Molecular Biology

A Complicated Start

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Science  15 Apr 2011:
Vol. 332, Issue 6027, pp. 284
DOI: 10.1126/science.332.6027.284-c

In the eukaryotic cell nucleus, DNA is compacted through its association with histone proteins. These are assembled into octomers to form nucelosomes; “linker” DNA connects nucleosomes and is associated with histone H1. DNA-histone interactions must be modified, however, for transcription to occur. Although much is known about transcription-induced changes to core histones, how linker histones are affected is less understood. Vicent et al. examined histone H1 dynamics at hormone receptor target genes and showed that four enzyme complexes act immediately after hormone induction. First, the ASCOM complex induces an activating H3K4me3 signal, which is increased by displacement of the demethylating complex KDM5B. This is followed by the rapid recruitment of the ATP-dependent NURF remodeling complex, CDk2 promoter binding and phosphorylation, and displacement of histone H1. Finally, the core histone proteins are displaced to allow access to hormone receptor target genes. Thus, substantial enzymatic complexity is required for the “eviction” of linker H1 to set up a remodeled chromatin template for regulated gene expression.

Genes Dev. 25, 10.1101/gad.621811 (2011).

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