2 to the PPARγ ligand-binding domain by multi-wavelength global fitting

2006 ◽  
Vol 393 (3) ◽  
pp. 749-755 ◽  
Author(s):  
Takuma Shiraki ◽  
Takashi S. Kodama ◽  
Sayaka Shiki ◽  
Tatsuo Nakagawa ◽  
Hisato Jingami
Keyword(s):  
Ligand Binding ◽  
Intermediate State ◽  
Covalent Binding ◽  
Binding Domain ◽  
Ligand Binding Domain ◽  
Binding Kinetics ◽  
Multi Wavelength ◽  
Lipid Metabolites ◽  
Kinetics Of ◽  
Global Fitting

PPARγ (peroxisome proliferator-activated receptor γ) is a nuclear receptor that is activated by natural lipid metabolites, including 15d-PGJ2 (15-deoxy-Δ12,14-prostaglandin J2). We previously reported that several oxidized lipid metabolites covalently bind to PPARγ through a Michael-addition to activate transcription. To separate the ligand-entering (dock) and covalent-binding (lock) steps in PPARγ activation, we investigated the binding kinetics of 15d-PGJ2 to the PPARγ 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–PPARγ complex without covalent binding. The extracted spectrum of the intermediate state in wild-type PPARγ 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 PPARγ activation by 15d-PGJ2.

Distinct Modulation of Wild-Type and Selective Gene Mutated Vitamin D Receptor by Essential Poly Unsaturated Fatty Acids

2021 ◽  
Vol 21 ◽  
Author(s):  
Hari Balaji ◽  
Selvaraj Ayyamperuma ◽  
Niladri Saha ◽  
Shyam Sundar Pottabathula ◽  
Jubie Selvaraj ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Vitamin D ◽  
Ligand Binding ◽  
Vitamin D Deficiency ◽  
Binding Affinity ◽  
Unsaturated Fatty Acids ◽  
Binding Domain ◽  
Ligand Binding Domain ◽  
Binding Energies ◽  
Wild Type

: Vitamin-D deficiency is a global concern. Gene mutations in the vitamin D receptor’s (VDR) ligand binding domain (LBD) variously alter the ligand binding affinity, heterodimerization with retinoid X receptor (RXR) and inhibit coactivator interactions. These LBD mutations may result in partial or total hormone unresponsiveness. A plethora of evidence report that selective long chain polyunsaturated fatty acids (PUFAs) including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) bind to the ligand-binding domain of VDR and lead to transcriptional activation. We therefore hypothesize that selective PUFAs would modulate the dynamics and kinetics of VDRs, irrespective bioactive of vitamin-D binding. The spatial arrangements of the selected PUFAs in VDR active site were examined by in-silico docking studies. The docking results revealed that PUFAs have fatty acid structure-specific binding affinity towards VDR. The calculated EPA, DHA & AA binding energies (Cdocker energy) were lesser compared to vitamin-D in wild type of VDR (PDB id: 2ZLC). Of note, the DHA has higher binding interactions to the mutated VDR (PDB id: 3VT7) when compared to the standard Vitamin-D. Molecular dynamic simulation was utilized to confirm the stability of potential compound binding of DHA with mutated VDR complex. These findings suggest the unique roles of PUFAs in VDR activation and may offer alternate strategy to circumvent vitamin-D deficiency.

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