What happens after the acetylation of lysines?

Acetylation involves the addition of an acetyl group to the lysine residues on the N-terminal tail of histone proteins.

In its unmodified state, lysine has a positive charge while acetyl groups have a negative charge. Adding an acetyl group changes the overall charge of lysine from positive to negative, weakening the attraction between the histone tail and DNA. This opens up the usually tightly packed chromatin. The more relaxed chromatin conformation makes it easier for transcription machinery to come in contact with the DNA template, increasing gene transcription.