Dynamic nucleosomes and gene transcription.

Gene transcription occurs on a nucleosomal template known as chromatin. The recruitment of the transcriptional regulators and the transcription machinery to promoter chromatin is coordinated by a genetic code on the DNA and an epigenetic code on the histone proteins. Chromatin is not a stable environment; rather, the histones, the transcription regulatory proteins and the enzymes that modify and mobilise nucleosomes are in a dynamic state. Thus, at any one time, the factors associated with a region will cooperate or compete to change the rate of inter-conversion between permissive and non-permissive chromatin states, leading to activation or repression of transcription. Here, new concepts such as dynamic nucleosomes and a dynamic histone code in gene transcription are explored.