Question

TSS/promoters of active genes tend to be nucleosome-free. Why do you think this is?

Answer 1

TSS or promoters of active genes are mostly remain in active state and accessible to transcription factors and polymerase to bind with it. In nucleosome, DNA often remain bound to histone proteins and therefore are not accessible to other proteins. To become accessible to other proteins, histone acetylation and other elaborate mechanisms are necessary which will take time.. . So to remain easily available to the regulatory proteins and polymerase, promoters remain nucleosome free.