Correction to: Nature Structural & Molecular Biology, published online 3 October 2019.

In the version of this article initially published, several of the links were incorrect. The correct links are as follows: Husmann and Gozani,; Zaware and Zhou,; Arrowsmith and Schapira,; Tzelepis, Rausch and Kouzarides,; and Noberini and Bonaldi, The errors have been corrected in the HTML and PDF versions of the article.