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Defining a minimal estrogen receptor DNA binding domain
S Mader1, P Chambon, J H White
1Laboratoire de Génétique Moléculaire des Eucaryotes du CNRS, Unité de Génie Génétique et de Biologie Moléculaire de l'INSERM, Faculté de Médecine, Strasbourg, France.
Nucleic Acids Research
|March 11, 1993
Summary
The minimal DNA binding region of the estrogen receptor (ER) requires more than its zinc finger core. Additional C-terminal amino acids are crucial for stabilizing DNA binding and dimerization, especially for imperfect estrogen response elements (EREs).
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- The estrogen receptor (ER) is a transcriptional regulator that binds to DNA sequences called estrogen response elements (EREs).
- A conserved 66-amino acid core with zinc fingers is known to be essential for DNA recognition, but the full extent of the minimal DNA binding region is not fully understood.
Purpose of the Study:
- To characterize the minimal DNA binding region of the human estrogen receptor (ER).
- To investigate the role of flanking amino acids beyond the zinc finger core in DNA binding and dimerization.
Main Methods:
- Analysis of deletion mutants of the human ER DNA binding domain (DBD) expressed in bacteria.
- Characterization of DNA binding properties using gel retardation assays.
- Site-directed mutagenesis to assess the role of specific amino acid regions in dimerization.
Main Results:
- The 66-amino acid zinc finger core alone does not bind DNA.
- Amino acids C-terminal to the zinc finger core, particularly within regions C and D, are essential for stabilizing binding to palindromic EREs and are required for binding to imperfect EREs.
- The ER DBD binds cooperatively as a dimer to EREs, and specific amino acids (222-226) within region C are critical for this dimerization.
Conclusions:
- The minimal DNA binding region of the ER extends beyond the zinc finger core, incorporating C-terminal amino acids.
- These flanking amino acids play a critical role in stabilizing DNA binding and are essential for recognizing imperfect EREs.
- A specific region within the ER DBD is crucial for mediating cooperative dimerization, which is vital for high-affinity DNA binding.