Correction to: Nature https://doi.org/10.1038/s41586-018-0396-4, published online 01 August 2018.

In the ‘Data availability’ section of this Letter, the Protein Data Bank (PDB) accessions were incorrectly listed as ‘6BH5, 6BHT and 6BHS’ instead of ‘6BHR, 6BHT and 6BHS’; this has been corrected online.