Question

Activation of specific genes often depends on a site-specific transcription factor binding to its site in chromatin. Suggest at least 2 different ways that a transcription factor might be able to access its binding site PRIOR to recruiting chromatin remodeling activity (hint: think about when or where DNA is exposed).

Answer 1

Histone modification plays a major role in chromatin remodelling. Acetylation and methylation on the histones alter the rate of DNA transcription.

1. Histone methylation
Methylation of the DNA strand in cytosine of eukaryotic DNA being converted to 5-methylcytosine, resulting in the repression of transcription. Demethylated in DNA strand increase the chromatin remodelling and opens the promoter site to bind for RNA polymerase.

2. Histone acetyltransferase
Histone acetyltransferases, allowing histones to remain acetylated and promoting transcription. Deacetylation removes the acetyl group and increase the chromatin condensation and inhibit the transcription process.