Question

1. Would you expect to see more or less acetylation in regions of DNA that are sensitive to digestion by Dnase I? WHY?

2. Suppose a chemist develops a new drug that neutralizes the positive charges on the tails of histone proteins. What would be the most likely effect of this new drug on chromatin structure? would this drug have any effect on gene expression? explain your answers.  

I have no idea how to answer these two questions in a proper way thanks.

Answer 1

Ans 1) We would expect to see more acetylation in the region of DNA that are sensitive to digest by DNase 1 because DNase 1 region's sensitivity is less condensed as compare to DNA that is not sensitive to DNase 1. The DNA which is sensitive ,is loosely associated with nucleosomes. Hence , it is in open state. Open state are the areas which reperesents euchromatin which undergoes transcription of DNA. In this state , acetylation of lysine residues in the region of N - terminal histone tails. Acetylation removes the positive charge present on the lysine residue and decreases the affection of histone towards the negatively charged phosphate of DNA backbone which leads to form more loose structure of chromatin.

Ans 2) As the ionic interaction present between the histone tails as well as DNA phosphate backbone gets disrupted which results in breaking of DNA from nucleosome. The drug may copy the effect of histone acetylation that neutrilise the positve charge present on the lysine residue. The chromatin structure changes due to alter the nucleosome DNA packing including the changes in the interaction with other chromatin by improving enzymes and proteins.

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