In this Article, owing to issues with the first 30 nucleotides of the sgRNA, which run in the opposite direction, corrections have been made to the Protein Data Bank (PDB) accessions in the 'Data availability' section, and this also affects Figs. 3, 4, Extended Data Fig. 6, Supplementary Table 1 and Supplementary Video 1. The original Article has been corrected online. See the accompanying Amendment for further details.