These authors contributed equally: Lukas Villiger, Julia Joung.

These authors jointly supervised this work: Omar O. Abudayyeh and Jonathan S. Gootenberg.

McGovern Institute for Brain Research, Massachusetts Institute of Technology Cambridge, Cambridge, MA, USA

Lukas Villiger, Omar O. Abudayyeh & Jonathan S. Gootenberg

Whitehead Institute for Biomedical Research, Cambridge, MA, USA

Julia Joung, Luke Koblan & Jonathan Weissman

Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA

Julia Joung, Luke Koblan & Jonathan Weissman

Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA

Jonathan Weissman

David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA

Jonathan Weissman

Correspondence to Omar O. Abudayyeh or Jonathan S. Gootenberg.