Chromatin remodelling: Covalent modifications.
~Each histone has a positively charted amino acids 'tail' at its N terminus.
~Histone acetyltransferases (HATs) can change the tails charge by adding acetyl groups to lysine residues (HDACs remove them).
~This opens up the nucleosomes, increasing DNA accessibility, facilitates transcription factor binding and recruitment of chromatin remodellers and activates transcription.