Protein-DNA interactions can be either specific or non-specific. Specific interactions involve transcription factors that regulate gene expression by binding to DNA motifs through domains like helix-loop-helix, leucine zipper, or zinc finger motifs. Non-specific interactions involve histones that help structure DNA into nucleosomes within chromatin and can be chemically modified through methylation, demethylation, acetylation, and phosphorylation.

1. DNA-Protein interactions
Specific interactions Non- Specific interactions
Transcription factors
Domains of Transcription
factors
1. Helix loop helix
2. Leucine zipper
3. Zinc fingefr motif
4. Lambda repressor
Chromatin
Nucleosome
Chemical modifications by
Methylation
Demethylation
Acetylation
Phosphorylation

2. Protein–DNA interactions are when a protein
binds a molecule of DNA, often to regulate the
biological function of DNA, usually the
expression of a gene.
Among the proteins that bind to DNA are
transcription factors that activate or repress
gene expression by binding to DNA motifs and
histones that form part of the structure of
DNA and bind to it less specifically.

3. 1. Transcription factors

6. Leucine zipper
LZ formed by the dimerization of two specific alpha helix monomers
bound to DNA.
The bZIP interacts with the DNA via its N-terminal, where the lysines
and arginines are located; these basic residues interact in the major
groove of the DNA, forming sequence-specific interactions

11. Non-specific interactions

12. Histone modification