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Updated: Aug 13, 2026
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A G-quadruplex DNA-affinity Approach for Purification of Enzymatically Active G4 Resolvase1
Published on: March 18, 2017
GCN4 binds with high affinity to DNA sequences containing a single consensus half-site
1Department of Chemistry, Indiana University, Bloomington 47405, USA.
Biochemistry
|June 1, 2000
Summary
The bZip protein GCN4 can bind DNA as a dimer, even to sites with only one half-site. One monomer binds specifically, while the other makes important nonspecific contacts, with both basic regions becoming helical upon DNA binding.
Area of Science:
- Molecular Biology
- Protein-DNA Interactions
- Transcription Factor Regulation
Background:
- bZip proteins are transcription factors with a bipartite DNA-binding motif.
- They typically form dimeric complexes, with each monomer recognizing half of a DNA site.
Purpose of the Study:
- Investigate the DNA binding mechanism of the bZip protein GCN4 to single half-sites.
- Explore the structural basis of GCN4 binding to DNA, considering potential monomeric binding roles.
Main Methods:
- Quantitative DNA binding assays
- Affinity cleaving studies
- Circular dichroism (CD) spectroscopy
Main Results:
- GCN4 binds with high affinity to DNA sites with a single consensus half-site.
- Binding occurs as a dimer, with one monomer specific and the other nonspecific DNA contact.
- CD studies show basic regions of both monomers are helical upon DNA binding.
Conclusions:
- GCN4 can bind DNA as a dimer to sites with single half-sites.
- Nonspecific contacts by one monomer are crucial for binding affinity.
- A protein folding transition, forming helical basic regions, is likely required for both specific and nonspecific DNA binding.
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