Question

The importance of naked DNA in eukaryotic transcription. Include in your answer a description of the roles of two different classes of proteins that are directly involved in exposing DNA to facilitate transcription. (15 min)

Answer 1

Histone acetyltransferases (HATs) and histone deacetylases (HDACs) are the two class of enzymes which modify chromatin structure for gene expression.

HATs catalyze the transfer of an acetyl group from acetyl coenzyme A on to lysine of the histone protein, which neutralizes the positive charge of lysine and disrupts the interaction between DNA and histone proteins. This opens up DNA for binding to transcription factors causing transcriptional activation.

HDACs, on the other hand, causes lysine of histone and DNA interaction restricting the DNA accessibility for transcription factors, hence depress the gene expression.