Regulated CRISPR Modules Exploit a Dual Defense Strategy of Restriction and Abortive Infection in a Model of Prokaryote-Phage Coevolution
(A) A sharp threshold-like behavior is observed with steady state prokaryotic densities in the (δ,β)space. Without a sufficient amount of CRISPR suppression in free cells, determined by δ, cells go extinct. (B) Time course trajectories of the species and spacer variables for several parameter settings. In the absence of strong regulation of auto-immunity, high host protospacer levels are extremely toxic and cause population extinction.