Song J, Gooding AR, Hemphill WO, Love BD, Robertson A, Yao L, Zon LI, North TE, Kasinath V, Cech TR. 2023. Structural basis for inactivation of PRC2 by G-quadruplex RNA. Science (New York, N.Y.). 381(6664):1331-1337. Pubmed: 37733873 DOI:10.1126/science.adh0059


Polycomb repressive complex 2 (PRC2) silences genes through trimethylation of histone H3K27. PRC2 associates with numerous precursor messenger RNAs (pre-mRNAs) and long noncoding RNAs (lncRNAs) with a binding preference for G-quadruplex RNA. In this work, we present a 3.3-Å-resolution cryo-electron microscopy structure of PRC2 bound to a G-quadruplex RNA. Notably, RNA mediates the dimerization of PRC2 by binding both protomers and inducing a protein interface composed of two copies of the catalytic subunit EZH2, thereby blocking nucleosome DNA interaction and histone H3 tail accessibility. Furthermore, an RNA-binding loop of EZH2 facilitates the handoff between RNA and DNA, another activity implicated in PRC2 regulation by RNA. We identified a gain-of-function mutation in this loop that activates PRC2 in zebrafish. Our results reveal mechanisms for RNA-mediated regulation of a chromatin-modifying enzyme.

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Photo of Len Zon

The Zon laboratory aims to dissect how assaults to the hematopoietic system cause severe diseases such as leukemias, lymphomas, and anemias. They investigate hematopoietic development and disease using chemical screens, genetic screens, and analysis of novel transgenic lines in zebrafish.

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