In an article just published in Genome Biology, Charles Hebert and Hugues Roest Crollius of the Ecole Normale Supérieure in Paris have shown the existence of a novel periodicity of nucleotide frequencies in the human genome that may have implications for the positioning of nucleosomes and gene regulation.
In their study, Hebert and Roest Crollius have aligned human genes relative to their transcription start sites and observe a pattern of YY dinucleotides (where Y is either C or T) spaced 10 base pairs apart in phase with the transcription start site. Importantly, analysis of nucleosome-positioning data shows that the nucleosomes are associated with the dinucleotides. The pattern is enriched in genes with binding sites for the EP300 nucleosome-modelling protein. The authors speculate that the repeating pattern may help to position the nucleosomes in such a way that they are easily modified by EP300, thus facilitating their displacement by RNA polymerase, although this model is currently speculative and will require confirmation in future work.
Nevertheless, this work presents an exciting new pattern in the human genome, and has implications for how positioned nucleosomes affect the transcription of genes.
Nucleosome rotational setting is associated with transcriptional regulation in promoters of tissue-specific human genes
Charles Hebert and Hugues Roest Crollius, Genome Biology 2010, 11:R51