Editors' ChoiceStructural Biology

A tripartite gene silencing complex

Sci. Signal.  20 Oct 2015:
Vol. 8, Issue 399, pp. ec304
DOI: 10.1126/scisignal.aad6484

The formation of specialized cell types during development involves the silencing of genes not required in those cell types. An important player in this silencing process is the polycomb repressive complex 2 (PRC2), which methylates histone H3 on lysine residue 27 (H3K27me). Jiao and Liu determined the x-ray crystal structure of a functional PRC2 complex from a thermophilic yeast species (see the Perspective by Schapira). The intimate association of the three subunits confers stability to PRC2. The structure also reveals how the reaction product, H3K27me, stimulates PRC2 allosterically and how a cancer-associated histone mutation blocks the PRC2 active site.

L. Jiao, X. Liu, Structural basis of histone H3K27 trimethylation by an active polycomb repressive complex 2. Science 350, aac4383 (2015). [Abstract] [Full Text]

M. Schapira, Chromatin complex, crystal clear. Science 350, 278–279 (2015). [Summary] [Full Text]

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