Understanding ligand binding effects on the conformation of estrogen receptor alpha-DNA complexes: a combinational quartz crystal microbalance with dissipation and surface plasmon resonance study.
Estrogen receptors are ligand-activated transcription factors that regulate gene expression by binding to specific DNA sequences. To date, the effect of ligands on the conformation of estrogen receptor alpha (ERalpha)-DNA complex remains a poorly understood issue. In our study, we are introducing the quartz crystal microbalance with dissipation monitoring (QCM-D) as a new alternative to study the conformational differences in protein-DNA complexes. Specifically, we have used QCM-D, in combination with surface plasmon resonance (SPR) spectroscopy, to monitor the binding of ERalpha to a specific DNA (estrogen response element, ERE) and a nonspecific DNA in the presence of either the agonist ligand, 17b-estradiol, the partial antagonist ligand, 4-hydroxytamoxifen, or vehicle alone. Both with presence and absence of ligand, the specific ERalpha-ERE complexes are observed to adopt a more compact conformation compared to nonspecific complexes. This observation is well correlated to the biophysical changes occurring during protein-DNA interaction shown by past structural and mechanism studies. Notably, pretreatment of ERalpha with E2 and 4OHT affects not only the viscoelasticity and conformation of the protein-DNA complex but also ERalpha binding capacity to immobilized ERE. These results affirm that ligands have remarkable effects on ERalpha-DNA complexes. Understanding these effects will provide insight into how ligand binding promotes subsequent events required for gene transcription.
Peh
Wendy Y X
WY
Institute of Materials Research and Engineering, Singapore 117602.
Reimhult
Erik
E
Teh
Huey Fang
HF
Thomsen
Jane S
JS
Su
Xiaodi
X
D001665:Binding Sites; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry* / Q000648:ultrastructure*; D047628:Estrogen Receptor alpha / Q000737:chemistry* / Q000648:ultrastructure*; D008846:Micromanipulation / Q000379:methods; D008956:Models, Chemical; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D020349:Surface Plasmon Resonance / Q000379:methods*
D047628:Estrogen Receptor alpha; D004247:DNA