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Human estrogen receptor bound to an estrogen response element bends DNA
A M Nardulli1, G L Greene, D J Shapiro
1Department of Physiology and Biophysics, University of Illinois, Urbana 61801.
Molecular Endocrinology (Baltimore, Md.)
|March 1, 1993
Summary
Human estrogen receptor (hER) binding to DNA response elements induces significant DNA bending. This DNA bending, influenced by associated proteins, may play a role in gene transcription activation.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- The human estrogen receptor (hER) plays a crucial role in regulating gene expression.
- Understanding the structural changes induced by hER binding to DNA is essential for elucidating its mechanism of action.
Purpose of the Study:
- To investigate the DNA bending induced by the binding of hER to estrogen response elements (EREs).
- To explore the influence of associated proteins and ligand binding on hER-induced DNA bending.
Main Methods:
- Gel mobility shift assays were employed to assess DNA bending.
- Competition and antibody supershift experiments were used to confirm specific hER-ERE interactions.
- DNA bending standards were utilized to quantify the degree of bending.
Main Results:
- Binding of hER to a single ERE induced a reproducible DNA bend of 56 degrees.
- This bending angle was consistent regardless of receptor occupancy by 17 beta-estradiol or trans-hydroxytamoxifen.
- Partially purified yeast-expressed hER induced similar DNA bending, while highly purified hER showed reduced DNA binding, suggesting the involvement of accessory proteins.
- The presence of two EREs led to a slight increase in DNA bending.
Conclusions:
- hER binding to EREs induces significant DNA bending.
- Associated proteins may be crucial for the efficient interaction of hER with EREs.
- DNA bending induced by hER binding is a potential mechanism contributing to ER-mediated transcriptional activation.