Zhang’s team is now working to use these sticky ends to improve the frequency with which researchers can replace a natural DNA sequence. Cuts left by Cas9 tend to be repaired by sticking the two ends back together, in a relatively sloppy repair process that can leave errors. Although it is possible that the cell will instead insert a designated, new sequence at that site, that kind of repair occurs at a much lower frequency. Zhang hopes that the unique properties of how Cpf1 cuts may be harnessed to make such insertions more frequent.

For Bing Yang, a plant biologist at the Iowa State University in Ames, this is the most exciting aspect of Cpf1. “Boosting the efficiency would be a big step for plant science,” he says. “Right now, it is a major challenge.”

Will the new enzyme surpass Cas9 in popularity? “It’s too early to tell,” says Zhang. “It certainly has some distinct advantages.” The CRISPR/Cas9 system is so popular — and potentially lucrative — that it has sparked a fierce patent fight between the University of California, Berkeley, and the Broad Institute and its ally, the Massachusetts Institute of Technology in Cambridge. Zhang says that his lab will make the CRISPR/Cpf1 components available to academic researchers, as it has done with its CRISPR/Cas9 tools.

For now, the results stand as a testament that researchers still have more to learn from the genome-editing systems that bacteria have evolved. “This study powerfully demonstrates that the natural evolutionary diversity of CRISPR systems is rich with potential solutions to the challenges facing the use of genome-editing agents,” says David Liu, a chemical biologist at Harvard University in Cambridge. (Zhang and Liu are both scientific advisers to Editas Medicine, a company in Cambridge that aims to develop CRISPR-based therapies.)

Microbiologist John van der Oost of Wageningen University in the Netherlands, who collaborated on the latest study with Zhang, plans to keep searching for new methods. “You never know whether one of these systems will be suitable for genome editing,” he says. “There are still surprises ahead of us.”