Correction to: Nature Structural & Molecular Biology https://doi.org/10.1038/s41594-019-0315-x, 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, https://doi.org/10.1038/s41594-019-0298-7; Zaware and Zhou, https://doi.org/10.1038/s41594-019-0309-8; Arrowsmith and Schapira, https://doi.org/10.1038/s41594-019-0290-2; Tzelepis, Rausch and Kouzarides, https://doi.org/10.1038/s41594-019-0312-0; and Noberini and Bonaldi, https://doi.org/10.1038/s41594-019-0279-x. The errors have been corrected in the HTML and PDF versions of the article.