Nat. Biotechnol.; 10.1038/nbt.4286; corrected online 18 December 2018

In the supplementary information originally posted, there were errors in the primer sequences in Supplementary Table 1. The following sequences have been corrected online in all sheets: backbone sequences for MM2, MM2B and MM2C; adapter sequences for MM2, MM2B and MM2C; and MM2B_right arm sequence.