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. Author manuscript; available in PMC: 2018 Mar 4.
Published in final edited form as: Nature. 2017 Sep 4;550(7674):137–141. doi: 10.1038/nature24020

Extended Data Figure 7. A mechanistic model for Cas1-Cas2 catalyzed step-wise spacer integration.

Extended Data Figure 7

a, Cas1-Cas2 loads a 30-bp prespacer. b, Cas2 serves as a fulcrum, non-specific contacts tilt the target DNA stochastically for half-site searching by Cas1. c, Cas1 preferentially binds to the leader-IR containing half-site, catalyzes half-site integration. d, Spacer-side IR is captured through DNA bending, full-integration takes place. e, While still under investigation, it is speculated that the post-integration complex is resolved by DNA replication, CRISPR repeat is duplicated on one-side. f, Opposite-side DNA replication duplicates the repeat on the opposite side; ligation finalizes spacer incorporation. The spacer flips its orientation during the process.