Correction to: Nature Structural & Molecular Biology https://doi.org/10.1038/nsmb.3476, published online 2 October 2017.

In the version of this article initially published, a grant and the awarding funding body were omitted from the Acknowledgements section. E.H. was supported by the European Research Council grant ADG 741781 GLOWSOME. The error has not been corrected in the original article.