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Sequence-specific DNA binding by glucocorticoid receptor "zinc finger peptides"
T K Archer1, G L Hager, J G Omichinski
1Laboratory of Experimental Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
Summary
Synthetic zinc finger peptides from the glucocorticoid receptor bind zinc ions, altering their structure. These peptides demonstrate sequence-specific DNA binding, crucial for regulating gene transcription.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Steroid hormone receptors regulate gene transcription by binding to DNA.
- The mechanism of DNA binding involves specific protein domains, including zinc fingers.
Purpose of the Study:
- To investigate the DNA-binding mechanism of synthetic zinc finger peptides from the rat glucocorticoid receptor.
- To determine the role of zinc ions in the DNA-binding activity of these peptides.
Main Methods:
- Individual synthesis of putative zinc finger peptides from the rat glucocorticoid receptor.
- Atomic absorption spectroscopy to quantify zinc binding.
- Circular dichroism spectroscopy to assess structural changes.
- DNA-binding assays using glucocorticoid response element (GRE)-containing DNA and control DNA.
Main Results:
- Synthetic zinc finger peptides bind zinc ions on an equimolar basis.
- Zinc binding induces significant alterations in the secondary structure of the peptides.
- Metal ion presence is essential for DNA binding.
- The amino-terminal zinc finger peptide exhibits higher affinity for GRE-containing DNA compared to control DNA.
Conclusions:
- A single synthetic zinc finger peptide can bind DNA in a sequence-specific manner.
- Zinc ions are critical for the DNA-binding function of these peptides.
- These findings elucidate the molecular mechanism of DNA recognition by steroid hormone receptor zinc fingers.