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DNA minor groove accessibility in the nucleosome core deduced from specific interactions with DAPI
R Caneva1, L Rossetti, M Savino
1Centro di Studio per gli Acidi Nucleici del CNR, Dipartimento di Genetica e Biologia Molecolare, Rome,Italy.
Biochimica Et Biophysica Acta
|May 2, 1996
Summary
The DNA-binding dye DAPI maintains its affinity for nucleosome cores, indicating specific minor groove interactions are possible within chromatin. This suggests chromatin structure does not impede DAPI
Area of Science:
- Molecular Biology
- Biophysics
- Chromatin Structure
Background:
- Nucleosomes are the fundamental units of DNA packaging in eukaryotes.
- The minor groove of DNA is a key site for sequence-specific binding by small molecules and proteins.
- Understanding DNA-ligand interactions within chromatin is crucial for deciphering gene regulation.
Purpose of the Study:
- To investigate the binding characteristics of 4',6-diamidino-2-phenylindole (DAPI) to purified nucleosome cores.
- To determine if the presence of histone proteins affects DAPI's affinity and binding site stoichiometry for DNA.
Main Methods:
- Utilizing fluorescence intensity enhancement assays to quantify DAPI binding.
- Comparing binding parameters of DAPI to isolated DNA versus DNA within nucleosome cores.
Main Results:
- DAPI exhibits preserved affinity and binding site number for the minor groove when associated with nucleosome cores compared to isolated DNA.
- The primary binding mode of DAPI involves interaction with the DNA minor groove.
Conclusions:
- The specific minor groove binding capacity of DAPI is retained in the context of nucleosome cores.
- Chromatin structure, in the form of nucleosomes, does not abolish the potential for specific DNA minor groove interactions by ligands like DAPI.