Custom CRISPR-Cas9 PAM variants via scalable engineering and machine learning.

Engineering and characterizing proteins can be time-consuming and cumbersome, motivating the development of generalist CRISPR-Cas enzymes to enable diverse genome-editing applications. However, such enzymes have caveats such as an increased risk of off-target editing. Here, to enable scalable reprogramming of Cas9 enzymes, we combined high-throughput protein engineering with machine learning to derive bespoke editors that are more uniquely suited to specific targets.