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Nucleosome binding by the constitutive transcription factor Sp1
1Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park 16802-4500.
The Journal of Biological Chemistry
|March 11, 1994
Summary
The transcription factor Sp1 binds to nucleosomal DNA, specifically the SV40 early promoter GC boxes. This binding affinity is reduced on nucleosomal DNA compared to naked DNA.
Area of Science:
- Molecular Biology
- Epigenetics
- Gene Regulation
Background:
- The transcription factor Sp1 regulates numerous viral and cellular genes.
- Sp1 is involved in creating nucleosome-free regions in Simian virus 40 (SV40) minichromosomes.
Purpose of the Study:
- To investigate the function of Sp1 in chromatin remodeling.
- To analyze Sp1's ability to bind GC boxes within nucleosome cores.
Main Methods:
- Reconstitution of DNA fragments into nucleosome cores.
- Analysis of Sp1 binding to GC boxes in nucleosomal DNA.
- Assessment of Sp1 peptide binding to nucleosomal DNA.
Main Results:
- Sp1 binds to GC boxes of the SV40 early promoter within nucleosome cores.
- Sp1's binding affinity is reduced 10-20 fold on nucleosomal DNA versus naked DNA.
- Sp1's zinc finger domain is sufficient for nucleosome binding; other domains are not required.
Conclusions:
- Sp1 can bind its recognition sites even when reconstituted into nucleosome cores.
- Sp1 binding to nucleosomes forms a ternary Sp1-nucleosome complex.
- The zinc finger domain of Sp1 mediates nucleosome binding.